图片上传功能<转>http://blog.csdn.net/u011159417/article/details/50126023

以前也实现过上传，只不过每次都是，写完之后没有总结，下次遇到时，还要重新写，重新调式，很是浪费时间，所以，今天实现一个上传图片的功能，包括简单的页面和servlet，下次再要写这个功能时，直接拿过来就可以了，没有理论，直接上代码+少量的注释。在最下面我会把项目上传，大家需要jar包，可以从项目中拿。

该项目用到的jar包如图，在下面的项目demo中有jar包：

一、upload.jsp页面代码：

[html] view plain copy

print ?

<%@ 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">
<meta http-equiv="pragma" content="no-cache" />
<base target="_self">
<title>文件上传</title>
</head>
<body>
<h5>文件上传</h5><hr/>
<form id="file_upload_id" name="file_upload_name" action="upload" method="post" enctype="multipart/form-data">
文件名称：<input type="text" name="fileName" value="aaa.jpg"/>
作者： <input type="text" name="author" value="jack"/>
<div><input type="file" name="file_upload"/></div>
<div><input type="submit" value="上传" /></div>
</form>
</body>
</html>

二、web.xml配置文件代码：

[html] view plain copy

print ?

<?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" 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>UploadDemo</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
<servlet>
<servlet-name>uploadPhoto</servlet-name>
<servlet-class>com.upload.demo.UploadServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>uploadPhoto</servlet-name>
<url-pattern>/upload</url-pattern>
</servlet-mapping>
</web-app>

三、UploadServlet代码：

[html] view plain copy

print ?

package com.upload.demo;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.UUID;
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.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import com.lidroid.xutils.http.RequestParams;
public class UploadServlet extends HttpServlet{
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
doPost(req, resp);
};
@Override
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
//服务器端接收,请求被后台拦截到这里
exeUploadedInfos(request, response);
};
/**
* 定义接口
*/
public interface UploadStatusListener {
public void status(boolean status, Map<String, String> params,
List<String> files, HttpServletRequest request);
}
UploadStatusListener mUploadStatusListener = null;
// 注册监听器，如果这里没有使用Vector而是使用ArrayList那么要注意同步问题
public void addStatusListener(UploadStatusListener listener) {
mUploadStatusListener = listener;
}
/**
* @function：回调方法，执行图片上传，根据成功或失败的状态完成其他的操作
* @param request
* @param response
*/
private void exeUploadedInfos(HttpServletRequest request,
HttpServletResponse response) {
UploadServlet up = new UploadServlet();
up.addStatusListener(new UploadStatusListener() {
public void status(boolean status, Map<String, String> params,
List<String> files, HttpServletRequest request) {
if (status) {//成功
//Map中取值
String memberId = params.get("memberId");
//List中取值
String fileUrl = files.get(0);
System.out.println("===================================成功");
} else {
//失败
System.out.println("========================================失败");
}
}
});
up.upload(request, response);
}
/**
* @function：具体上传图片的功能在这里完成，
* 然后调用接口回调方法mUploadStatusListener.status(flag, params, filenames , request);跳转到回调函数中
* @param request
* @param response
*/
public void upload(HttpServletRequest request, HttpServletResponse response) {
boolean flag = false;
Map<String, String> params = new HashMap<String, String>();
List<String> filenames = new ArrayList<String>();
try {
System.out.println("开始文件上传****************");
request.setCharacterEncoding("utf-8"); // 设置编码
// 设置上传文件最大为 3M
final long MAX_SIZE = 3 * 1024 * 1024;
// 1.创建一个解析器工厂
DiskFileItemFactory factory = new DiskFileItemFactory();
// 获取临时文件路径
String savePath = "F:/upload/" ;//具体的路径
if(!new File(savePath).exists()){
new File(savePath).mkdirs();
}
factory.setRepository(new File(savePath));
factory.setSizeThreshold(4096);
// 2.得到一个解析器
ServletFileUpload upload = new ServletFileUpload(factory);
upload.setSizeMax(MAX_SIZE);
// upload.setHeaderEncoding("UTF-8");
// 3.将请求传入解析器，对请求进行解析
List<FileItem> list = upload.parseRequest(request);
// 4.迭代list集合，得到每个输入项的数据
int count = 0 ;
for (FileItem item : list) {
count ++ ;
// 5.判断item的类型
if (item.isFormField()) {
// 普通文本输入项
String inputName = item.getFieldName();
String inputValue = item.getString();
params.put(inputName, inputValue);
System.out.println("==================传进来的参数： "+count+"、"+inputName + "=" + inputValue);
} else {
// 上传文件输入项（如图片）
String fileName = item.getName();// 获取文件名
if (!"".equals(fileName)) {
fileName = fileName.substring(fileName.lastIndexOf("\") + 1);
System.out.println("*************存放传过来的图片****************");
InputStream in = item.getInputStream();
FileOutputStream out = new FileOutputStream(savePath+fileName);
byte[] buf = new byte[1024];
int len = 0;
while ((len = in.read(buf)) > 0) {
out.write(buf, 0, len);
}
in.close();
out.close();
item.delete();// 删除临时文件
filenames.add("上传成功了") ;
flag = true;
if (mUploadStatusListener != null) {
System.out.println("======文件上传： ===flag=" + flag +";==="+ params.toString()
+ "==文件名fileName：=" + fileName);
mUploadStatusListener.status(flag, params, filenames , request);
}
System.out.println("文件上传结束****************");
}
}
}
} catch (Exception e) {
e.printStackTrace();
request.setAttribute("message", "上传失败");
System.out.println("***********上传失败******************");
if (mUploadStatusListener != null) {
System.out.println("****************上传失败*******************************");
mUploadStatusListener.status(flag, params, filenames , request);
}
}
}
}

四、代码解释：

1、访问路径：http://localhost:8080/UploadDemo/upload.jsp

如图：

2、点击上传后，进入UploadServlet类

List<FileItem> list = upload.parseRequest(request);
产生临时上传文件

如图：

3、FileOutputStream out = new FileOutputStream(savePath+fileName);
创建要生成的图片

如图：

4、out.close();
执行完这行代码，上传图片的字节流写入完毕，完整图片如图

5、item.delete();// 删除临时文件，删除后如图：

五、项目下载：

上传图片demo下载，点这里