struts2文件上传

最新推荐文章于 2024-08-11 21:37:06 发布

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文章标签：

#struts #upload #string #stylesheet #buffer #encoding

本文详细介绍了Struts2中文件上传的原理、配置与实践，包括上传页面的创建、Java代码实现、Struts.xml配置及web.xml配置，以及如何通过Struts2简化文件上传过程。

一.简介

Struts2并未提供自己的请求解析器，也就是就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基础上做了进一步封装，更进一步简化了文件上传。
Struts2默认使用的是Jakarta的Common-FileUpload框架来上传文件，因此，要在web应用中增加两个Jar文件：commons-fileupload-1.2.jar和commons-io-1.3.1.jar。它在原上传框架上做了进一步封装，简化了文件上传的代码实现，取消了不同上传框架上的编程差异。
如果要改成其它的文件上传框架，可以修改struts.multipart.parser常量的值为cos/pell，默认值是jakata。并在classpath中增加相应上传组件的类库

例如配置成cos上传

struts.multipart.parser=cos

struts.multipart.maxSize=1024 指定文件的最大字结数

二.原理

不管用common-fileUPload框架，还是用cos，都是通过将HTTP的数据保存到临时文件夹，然后Struts使用fileUpload拦截器将文件绑定到Action的实例中。

三.需要的jar包(默认使用commons-fileupload,如果使用cos，要将jar引进来)

commons-logging-1.1.jar
freemarker-2.3.8.jar
ognl-2.6.11.jar
struts2-core-2.0.6.jar
xwork-2.0.1.jar
commons-io-1.3.1.jar
commons-fileupload-1.2.jar

四.实例

1.首先，创建上传页面

Html代码

<%@page language="java" contentType = "text/html; charset=utf-8" pageEncoding = "utf-8"%>
<%@taglib prefix="s" uri ="/struts-tags"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP 'FileUpload.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">
-->
</head>
<body>
<s:form action ="fileUpload" method ="POST" enctype ="multipart/form-data">
<s:fielderror />
<s:file name ="upload"/>
<s:submit />
</s:form >
</body>
</html>

<%@page language="java" contentType = "text/html; charset=utf-8" pageEncoding = "utf-8"%> 
<%@taglib prefix="s" uri ="/struts-tags"%> 


<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>

    <title>My JSP 'FileUpload.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">
	-->

  </head>
  
  <body>
   <s:form action ="fileUpload" method ="POST" enctype ="multipart/form-data"> 
		<s:fielderror />
        <s:file name ="upload"/>   
        <s:submit /> 
    </s:form > 

  </body>
</html>

2.action

Java代码

package com;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Date;
import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionSupport;
public class FileUploadAction extends ActionSupport {
private static final long serialVersionUID = 572146812454l;
private File upload;
private String uploadContentType;
private String uploadFileName;
private String imageFileName;
public String getUploadContentType() {
return uploadContentType;
}
public void setUploadContentType(String uploadContentType) {
this.uploadContentType = uploadContentType;
}
public File getUpload() {
return upload;
}
public void setUpload(File upload) {
this.upload = upload;
}
public String getUploadFileName() {
return uploadFileName;
}
public void setUploadFileName(String uploadFileName) {
this.uploadFileName = uploadFileName;
}
public void setImageFileName(String imageFileName) {
this.imageFileName = imageFileName;
}
public String getImageFileName() {
return imageFileName;
}
private static void copy(File src, File dst) {
try {
InputStream in = null;
OutputStream out = null;
try {
in = new BufferedInputStream(new FileInputStream(src));
out = new BufferedOutputStream(new FileOutputStream(dst));
byte[] buffer = new byte[1024*10];
while (in.read(buffer) > 0) {
out.write(buffer);
}
} finally {
if (null != in) {
in.close();
}
if (null != out) {
out.close();
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public String execute() {
System.out.println(uploadFileName);
imageFileName = System.currentTimeMillis() + uploadFileName.substring(uploadFileName.lastIndexOf("."));
File imageFile = new File(ServletActionContext.getServletContext()
.getRealPath("/uploadImages")
+ "/" + imageFileName);
copy(upload, imageFile);
return SUCCESS;
}
}

package com;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Date;

import org.apache.struts2.ServletActionContext;

import com.opensymphony.xwork2.ActionSupport;

public class FileUploadAction extends ActionSupport {
	
	private static final long serialVersionUID = 572146812454l;

	private File upload;

	private String uploadContentType;

	private String uploadFileName;

	private String imageFileName;

	public String getUploadContentType() {
		return uploadContentType;
	}

	public void setUploadContentType(String uploadContentType) {
		this.uploadContentType = uploadContentType;
	}

	public File getUpload() {
		return upload;
	}

	public void setUpload(File upload) {
		this.upload = upload;
	}

	public String getUploadFileName() {
		return uploadFileName;
	}

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

	public void setImageFileName(String imageFileName) {
		this.imageFileName = imageFileName;
	}

	public String getImageFileName() {
		return imageFileName;
	}

	private static void copy(File src, File dst) {
		try {
			InputStream in = null;
			OutputStream out = null;
			try {
				in = new BufferedInputStream(new FileInputStream(src));
				out = new BufferedOutputStream(new FileOutputStream(dst));
				byte[] buffer = new byte[1024*10];
				while (in.read(buffer) > 0) {
					out.write(buffer);
				}
			} finally {
				if (null != in) {
					in.close();
				}
				if (null != out) {
					out.close();
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	@Override
	public String execute() {
		System.out.println(uploadFileName);
		
		imageFileName = System.currentTimeMillis() + uploadFileName.substring(uploadFileName.lastIndexOf("."));
		File imageFile = new File(ServletActionContext.getServletContext()
				.getRealPath("/uploadImages")
				+ "/" + imageFileName);
		copy(upload, imageFile);
		return SUCCESS;
	}

}

表单的enctype ="multipart/form-data，与一般的上传一样．

<s:file name="upload">会将upload绑定到action的upload,其次他还会将上传记文件的MIME类型绑定到uploadContentType,文件名绑定到uploadFileName中，他们是通过setUploadContentType和setUploadFileName进行绑定的

3.struts.xml的配置

Xml代码

<?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="fileUploadDemo" extends="struts-default">
<action name ="fileUpload" class ="com.FileUploadAction">
<interceptor-ref name ="fileUpload">
<param name ="allowedTypes">image/bmp,image/png,image/gif,image/jpeg,image/jpg</param>
</interceptor-ref>
<interceptor-ref name ="defaultStack"/>
<result name ="input" >/fileUpload.jsp</result>
<result name ="success">/showUpload.jsp </result>
</action>
</package>
</struts>

<?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="fileUploadDemo" extends="struts-default">
    	<action name ="fileUpload" class ="com.FileUploadAction"> 
    		<!-- 验证上传文件的类型 -->
           	<interceptor-ref name ="fileUpload"> 
                <param name ="allowedTypes">image/bmp,image/png,image/gif,image/jpeg,image/jpg</param> 
            </interceptor-ref> 
            <interceptor-ref name ="defaultStack"/> 
            <!-- 如果加入了验证上传文件的类型,必须要加input -->
            <result name ="input" >/fileUpload.jsp</result>
            <result name ="success">/showUpload.jsp </result> 
        </action> 
    </package>
</struts>

4.最后是web.xml的配置

Xml代码