Android http post 文件 bad request 400

一直出现bad request的错误，缺少httpclient-4.2.1.jar

public class UploadUtil {

private static final int TIME_OUT = 10 * 1000; // 超时时间
private static final String CHARSET = "utf-8"; // 设置编码
    
public void uploadFile(File file, String RequestURL) {
   
String end = "\r\n";
String twoHyphens = "--";
String boundary = "*****";
   
try
{
URL url =new URL(RequestURL);
  HttpURLConnection con=(HttpURLConnection)url.openConnection();
          /* 允许Input、Output，不使用Cache */
          con.setDoInput(true);
          con.setDoOutput(true);
          con.setUseCaches(false);
          /* 设置传送的method=POST */
          con.setRequestMethod("POST");
          /* setRequestProperty */
          con.setRequestProperty("Connection", "Keep-Alive");
          con.setRequestProperty("Charset", "UTF-8");
          con.setRequestProperty("Content-Type",
                             "multipart/form-data;boundary="+boundary);
          /* 设置DataOutputStream */
          DataOutputStream ds = 
            new DataOutputStream(con.getOutputStream());
          ds.writeBytes(twoHyphens + boundary + end);
          ds.writeBytes("Content-Disposition: form-data; " +
                        "name=\"file\";filename=\"" +
                        file.getName() +"\"" + end);
          ds.writeBytes(end);   


          /* 取得文件的FileInputStream */
          FileInputStream fStream = new FileInputStream(file);
          /* 设置每次写入1024bytes */
          int bufferSize = 1024;
          byte[] buffer = new byte[bufferSize];


          int length = -1;
          /* 从文件读取数据至缓冲区 */
          while((length = fStream.read(buffer)) != -1)
          {
            /* 将资料写入DataOutputStream中 */
            ds.write(buffer, 0, length);
          }
          ds.writeBytes(end);
          ds.writeBytes(twoHyphens + boundary + twoHyphens + end);


          /* close streams */
          fStream.close();
          ds.flush();


          /* 取得Response内容 */
          InputStream is = con.getInputStream();
          int ch;
          StringBuffer b =new StringBuffer();
          while( ( ch = is.read() ) != -1 )
          {
            b.append( (char)ch );
          }
          Log.v("out","Upload Success"+b.toString().trim());
          /* 关闭DataOutputStream */
          ds.close();
        }
        catch(Exception e)
        {
        Log.v("out", "Upload Fail");
        }
    }
}