post 附件

在做嘀咕客户端的时候，要实现拍照上传的功能。根据嘀咕api提供的接口，文档看上去很复杂，我用一个简单html文件来说明问题。

几个关键点：

这个表单使用post方法

有几个文本域，还用到file域，即文件上传

编码用utf-8

接下来，我在android中使用HttpURLConnection来构建一个符合这些规则的表单Post到服务器。

到底这个表单是怎么样的一种结构，它肯定是要根据http传输协议来构造出来的。我介绍一种非常直观的方法。利用FireFox的FireBug插件，我们在这个html表单上点击提交时候，可以看到这个请求到底是怎么样的。

明白了要做什么事情，接下来就是用java代码来构建这样的StringBuffer了。

下面给出代码

/**
	 * 上传附件 （拍照）
	 * @param bitmap  待上传的Bitmap图
	 * @param fileKey 表单变量名
	 * @param urlstr  上传地址
	 * @param hmap    参数
	 * @param ctx     context
	 * @return
	 */
	public static String postFileFromBitmap2(String urlstr, HashMap<String, String> hmap) {
		dout("postURLContent:" + urlstr);
		String fileKey = "image0";
		String rs = "";
		String temp = "temp.jpg";
		Bitmap2File(bitmap, temp, U.ctx_for_getResString);
		String exsistingFileName = U.ctx_for_getResString.getFilesDir() + "/" + temp;

		String lineEnd = "\r\n";
		String twoHyphens = "--";

		String boundary = "---------------------------11538186919912";
		try {
			File f = new File(exsistingFileName);
			FileInputStream fileInputStream = new FileInputStream(f);
			if (!f.exists())
				return rs;
			URL url = new URL(urlstr);
			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", "multipart/form-data;boundary=" + boundary);
			//兼容嘀咕的用户账户密码信息必须通过 AUTH_HTTP 方式提供
			if(hmap.containsKey("AUTH_HTTP_ENCODING")){
				conn.setRequestProperty("Authorization", "Basic " + hmap.get("AUTH_HTTP_ENCODING"));
			}

			DataOutputStream dos = new DataOutputStream(conn.getOutputStream());

			dos.writeBytes(twoHyphens + boundary + lineEnd);
	        dos.writeBytes("Content-Disposition: form-data; name=\"content\""+ lineEnd);
	        dos.writeBytes(lineEnd + URLEncoder.encode(""+hmap.get("content"), "UTF-8")+ lineEnd);

			dos.writeBytes(twoHyphens + boundary + lineEnd);
	        dos.writeBytes("Content-Disposition: form-data; name=\"source\""+ lineEnd);
	        dos.writeBytes(lineEnd + URLEncoder.encode(""+hmap.get("source"), "UTF-8")+ lineEnd);

			dos.writeBytes(twoHyphens + boundary + lineEnd);
	        dos.writeBytes("Content-Disposition: form-data; name=\"uploadImg\""+ lineEnd);
	        dos.writeBytes(lineEnd + URLEncoder.encode("xiexiezhichi", "UTF-8")+ lineEnd);

	        dos.writeBytes(twoHyphens + boundary + lineEnd);
			dos.writeBytes("Content-Disposition: form-data; name=\"" + fileKey + "\";filename=\"" + exsistingFileName+ "\"" + lineEnd);
			dos.writeBytes("Content-Type: image/jpeg"+lineEnd);
			dos.writeBytes(lineEnd);

			int bytesAvailable = fileInputStream.available();
			byte[] buffer = new byte[bytesAvailable];
			int bytesRead = fileInputStream.read(buffer, 0, bytesAvailable);
			while (bytesRead > 0) {
				dos.write(buffer, 0, bytesAvailable);
				bytesAvailable = fileInputStream.available();
				bytesRead = fileInputStream.read(buffer, 0, bytesAvailable);
			}
			dos.writeBytes(lineEnd);
			dos.writeBytes(boundary + lineEnd);
			fileInputStream.close();

			dos.writeBytes(twoHyphens + boundary + lineEnd);
			dos.writeBytes("Content-Disposition: form-data; name=\"image1\";filename=\"\"" + lineEnd);
			dos.writeBytes("Content-Type: application/octet-stream"+lineEnd);
			dos.writeBytes(lineEnd);
			dos.writeBytes(twoHyphens + boundary + lineEnd);

			dos.writeBytes("Content-Disposition: form-data; name=\"image2\";filename=\"\"" + lineEnd);
			dos.writeBytes("Content-Type: application/octet-stream"+lineEnd);
			dos.writeBytes(lineEnd);
			dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);

			dos.flush();
			dos.close(); 

			InputStream in = conn.getInputStream();
			BufferedReader br = new BufferedReader(new InputStreamReader(in));
			StringBuffer sb2 = new StringBuffer();
			String tmp = null;
			while ((tmp = br.readLine()) != null) {
				sb2.append(tmp);
			}
			br.close();
			in.close();
			return sb2.toString();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return rs;
	}