public class ValidateAction extends ActionSupport {private static final long serialVersionUID = 1L;private String username;public Map<String, Object> result = new HashMap<String, Object>();public Map<String, Object> getResult() {return result;}public String execute() throws Exception {if ("zhangsan".equals(username)) {result.put("message", "success结果");return Action.SUCCESS;}else {System.out.println("error结果");result.put("message", "error结果");return Action.ERROR;}}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}} 配置Action<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN" ""><struts><package name="default" extends="json-default"><action name="validate" class="ValidateAction"><result type="json" /><result name="error" type="json"></result></action></package></struts> 页面访问json
<%@ page language="java" contentType="text/html; charset=utf-8"pageEncoding="utf-8"%><%String path = request.getContextPath();String basePath = request.getScheme() + "://"+ request.getServerName() + ":" + request.getServerPort()+ path + "/";%><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" ""><html xmlns=""> <head><meta http-equiv="Content-type" content="text/html; charset=utf-8" /><title>Welcome to BoadVedio</title><script type='text/javascript' src="<%=basePath%>resource/js/jquery-1.8.3.js"></script><script type="text/javascript">var basePath = '<%=basePath%>';function validate(){var username = document.getElementById("username").value;$.ajax({url:basePath+"validate.action",type:"post",dataType:"json",data:{username:username},success:function(data){var message = data.result.message;$('#message').html(message);},error : function(XMLHttpRequest, textStatus, errorThrown) {alert("error when insert.");}});}</script> </head> <body><input type="text" name="username" id="username"/><input type="button" value="提交" onclick="validate();"/><div id="message"></div> </body></html> 测试基本功能没有问题。只是对于Action的返回值是SUCCESS还是ERROR，对页面是有影响的。上述配置，action配置中的success和error类型都是JSON，这样不管Action走入的是return SUCCESS还是ERROR分支，都会把成员变量result对象转化成JSON返回给页面的，ajax请求都是走入success分支中的。但是如果把error类型配置成一个jsp，那么，此时ajax的请求返回时是进入了error分支了
<struts><package name="default" extends="json-default"><action name="validate" class="ValidateAction"><result type="json" /><result name="error" >/error.jsp</result></action></package></struts> 而且浏览器并没有自动跳转到error.jsp页面去。那么问题来了：为什么配置error为error.jsp的时候，ajax请求走入了error分支呢？这个应该是ajax请求的dataType类型设置成了json，如果此时Action返回了error.jsp，，那么ajax会视为异常。
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