准备
新建工程
![](https://img.haomeiwen.com/i16823531/5ff7f00920ea5265.png)
![](https://img.haomeiwen.com/i16823531/5e9148d9071fe047.png)
![](https://img.haomeiwen.com/i16823531/5cea4edace306d91.png)
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.neuedu</groupId>
<artifactId>springMVC_demo02_response</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>
<name>springMVC_demo02_response Maven Webapp</name>
<!-- FIXME change it to the project's website -->
<url>http://www.example.com</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
<spring.version>5.0.2.RELEASE</spring.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>jsp-api</artifactId>
<version>2.0</version>
<scope>provided</scope>
</dependency>
</dependencies>
<build>
<finalName>springMVC_demo02_response</finalName>
<pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
<plugins>
<plugin>
<artifactId>maven-clean-plugin</artifactId>
<version>3.1.0</version>
</plugin>
<!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->
<plugin>
<artifactId>maven-resources-plugin</artifactId>
<version>3.0.2</version>
</plugin>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.0</version>
</plugin>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.22.1</version>
</plugin>
<plugin>
<artifactId>maven-war-plugin</artifactId>
<version>3.2.2</version>
</plugin>
<plugin>
<artifactId>maven-install-plugin</artifactId>
<version>2.5.2</version>
</plugin>
<plugin>
<artifactId>maven-deploy-plugin</artifactId>
<version>2.8.2</version>
</plugin>
</plugins>
</pluginManagement>
</build>
</project>
web.xml
<!DOCTYPE web-app PUBLIC
"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd" >
<web-app>
<display-name>Archetype Created Web Application</display-name>
<!--配置前端控制器-->
<servlet>
<servlet-name>dispatcherServlet</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>dispatcherServlet</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<!--配置解决中文乱码的过滤器-->
<filter>
<filter-name>characterEncodingFilter</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>characterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
springMVC.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd">
<!-- 开启注解扫描 -->
<context:component-scan base-package="com.neuedu"/>
<!-- 视图解析器对象 -->
<bean id="internalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/pages/"/>
<property name="suffix" value=".jsp"/>
</bean>
<!-- 开启SpringMVC框架注解的支持 -->
<mvc:annotation-driven />
</beans>
1. 返回值分类
1.1字符串
![](https://img.haomeiwen.com/i16823531/568a1d7815ed11dd.png)
<a href="user/testString" >testString</a>
![](https://img.haomeiwen.com/i16823531/5a9fd0d1cac6a6ad.png)
实体类User
![](https://img.haomeiwen.com/i16823531/96708e9b65cb7d10.png)
package com.neuedu.domain;
import java.io.Serializable;
public class User implements Serializable {
private String username;
private String password;
private Integer age;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
}
UserController类
![](https://img.haomeiwen.com/i16823531/5cccfdf17935b3aa.png)
package com.neuedu.controller;
import com.neuedu.domain.User;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
@Controller
@RequestMapping("/user")
public class UserController {
/**
* 返回String
* @param model
* @return
*/
@RequestMapping("/testString")
public String testString(Model model){
System.out.println("testString方法执行了...");
// 模拟从数据库中查询出User对象
User user = new User();
user.setUsername("哈哈");
user.setPassword("123");
user.setAge(30);
// model对象
model.addAttribute("user",user);
return "success";
}
}
success.jsp
<h3>执行成功</h3>
${user.age}
${user.password}
![](https://img.haomeiwen.com/i16823531/b387404e69a3109e.png)
![](https://img.haomeiwen.com/i16823531/92de77d4a3d6e3bc.png)
1.2 void
<a href="user/testVoid" >testVoid</a>
/**
* 是void
* 请求转发一次请求,不用编写项目的名称
*/
@RequestMapping("/testVoid")
public void testVoid(HttpServletRequest request, HttpServletResponse response) throws Exception {
System.out.println("testVoid方法执行了...");
// 编写请求转发的程序
// request.getRequestDispatcher("/WEB-INF/pages/success.jsp").forward(request,response);
// 重定向
// response.sendRedirect(request.getContextPath()+"/index.jsp");
// 设置中文乱码
response.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
// 直接会进行响应
response.getWriter().print("你好");
return;
}
![](https://img.haomeiwen.com/i16823531/b3469e74d74954b8.png)
1.3 ModelAndView
ModelAndView 是 SpringMVC 为我们提供的一个对象,该对象也可以用作控制器方法的返回值。
该对象中有两个方法:
![](https://img.haomeiwen.com/i16823531/043320d47295b93b.png)
![](https://img.haomeiwen.com/i16823531/936ad1ee132d4e45.png)
<a href="user/testModelAndView" >testModelAndView</a>
/**
* 返回ModelAndView
* @return
*/
@RequestMapping("/testModelAndView")
public ModelAndView testModelAndView(){
// 创建ModelAndView对象
ModelAndView mv = new ModelAndView();
System.out.println("testModelAndView方法执行了...");
// 模拟从数据库中查询出User对象
User user = new User();
user.setUsername("哈哈");
user.setPassword("456");
user.setAge(30);
// 把user对象存储到mv对象中,也会把user对象存入到request对象
mv.addObject("user",user);
// 跳转到哪个页面
mv.setViewName("success");
return mv;
}
![](https://img.haomeiwen.com/i16823531/638ff28a78ec2e28.png)
2 转发和重定向
2.1 forward
/**
* 使用关键字的方式进行转发或者重定向
* @return
*/
@RequestMapping("/testForwardOrRedirect")
public String testForwardOrRedirect(){
System.out.println("testForwardOrRedirect方法执行了...");
// 请求的转发
return "forward:/pages/success.jsp";
}
需要注意的是,如果用了 formward :则路径必须写成实际视图 url,不能写逻辑视图。
它相当于“request.getRequestDispatcher("url").forward(request,response)”。使用请求转发,既可以转发到 jsp,也可以转发到其他的控制器方法。
2.2 Redirect 重定向
/**
* 使用关键字的方式进行转发或者重定向
* @return
*/
@RequestMapping("/testForwardOrRedirect")
public String testForwardOrRedirect(){
System.out.println("testForwardOrRedirect方法执行了...");
// 重定向
return "redirect:/index.jsp";
}
它相当于“response.sendRedirect(url)”。需要注意的是,如果是重定向到 jsp 页面,则 jsp 页面不能写在 WEB-INF 目录中,否则无法找到。
3. ResponseBody响应json数据
作用:
该注解用于将 Controller 的方法返回的对象,通过 HttpMessageConverter 接口转换为指定格式的数据如:json,xml 等,通过 Response 响应给客户端
需求:
使用@ResponseBody 注解实现将 controller 方法返回对象转换为 json 响应给客户端。
前置知识点:
Springmvc 默认用 MappingJacksonHttpMessageConverter 对 json 数据进行转换,需要加入jackson 的包。
![](https://img.haomeiwen.com/i16823531/cf0f6d5635369e7c.png)
3.1 准备
过滤静态资源
导入jquery.js
![](https://img.haomeiwen.com/i16823531/1e4d20d602c5b1bd.png)
response.jsp
<script src="/js/jquery-3.4.1.js"></script>
<script>
// 页面加载,绑定单击事件
$(function(){
$("#btn").click(function(){
alert("hello btn");
});
});
</script>
<button id="btn">发送ajax的请求</button>
3.1 使用说明
点击按钮并没有反应
原理:web.xml文件中的前端控制器dispatcherServlet会进行拦截
解决:告诉它,哪些静态资源不能拦截,在springMVC.xml中设置
<!--前端控制器,哪些静态资源不拦截-->
<mvc:resources location="/css/" mapping="/css/**"/>
<mvc:resources location="/images/" mapping="/images/**"/>
<mvc:resources location="/js/" mapping="/js/**"/>
或者可以写成:
<mvc:default-servlet-handler></mvc:default-servlet-handler>
编写原生ajax请求
// 发送ajax请求
$.ajax({
// 编写json格式,设置属性和值
url:"user/testAjax",
contentType:"application/json;charset=UTF-8",
data:'{"username":"hehe","password":"123","age":30}',
dataType:"json",
type:"post",
success:function(data){
// data服务器端响应的json的数据,进行解析
}
});
服务器UserController处理ajax请求数据
/**
* 模拟异步请求响应
*/
@RequestMapping("/testAjax")
public void testAjax(@RequestBody String body){
System.out.println("testAjax方法执行了...");
System.out.println(body);
}
![](https://img.haomeiwen.com/i16823531/b34eb620d0e71c35.png)
3.2 使用示例
向pom.xml导入坐标
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.9.0</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>2.9.0</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-annotations</artifactId>
<version>2.9.0</version>
</dependency>
/**
* 模拟异步请求响应
*/
@RequestMapping("/testAjax")
public @ResponseBody User testAjax(@RequestBody User user){
System.out.println("testAjax方法执行了...");
// 客户端发送ajax的请求,传的是json字符串,后端把json字符串封装到user对象中
System.out.println(user);
// 做响应,模拟查询数据库
user.setUsername("haha");
user.setAge(40);
// 做响应
return user;
}
// 发送ajax请求
$.ajax({
// 编写json格式,设置属性和值
url:"user/testAjax",
contentType:"application/json;charset=UTF-8",
data:'{"username":"hehe","password":"123","age":30}',
dataType:"json",
type:"post",
success:function(data){
// data服务器端响应的json的数据,进行解析
alert(data);
alert(data.username);
alert(data.password);
alert(data.age);
}
});
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