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:
![[转载]Struts2文件上传实例](http://simg.sinajs.cn/blog7style/images/common/sg_trans.gif "[转载]Struts2文件上传实例")
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！
