寫專案的時候接觸了上傳圖片這個模組。第一次使用OKhttputils上傳圖片時發現有時候上傳成功，有時候失敗報500錯誤，我糾結了一天，用postman測試介面是沒有問題的，最後換回原生的okhttp框架去寫。後來發現可能是之前的OKhttputils版本太低了導致的（2.6.2），現在用的Okhttp版本是（3.2.0）

private static final String TAG = "MainActivity";
private Button btn_up;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super
 
.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btn_up = (Button) findViewById(R.id.btn_up);
btn_up.setOnClickListener(this);
}



private void upImage() {
    OkHttpClient mOkHttpClent = new OkHttpClient();
File file = new File(Environment.getExternalStorageDirectory()+"/HeadPortrait.jpg"
 
);
MultipartBody.Builder builder = new MultipartBody.Builder()
            .setType(MultipartBody.FORM)
            .addFormDataPart("img", "HeadPortrait.jpg",
RequestBody.create(MediaType.parse("image/png"), file));
RequestBody requestBody = builder.build();
Request request = new Request.Builder()
            .url(url
 
)
            .post(requestBody)
            .build();
Call call = mOkHttpClent.newCall(request);
call.enqueue(new Callback() {
        @Override
public void onFailure(Call call, IOException e) {
            Log.e(TAG, "onFailure: "+e );
runOnUiThread(new Runnable() {
                @Override
public void run() {
                    Toast.makeText(MainActivity.this, "失敗", Toast.LENGTH_SHORT).show();
}
            });
}

        @Override
public void onResponse(Call call, Response response) throws IOException {
            Log.e(TAG, "成功"+response);
runOnUiThread(new Runnable() {
                @Override
public void run() {
                    Toast.makeText(MainActivity.this, "成功", Toast.LENGTH_SHORT).show();
}
            });
}
    });
}

@Override
public void onClick(View v) {
    Log.e(TAG, "onClick: " );
    new Thread(new Runnable() {
        @Override
public void run() {
            upImage();
}
    }).start();
}