SpringMVC

04312

SpringMVC

1. 初识SrpingMVC

ssm：spring+springmvc+mybatis MVC三层架构

Spring：IOC 和 AOP

SpringMVC：SpringMVC的执行流程！

MVC：模型(dao,service)，视图(jsp)，控制器(Servlet)

  • pojo：实体类，如User

  • vo：视图层的对象实体类，如UserVo

  • dto：数据传输的时候的对象实体类，如UserDto

SpringMVC特点：

  1. 轻量级，简单易学
  2. 高效，基于请求响应的MVC框架
  3. 与Spring兼容性好，无缝结合
  4. 约定优于配置
  5. 功能强大：RESTful，数据验证，格式化，本地化，主题等
  6. 简洁灵活

Spring的web框架围绕DispatcherServlet设计。DispatcherServlet的作用是将请求分发到不同的处理器。从Spring2.5开始，使用java5或以上版本的用户可以采用注解的controller声明方式

快速入门：

  1. 在web.xml配置

    <!--注册DispatcherServlet-->
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <!--关联一个springmvc配置文件：springmvc-servlet.xml-->
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc-servlet.xml</param-value>
        </init-param>
        <!--启动级别1-->
        <load-on-startup>1</load-on-startup>
    </servlet>
    <!--/ 匹配所有的请求：(不包括.jsp)-->
    <!--/* 匹配所有的请求：(包括.jsp)-->
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    <!--注册DispatcherServlet-->
<servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <!--关联一个springmvc配置文件：springmvc-servlet.xml-->
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:springmvc-servlet.xml</param-value>
    </init-param>
    <!--启动级别1-->
    <load-on-startup>1</load-on-startup>
</servlet>
<!--/ 匹配所有的请求：(不包括.jsp)-->
<!--/* 匹配所有的请求：(包括.jsp)-->
<servlet-mapping>
    <servlet-name>springmvc</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>
    <!--注册DispatcherServlet-->
<servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <!--关联一个springmvc配置文件：springmvc-servlet.xml-->
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:springmvc-servlet.xml</param-value>
    </init-param>
    <!--启动级别1-->
    <load-on-startup>1</load-on-startup>
</servlet>
<!--/ 匹配所有的请求：(不包括.jsp)-->
<!--/* 匹配所有的请求：(包括.jsp)-->
<servlet-mapping>
    <servlet-name>springmvc</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>

  2. 新建一个配置文件spring-mvc.xml

    <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xmlns:context="http://www.springframework.org/schema/context"
           xmlns:aop="http://www.springframework.org/schema/aop"
           xsi:schemaLocation="http://www.springframework.org/schema/beans
            https://www.springframework.org/schema/beans/spring-beans.xsd
            http://www.springframework.org/schema/aop
            https://www.springframework.org/schema/aop/spring-aop.xsd">
        <!--处理器映射器-->
        <bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>
        
        <!--处理器适配器-->
        <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>
        
      <!--视图解析器：DispatcherServlet给他的ModelAndView-->
        <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="InternalResourceViewResolver">
            <!--前缀-->
            <property name="prefix" value="/WEB-INF/jsp/"/>
            <!--后缀-->
            <property name="suffix" value=".jsp"/>
        </bean>
    </beans>
    <?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/aop
        https://www.springframework.org/schema/aop/spring-aop.xsd">

    <!--处理器映射器-->
    <bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>
    
    <!--处理器适配器-->
    <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>
    
  <!--视图解析器：DispatcherServlet给他的ModelAndView-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="InternalResourceViewResolver">
        <!--前缀-->
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <!--后缀-->
        <property name="suffix" value=".jsp"/>
    </bean>
</beans>
    <?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/aop
        https://www.springframework.org/schema/aop/spring-aop.xsd">

    <!--处理器映射器-->
    <bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>
    
    <!--处理器适配器-->
    <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>
    
	<!--视图解析器：DispatcherServlet给他的ModelAndView-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="InternalResourceViewResolver">
        <!--前缀-->
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <!--后缀-->
        <property name="suffix" value=".jsp"/>
    </bean>
</beans>

  3. 写一个Controller类

    public class HelloController implements Controller {
        public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
            //ModelAndView 模型和视图
            ModelAndView mv = new ModelAndView();
            
            // 封装对象，放在ModelAndView中
            mv.addObject("msg","HelloSpringMVC!");
            
            // 封装要跳转的视图，放在ModelAndView中
            mv.setViewName("hello");
            return mv;
        }
    }
    public class HelloController implements Controller {
    public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
        //ModelAndView 模型和视图
        ModelAndView mv = new ModelAndView();
        
        // 封装对象，放在ModelAndView中
        mv.addObject("msg","HelloSpringMVC!");
        
        // 封装要跳转的视图，放在ModelAndView中
        mv.setViewName("hello");
        return mv;
    }
}
    public class HelloController implements Controller {
    public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
        //ModelAndView 模型和视图
        ModelAndView mv = new ModelAndView();
        
        // 封装对象，放在ModelAndView中
        mv.addObject("msg","HelloSpringMVC!");
        
        // 封装要跳转的视图，放在ModelAndView中
        mv.setViewName("hello");
        return mv;
    }
}

  4. 编辑配置文件spring-mvc.xml，将Controller类放入IOC中

    <bean id="/hello" class="cn.codewei.controller.HelloController"/>
    <bean id="/hello" class="cn.codewei.controller.HelloController"/>
    <bean id="/hello" class="cn.codewei.controller.HelloController"/>

  5. 编写jsp页面

    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
    <head>
        <title>Title</title>
    </head>
    <body>
        ${pageContext.request.getAttribute("msg")}
    </body>
    </html>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    ${pageContext.request.getAttribute("msg")}
</body>
</html>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    ${pageContext.request.getAttribute("msg")}
</body>
</html>

可能遇到的问题：访问出现404，排查步骤：

  1. 查看控制台输出，看一下是不是缺少了什么jar包

  2. 如果jar包存在，显示无法输出，就在IDEA项目结构中，添加lib依赖

  3. 重启tomcat，即可解决

2. SpringMVC执行原理

实际开发中，我们不会这么去做，我们一般通过注解来实现！！

3. 使用注解实现SpringMVC

  1. 在web.xml配置

    <?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
             version="4.0">
        <servlet>
            <servlet-name>springmvc</servlet-name>
            <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
            <init-param>
                <param-name>contextConfigLocation</param-name>
                <param-value>classpath:springmvc.xml</param-value>
            </init-param>
            <load-on-startup>1</load-on-startup>
        </servlet>
        <servlet-mapping>
            <servlet-name>springmvc</servlet-name>
            <url-pattern>/</url-pattern>
        </servlet-mapping>
    </web-app>
    <?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">

    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>
    <?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">

    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

  2. 在springmvc.xml中配置

    <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xmlns:context="http://www.springframework.org/schema/context"
           xmlns:mvc="http://www.springframework.org/schema/mvc"
           xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd
       http://www.springframework.org/schema/mvc
       https://www.springframework.org/schema/mvc/spring-mvc.xsd">
        <!--自动扫描包，让指定包下的注解生效，由IOC统一管理-->
        <context:component-scan base-package="cn.codewei.controller"/>
        <!--让springmvc不再处理静态资源-->
        <mvc:default-servlet-handler/>
        <!--
            支持mvc注解驱动
            在spring中一般采用@RequestMapping注解来完成映射
            要想使@RequestMapping生效
            必须向上下文注册DefaultAnnotationHandlerMapping
            和一个AnnotationMethodHandlerAdapter实例
            这两个实例分别在类级别和方法级别处理
            而annotation-driver配置帮助我们自动完成上述两个实例的注入
        -->
        <mvc:annotation-driven/>
        <!--视图解析器-->
        <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
            <!--前缀-->
            <property name="prefix" value="/WEB-INF/jsp/"/>
            <!--后缀-->
            <property name="suffix" value=".jsp"/>
        </bean>
    </beans>
    <?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
   http://www.springframework.org/schema/beans/spring-beans.xsd
   http://www.springframework.org/schema/context
   http://www.springframework.org/schema/context/spring-context.xsd
   http://www.springframework.org/schema/mvc
   https://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <!--自动扫描包，让指定包下的注解生效，由IOC统一管理-->
    <context:component-scan base-package="cn.codewei.controller"/>
    <!--让springmvc不再处理静态资源-->
    <mvc:default-servlet-handler/>

    <!--
        支持mvc注解驱动
        在spring中一般采用@RequestMapping注解来完成映射
        要想使@RequestMapping生效
        必须向上下文注册DefaultAnnotationHandlerMapping
        和一个AnnotationMethodHandlerAdapter实例
        这两个实例分别在类级别和方法级别处理
        而annotation-driver配置帮助我们自动完成上述两个实例的注入
    -->
    <mvc:annotation-driven/>

    <!--视图解析器-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <!--前缀-->
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <!--后缀-->
        <property name="suffix" value=".jsp"/>
    </bean>

</beans>
    <?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
   http://www.springframework.org/schema/beans/spring-beans.xsd
   http://www.springframework.org/schema/context
   http://www.springframework.org/schema/context/spring-context.xsd
   http://www.springframework.org/schema/mvc
   https://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <!--自动扫描包，让指定包下的注解生效，由IOC统一管理-->
    <context:component-scan base-package="cn.codewei.controller"/>
    <!--让springmvc不再处理静态资源-->
    <mvc:default-servlet-handler/>

    <!--
        支持mvc注解驱动
        在spring中一般采用@RequestMapping注解来完成映射
        要想使@RequestMapping生效
        必须向上下文注册DefaultAnnotationHandlerMapping
        和一个AnnotationMethodHandlerAdapter实例
        这两个实例分别在类级别和方法级别处理
        而annotation-driver配置帮助我们自动完成上述两个实例的注入
    -->
    <mvc:annotation-driven/>

    <!--视图解析器-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <!--前缀-->
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <!--后缀-->
        <property name="suffix" value=".jsp"/>
    </bean>

</beans>

    在视图解析器中我们把所有视图都存放在/WEB-INF/目录下，这样可以保证视图安全，因为这个目录下的文件，客户端不能直接访问

  3. 编写一个Controller类

    @Controller  //代表这个类会被springIOC托管,被这个注解的类中的所有方法，如果返回值是String，并且由具体的页面可以跳转，那么就会被视图解析器解析
    @RequestMapping("/hello")
    public class HelloController  {
        @RequestMapping("/controllerhello")
        public String Controllerhello(Model model){
            // 封装数据
            model.addAttribute("msg","HelloSrpingMVC!");
            return "hello"; // 被视图解析器处理
        }
    }
    @Controller  //代表这个类会被springIOC托管,被这个注解的类中的所有方法，如果返回值是String，并且由具体的页面可以跳转，那么就会被视图解析器解析
@RequestMapping("/hello")
public class HelloController  {

    @RequestMapping("/controllerhello")
    public String Controllerhello(Model model){
        // 封装数据
        model.addAttribute("msg","HelloSrpingMVC!");
        return "hello"; // 被视图解析器处理
    }
}
    @Controller  //代表这个类会被springIOC托管,被这个注解的类中的所有方法，如果返回值是String，并且由具体的页面可以跳转，那么就会被视图解析器解析
@RequestMapping("/hello")
public class HelloController  {

    @RequestMapping("/controllerhello")
    public String Controllerhello(Model model){
        // 封装数据
        model.addAttribute("msg","HelloSrpingMVC!");
        return "hello"; // 被视图解析器处理
    }
}

SpringMVC必须配置的三大件：

处理器映射器，处理器适配器，视图解析器

实现接口Controller定义控制器是较老的办法

缺点是：一个控制器只有一个方法，如果要多个方法则需要定义多个Controller

@Component    组件
@Service    serivce层
@Controller    controller层
@Repository    dao层
@Component    组件
@Service    serivce层
@Controller    controller层
@Repository    dao层
@Component		组件
@Service		serivce层
@Controller		controller层
@Repository		dao层

4. RestFul风格

RestFul就是一个资源定位及资源操作的风格，不是标准也不是协议，只是一种风格

使用RestFul操作资源：可以通过不同的请求方式来实现不同的效果！

如下：请求地址一样，但是功能可能不同

http://127.0.0.1/item/1 查询，GET

http://127.0.0.1/item 新增，POST

http://127.0.0.1/item 更新，PUT

http://127.0.0.1/item/1 删除，DELETE

原来的：http://localhost:8080/add?a=2&b=3

RestFul：http://http/localhost:8080/add/1/2

在SpringMVC中可以使用@PathVariable注解，让方法参数的值对应绑定到一个URI模板变量上

@Controller
public class RestFulController {
    @RequestMapping("/add/{a}/{b}")
    public String test(@PathVariable int a,@PathVariable int b, Model model){
        int result = a +b;
        model.addAttribute("msg","执行了add方法！"+result);
        return "login";
    }
}
@Controller
public class RestFulController {
    @RequestMapping("/add/{a}/{b}")
    public String test(@PathVariable int a,@PathVariable int b, Model model){
        int result = a +b;
        model.addAttribute("msg","执行了add方法！"+result);
        return "login";
    }
}
@Controller
public class RestFulController {
    @RequestMapping("/add/{a}/{b}")
    public String test(@PathVariable int a,@PathVariable int b, Model model){
        int result = a +b;
        model.addAttribute("msg","执行了add方法！"+result);
        return "login";
    }
}

可以通过设置method来设置请求的的方式，如只能通过GET方式访问的到：

@Controller
public class RestFulController {
    @RequestMapping(value = "/add/{a}/{b}",method = RequestMethod.GET)
    public String test(@PathVariable int a,@PathVariable int b, Model model){
        int result = a +b;
        model.addAttribute("msg","执行了add方法！"+result);
        return "login";
    }
}
@Controller
public class RestFulController {
    @RequestMapping(value = "/add/{a}/{b}",method = RequestMethod.GET)
    public String test(@PathVariable int a,@PathVariable int b, Model model){
        int result = a +b;
        model.addAttribute("msg","执行了add方法！"+result);
        return "login";
    }
}
@Controller
public class RestFulController {
    @RequestMapping(value = "/add/{a}/{b}",method = RequestMethod.GET)
    public String test(@PathVariable int a,@PathVariable int b, Model model){
        int result = a +b;
        model.addAttribute("msg","执行了add方法！"+result);
        return "login";
    }
}

可是使用注解来设置允许请求的方式，如

@Controller
public class RestFulController {
    @GetMapping("/add/{a}/{b}")
    public String test(@PathVariable int a,@PathVariable int b, Model model){
        int result = a +b;
        model.addAttribute("msg","执行了add方法！"+result);
        return "login";
    }
}
@Controller
public class RestFulController {

    @GetMapping("/add/{a}/{b}")
    public String test(@PathVariable int a,@PathVariable int b, Model model){
        int result = a +b;
        model.addAttribute("msg","执行了add方法！"+result);
        return "login";
    }
}
@Controller
public class RestFulController {

    @GetMapping("/add/{a}/{b}")
    public String test(@PathVariable int a,@PathVariable int b, Model model){
        int result = a +b;
        model.addAttribute("msg","执行了add方法！"+result);
        return "login";
    }
}

@GetMapping(“/add/{a}/{b}”)

@PostMapping(“…”)

@DeleteMapping(“…”)

@PutMapping(“…”)

通过设置访问方式的约束，可以来实现通过相同的URL，不同的访问方式，得到的访问结果是不同的

5. 重定向和转发

结果跳转方式：

页面：{视图解析器前缀}+名字{视图解析器后缀}

方式一：可能通过原生的HttpServletRequest request, HttpServletResponse response的形式

@Controller
public class ModelTest1 {
    @GetMapping("/modelTest1")
    public String test1(HttpServletRequest request, HttpServletResponse response){
        request.setAttribute("msg","helloModelTest1!");
        return  "test";
    }
}
@Controller
public class ModelTest1 {

    @GetMapping("/modelTest1")
    public String test1(HttpServletRequest request, HttpServletResponse response){
        request.setAttribute("msg","helloModelTest1!");
        return  "test";
    }
}
@Controller
public class ModelTest1 {

    @GetMapping("/modelTest1")
    public String test1(HttpServletRequest request, HttpServletResponse response){
        request.setAttribute("msg","helloModelTest1!");
        return  "test";
    }
}

方式二：不再配置视图解析器

  1. 删除springmvc.xml中的配置

        <!--视图解析器-->
        <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
            <!--前缀-->
            <property name="prefix" value="/WEB-INF/jsp/"/>
            <!--后缀-->
            <property name="suffix" value=".jsp"/>
        </bean>
        <!--视图解析器-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <!--前缀-->
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <!--后缀-->
        <property name="suffix" value=".jsp"/>
    </bean>
        <!--视图解析器-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <!--前缀-->
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <!--后缀-->
        <property name="suffix" value=".jsp"/>
    </bean>

  2. 通过return 来实现转发或重定向

    @Controller
    public class ResultSpringMVC{
        @RequestMapping("/rsm/t1")
        public String test1(){
            // 转发
            return "/index.jsp";
        }
        
        @RequestMapping("/rsm/t2")
        public String test2(){
            // 转发二
            return "forward:/index.jsp";
        }
        
        @RequestMapping("/rsm/t3")
        public String test3(){
            // 重定向
            return "redirect:/index.jsp";
        }
    }
    @Controller
public class ResultSpringMVC{
    @RequestMapping("/rsm/t1")
    public String test1(){
        // 转发
        return "/index.jsp";
    }
    
    @RequestMapping("/rsm/t2")
    public String test2(){
        // 转发二
        return "forward:/index.jsp";
    }
    
    @RequestMapping("/rsm/t3")
    public String test3(){
        // 重定向
        return "redirect:/index.jsp";
    }
}
    @Controller
public class ResultSpringMVC{
    @RequestMapping("/rsm/t1")
    public String test1(){
        // 转发
        return "/index.jsp";
    }
    
    @RequestMapping("/rsm/t2")
    public String test2(){
        // 转发二
        return "forward:/index.jsp";
    }
    
    @RequestMapping("/rsm/t3")
    public String test3(){
        // 重定向
        return "redirect:/index.jsp";
    }
}

方式三：有视图解析器时，转发和重定向(经常使用)

在有视图解析器时，转发，直接写转发到的文件的名字，重定向，加上前缀，写上路径，如

return "redirect:/index.jsp";    //重定向
return "index";      // 转发
return "redirect:/index.jsp";    //重定向
return "index";      // 转发
return "redirect:/index.jsp";		//重定向
return "index";			// 转发

6. 接收请求参数及数据回显

6.1 处理提交数据

1. 提交的参数名称和处理方法的参数名一致

如：localhost:8080/hello?name=codewei

处理方法：

@RequestMapping("/hello")
public String hello(String name){
    ...;
    return "...";
}
@RequestMapping("/hello")
public String hello(String name){
    ...;
    return "...";
}
@RequestMapping("/hello")
public String hello(String name){
    ...;
    return "...";
}

2. 提交的参数名和处理的参数名不一致

如：localhost:8080/hello?username=codewei

处理方法：

@RequestMapping("/hello")
public String hello(@RequestParam("usermae") String name){
    ...;
    return "...";
}
@RequestMapping("/hello")
public String hello(@RequestParam("usermae") String name){
    ...;
    return "...";
}
@RequestMapping("/hello")
public String hello(@RequestParam("usermae") String name){
    ...;
    return "...";
}

3. 提交的是一个对象

如：localhost:8080/hello?name=codewei&id=1&age=20

封装成一个实体类

public class User {
    private int id;
    private String name;
    private int age;
    ...;
}
public class User {
    private int id;
    private String name;
    private int age;
    ...;
}
public class User {
    private int id;
    private String name;
    private int age;
    ...;
}

处理方法

@Controller
public class UserControllerTest {
    @RequestMapping("/user")
    public String userTest(User user, Model model){
        model.addAttribute("user",user);
        return "login";
    }
}
@Controller
public class UserControllerTest {
    @RequestMapping("/user")
    public String userTest(User user, Model model){
        model.addAttribute("user",user);
        return "login";
    }
}
@Controller
public class UserControllerTest {
    @RequestMapping("/user")
    public String userTest(User user, Model model){
        model.addAttribute("user",user);
        return "login";
    }
}

6.2 数据回显到前端

方式一：通过ModelAndView

public class HelloController implements Controller {
    public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
        ModelAndView mv = new ModelAndView();
        String result = "HelloSpringMVC!";
        mv.addObject("msg",result);
        mv.setViewName("test");
        return mv;
    }
}
public class HelloController implements Controller {
    public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
        ModelAndView mv = new ModelAndView();

        String result = "HelloSpringMVC!";

        mv.addObject("msg",result);
        mv.setViewName("test");
        return mv;
    }
}
public class HelloController implements Controller {
    public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
        ModelAndView mv = new ModelAndView();

        String result = "HelloSpringMVC!";

        mv.addObject("msg",result);
        mv.setViewName("test");
        return mv;
    }
}

方式二：通过Model(通常使用Mode)

@Controller
public class UserControllerTest {
    @RequestMapping("/user")
    public String userTest(User user, Model model){
        model.addAttribute("user",user);
        return "login";
    }
}
@Controller
public class UserControllerTest {
    @RequestMapping("/user")
    public String userTest(User user, Model model){
        model.addAttribute("user",user);
        return "login";
    }
}
@Controller
public class UserControllerTest {
    @RequestMapping("/user")
    public String userTest(User user, Model model){
        model.addAttribute("user",user);
        return "login";
    }
}

方式三：通过ModelMap

继承了LinkedMap的方法和特性，和Model用法基本一样

LinkedHashMap–>ModelMap–>Model

7. 乱码问题解决

可以解决过滤器Filter解决

@WebFilter("/*")
public class EncodingFilter implements Filter {
    public void init(FilterConfig filterConfig) throws ServletException {
    }
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        servletRequest.setCharacterEncoding("utf-8");
        filterChain.doFilter(servletRequest,servletResponse);
    }
    public void destroy() {
    }
}
@WebFilter("/*")
public class EncodingFilter implements Filter {
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        servletRequest.setCharacterEncoding("utf-8");
        filterChain.doFilter(servletRequest,servletResponse);
    }

    public void destroy() {

    }
}
@WebFilter("/*")
public class EncodingFilter implements Filter {
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        servletRequest.setCharacterEncoding("utf-8");
        filterChain.doFilter(servletRequest,servletResponse);
    }

    public void destroy() {

    }
}

使用springmvc，我们可以不再像之前一样写Filter过滤器类了，我们可以直接在web.xml配置

<!--配置过滤器：utf-8-->
<filter>
    <filter-name>encoding</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
        <param-name>encoding</param-name>
        <param-value>utf-8</param-value>
    </init-param>
</filter>
<filter-mapping>
    <filter-name>encoding</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>
<!--配置过滤器：utf-8-->
<filter>
    <filter-name>encoding</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
        <param-name>encoding</param-name>
        <param-value>utf-8</param-value>
    </init-param>
</filter>

<filter-mapping>
    <filter-name>encoding</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>
<!--配置过滤器：utf-8-->
<filter>
    <filter-name>encoding</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
        <param-name>encoding</param-name>
        <param-value>utf-8</param-value>
    </init-param>
</filter>

<filter-mapping>
    <filter-name>encoding</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

JSON乱码问题解决：

可通过注解@RequestMapping中的一个参数进行设置，如

@RequestMapping(value="/j1",produces="application/json;charset=utf-8")
@RequestMapping(value="/j1",produces="application/json;charset=utf-8")
@RequestMapping(value="/j1",produces="application/json;charset=utf-8")

但是我们一般不会这么做

我们在spring-mvc.xml中的mvc:annotation-driven中进行配置

<mvc:annotation-driven>
    <mvc:message-converters>
        <bean class="org.springframework.http.converter.StringHttpMessageConverter">
            <constructor-arg value="UTF-8"/>
        </bean>
        <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
            <property name="objectMapper">
                <bean class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
                    <property name="failOnEmptyBeans" value="false"/>
                </bean> 
            </property>
        </bean>
    </mvc:message-converters>
</mvc:annotation-driven>
<mvc:annotation-driven>
    <mvc:message-converters>
        <bean class="org.springframework.http.converter.StringHttpMessageConverter">
            <constructor-arg value="UTF-8"/>
        </bean>
        <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
            <property name="objectMapper">
                <bean class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
                    <property name="failOnEmptyBeans" value="false"/>
                </bean> 
            </property>
        </bean>
    </mvc:message-converters>
</mvc:annotation-driven>
<mvc:annotation-driven>
    <mvc:message-converters>
        <bean class="org.springframework.http.converter.StringHttpMessageConverter">
            <constructor-arg value="UTF-8"/>
        </bean>
        <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
            <property name="objectMapper">
                <bean class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
                    <property name="failOnEmptyBeans" value="false"/>
                </bean> 
            </property>
        </bean>
    </mvc:message-converters>
</mvc:annotation-driven>

9. 补充

@ResponseBody // 它就不会走视图解析器，会直接返回一个字符串

@Controller
public class UserController {
    @ResponseBody  // 它就不会走视图解析器，会直接返回一个字符串
    public String json1(){
        return "test";
    }
}
@Controller
public class UserController {
    @ResponseBody  // 它就不会走视图解析器，会直接返回一个字符串
    public String json1(){
        return "test";
    }
}
@Controller
public class UserController {
    @ResponseBody  // 它就不会走视图解析器，会直接返回一个字符串
    public String json1(){
        return "test";
    }
}

这样return就是单纯的返回一个字符串

@RestController //放在类上，该类下所有方法只会返回JSON字符串，不会走视图解析器

@Controller
@RestController  // 该类下所有方法只会返回JSON字符串，不会走视图解析器**
public class UserController {
    @GetMapping("/j1")
    public String json1() throws JsonProcessingException {
        ObjectMapper objectMapper = new ObjectMapper();
        User user = new User(1,"唐嫣",33);
        String s = objectMapper.writeValueAsString(user);
        return s;
    }
}
@Controller
@RestController  // 该类下所有方法只会返回JSON字符串，不会走视图解析器**
public class UserController {
    @GetMapping("/j1")
    public String json1() throws JsonProcessingException {
        ObjectMapper objectMapper = new ObjectMapper();
        User user = new User(1,"唐嫣",33);
        String s = objectMapper.writeValueAsString(user);
        return s;
    }
}
@Controller
@RestController  // 该类下所有方法只会返回JSON字符串，不会走视图解析器**
public class UserController {
    @GetMapping("/j1")
    public String json1() throws JsonProcessingException {
        ObjectMapper objectMapper = new ObjectMapper();
        User user = new User(1,"唐嫣",33);
        String s = objectMapper.writeValueAsString(user);
        return s;
    }
}

Json工具类

public class JsonUtils {
    // json工具类  获取json
    public static String getJson(Object object){
        return getJson(object,"yyyy-MM-dd HH:mm:ss");
    }
    public static String getJson(Object object,String dateFormat){
        ObjectMapper mapper = new ObjectMapper();
        mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS,false);
        SimpleDateFormat sdf = new SimpleDateFormat(dateFormat);
        mapper.setDateFormat(sdf);
        try {
            return mapper.writeValueAsString(object);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
        return null;
    }
}
public class JsonUtils {
    // json工具类  获取json

    public static String getJson(Object object){
        return getJson(object,"yyyy-MM-dd HH:mm:ss");
    }

    public static String getJson(Object object,String dateFormat){
        ObjectMapper mapper = new ObjectMapper();
        mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS,false);
        SimpleDateFormat sdf = new SimpleDateFormat(dateFormat);
        mapper.setDateFormat(sdf);

        try {
            return mapper.writeValueAsString(object);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
        return null;
    }
}
public class JsonUtils {
    // json工具类  获取json

    public static String getJson(Object object){
        return getJson(object,"yyyy-MM-dd HH:mm:ss");
    }

    public static String getJson(Object object,String dateFormat){
        ObjectMapper mapper = new ObjectMapper();
        mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS,false);
        SimpleDateFormat sdf = new SimpleDateFormat(dateFormat);
        mapper.setDateFormat(sdf);

        try {
            return mapper.writeValueAsString(object);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
        return null;
    }
}

10. 拦截器

  1. 自定义拦截器类，就必须实现HandlerInterceptor接口

    public class MyInterceptor implements HandlerInterceptor {
        // return true;放行 执行下一个拦截器
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
            System.out.println("=====处理前===========");
            return true;
        }
        public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
            System.out.println("============处理后============");
        }
        public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
            System.out.println("===========清理==========");
        }
    }
    public class MyInterceptor implements HandlerInterceptor {
    // return true;放行 执行下一个拦截器
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("=====处理前===========");
        return true;
    }

    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("============处理后============");
    }

    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("===========清理==========");
    }
}
    public class MyInterceptor implements HandlerInterceptor {
    // return true;放行 执行下一个拦截器
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("=====处理前===========");
        return true;
    }

    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("============处理后============");
    }

    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("===========清理==========");
    }
}

  2. 在springmvc.xml中配置拦截器

    <mvc:interceptors>
        <mvc:interceptor>
            <!--包括这个请求下面的所有请求-->
            <mvc:mapping path="/**"/>
            <bean class="cn.codewei.config.MyInterceptor"/>
        </mvc:interceptor>
    </mvc:interceptors>
    <mvc:interceptors>
    <mvc:interceptor>
        <!--包括这个请求下面的所有请求-->
        <mvc:mapping path="/**"/>
        <bean class="cn.codewei.config.MyInterceptor"/>
    </mvc:interceptor>
</mvc:interceptors>
    <mvc:interceptors>
    <mvc:interceptor>
        <!--包括这个请求下面的所有请求-->
        <mvc:mapping path="/**"/>
        <bean class="cn.codewei.config.MyInterceptor"/>
    </mvc:interceptor>
</mvc:interceptors>

11. 文件上传

在前端页面要设置表单中的enctype属性

  1. application/x-www=form-urlencode：默认方式，只处理表单域中的value属性值，采用这种编码方式的表单会将表单域中的值处理成URL编码方式
  2. multipart/form-data：这种编码方式会以二进制流的方式来处理表单数据，这种编码方式会把文件域指定文件的内容也封装到请求参数中，不会对字符集编码
  3. text/plain：除了把空格转换为”+”号外，其他字符都不做编码处理，这种方式适用直接通过表单发送邮件

1. 导入jar包

<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.3</version>
</dependency>
<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.3</version>
</dependency>
<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.3</version>
</dependency>

2. 配置

SpringMVC为文件上传提供了直接的支持，这种支持是即插即用的MultipartResolver实现的

<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <!--请求编码格式，必须和jsp的pageEncoding一致-->
    <property name="defaultEncoding" value="utf-8"/>
    <!--上传文件大小限制 单位为字节-->
    <property name="maxUploadSize" value="10485760"/>
    <property name="maxInMemorySize" value="40960"/>
</bean>
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <!--请求编码格式，必须和jsp的pageEncoding一致-->
    <property name="defaultEncoding" value="utf-8"/>
    <!--上传文件大小限制 单位为字节-->
    <property name="maxUploadSize" value="10485760"/>
    <property name="maxInMemorySize" value="40960"/>
</bean>
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <!--请求编码格式，必须和jsp的pageEncoding一致-->
    <property name="defaultEncoding" value="utf-8"/>
    <!--上传文件大小限制 单位为字节-->
    <property name="maxUploadSize" value="10485760"/>
    <property name="maxInMemorySize" value="40960"/>
</bean>

3. 上传文件：方式一

@RestController
public class FileController {
    @RequestMapping("/upload")
    public String fileUpload(@RequestParam("file") CommonsMultipartFile file, HttpServletRequest request) throws IOException {
        // 获取文件名
        String filename = file.getOriginalFilename();
        // 如果文件为空，直接回到首页
        if ("".equals(filename)){
            return "redirect:/index.jsp";
        }
        System.out.println("上传文件名：" + filename);
        // 上传路径保存设置
        String path = request.getRealPath("/upload");
        // 如果路径不存在，创建一个
        File realPath = new File(path);
        if (!realPath.exists()){
            realPath.mkdir();
        }
        System.out.println("上传文件保存地址：" + realPath);
        InputStream is = file.getInputStream();  // 文件输入流
        FileOutputStream os = new FileOutputStream(new File(realPath, filename)); //文件输出流
        // 读取写出
        int len=0;
        byte[] bytes = new byte[1024];
        while((len =is.read(bytes))!=-1){
            os.write(bytes,0,len);
            os.flush();
        }
        os.close();
        is.close();
        return "redirect:/index.jsp"
    }
}
@RestController
public class FileController {

    @RequestMapping("/upload")
    public String fileUpload(@RequestParam("file") CommonsMultipartFile file, HttpServletRequest request) throws IOException {
        // 获取文件名
        String filename = file.getOriginalFilename();

        // 如果文件为空，直接回到首页
        if ("".equals(filename)){
            return "redirect:/index.jsp";
        }
        System.out.println("上传文件名：" + filename);

        // 上传路径保存设置
        String path = request.getRealPath("/upload");

        // 如果路径不存在，创建一个
        File realPath = new File(path);
        if (!realPath.exists()){
            realPath.mkdir();
        }
        System.out.println("上传文件保存地址：" + realPath);

        InputStream is = file.getInputStream();  // 文件输入流
        FileOutputStream os = new FileOutputStream(new File(realPath, filename)); //文件输出流

        // 读取写出
        int len=0;
        byte[] bytes = new byte[1024];
        while((len =is.read(bytes))!=-1){
            os.write(bytes,0,len);
            os.flush();
        }

        os.close();
        is.close();
        return "redirect:/index.jsp"
    }
}
@RestController
public class FileController {

    @RequestMapping("/upload")
    public String fileUpload(@RequestParam("file") CommonsMultipartFile file, HttpServletRequest request) throws IOException {
        // 获取文件名
        String filename = file.getOriginalFilename();

        // 如果文件为空，直接回到首页
        if ("".equals(filename)){
            return "redirect:/index.jsp";
        }
        System.out.println("上传文件名：" + filename);

        // 上传路径保存设置
        String path = request.getRealPath("/upload");

        // 如果路径不存在，创建一个
        File realPath = new File(path);
        if (!realPath.exists()){
            realPath.mkdir();
        }
        System.out.println("上传文件保存地址：" + realPath);

        InputStream is = file.getInputStream();  // 文件输入流
        FileOutputStream os = new FileOutputStream(new File(realPath, filename)); //文件输出流

        // 读取写出
        int len=0;
        byte[] bytes = new byte[1024];
        while((len =is.read(bytes))!=-1){
            os.write(bytes,0,len);
            os.flush();
        }

        os.close();
        is.close();
        return "redirect:/index.jsp"
    }
}

4. 上传文件：方式二

@RestController
public class FileController {
    @RequestMapping("/upload")
    public String fileUpload(@RequestParam("file") CommonsMultipartFile file, HttpServletRequest request) throws IOException {
        // 上传路径保存设置
        String path = request.getRealPath("/upload");
        File realPath = new File(path);
        if (!realPath.exists()){
            realPath.mkdir();
        }
        // 通过CommonsMultipartFile的方法直接写文件
        file.transferTo(new File(realPath+"/"+file.getOriginalFilename()));
        return "redirect:/index.jsp";
    }
}
@RestController
public class FileController {

    @RequestMapping("/upload")
    public String fileUpload(@RequestParam("file") CommonsMultipartFile file, HttpServletRequest request) throws IOException {
        // 上传路径保存设置
        String path = request.getRealPath("/upload");
        File realPath = new File(path);
        if (!realPath.exists()){
            realPath.mkdir();
        }

        // 通过CommonsMultipartFile的方法直接写文件
        file.transferTo(new File(realPath+"/"+file.getOriginalFilename()));

        return "redirect:/index.jsp";
    }
}
@RestController
public class FileController {

    @RequestMapping("/upload")
    public String fileUpload(@RequestParam("file") CommonsMultipartFile file, HttpServletRequest request) throws IOException {
        // 上传路径保存设置
        String path = request.getRealPath("/upload");
        File realPath = new File(path);
        if (!realPath.exists()){
            realPath.mkdir();
        }

        // 通过CommonsMultipartFile的方法直接写文件
        file.transferTo(new File(realPath+"/"+file.getOriginalFilename()));

        return "redirect:/index.jsp";
    }
}

原文链接：SpringMVC

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