使用Android应用程序中的文件和文本发出POST请求

Question

我在从Android应用程序向我的Web服务（Google Cloud和PHP）发出正确的POST请求时遇到了一些问题。

当我尝试从Android发送图片时，它会返回“200 OK”响应，但图片不会保存在Google云端存储上的存储桶中。我知道问题在于Android应用程序中我的方法发出的POST请求，因为我已经使用Postman进行了测试并且没有任何问题。所以我的应用程序的下面一段代码出了问题：

public void uploadFile(String uploadUrl, String filename, String newFileName) throws IOException {
        FileInputStream fileInputStream = new FileInputStream(new File(filename));

        URL url = new URL(uploadUrl);
        connection = (HttpURLConnection) url.openConnection();

        // Allow Inputs & Outputs.
        connection.setDoInput(true);
        connection.setDoOutput(true);
        connection.setUseCaches(false);

        // Set HTTP method to POST.
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Connection", "Keep-Alive");
        connection.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);

        outputStream = new DataOutputStream(connection.getOutputStream() );
        outputStream.writeBytes(twoHyphens + boundary + lineEnd);
        outputStream.writeBytes("Content-Disposition: form-data; name=\"img\";filename=\"" + filename + "\"" + lineEnd);
        outputStream.writeBytes(lineEnd);

        bytesAvailable = fileInputStream.available();
        bufferSize = Math.min(bytesAvailable, maxBufferSize);
        buffer = new byte[bufferSize];

        // Read file
        bytesRead = fileInputStream.read(buffer, 0, bufferSize);

        while (bytesRead > 0) {
            outputStream.write(buffer, 0, bufferSize);
            bytesAvailable = fileInputStream.available();
            bufferSize = Math.min(bytesAvailable, maxBufferSize);
            bytesRead = fileInputStream.read(buffer, 0, bufferSize);
        }

        outputStream.writeBytes(lineEnd);
        outputStream.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);

        // Responses from the server (code and message)
        int serverResponseCode = connection.getResponseCode();
        String serverResponseMessage = connection.getResponseMessage();


        System.out.println(serverResponseMessage);
        System.out.println(serverResponseCode);


        fileInputStream.close();
        outputStream.flush();
        outputStream.close();
    }

我已经测试过所有参数都是100％正确的，所以你不必担心。

如果您需要从Web服务中查看用于接收请求的PHP代码，请执行以下操作：

<?php
$img = $_FILES['img']['tmp_name'];
move_uploaded_file($img, 'gs://routeimages/yeeeeeeees.jpg');

echo "done";

?>

这段代码中的问题可能出在哪里？

额外

我还需要在文件/图像之外添加一些文本。如何将此添加到请求中？

Answer 1

看起来你缺少正在发送的图像文件的Content-type。

请查看以下HTTP Post标头以发送文件

Content-type: multipart/form-data, boundary=AaB03x
    --AaB03x
    content-disposition: form-data; name="pics", filename="file2.gif"
    Content-type: image/gif
    Content-Transfer-Encoding: binary

    ...contents of file2.gif...
    --AaB03x--

所以你需要在代码中添加Content-type属性，如下所示：

outputStream = new DataOutputStream(connection.getOutputStream() );
outputStream.writeBytes(twoHyphens + boundary + lineEnd); 
outputStream.writeBytes("Content-Disposition: form-data; name=\"img\";filename=\"" + filename + "\"" + lineEnd);
outputStream.writeBytes("Content-type: image/gif" + lineEnd); // or whatever format you are sending.
outputStream.writeBytes("Content-Transfer-Encoding: binary" + lineEnd); 
outputStream.writeBytes(lineEnd);

我希望这段代码可以帮助您解决问题。

附加：我还需要添加除文件/图像之外的一些文本。如何将此添加到请求中？要发送一些额外的参数（某些文本），请查看以下http格式，该格式与文本参数一起发送图像：

    Content-type: multipart/form-data, boundary=AaB03x
    --AaB03x
    content-disposition: form-data; name="pics", filename="file2.gif"
    Content-type: image/gif
    Content-Transfer-Encoding: binary

    ...contents of file2.gif...
    --AaB03x--
    content-disposition: form-data; name="field1"

    Joe Blow
    --AaB03x

我希望你现在可以借助上面的图像上传说明和这种格式编写额外参数的代码。

Answer 2

为什么不使用Volley lib？它的方式更容易和干净。像这个例子：

private void uploadImage(){
        //Showing the progress dialog
        final ProgressDialog loading = ProgressDialog.show(this,"Uploading...","Please wait...",false,false);
        StringRequest stringRequest = new StringRequest(Request.Method.POST, UPLOAD_URL,
                new Response.Listener<String>() {
                    @Override
                public void onResponse(String s) {
                    //Disimissing the progress dialog
                    loading.dismiss();
                    //Showing toast message of the response
                    Toast.makeText(MainActivity.this, s , Toast.LENGTH_LONG).show();
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError volleyError) {
                    //Dismissing the progress dialog
                    loading.dismiss();

                    //Showing toast
                    Toast.makeText(MainActivity.this, volleyError.getMessage().toString(), Toast.LENGTH_LONG).show();
                }
            }){
        @Override
        protected Map<String, String> getParams() throws AuthFailureError {
            //Converting Bitmap to String
            String image = getStringImage(bitmap);

            //Getting Image Name
            String name = editTextName.getText().toString().trim();

            //Creating parameters
            Map<String,String> params = new Hashtable<String, String>();

            //Adding parameters
            params.put(KEY_IMAGE, image);
            params.put(KEY_NAME, name);

            //returning parameters
            return params;
        }
    };

    //Creating a Request Queue
    RequestQueue requestQueue = Volley.newRequestQueue(this);

    //Adding request to the queue
    requestQueue.add(stringRequest);
}

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