• 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?

    1. <%@ page language="java" contentType="text/html; charset=UTF-8"
    2. pageEncoding="UTF-8"%>
    3. <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    4. <html>
    5. <head>
    6. <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    7. <meta http-equiv="pragma" content="no-cache" />
    8. <base target="_self">
    9. <title>文件上传</title>
    10. </head>
    11. <body>
    12. <h5>文件上传</h5><hr/>
    13. <form id="file_upload_id" name="file_upload_name" action="upload" method="post" enctype="multipart/form-data">
    14.         文件名称：<input type="text" name="fileName" value="aaa.jpg"/>
    15.         作       者： <input type="text" name="author" value="jack"/>
    16. <div><input type="file" name="file_upload"/></div>
    17. <div><input type="submit" value="上传" /></div>
    18. </form>
    19. </body>
    20. </html>

    二、web.xml配置文件代码：

    [html] view plain copy

    print?

    1. <?xml version="1.0" encoding="UTF-8"?>
    2. <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">
    3. <display-name>UploadDemo</display-name>
    4. <welcome-file-list>
    5. <welcome-file>index.html</welcome-file>
    6. <welcome-file>index.htm</welcome-file>
    7. <welcome-file>index.jsp</welcome-file>
    8. <welcome-file>default.html</welcome-file>
    9. <welcome-file>default.htm</welcome-file>
    10. <welcome-file>default.jsp</welcome-file>
    11. </welcome-file-list>
    14. <servlet>
    15. <servlet-name>uploadPhoto</servlet-name>
    16. <servlet-class>com.upload.demo.UploadServlet</servlet-class>
    17. </servlet>
    18. <servlet-mapping>
    19. <servlet-name>uploadPhoto</servlet-name>
    20. <url-pattern>/upload</url-pattern>
    21. </servlet-mapping>
    23. </web-app>

    三、UploadServlet代码：

    [html] view plain copy

    print?

    1. package com.upload.demo;  
    3. import java.io.BufferedReader;  
    4. import java.io.File;  
    5. import java.io.FileOutputStream;  
    6. import java.io.IOException;  
    7. import java.io.InputStream;  
    8. import java.io.InputStreamReader;  
    9. import java.util.ArrayList;  
    10. import java.util.Date;  
    11. import java.util.HashMap;  
    12. import java.util.List;  
    13. import java.util.Map;  
    14. import java.util.Properties;  
    15. import java.util.UUID;  
    17. import javax.servlet.ServletException;  
    18. import javax.servlet.http.HttpServlet;  
    19. import javax.servlet.http.HttpServletRequest;  
    20. import javax.servlet.http.HttpServletResponse;  
    22. import org.apache.commons.fileupload.FileItem;  
    23. import org.apache.commons.fileupload.disk.DiskFileItemFactory;  
    24. import org.apache.commons.fileupload.servlet.ServletFileUpload;  
    26. import com.lidroid.xutils.http.RequestParams;  
    29. public class UploadServlet extends HttpServlet{  
    31.     @Override  
    32.     protected void doGet(HttpServletRequest req, HttpServletResponse resp)  
    33.             throws ServletException, IOException {  
    34.         doPost(req, resp);  
    35.     };  
    37.     @Override  
    38.     protected void doPost(HttpServletRequest request,  
    39.             HttpServletResponse response) throws ServletException, IOException {  
    40.         //服务器端接收,请求被后台拦截到这里  
    41.         exeUploadedInfos(request, response);  
    43.     };  
    45.     /**  
    46.      *  定义接口  
    47.      */  
    48.     public interface UploadStatusListener {  
    49.         public void status(boolean status, Map<String, String> params,  
    50.                 List<String> files, HttpServletRequest request);  
    51.     }  
    52.     UploadStatusListener mUploadStatusListener = null;  
    53.     // 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  
    54.     public void addStatusListener(UploadStatusListener listener) {  
    55. mUploadStatusListener = listener;  
    56.     }  
    58.     /**  
    59.      * @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  
    60.      * @param request  
    61.      * @param response  
    62.      */  
    63.     private void exeUploadedInfos(HttpServletRequest request,  
    64.             HttpServletResponse response) {  
    65.         UploadServlet up = new UploadServlet();  
    66.         up.addStatusListener(new UploadStatusListener() {  
    67.             public void status(boolean status, Map<String, String> params,  
    68.                     List<String> files, HttpServletRequest request) {  
    69.                 if (status) {//成功  
    70.                     //Map中取值  
    71.                     String memberId = params.get("memberId");  
    72.                     //List中取值  
    73.                     String fileUrl = files.get(0);  
    74.                     System.out.println("===================================成功");  
    75.                 } else {  
    76.                     //失败  
    77.                     System.out.println("========================================失败");  
    78.                 }  
    79.             }  
    80.         });  
    81.         up.upload(request, response);  
    83.     }  
    85.     /**  
    86.      * @function：具体上传图片的功能在这里完成，  
    87.      * 然后调用接口回调方法mUploadStatusListener.status(flag, params, filenames , request);跳转到回调函数中  
    88.      * @param request  
    89.      * @param response  
    90.      */  
    91.     public void upload(HttpServletRequest request, HttpServletResponse response) {  
    92.         boolean flag = false;  
    93.         Map<String, String> params = new HashMap<String, String>();  
    94.         List<String> filenames = new ArrayList<String>();  
    95.         try {  
    96.             System.out.println("开始文件上传****************");  
    97.             request.setCharacterEncoding("utf-8"); // 设置编码  
    98.             // 设置上传文件最大为 3M  
    99.             final long MAX_SIZE = 3 * 1024 * 1024;  
    100.             // 1.创建一个解析器工厂  
    101.             DiskFileItemFactory factory = new DiskFileItemFactory();  
    102.             // 获取临时文件路径  
    103.             String savePath = "F:/upload/" ;//具体的路径  
    104.             if(!new File(savePath).exists()){  
    105.                 new File(savePath).mkdirs();  
    106.             }  
    107.             factory.setRepository(new File(savePath));  
    108.             factory.setSizeThreshold(4096);  
    109.             // 2.得到一个解析器  
    110.             ServletFileUpload upload = new ServletFileUpload(factory);  
    111.             upload.setSizeMax(MAX_SIZE);  
    112.             // upload.setHeaderEncoding("UTF-8");  
    113.             // 3.将请求传入解析器，对请求进行解析  
    114.             List<FileItem> list = upload.parseRequest(request);  
    115.             // 4.迭代list集合，得到每个输入项的数据  
    116.             int count = 0 ;  
    117.             for (FileItem item : list) {  
    118.                 count ++ ;  
    119.                 // 5.判断item的类型  
    120.                 if (item.isFormField()) {  
    121.                     // 普通文本输入项  
    122.                     String inputName = item.getFieldName();  
    123.                     String inputValue = item.getString();  
    124.                     params.put(inputName, inputValue);  
    125.                     System.out.println("==================传进来的参数：  "+count+"、"+inputName + "=" + inputValue);  
    127.                 } else {  
    128.                     // 上传文件输入项（如图片）  
    129.                     String fileName = item.getName();// 获取文件名  
    130.                     if (!"".equals(fileName)) {  
    131. fileName = fileName.substring(fileName.lastIndexOf("\") + 1);  
    132.                         System.out.println("*************存放传过来的图片****************");  
    133.                         InputStream in = item.getInputStream();  
    134.                         FileOutputStream out = new FileOutputStream(savePath+fileName);  
    135.                         byte[] buf = new byte[1024];  
    136.                         int len = 0;  
    137.                         while ((len = in.read(buf)) > 0) {  
    138.                             out.write(buf, 0, len);  
    139.                         }  
    140.                         in.close();  
    141.                         out.close();  
    142.                         item.delete();// 删除临时文件  
    143.                         filenames.add("上传成功了") ;  
    144. flag = true;  
    145.                         if (mUploadStatusListener != null) {  
    146.                             System.out.println("======文件上传：  ===flag=" + flag +";==="+ params.toString()  
    147.                                     + "==文件名fileName：=" + fileName);  
    148.                             mUploadStatusListener.status(flag, params, filenames , request);  
    149.                         }  
    150.                         System.out.println("文件上传结束****************");  
    151.                     }  
    152.                 }  
    153.             }  
    155.         } catch (Exception e) {  
    156.             e.printStackTrace();  
    157.             request.setAttribute("message", "上传失败");  
    158.             System.out.println("***********上传失败******************");  
    159.             if (mUploadStatusListener != null) {  
    160.                 System.out.println("****************上传失败*******************************");  
    161.                 mUploadStatusListener.status(flag, params, filenames , request);  
    162.             }  
    163.         }  
    164.     }  
    167. } 

    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
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  • 原文地址：https://www.cnblogs.com/zhangzs000/p/6059469.html
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