SSM-SpringMVC-20：SpringMVC中处理器方法之返回值void篇

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处理器的方法我们之前做过，返回值为String的，返回值为ModelAndView的，我们这个讲的这个返回值void的做什么的？

答：最主要的是ajax的时候用的

案例如下：

俩个类：实体类UserInfo和处理器类：

UserInfo类：

package cn.dawn.day12return;/**
* Created by Dawn on 2018/3/26.
*/
public class UserInfo {
private String username;
private String password; public UserInfo() {
} public UserInfo(String username, String password) {
this.username = username;
this.password = password;
} 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;
}
}

自定义的处理器类：

package cn.dawn.day12return;import com.alibaba.fastjson.JSON;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;/**
* Created by Dawn on 2018/3/26.
*/
@Controller
public class MyReturnDemoController {
@RequestMapping("/doreturnVoidAjax")
public void doreturnVoidAjax(HttpServletResponse response) throws IOException {
List<UserInfo> lists=new ArrayList<UserInfo>();
UserInfo u1=new UserInfo("M","");
UserInfo u2=new UserInfo("",""); lists.add(u1);
lists.add(u2); String json = JSON.toJSONString(lists);
response.getWriter().write(json);
}
}

此处用到了阿里的fastjson的jar包，自已引一个即可，不说这个jar了

自己的xml配置文件：

在web.xml中把中央调度器调度到自己当前写的这个xml配置文件，再解决乱码，再解决静态资源js不能引用的问题

<!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> 
<filter>
<filter-name>CharacterEncoding</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>

<init-param>
<param-name>encoding</param-name>
<param-value>utf-</param-value>
</init-param>

<init-param>
<param-name>forceEncoding</param-name>
<param-value>true</param-value>
</init-param>
</filter> <filter-mapping>
<filter-name>CharacterEncoding</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping> 
<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:ApplicationContext-day12return.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> 
<servlet-mapping>
<servlet-name>default</servlet-name>
<url-pattern>*.js</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>default</servlet-name>
<url-pattern>*.css</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>default</servlet-name>
<url-pattern>*.jpg</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>default</servlet-name>
<url-pattern>*.png</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>default</servlet-name>
<url-pattern>*.gif</url-pattern>
</servlet-mapping></web-app>

jsp页面

<%@ page language="java" pageEncoding="utf-8" isELIgnored="false" %>
<html>
<head>
<title>Ajax</title>
<script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery-1.8.3.min.js"></script>
<script type="text/javascript"> $(function () { $("input").on("click",function () {
$.ajax({
url:"${pageContext.request.contextPath}/doreturnVoidAjax",
type:"POST",
data:{},
success:function (data) { //data:String json串 data:Object json对象 //用户名
$.each(eval("("+data+")"),function (i,dom) {
alert(dom.username);
});
}
});
});
}); </script>
</head><body>
<%--<img src="data:image/1.jpg">--%>
<input type="button" value="想发送Ajax？,点我不要赔的喔！！！呵呵哒~~~~~~"/>
</body>
</html>