风中叶之struts2学习笔记四

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1，进行文件上传时，必须将表单的method属性设置为post，将enctype属性设置为multipart/form-data。

2， http://apache.etoak.com//commons/fileupload/binaries/commons-fileupload-1.2.2-bin.zip：文件上传组件到apache官网下的顶级项目commons的子项目FileUpload去下载。FileUpload依赖于commons-io，因此还要下载它。我们只需要将commons-fileupload-1.2.2.jar，commons-io-2.4.jar加入到项目的/WebRoot/WEB-INF/lib目录下。

3， struts2实现文件上传，实际上是两步完成的

1）首先将客户端上传的文件保存到struts.multipart.saveDir键所指定的目录中，如果该键对应的目录不存在，那么就保存到javax.servlet.context.tempdir环境变量所指定的目录中；

2） Action中所定义的File类型的成员变量实际上指向的是临时目录的临时文件，然后在服务器端通过IO的方式将临时文件写入到指定服务器目录中。

文件上传：

4，一个页面上传多个文件

5， Struts2默认最大上传文件大小是2M，我们可以在src目录下新建一个名为struts.properties的文件覆盖struts2-core-2.3.4.jar/org.apache.struts2/default.properties文件中的相关属性值。

文件大小处理：在struts.properties中设置struts.multipart.maxSize=A A设置的尽量大一些，这样上传就不会出错，然后在程序中进行判断处理。

也可以在struts.xml中以常量的形式指定相关的属性值。

6，文件下载

7，文件下载2

8， struts2可以使用struts2-convention-plugin-2.2.1.1.jar插件实现基于注解的配置

9，异步处理请求返回XML，需要用到dom4j.jar struts2整合jquery

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme() + "://"+ request.getServerName() + ":" + request.getServerPort()+ path + "/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><base href="<%=basePath%>"><title>My JSP 'getXML.jsp' starting page</title><script type="text/javascript" src="scripts/jquery-1.4.4.js"></script><meta http-equiv="pragma" content="no-cache"><meta http-equiv="cache-control" content="no-cache"><meta http-equiv="expires" content="0"><meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="This is my page"><!--<link rel="stylesheet" type="text/css" href="styles.css">--><script type="text/javascript">function getInfo() {$.post("getXMLAction.action",{name : $("#name").val()},function(returnedData, status) {var id = $(returnedData).find("id").text();var name = $(returnedData).find("name").text();var age = $(returnedData).find("age").text();var address = $(returnedData).find("address").text();var html = "<table width='60%' border='1' align='center'>__tag_39$60_<th>id__tag_39$70_<th>name__tag_39$83_<th>age__tag_39$95_<th>address__tag_39$111_<tr align='center'>__tag_39$135_"+ id+ "__tag_39$149_<td>"+ name+ "__tag_39$170_<td>"+ age+ "__tag_39$190_<td>"+ address+ "__tag_39$214_</tr>__tag_39$224_";$("#theBody</script></head><body id="theBody"><select id="name"><option value="zhangsan">zhangsan</option><option value="lisi">lisi</option></select><input type="button" value="get information" onclick=getInfo();;></body></html>

GetXMLAction.java

package com.shengsiyuan.action.xml;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 com.opensymphony.xwork2.ActionSupport;public class GetXMLAction extends ActionSupport{private String name;public String getName(){return name;}public void setName(String name){this.name = name;}@Overridepublic String execute() throws Exception{//zhang sanPeople people1 = new People();people1.setId(1);people1.setName("zhangsan");people1.setAge(30);people1.setAddress("beijing");People people2 = new People();people2.setId(2);people2.setName("lisi");people2.setAge(50);people2.setAddress("tianjin");Document document = DocumentHelper.createDocument();Element rootElement = document.addElement("persons");rootElement.addComment("This is comment!!");Element e = rootElement.addElement("person");Element idElement = e.addElement("id");Element nameElement = e.addElement("name");Element ageElement = e.addElement("age");Element addressElement = e.addElement("address");if("zhangsan".equals(name)){idElement.setText(people1.getId() + "");nameElement.setText(people1.getName());ageElement.setText(people1.getAge() + "");addressElement.setText(people1.getAddress());}else{idElement.setText(people2.getId() + "");nameElement.setText(people2.getName());ageElement.setText(people2.getAge() + "");addressElement.setText(people2.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;}}

struts.xml

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE struts PUBLIC    "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"    "http://struts.apache.org/dtds/struts-2.0.dtd">    <struts> <package name="struts2_ajax" extends="json-default"><action name="getXMLAction" class="com.shengsiyuan.action.xml.GetXMLAction"></action><action name="getJsonAction" class="com.shengsiyuan.action.json.GetJsonAction"></action><action name="getJsonAction2" class="com.shengsiyuan.action.json.GetJsonAction2"><result name="success" type="json"><param name="excludeProperties">address</param></result></action></package></struts>

10，异步处理请求返回JSON，需要用到json.jar，下面列出的代码是与xml不同的地方。

Struts2提供了struts2-json-plugin-2.3.4.jar插件，我们可以以另外的方式处理

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <base href="<%=basePath%>">        <title>My JSP 'json.jsp' starting page</title>    <meta http-equiv="pragma" content="no-cache"><meta http-equiv="cache-control" content="no-cache"><meta http-equiv="expires" content="0">    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="This is my page"><!--<link rel="stylesheet" type="text/css" href="styles.css">--><script type="text/javascript" src="scripts/jquery-1.4.4.js"></script><script type="text/javascript">$(function(){$("#button1").click(function(){$.post("getJsonAction2.action",{name: $("#name").val()}, function(returnedData, status){var people = returnedData;var id = people.id;var name = people.name;var age = people.myAge;var address = people.address;var html = "<table width='60%' border='1' align='center'><tr><th>id</th><th>name</th><th>age</th><th>address</th><tr align='center'><td>" + id + "</td><td>" + name + "</td><td>" + age + "</td><td>" + address + "</td></tr></table>";$("#theBody table:eq(0)").remove();$("#theBody").append(html);});});});</script>  </head>    <body id="theBody">       <select id="name"><option value="zhangsan">zhangsan</option><option value="lisi">lisi</option>   </select>              <input type="button" value="get json content from server" id="button1">      </body></html>

GetJsonAction.java

package com.shengsiyuan.action.json;import java.io.PrintWriter;import javax.servlet.http.HttpServletResponse;import org.apache.struts2.ServletActionContext;import com.google.gson.Gson;import com.opensymphony.xwork2.ActionSupport;import com.shengsiyuan.action.xml.People;public class GetJsonAction extends ActionSupport{private String name;public String getName(){return name;}public void setName(String name){this.name = name;}@Overridepublic String execute() throws Exception{People people = new People();people.setId(1);people.setName(name);people.setAge(30);people.setAddress("beijing");Gson gson = new Gson();String result = gson.toJson(people);HttpServletResponse response = ServletActionContext.getResponse();response.setContentType("application/json; charset=utf-8");response.setHeader("cache-control", "no-cache"); PrintWriter out = response.getWriter();out.print(result);out.flush();out.close();return null;}}

GetJsonAction2.java

package com.shengsiyuan.action.json;import org.apache.struts2.json.annotations.JSON;import com.opensymphony.xwork2.ActionSupport;public class GetJsonAction2 extends ActionSupport{private String name;private int id;private int age;private String address;public String getName(){return name;}public void setName(String name){this.name = name;}public int getId(){return id;}public void setId(int id){this.id = id;}@JSON(name="myAge")public int getAge(){return age;}public void setAge(int age){this.age = age;}public String getAddress(){return address;}public void setAddress(String address){this.address = address;}@Overridepublic String execute() throws Exception{this.id = 1;this.age = 30;this.address = "beijing";return SUCCESS;}}

struts.xml

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE struts PUBLIC    "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"    "http://struts.apache.org/dtds/struts-2.0.dtd">    <struts> <package name="struts2_ajax" extends="json-default"><action name="getXMLAction" class="com.shengsiyuan.action.xml.GetXMLAction"></action><action name="getJsonAction" class="com.shengsiyuan.action.json.GetJsonAction"></action><action name="getJsonAction2" class="com.shengsiyuan.action.json.GetJsonAction2"><result name="success" type="json"><param name="excludeProperties">address</param></result></action></package></struts>