一个简单的安卓+Servlet图片上传例子

       例子比较 简单，服务端为Java Web Servlet，doPost方法中接收图片并保存，然后将保存的图片名返回给客户端，关键代码：

@SuppressWarnings("deprecation")
	public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");  //设置编码  
        //获得磁盘文件条目工厂  
        DiskFileItemFactory factory = new DiskFileItemFactory();  
        //获取文件需要上传到的路径  
        String path = request.getRealPath("/upload");  
        File file=new File(path);
        if(!file.exists()){
        	file.mkdirs();
        }
        factory.setRepository(new File(path));  
        //设置 缓存的大小
        factory.setSizeThreshold(1024*1024) ;  
        //文件上传处理  
        ServletFileUpload upload = new ServletFileUpload(factory);  
        try {  
            //可以上传多个文件  
            List<FileItem> list = (List<FileItem>)upload.parseRequest(request);  
            for(FileItem item : list){  
                //获取属性名字  
                String name = item.getFieldName();  
                //如果获取的 表单信息是普通的 文本 信息  
                if(item.isFormField()){                     
                    //获取用户具体输入的字符串,因为表单提交过来的是 字符串类型的  
                    String value = item.getString() ;  
                    request.setAttribute(name, value);  
                }else{  
                    //获取路径名  
                    String value = item.getName() ;  
                    //索引到最后一个反斜杠  
                    int start = value.lastIndexOf("\\");  
                    //截取 上传文件的 字符串名字，加1是 去掉反斜杠，  
                    String filename = value.substring(start+1);  
                    request.setAttribute(name, filename);  
                    //写到磁盘上  
                    item.write( new File(path,filename) );//第三方提供的  
                    System.out.println("上传成功："+filename);
                    response.getWriter().print(filename);//将路径返回给客户端
                }  
            }  
              
        } catch (Exception e) {  
        	System.out.println("上传失败");
        	response.getWriter().print("上传失败："+e.getMessage());
        }  
		
	}

客户端关键代码：

/**
	 * 文件上传
	 * 
	 * @param urlStr 接口路径
	 * @param filePath 本地图片路径
	 * @return
	 */
	public static String formUpload(String urlStr, String filePath) {
		String rsp = "";
		HttpURLConnection conn = null;
		String BOUNDARY = "|"; // request头和上传文件内容分隔符
		try {
			URL url = new URL(urlStr);
			conn = (HttpURLConnection) url.openConnection();
			conn.setConnectTimeout(5000);
			conn.setReadTimeout(30000);
			conn.setDoOutput(true);
			conn.setDoInput(true);
			conn.setUseCaches(false);
			conn.setRequestMethod("POST");
			conn.setRequestProperty("Connection", "Keep-Alive");
			conn.setRequestProperty("User-Agent",
					"Mozilla/5.0 (Windows; U; Windows NT 6.1; zh-CN; rv:1.9.2.6)");
			conn.setRequestProperty("Content-Type",
					"multipart/form-data; boundary=" + BOUNDARY);

			OutputStream out = new DataOutputStream(conn.getOutputStream());
			File file = new File(filePath);
			String filename = file.getName();
			String contentType = "";
			if (filename.endsWith(".png")) {
				contentType = "image/png";
			}
			if (filename.endsWith(".jpg")) {
				contentType = "image/jpg";
			}
			if (filename.endsWith(".gif")) {
				contentType = "image/gif";
			}
			if (filename.endsWith(".bmp")) {
				contentType = "image/bmp";
			}
			if (contentType == null || contentType.equals("")) {
				contentType = "application/octet-stream";
			}
			StringBuffer strBuf = new StringBuffer();
			strBuf.append("\r\n").append("--").append(BOUNDARY).append("\r\n");
			strBuf.append("Content-Disposition: form-data; name=\"" + filePath
					+ "\"; filename=\"" + filename + "\"\r\n");
			strBuf.append("Content-Type:" + contentType + "\r\n\r\n");
			out.write(strBuf.toString().getBytes());
			DataInputStream in = new DataInputStream(new FileInputStream(file));
			int bytes = 0;
			byte[] bufferOut = new byte[1024];
			while ((bytes = in.read(bufferOut)) != -1) {
				out.write(bufferOut, 0, bytes);
			}
			in.close();
			byte[] endData = ("\r\n--" + BOUNDARY + "--\r\n").getBytes();
			out.write(endData);
			out.flush();
			out.close();

			// 读取返回数据
			StringBuffer buffer = new StringBuffer();
			BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream(), "utf-8"));
			String line = null;
			while ((line = reader.readLine()) != null) {
				buffer.append(line).append("\n");
			}
			rsp = buffer.toString();
			reader.close();
			reader = null;
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (conn != null) {
				conn.disconnect();
				conn = null;
			}
		}
		return rsp;
	}

客户端图例：

注意：测试的时候，请在客户端书写完整的本机局域网IP地址：

/**
	 * 图片上传路径
	 */
	public static final String UPLOAD_URL="http://192.168.1.188:8080/uploadImage/UploadServlet";
	
	/**
	 * 图片下载路径
	 */
	public static final String DOWNLOAD_URL="http://192.168.1.188:8080/uploadImage/upload/";