发送图像到网络服务器并接收信息

Question

我是 android 和 java 新手，所以请容忍我使用的不正确术语。我正在编写一个应用程序，帮助识别图像的位置。

1. 从相机捕获图像
2. 将捕获的图像发送到 Web 服务器
3. 侦听并接收来自 Web 服务器的有关捕获图像的位置的信息并显示给用户。

因此主要问题是：

• 将图像发送到 Web 服务器
• 从 Web 服务器接收信息

Answer 1

我使用这个方法（我从某个地方得到的，但不知道从哪里来），它对我有用：

private void doFileUpload() {

    HttpURLConnection conn = null;
    DataOutputStream dos = null;
    DataInputStream inStream = null;
    String lineEnd = "\r\n";
    String twoHyphens = "--";
    String boundary = "*****";
    int bytesRead, bytesAvailable, bufferSize;
    byte[] buffer;
    int maxBufferSize = 1 * 1024 * 1024; //size of your image
    String responseFromServer = "";
    String urlString = "http://yourwebserver/receiver.php";

    try {
        // ------------------ CLIENT REQUEST
        FileInputStream fileInputStream = new FileInputStream(new File(
                mFileName));
        // open a URL connection to the Servlet
        URL url = new URL(urlString);
        // Open a HTTP connection to the URL
        conn = (HttpURLConnection) url.openConnection();
        // Allow Inputs
        conn.setDoInput(true);
        // Allow Outputs
        conn.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=\"uploadedfile\";filename=\""
                + mFileName + "\"" + lineEnd);
        dos.writeBytes(lineEnd);
        // create a buffer of maximum size
        bytesAvailable = 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 streams
        Log.e("Debug", "File is written");
        fileInputStream.close();
        dos.flush();
        dos.close();
    } catch (MalformedURLException ex) {
        Log.e("Debug", "error: " + ex.getMessage(), ex);
    } catch (IOException ioe) {
        Log.e("Debug", "error: " + ioe.getMessage(), ioe);
    }
    // ------------------ read the SERVER RESPONSE
    try {
        inStream = new DataInputStream(conn.getInputStream());
        String str;
        while ((str = inStream.readLine()) != null) {
            Log.e("Debug", "Server Response " + str);
        }
        inStream.close();
    } catch (IOException ioex) {
        Log.e("Debug", "error: " + ioex.getMessage(), ioex);
    }
}

该文件将位于网络服务器上的 $_FILES 数组中。