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用commons-fileupload-1.2 实现文件上传

2013-02-26 23:31 531 查看

1.首先，记得导入tomcat下的jar包

jsp代码 uploadSS.jsp

<%@ 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>upload</title>
</head>

<body>
<form action="FileUploadServlet" method="post"
enctype="multipart/form-data">
<input type="file" size="30" name="test" />
<br />
<input name="up" type="submit" value="上传" />
</form>
</body>
</html>

然后编写此页面跳转的servlet

package com.netcloud.upload;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
//测试成功
public class FileUploadServlet extends HttpServlet {

public FileUploadServlet() {
super();
}

public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}

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

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
final long MAX_SIZE = 3 * 1024 * 1024;// 设置上传文件最大为 3M
// 允许上传的文件格式的列表
final String[] allowedExt = new String[] { "jpg", "jpeg", "gif", "txt",
"doc", "docx", "mp3", "wma", "m4a" };
response.setContentType("text/html");
// 设置字符编码为UTF-8, 这样支持汉字显示
response.setCharacterEncoding("UTF-8");

// 实例化一个硬盘文件工厂,用来配置上传组件ServletFileUpload
DiskFileItemFactory dfif = new DiskFileItemFactory();
dfif.setSizeThreshold(4096);// 设置上传文件时用于临时存放文件的内存大小,这里是4K.多于的部分将临时存在硬盘
dfif.setRepository(new File(request.getRealPath("/")
+ "ImagesUploadTemp"));// 设置存放临时文件的目录,web根目录下的ImagesUploadTemp目录

// 用以上工厂实例化上传组件
ServletFileUpload sfu = new ServletFileUpload(dfif);
// 设置最大上传尺寸
sfu.setSizeMax(MAX_SIZE);

PrintWriter out = response.getWriter();
// 从request得到 所有 上传域的列表
List fileList = null;
try {
fileList = sfu.parseRequest(request);
} catch (FileUploadException e) {// 处理文件尺寸过大异常
if (e instanceof SizeLimitExceededException) {
out.println("文件尺寸超过规定大小:" + MAX_SIZE + "字节<p />");
out.println("<a href=\"uploadSS.jsp\" target=\"_top\">返回</a>");
return;
}
e.printStackTrace();
}
// 没有文件上传
if (fileList == null || fileList.size() == 0) {
out.println("请选择上传文件<p />");
out.println("<a href=\"uploadSS.jsp\" target=\"_top\">返回</a>");
return;
}
// 得到所有上传的文件
Iterator fileItr = fileList.iterator();
// 循环处理所有文件
while (fileItr.hasNext()) {
FileItem fileItem = null;
String path = null;
long size = 0;
// 得到当前文件
fileItem = (FileItem) fileItr.next();
// 忽略简单form字段而不是上传域的文件域(<input type="text" />等)
if (fileItem == null || fileItem.isFormField()) {
continue;
}
// 得到文件的完整路径
path = fileItem.getName();
// 得到文件的大小
size = fileItem.getSize();
if ("".equals(path) || size == 0) {
out.println("请选择上传文件<p />");
out.println("<a href=\"uploadSS.jsp\" target=\"_top\">返回</a>");
return;
}

// 得到去除路径的文件名
String t_name = path.substring(path.lastIndexOf("\\") + 1);
// 得到文件的扩展名(无扩展名时将得到全名)
String t_ext = t_name.substring(t_name.lastIndexOf(".") + 1);
// 拒绝接受规定文件格式之外的文件类型
int allowFlag = 0;
int allowedExtCount = allowedExt.length;
for (; allowFlag < allowedExtCount; allowFlag++) {
if (allowedExt[allowFlag].equals(t_ext))
break;
}
if (allowFlag == allowedExtCount) {
out.println("请上传以下类型的文件<p />");
for (allowFlag = 0; allowFlag < allowedExtCount; allowFlag++)
out.println("*." + allowedExt[allowFlag]
+ "   ");
out.println("<p /><a href=\"uploadSS.jsp\" target=\"_top\">返回</a>");
return;
}

long now = System.currentTimeMillis();
// 根据系统时间生成上传后保存的文件名
String prefix = String.valueOf(now);
// 保存的最终文件完整路径,保存在web根目录下的ImagesUploaded目录下
String u_name = request.getRealPath("/") + "ImagesUploaded/"
+ prefix + "." + t_ext;
try {
// 保存文件
fileItem.write(new File(u_name));
out.println("文件上传成功. 已保存为: " + prefix + "." + t_ext
+ "   文件大小: " + size + "字节<p />");
out.println("<a href=\"uploadSS.jsp\" target=\"_top\">继续上传</a>");
} catch (Exception e) {
e.printStackTrace();
}
}

}

public void init() throws ServletException {
// Put your code here
}

}

注意新建servlet生成的web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
<display-name>TestLearn</display-name>
<servlet>
<servlet-name>FileUploadServlet</servlet-name>
<servlet-class>com.netcloud.upload.FileUploadServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>FileUploadServlet</servlet-name>
<url-pattern>/FileUploadServlet</url-pattern>
</servlet-mapping>
</web-app>

注意：servlet提到的ImagesUploaded ImagesUploadTemp二个文件夹要放在tomcat的目录下

如D:\apache-tomcat-7.0.23\wtpwebapps\TestLearn

2.这是另外一种看起来比较简洁但是实际上跟第一种一样原理的方法：

<%@ 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>→uploadServlet→redult.jsp</title>

</head>
<body>
<form action="uploadServlet" method="POST" enctype="multipart/form-data" >
upload:<input type="file" name="text" size="30"/>
<input type="submit" value="view>>>">

</form>

</body>
</html>

跳转的servlet

package com.netcloud.upload;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.util.List;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileItem;

import org.apache.commons.fileupload.FileUploadException;

import org.apache.commons.fileupload.disk.DiskFileItemFactory;

import org.apache.commons.fileupload.servlet.ServletFileUpload;

/**
* 文件上传如果文件小,上传组件可以将文件存放在内存中,
* 如果过大时会放在临时目录里面,之后再通过IO流操作
* @author LEPING LI
*
*/
@SuppressWarnings("unchecked")
public class uploadServlet extends HttpServlet{
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
//磁盘文件条目工厂
DiskFileItemFactory factory=new DiskFileItemFactory();
// 文件上传如果文件小,上传组件可以将文件存放在内存中,
//如果过大时会放在临时目录里面,之后再通过IO流操作
//获取目录真实路径   / 代表 WebRoot目录下面
String path=request.getRealPath("/");
//设置临时目录
factory.setRepository(new File(path));
//设置上传文件大小
factory.setSizeThreshold(1024*1024);
//创建一个ServletFileUpload 实例
ServletFileUpload sfu=new ServletFileUpload(factory);
try {
//解析请求,取得FileItem 列表
List<FileItem> lis=sfu.parseRequest(request);
//循环遍历
for(FileItem item:lis){
//判断是否是简单的表单字段
if(item.isFormField()){
String name=item.getFieldName();
String value=item.getString("UTF-8");
request.setAttribute(name, value);
}else{
//取得字段名
String name=item.getFieldName();
//       取得文件路径名
String value=item.getName();
System.out.println("value:"+value);
//为了屏蔽各个浏览器提供的路径不同异常
int start=value.lastIndexOf("//");
//取得文件名
String fileName=value.substring(start+1);
request.setAttribute(name, fileName);

item.write(new File(path,fileName));   //这句代码与下面高亮显示的代表功能相同

//获取文件输出流
File f=new File(path,fileName);
OutputStream os=new FileOutputStream(f);
//获取文件条目的输入流
InputStream in=item.getInputStream();
byte[] buffer=new byte[400];
int length=0;
//读写文件
while((length=in.read(buffer))>0){
os.write(buffer,0,length);
}
os.flush();
os.close();
in.close();

}
}
} catch (FileUploadException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
request.getRequestDispatcher("result.jsp").forward(request, response);
}
}

servlet跳转的result.jsp

<%@ 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>Insert title here</title>
</head>
<body>
文件目录:${requestScope.text }<br>
</body>
</html>

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