springMVC的返回值有ModelAndView,String,void,Object类型。今天就来整理一下。
目录结构：
依赖：
<!-- jackson -->
<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.10.0</version>
</dependency>
<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-core -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>2.10.0</version>
</dependency>
<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-annotations -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-annotations</artifactId>
<version>2.10.0</version>
</dependency>
老版本的Jackson使用的包名为org.codehaus.jackson，而新版本使用的是com.fasterxml.jackson。
Jackson主要包含了3个模块：
- jackson-core
- jackson-annotations
- jackson-databind
其中，jackson-annotations依赖于jackson-core，jackson-databind又依赖于jackson-annotations。
Jackson有三种方式处理Json：
- 使用底层的基于Stream的方式对Json的每一个小的组成部分进行控制
- 使用Tree Model，通过JsonNode处理单个Json节点
- 使用databind模块，直接对Java
对象进行序列化和反序列化
关键代码：
ReturnValueController
package com.kaspar.controller;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.servlet.ModelAndView;
@Controller
@RequestMapping(value="/returnValue")
public class ReturnValueController {
@RequestMapping("/returnModelAndView") //返回ModelAndView
public ModelAndView doModelAndView(String name, String password, ModelAndView mav){
mav.addObject("name", name);
mav.addObject("password", password);
mav.setViewName("/showReturn.jsp");
return mav;
}
@RequestMapping("/returnString") //返回String类型, 可以通过HttpServletRequest 来传递参数
public String doString(String sname, String spassword, HttpServletRequest request){
request.setAttribute("sname", sname);
request.setAttribute("spassword", spassword);
return "/showReturn.jsp";
}
@RequestMapping("/returnVoid") //无返回值,通过ServletAPI完成参数传递和跳转
public void doVoid(String vname, String vpassword, HttpServletRequest request, HttpServletResponse response) throws Exception{
request.setAttribute("vname", vname);
request.setAttribute("vpassword", vpassword);
request.getRequestDispatcher("/showReturn.jsp").forward(request, response);
}
@RequestMapping("/returnObjectValue") //返回Object对象需要开启消息转换器HttpMessageConverter,<mvc:annotation-driven/>
@ResponseBody
public Object doObjectValue(){
return 12.34;
}
@RequestMapping("/returnObjectString") //返回String
@ResponseBody
public Object doObjectString(){
return "Hello SpringMVC";
}
@RequestMapping("/returnObjectList") //返回List
@ResponseBody
public Object doObjectList(){
List<String> list = new ArrayList<String>();
list.add("String1");
list.add("String2");
list.add("String3");
return list;
}
@RequestMapping("/returnObjectMap") //返回Map
@ResponseBody
public Object doObjectMap(){
Map<String, String> map = new HashMap<String, String>();
map.put("mk1", "kv1");
map.put("mk2", "kv2");
map.put("mk3", "kv3");
return map;
}
}
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:mvc="http://www.springframework.org/schema/mvc"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-4.0.xsd">
<!-- 开启驱动器注解 -->
<mvc:annotation-driven />
<!-- 静态资源设置,因为需要加入js静态资源 -->
<mvc:resources location="/js/" mapping="/js/**"/>
<!-- 扫描注解 -->
<context:component-scan base-package="com.kaspar.controller" />
</beans>
测试页面returnValue.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jstl/core"%>
<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<base href="<%=basePath%>">
<title>ReturnValue</title>
<script type="text/javascript" src="js/jquery-1.9.0.min.js"></script>
<script type="text/javascript">
$(function() {
//获取value值得ajax
$("#value").on("click", function() {
alert("123");
$.ajax({
type : "get",
url : "returnValue/returnObjectValue.do",
success : function(data) {
alert("data: " + data);
}
});
});
//获取String值得ajax
$("#string").on("click", function() {
alert("123");
$.ajax({
type : "get",
url : "returnValue/returnObjectString.do",
success : function(data) {
alert("data: " + data);
}
});
});
//获取List值得ajax
$("#list").on("click", function() {
alert("123");
$.ajax({
type : "get",
url : "returnValue/returnObjectList.do",
success : function(data) {
for (var i = 0; i < data.length; i++)
alert("data: " + data[i]);
}
});
});
//获取Map值得ajax
$("#map").on("click", function() {
alert("123");
$.ajax({
type : "get",
url : "returnValue/returnObjectMap.do",
success : function(data) {
for ( var key in data) {
alert("key: " + key + " value: " + data[key]);
}
}
});
});
});
</script>
</head>
<body>
返回ModelAndView
<form action="returnValue/returnModelAndView.do">
name: <input type="text" name="name"><br /> password:<input
type="text" name="name"><br /> <input type="submit"
value="submit">
</form>
<hr>
返回String类型
<form action="returnValue/returnString.do">
name: <input type="text" name="sname"><br /> password:<input
type="text" name="spassword"><br /> <input type="submit"
value="submit">
</form>
<hr>
无返回值
<form action="returnValue/returnVoid.do">
name: <input type="text" name="vname"><br /> password:<input
type="text" name="vname"><br /> <input type="submit"
value="submit">
</form>
<hr>
返回Object对象,类型为数值型
<input id="value" type="button" value="AjaxgetValue">
<hr>
返回Object对象,类型为String
<input id="string" type="button" value="AjaxgetString">
<hr>
返回Object对象,类型为List
<input id="list" type="button" value="AjaxgetList">
<hr>
返回Object对象,类型为Map
<input id="map" type="button" value="AjaxgetMap">
</body>
</html>
跳转后的页面showReturn.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jstl/core" %>
<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<base href="<%=basePath %>">
<title>ShowReturn</title>
</head>
<body>
返回ModelAndView
<div>
<h3><c:out value="${name }" /></h3>
<h3><c:out value="${password }" /></h3>
</div>
<hr>
返回String类型
<div>
<h3><c:out value="${sname }" /></h3>
<h3><c:out value="${spassword }" /></h3>
</div>
<hr>
无返回值
<div>
<h3><c:out value="${vname }" /></h3>
<h3><c:out value="${vpassword }" /></h3>
</div>
</body>
</html>
web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> <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:config/Spring-mvc.xml</param-value> </init-param> <load-on-startup>0</load-on-startup> </servlet> <servlet-mapping> <servlet-name>springmvc</servlet-name> <url-pattern>*.do</url-pattern> </servlet-mapping> <!-- 解决中文乱码 --> <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>
