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Struts2文件上传

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Struts2文件上传

上传单个文件

Struts2中，提供了一个很容易操作的文件上传组件。
用Struts2上传单个文件的功能非常容易实现，只要使用普通的Action即可。但为了获得一些文件上传的信息，如上传文件名等，需要按照一定规则来为Action类增加一些getter和setter方法。
Struts2的文件上传默认使用的是Jakarta的Common-FileUpload文件上传框架。因此需要在Web应用中增加两个Jar包，即common-io-*.jar和common-fileupload-*.jar。

我们接着在struts2概述中的struts2项目中开发文件上传实例。

指定文件夹

在D盘下新建upload文件夹，上传的文件放到这个目录下。

upload.jsp

在WebContent中新建upload.jsp，代码如下：

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<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib uri="/struts-tags" prefix="s"%>
<!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>文件上传</title>
</head>
<body>
	<s:form action="upload.action" method="post" enctype="multipart/form-data">
		<s:file name="upload" label="上传的文件"></s:file>
		<s:submit value="上传"></s:submit>
	</s:form>

</body>
</html>

UploadAction

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package com.voidking.struts2.action;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;

import com.opensymphony.xwork2.ActionSupport;

public class UploadAction extends ActionSupport{
	private File upload;
	private String uploadFileName;
	
	public String getUploadFileName() {
		return uploadFileName;
	}

	public void setUploadFileName(String uploadFileName) {
		this.uploadFileName = uploadFileName;
	}

	public File getUpload()
	{
		return upload;
	}
	
	public void setUpload(File upload)
	{
		this.upload=upload;
	}
	
	public String execute() throws Exception{
		InputStream is=new FileInputStream(getUpload());
		OutputStream os = new FileOutputStream("d:\\upload\\"+uploadFileName);
		byte buffer[] = new byte[1024];
		int count= 0;
		while((count=is.read(buffer))>0)
		{
			os.write(buffer,0,count);
		}
		os.close();
		is.close();
		return SUCCESS;
	}
	
}

上传的文件经过Action处理后，会被写到指定的路径下。其实也可以把上传的文件写入数据库中，之后的例子会介绍如何把照片写入到数据库。
需要注意的是，Struts2上传文件的默认大小限制为2MB，如果需要修改默认大小，只需要在Struts2的struts.properties文件中修改struts.multipart.maxSize。如struts.mulitipart.maxSize=1024表示上传文件的总大小不能超过1KB。

struts.xml

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<?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="default" namespace="/" extends="struts-default">
    
    	<interceptors>
    		<interceptor name="myInterceptor" class="com.voidking.struts2.tool.MyInterceptor"></interceptor>
    	</interceptors>
    	<default-interceptor-ref name=""></default-interceptor-ref>
    	
        <default-action-ref name="index" />
        <action name="struts" class="com.voidking.struts2.action.StrutsAction">
            <result name="success">/welcome.jsp</result>
            <result name="error">/hello.jsp</result>
            <result name="input">/hello.jsp</result>
            
            <!-- 拦截配置在result后面 -->
            <!-- 使用系统默认拦截器栈 -->
            <interceptor-ref name="defaultStack"></interceptor-ref>
            <!-- 配置拦截器 -->
            <interceptor-ref name="myInterceptor"></interceptor-ref>
            
        </action>
        
        <action name="upload" class="com.voidking.struts2.action.UploadAction">
        	<result name="success">/uploadsuccess.jsp</result>
        </action>
    </package>
</struts>

uploadsuccess.jsp

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<%@ 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>上传成功</title>
</head>
<body>
	恭喜你，上传成功！
</body>
</html>

404错误

部署项目，启动Tomcat，访问：http://localhost:8080/struts2/upload.jsp ，提示 HTTP Status 404 - /struts2/upload.jsp。访问主页：http://localhost:8080/struts2/ ，同样提示404错误！

啊勒，这是肿么回事？想来想去，引起错误的原因，可能是昨天关闭eclipse的时候，没有先关闭Tomcat服务器，引起了一些配置错误。

查看tomcat/conf文件夹下的配置文件，server.xml和tomcat-users.xml，感觉没啥问题。

访问：http://localhost:8080 ，使用manager-gui账户登录tomcat，Manager App，可以看到，struts2项目的Running属性的值为false。奥~这就是问题所在了！点击start按钮，啊勒，无效！

删除webapps下的struts2工程，重新发布，运行tomcat，还是404错误！

再次点击start按钮，同时观察Console下面的信息：

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SEVERE: Exception starting filter struts2
Unable to load configuration. - package - file:/D:/Server/tomcat/webapps/struts2/WEB-INF/classes/struts.xml:7:67
......
SEVERE: Error filterStart

经过查找资料，确定了是struts.xml的配置问题。首先修改struts.xm如下：

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<?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="default" namespace="/" extends="struts-default">
    
    	<interceptors>
    		<interceptor name="myInterceptor" class="com.voidking.struts2.tool.MyInterceptor"></interceptor>
    	</interceptors>
    	<default-interceptor-ref name=""></default-interceptor-ref>
    	
        <default-action-ref name="index" />
        <action name="struts" class="com.voidking.struts2.action.StrutsAction">
            <result name="success">/welcome.jsp</result>
            <result name="error">/hello.jsp</result>
            <result name="input">/hello.jsp</result>
            
            <!-- 拦截配置在result后面 -->
            <!-- 使用系统默认拦截器栈 -->
            <interceptor-ref name="defaultStack"></interceptor-ref>
            <!-- 配置拦截器 -->
            <interceptor-ref name="myInterceptor"></interceptor-ref>
            
        </action>
    </package>
</struts>

启动Tomcat，项目果然可以访问了！那么，为什么在package中多加了一个action就会出错呢？很多教程中，明明可以多个action写在一个package里啊！再看这个package，有何特殊之处？配置了拦截器！那么，接下来的action是否必须配置拦截器？修改试试。

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<?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="default" namespace="/" extends="struts-default">
    
    	<interceptors>
    		<interceptor name="myInterceptor" class="com.voidking.struts2.tool.MyInterceptor"></interceptor>
    	</interceptors>
    	<default-interceptor-ref name=""></default-interceptor-ref>
    	
        <default-action-ref name="index" />
        <action name="struts" class="com.voidking.struts2.action.StrutsAction">
            <result name="success">/welcome.jsp</result>
            <result name="error">/hello.jsp</result>
            <result name="input">/hello.jsp</result>
            
            <!-- 拦截配置在result后面 -->
            <!-- 使用系统默认拦截器栈 -->
            <interceptor-ref name="defaultStack"></interceptor-ref>
            <!-- 配置拦截器 -->
            <interceptor-ref name="myInterceptor"></interceptor-ref>
            
        </action>
        
        <action name="upload" class="com.voidking.struts2.action.UploadAction">
        	<result name="success">/uploadsuccess.jsp</result>
        	<interceptor-ref name="defaultStack"></interceptor-ref>
        </action>
    </package>
</struts>

启动Tomcat，项目可以正常访问。综上，可以得出一个结论：package包中如果定义了拦截器，那么，接下来的action中必须配置拦截器，否则会引起项目无法启动！

警告

我们的项目已经可以正常运行，上传功能也正常。但是，当我们访问：http://localhost:8080/struts2/upload.jsp ，会报出如下警告：

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'upload.action' in namespace: ''. Form action defaulting to 'action' attribute's literal value.

经过查找资料，原来这是因为没有正确使用tag，upload.jsp修改如下：

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<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib uri="/struts-tags" prefix="s"%>
<!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>文件上传</title>
</head>
<body>
	<s:form action="upload" namespace="/" method="post" enctype="multipart/form-data">
		<s:file name="upload" label="上传的文件"></s:file>
		<s:submit value="上传"></s:submit>
	</s:form>

</body>
</html>

再次访问，已经没有警告了。但是还是有提示信息：

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At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.

对于有洁癖的同学可以参考下面的参考文档去除这个信息，小编这里不再赘述。

多文件上传

多文件上传和单文件上传类似，只需要改动几个地方即可。

upload.jsp

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<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib uri="/struts-tags" prefix="s"%>
<!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>文件上传</title>
</head>
<body>
	<s:form action="upload" namespace="/" method="post" enctype="multipart/form-data">
		<s:file name="upload" label="上传的文件"></s:file>
		<s:submit value="上传"></s:submit>
	</s:form>
	<hr/>
	<s:form action="upload2" namespace="/" method="post" enctype="multipart/form-data">
		<s:file name="upload2" label="上传的文件"></s:file>
		<s:file name="upload2" label="上传的文件"></s:file>
		<s:file name="upload2" label="上传的文件"></s:file>
		<s:submit value="批量上传"></s:submit>
	</s:form>
</body>
</html>

Upload2Action

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package com.voidking.struts2.action;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.List;

import com.opensymphony.xwork2.ActionSupport;

public class Upload2Action extends ActionSupport{
	private List<File> upload2;
	private List<String> upload2FileName;
	
	
	
	public List<File> getUpload2() {
		return upload2;
	}



	public void setUpload2(List<File> upload2) {
		this.upload2 = upload2;
	}


	public List<String> getUpload2FileName() {
		return upload2FileName;
	}



	public void setUpload2FileName(List<String> upload2FileName) {
		this.upload2FileName = upload2FileName;
	}



	public String execute() throws Exception{
		
		if(upload2!=null || upload2FileName!=null)
		{
			for(int i=0;i<upload2.size();i++)
			{
				InputStream is = new FileInputStream(upload2.get(i));
				OutputStream os=new FileOutputStream("d:\\upload\\"+getUpload2FileName().get(i));
				byte buffer[] = new byte[1024];
				int count=0;
				while((count=is.read(buffer))>0)
				{
					os.write(buffer,0,count);
				}
				os.close();
				is.close();
				
				return SUCCESS;
			}
		}
		
		return ERROR;
	}
	
}

这里需要注意的是属性命名问题，如果private List<File> upload2;，那么必须private List<String> upload2FileName;，否则无法获取到文件名。

struts.xml

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<?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>
	<constant name="struts.multipart.saveDir" value="/tmp"/>
    <package name="default"  extends="struts-default">
    
    	<interceptors>
    		<interceptor name="myInterceptor" class="com.voidking.struts2.tool.MyInterceptor"></interceptor>
    	</interceptors>
    	<default-interceptor-ref name=""></default-interceptor-ref>
    	
        <default-action-ref name="index" />
        <action name="struts" class="com.voidking.struts2.action.StrutsAction">
            <result name="success">/welcome.jsp</result>
            <result name="error">/hello.jsp</result>
            <result name="input">/hello.jsp</result>
            
            <!-- 拦截配置在result后面 -->
            <!-- 使用系统默认拦截器栈 -->
            <interceptor-ref name="defaultStack"></interceptor-ref>
            <!-- 配置拦截器 -->
            <interceptor-ref name="myInterceptor"></interceptor-ref>
            
        </action>
        
        <action name="upload" class="com.voidking.struts2.action.UploadAction">
        	<result name="success">/uploadsuccess.jsp</result>
        	<interceptor-ref name="defaultStack"></interceptor-ref>
        </action>
        
        <action name="upload2" class="com.voidking.struts2.action.Upload2Action">
        	<result name="success">/uploadsuccess.jsp</result>
        	<interceptor-ref name="defaultStack"></interceptor-ref>
        </action>
    </package>
</struts>

其中，<constant name="struts.multipart.saveDir" value="/tmp"/>最好保留，不然会有提示信息:
INFO: Unable to find 'struts.multipart.saveDir' property setting.。另一个解决办法是在struts.properties加入：
struts.multipart.saveDir = /tmp。

参考文档

《Java EE基础实用教程》，郑阿奇主编

Form action defaulting to ‘action’ attribute’s literal value：
http://www.blogjava.net/parable-myth/archive/2010/10/28/336387.html

解决Tomcat7“At least one JAR was scanned for TLDs yet contained no TLDs”问题：
http://mov-webhobo.iteye.com/blog/1939655
http://love-love-l.blog.163.com/blog/static/2107830420131159580327/