我已经为此绞尽脑汁了一段时间，如果有人对这个问题有一些洞察力可以帮助我，我将不胜感激！
我正在尝试使用来自 Android Studio 的 POST（通过使用相机拍照）将图像上传到 Watson 的 Visual Recognition API。
我已经设法 - 用相机拍照后保存图像 - 在应用程序上将其显示为位图图像
我正在尝试将文件上传到 Watson API，但我不断收到此错误
"description": "无效的图像数据。支持的格式有 JPG、PNG 和 GIF。"
如果有人能对我在这里做错的事情提供一些见解，我将不胜感激。提前致谢！
我现在正在使用 HttpUrlConnection 和 DataOutputStream 进行 POST，代码如下：
imgName 和 imgPath 都被正确识别，name="images_file" 是 Watson Visual Recognition API 请求 name 的方式
public void uploadImage(){
HttpURLConnection conn = null;
DataOutputStream dos = null;
String lineEnd = "\r\n";
String twoHyphens = "--";
String boundary = "*****";
int bytesRead, bytesAvailable, bufferSize;
byte[] buffer;
int maxBufferSize = 1 * 1024 * 1024;
try{
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
URL url = new URL("https://gateway-a.watsonplatform.net/visual-recognition/api/v3/classify?api_key=APIKEY&version=2016-05-20");
conn= (HttpURLConnection) url.openConnection();
FileInputStream fileInputStream = new FileInputStream(file);
conn.setDoInput(true);
conn.setDoOutput(true);
conn.setUseCaches(false);
conn.setRequestMethod("POST");
conn.setRequestProperty("Connection", "Keep-Alive");
conn.setRequestProperty("ENCTYPE", "multipart/form-data");
conn.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
conn.setRequestProperty("images_file", imgPath);
dos = new DataOutputStream(conn.getOutputStream());
dos.writeBytes(twoHyphens + boundary + lineEnd);
dos.writeBytes("Content-Disposition: form-data; name=\"images_file\"; filename = \"" + imgName + "\"" + lineEnd);
dos.writeBytes(lineEnd);
bytesAvailable = fileInputStream.available();
bufferSize = Math.min(bytesAvailable, maxBufferSize);
buffer = new byte[bufferSize];
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);
// Responses from the server (code and message)
serverResponseCode = conn.getResponseCode();
String serverResponseMessage = conn.getResponseMessage();
Log.i("uploadFile", "HTTP Response is : "
+ serverResponseMessage + ": " + serverResponseCode);
if(serverResponseCode == 200){
BufferedReader br = new BufferedReader(new InputStreamReader((conn.getInputStream())));
StringBuilder sb = new StringBuilder();
String output;
while ((output = br.readLine()) !=null) {
sb.append(output);
}
Log.d("debugging", sb.toString());
runOnUiThread(new Runnable() {
public void run() {
String msg = "File Upload Completed.\n\n See uploaded file here : \n\n"
+" http://www.androidexample.com/media/uploads/"
+imgName;
Toast.makeText(getApplicationContext(), "File Upload Complete.",
Toast.LENGTH_SHORT).show();
}
});
}
//close the streams //
fileInputStream.close();
dos.flush();
dos.close();
} catch (MalformedURLException ex) {
ex.printStackTrace();
runOnUiThread(new Runnable() {
public void run() {
Toast.makeText(getApplicationContext(), "MalformedURLException",
Toast.LENGTH_SHORT).show();
}
});
Log.e("Upload file to server", "error: " + ex.getMessage(), ex);
} catch (Exception e) {
e.printStackTrace();
runOnUiThread(new Runnable() {
public void run() {
Toast.makeText(getApplicationContext(), "Got Exception : see logcat ",
Toast.LENGTH_SHORT).show();
}
});
Log.e("Debugging", "Exception : "
+ e.getMessage(), e);
}
Log.d("Debugging", "responseCode:" + serverResponseCode);
}