SSH学习（五）Struts2文件上传

原文来自搬砖工，如需转载请注明出处

博主SSH框架专栏请戳这里http://blog.csdn.net/column/details/14227.html
一、使用commons-fileupload上传文件

commons-fileupload是一个开源框架，要使用该项目实现文件上传需要使用两个文件：

1.commons-io.jar

2.commons-fileupload.jar

实现上传文件的步骤如下：

1.创建上传页面，注意form表单的enctype的属性值应为“multipart/form-data”

2.创建servlet调用commons-fileupload API实现文件上传 

示例代码如下：

上传页面form表单

<form name="" id="" action="/servlet/UploadServlet" enctype="multipart/form-data" method="post">
<table border="0">
<tr>
<td>File:</td>
<td><input type="file" name="f" /></td>
</tr>
<tr>
<td colspan="2" align="center" ><input type="submit"/></td>
</tr>
</table>
</form>

然后创建一个servlet，重新UploadServlet的doPost方法：

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
try {
List items = upload.parseRequest(request);
Iterator iter = items.iterator();
while(iter.hasNext()){
FileItem item = (FileItem) iter.next();
if(item.isFormField()){
System.out.println(item.getFieldName());
}else{
System.out.println(item.getFieldName());
String filename = item.getName();
System.out.println(filename);

String path = this.getServletContext().getRealPath("\\file");
File file = new File(path+"\\"+filename);

item.write(file);
}
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

注意：表单在设置参数的时候必须加上method=post，否则后台会报错。
二、使用Struts2上传文件

首先创建一个UploadAction

package com.study.action;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionSupport;

public class UploadAction extends ActionSupport{
private File upload;
private String uploadContentType;
private String uploadFileName;
private String savePath;

public String execute() throws Exception {
String path = this.getSavePath();
String filename = this.getUploadFileName();
System.out.println(path);
System.out.println(filename);
FileOutputStream out = new FileOutputStream(path+"//"+filename);
FileInputStream in = new FileInputStream(this.getUpload());
byte[]b = new byte[in.available()];
in.read(b);
out.write(b);
in.close();
out.close();
return SUCCESS;
}
public File getUpload() {
return upload;
}
public void setUpload(File upload) {
this.upload = upload;
}
public String getUploadContentType() {
return uploadContentType;
}
public void setUploadContentType(String uploadContentType) {
this.uploadContentType = uploadContentType;
}
public String getUploadFileName() {
return uploadFileName;
}
public void setUploadFileName(String uploadFileName) {
this.uploadFileName = uploadFileName;
}
public String getSavePath() {
savePath = ServletActionContext.getServletContext().getRealPath("//file");
return savePath;
}
public void setSavePath(String savePath) {
this.savePath = savePath;
}

}

在Action中包含了如下参数，一个File对象upload，文件名称uploadFileName，ContentType是uploadContentType还有一个保存路径savePath。在Struts2中，根据特有的命名规则，根据upload文件对象就可以给uploadFileName赋真实的文件名称。而upload实际中是取得的一个临时文件。最后保存到我们指定的路径下。

struts.xml中的配置：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd">
<struts>
<constant name="struts.multipart.saveDir" value="c:\\temp"></constant>
<package name="example" namespace="/" extends="struts-default">
<action name="upload" class="com.study.action.UploadAction">
<result name="success">/Success.jsp</result>
<param name="savePath">/file</param>
</action>
</package>
</struts>

在配置中，我们指定一个临时文件路径struts.multipart.saveDir，自己创建一个文件夹来当做临时文件夹。临时文件在文件操作完毕后会自动删除。然后我们在action中声明一个参数savePath，它的值就是/file。对于如何根据upload取得uploadFileName，大家可以理解为将upload当做参数{1}，然后文件名属性就是*FileName。其他的同理。

然后就是一个简单的jsp页面

<form name="" id="" action="<%= path%>/upload.action" enctype="multipart/form-data" method="post">
<table border="0">
<tr>
<td>File:</td>
<td><input type="file" name="upload" /></td>
</tr>
<tr>
<td colspan="2" align="center" ><input type="submit"/></td>
</tr>
</table>
</form>

注意，在这里的input就必须定义名称name，它的值就是我们后台所命名的属性值名称。

三、多个文件上传

对于同时提交多个文件，我们需要把Action中的属性定义为数组类型或list类型。在文件读写的时候用for循环取出所有文件即可，如：

package com.study.action;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import com.opensymphony.xwork2.ActionSupport;

public class UploadAction extends ActionSupport{
private File[] upload;
private String[] uploadContentType;
private String[] uploadFileName;
private String savePath;
public String execute() throws Exception {
String path = this.getSavePath();
for (int i = 0; i < upload.length; i++) {
String filename = this.getUploadFileName()[i];
System.out.println(path);
System.out.println(filename);
FileOutputStream out = new FileOutputStream(path+"//"+filename);
FileInputStream in = new FileInputStream(this.getUpload()[i]);
byte[]b = new byte[in.available()];
in.read(b);
out.write(b);
in.close();
out.close();
}

return SUCCESS;
}
public File[] getUpload() {
return upload;
}
public void setUpload(File[] upload) {
this.upload = upload;
}
public String[] getUploadContentType() {
return uploadContentType;
}
public void setUploadContentType(String[] uploadContentType) {
this.uploadContentType = uploadContentType;
}
public String[] getUploadFileName() {
return uploadFileName;
}
public void setUploadFileNa
4000
me(String[] uploadFileName) {
this.uploadFileName = uploadFileName;
}
public String getSavePath() {
return savePath;
}
public void setSavePath(String savePath) {
this.savePath = savePath;
}
}

注：在Struts2中还可以使用它的标签来作文件上传