[转载]Struts2文件上传实例

struts2没有提供自己的请求解析器,也就是说,struts2不会自己去处理multipart/form-data的请求,它需要调用其他请求解析器,将HTTP请求中的表单域解析出来,但struts2在原有的上传解析器上作了进一步封装，更进一步简化了文件上传,Struts2的struts.properties配置文件中,配置struts2的上传文件解析器struts.multipart.parser=jakarta(srtuts2默认),也可以设置为常用的cos,pell等。

项目结构示意图:

web.xml文件内容:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>

</web-app>

这里web.xml多配置了一个ActionContextCleanUp的配置,这个类是一个filter,他的作用是方便strut2与sitemesh整合,与文件上传本没有关系,但不加载这个filter,可能在上传中出现莫名的异常,加入后就稳定了,可能是strut2的bug吧。

index.jsp文件内容:

<%@page language="java" pageEncoding="GBK"%>
<%@taglib prefix="s" uri="/struts-tags"%>
<%@taglib prefix="c" uri="http://java.sun.com/jstl/core_rt"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
  <meta http-equiv="pragma" content="no-cache">
  <meta http-equiv="cache-control" content="no-cache">
  <meta http-equiv="expires" content="0">
</head>
<body>
  ${requestScope.typeError}
  <form action="upload.action" method="post"
   enctype="multipart/form-data">
   <input type="text" name="title" />
   <br>
   <input type="file" name="upload" />
   <br>
   <input value="upload" type="submit" />
  </form>
</body>
</html>
success.jsp文件内容:

<%@ page language="java" pageEncoding="GBK"%>
<%@taglib prefix="s" uri="/struts-tags"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
  <meta http-equiv="pragma" content="no-cache">
  <meta http-equiv="cache-control" content="no-cache">
  <meta http-equiv="expires" content="0">
</head>

<body>
  上传成功!
  <br>
  文件标题:
  <s:property value=" + title" />
  <br>
  文件为：
  <img src="<s:property value="'upload/' + uploadFileName"/>" />
  <br>
</body>
</html>
struts.properties文件内容:

struts.locale=zh_CN
struts.i18n.encoding=GBK
struts.multipart.parser=jakarta
struts.xml文件内容:

<?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>
<include file="struts-default.xml" />
    <constant name="struts.multipart.maxSize" value="20971520" />
<constant name="struts.custom.i18n.resources"
  value="globalMessages" />
<constant name="struts.i18n.encoding" value="GBK" />
<package name="lee" extends="struts-default">
  <action name="upload" class="lee.UploadAction">
   <param name="allowTypes">
    image/pjpeg,image/bmp,image/jpg,image/png,image/gif,image/jpeg
   </param>
   <param name="savePath">/upload</param>
   <result>/success.jsp</result>
   <result name="input">/index.jsp</result>
  </action>
</package>
</struts>
参看tomcat的web.xml中的mime:
<mime-mapping>
   <extension>gif</extension>
   <mime-type>image/gif</mime-type>
</mime-mapping>

UploadAction.java文件内容:

package lee;

import java.io.*;
import com.opensymphony.xwork2.ActionContext;
import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionSupport;

public class UploadAction extends ActionSupport {
private String title;
private File upload;
private String uploadContentType;
private String uploadFileName;
private String allowTypes;
// 接受依赖注入的属性
private String savePath;
// 接受依赖注入的方法
public void setSavePath(String value) {
  this.savePath = value;
}
private String getSavePath() throws Exception {
  return ServletActionContext.getServletContext().getRealPath(savePath);
}
public void setTitle(String title) {
  this.title = title;
}
public void setUpload(File upload) {
  this.upload = upload;
}
public void setUploadContentType(String uploadContentType) {
  this.uploadContentType = uploadContentType;
}
public void setUploadFileName(String uploadFileName) {
  this.uploadFileName = uploadFileName;
}
public String getTitle() {
  return (this.title);
}
public File getUpload() {
  return (this.upload);
}
public String getUploadContentType() {
  return (this.uploadContentType);
}
public String getUploadFileName() {
  return (this.uploadFileName);
}
@Override
public String execute() throws Exception {
  System.out.println("开始上传单个文件---");
  System.out.println(getSavePath());
  System.out.println("==========" + getUploadFileName());
  System.out.println("==========" + getUploadContentType());
  System.out.println("==========" + getUpload());
  // 判断是否允许上传
  String filterResult = filterType(this.getAllowTypes().split(","));
  if (filterResult != null) {
   ActionContext.getContext().put("typeError","您要上传的文件类型不正确");
   return filterResult;
  }
  // 以服务器的文件保存地址和原文件名建立上传文件输出流
  FileOutputStream fos = new FileOutputStream(getSavePath() + ""
    + getUploadFileName());
  FileInputStream fis = new FileInputStream(getUpload());
  byte[] buffer = new byte[1024];
  int len = 0;
  while ((len = fis.read(buffer)) > 0) {
   fos.write(buffer, 0, len);
  }
  return SUCCESS;
}
public String filterType(String[] types) {
  String fileType = this.getUploadContentType();
  for (String type : types) {
   if (type.equals(fileType)) {
    return null;
   }
  }
  return INPUT;
}
public String getAllowTypes() {
  return allowTypes;
}
public void setAllowTypes(String allowTypes) {
  this.allowTypes = allowTypes;
}
}
Struts2针对表单中名为xxx的文件域,在对应的Action类中使用3个属性来封装该文件域信息：
1.类型为File的xxx属性:用来封装页面文件域对应的文件内容。
2.类型为String的xxxFileName属性:用来封装该文件域对应的文件的文件名。
3.类型为String的xxxContentType属性:用来封装该文件域应用的文件的文件类型。

以上程序调试通过！