文件上传代理服务

j2eeli

近日在工作中要用到图片服务器的功能，由于图片服务器和后台系统不在同一个域下，导致上传文件后JS无法跨域处理上传结果。解决办法就是通用的proxy方法，在后台系统写一个代理方法处理上传文件并返回结果。在Action中用流交互数据，可始终无法上传，图片服务器报500，在网上找了资料才知道输入到文件服务器的流要稍微处理下，否则协议不完整导致功能无法完成。附代码：(11-13行的POST、Connection、contentType设置非常重要)
String fileServerUrl = "http://img.aaa.com/uploadFile.jsp";     InputStream is = request.getInputStream();   String contentType = request.getContentType();     URL url = new URL(fileServerUrl);   HttpURLConnection conn = (HttpURLConnection)url.openConnection();   conn.setDoInput(true);   conn.setDoOutput(true);   conn.setUseCaches(false);   conn.setRequestMethod("POST");   conn.setRequestProperty("Connection", "Keep-Alive");   conn.setRequestProperty("Content-Type", contentType);   conn.connect();   OutputStream connOs = conn.getOutputStream();     byte[] b = new byte[1024];   int num=0;while((num=is.read(b)) != -1){       connOs.write(b,0,num);   }   InputStream connIs=conn.getInputStream();   BufferedReader connBr = new BufferedReader(new InputStreamReader(connIs));   StringBuffer sb = new StringBuffer();   String str;   while((str=connBr.readLine())!=null){       sb.append(str);   }   log.info("结果------"+sb);   connOs.close();   connBr.close();   connIs.close();  
参考的源码是一个老外写的，“用JAVA程序封装一个HTTP上传请求上传文件”，参考代码如下：
import java.io.*;import java.net.*;public class ServletCom {public static void main(String[] args) throws Exception {HttpURLConnection conn = null;BufferedReader br = null;DataOutputStream dos = null;DataInputStream inStream = null;InputStream is = null;OutputStream os = null;boolean ret = false;String StrMessage = "";String exsistingFileName = "C:\\account.xls";String lineEnd = "\r\n";String twoHyphens = "--";String boundary = "*****";int bytesRead, bytesAvailable, bufferSize;byte[] buffer;int maxBufferSize = 1 * 1024 * 1024;String responseFromServer = "";String urlString = "http://localhost:8080/FileUpload/requestupload";try {// ------------------ CLIENT REQUESTFileInputStream fileInputStream = new FileInputStream(new File(exsistingFileName));// open a URL connection to the ServletURL url = new URL(urlString);// Open a HTTP connection to the URLconn = (HttpURLConnection) url.openConnection();// Allow Inputsconn.setDoInput(true);// Allow Outputsconn.setDoOutput(true);// Don't use a cached copy.conn.setUseCaches(false);// Use a post method.conn.setRequestMethod("POST");conn.setRequestProperty("Connection", "Keep-Alive");conn.setRequestProperty("Content-Type","multipart/form-data;boundary=" + boundary);dos = new DataOutputStream(conn.getOutputStream());dos.writeBytes(twoHyphens + boundary + lineEnd);dos.writeBytes("Content-Disposition: form-data; name=\"upload\";"+ " filename=\"" + exsistingFileName + "\"" + lineEnd);dos.writeBytes(lineEnd);// create a buffer of maximum sizebytesAvailable = fileInputStream.available();bufferSize = Math.min(bytesAvailable, maxBufferSize);buffer = new byte[bufferSize];// read file and write it into form...bytesRead = fileInputStream.read(buffer, 0, bufferSize);while (bytesRead > 0) {dos.write(buffer, 0, bufferSize);bytesAvailable = fileInputStream.available();bufferSize = Math.min(bytesAvailable, maxBufferSize);bytesRead = fileInputStream.read(buffer, 0, bufferSize);}// send multipart form data necesssary after file data...dos.writeBytes(lineEnd);dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);// close streamsfileInputStream.close();dos.flush();dos.close();} catch (MalformedURLException ex) {System.out.println("From ServletCom CLIENT REQUEST:" + ex);}catch (IOException ioe) {System.out.println("From ServletCom CLIENT REQUEST:" + ioe);}// ------------------ read the SERVER RESPONSEtry {inStream = new DataInputStream(conn.getInputStream());String str;while ((str = inStream.readLine()) != null) {System.out.println("Server response is: " + str);System.out.println("");}inStream.close();} catch (IOException ioex) {System.out.println("From (ServerResponse): " + ioex);}}}