Struts2学习笔记（十五）异步传输机制

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进行异步数据传输时，我们有两种选择：xml和json。

实现的功能时，选择框中选择不同的人名，显示相应的信息。

1、xml格式的异步数据传输

（1）首先，新建xml.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!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"><title>Insert title here</title><script type="text/javascript" src="js/jquery-1.11.1.js"></script><script type="text/javascript">function getInfo(){$.post("xmlAction.action",{username:$("#username").val()},function(returnedData,status){var username=$(returnedData).find("username").text();var age=$(returnedData).find("age").text();var address=$(returnedData).find("address").text();var html="<table width='60%' border='1' align='center'> <tr><th>username</th><th>age</th><th>address</th></tr><tr><td>"+username+"</td><td>"+age+"</td><td>"+address+"</tr></table>";$("#theBody table:eq(0)").remove();$("#theBody").append(html);});}</script></head><body id="theBody"><select id="username"><option>zhangsan</option><option>lisi</option></select><input type="button" value="choose" onclick="getInfo()"></body></html>

（2）XMLAction

package cn.sict.action;import java.io.PrintWriter;import javax.servlet.http.HttpServletResponse;import org.apache.struts2.ServletActionContext;import org.dom4j.Document;import org.dom4j.DocumentHelper;import org.dom4j.Element;import org.dom4j.io.OutputFormat;import org.dom4j.io.XMLWriter;import cn.sict.domain.Person;import com.opensymphony.xwork2.ActionSupport;public class XMLAction extends ActionSupport{private String username;private int age;private String address;public String getAddress() {return address;}public void setAddress(String address) {this.address = address;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}@Overridepublic String execute() throws Exception {Person person1=new Person();Person person2=new Person();person1.setUsername("zhangsan");person1.setAge(20);person1.setAddress("beijing");person2.setUsername("lisi");person2.setAge(22);person2.setAddress("shanghai");Document document=DocumentHelper.createDocument();Element rootElement=document.addElement("persons");Element element=rootElement.addElement("person");Element username_element=element.addElement("username");Element age_element=element.addElement("age");Element address_element=element.addElement("address");if("zhangsan".equals(username)){username_element.setText(person1.getUsername());age_element.setText(person1.getAge()+"");address_element.setText(person1.getAddress());}else{username_element.setText(person2.getUsername());age_element.setText(person2.getAge()+"");address_element.setText(person2.getAddress());}HttpServletResponse response=ServletActionContext.getResponse();response.setContentType("text/xml;charset=utf-8");response.setHeader("cache-control", "no-cache");PrintWriter out=response.getWriter();OutputFormat format=OutputFormat.createPrettyPrint();format.setEncoding("utf-8");XMLWriter writer=new XMLWriter(out,format);writer.write(document);out.flush();out.close();return null;//返回null值，struts.xml中对应类不进行结果处理}}

（3）配置struts文件

<action name="xmlAction" class="cn.sict.action.AjaxAction"></action>

2、json数据格式传输，（3）步同上

（1）getInfo方法，其余同上

function getInfo(){$.post("gsonAction.action",{username:$("#username").val()},function(returnedData,status){var person=returnedData;var username=person.username;var age=person.age;var address=person.address;var html="<table width='60%' border='1' align='center'> <tr><th>username</th><th>age</th><th>address</th></tr><tr><td>"+username+"</td><td>"+age+"</td><td>"+address+"</tr></table>";$("#theBody table:eq(0)").remove();$("#theBody").append(html);});}

（2）GsonAction类

package cn.sict.action;import java.io.PrintWriter;import javax.servlet.http.HttpServletResponse;import org.apache.struts2.ServletActionContext;import org.dom4j.io.OutputFormat;import cn.sict.domain.Person;import com.google.gson.Gson;import com.opensymphony.xwork2.ActionSupport;public class GsonAction extends ActionSupport {private String username;private int age;private String address;public String getAddress() {return address;}public void setAddress(String address) {this.address = address;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}@Overridepublic String execute() throws Exception {Person person1 = new Person();Person person2 = new Person();person1.setUsername("zhangsan");person1.setAge(20);person1.setAddress("beijing");person2.setUsername("lisi");person2.setAge(22);person2.setAddress("shanghai");String result=null;Gson gson=new Gson();if ("zhangsan".equals(username)) {result=gson.toJson(person1);} else {result=gson.toJson(person2);}HttpServletResponse response = ServletActionContext.getResponse();response.setContentType("application/json;charset=utf-8");response.setHeader("cache-control", "no-cache");PrintWriter out = response.getWriter();OutputFormat format = OutputFormat.createPrettyPrint();format.setEncoding("utf-8");out.print(result);out.flush();out.close();return null;}}

运行的结果如下所示：

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