Android多次加載bitmap後，提示記憶體溢出。可以在onDestroy中釋放記憶體資源

package com.example.suzyulin.emergency;

import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

import com.common.AppData;
import com.common.Common;
import com.common.UploadUtil1;

import org.json.JSONArray;
import org.json.JSONObject;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.HashMap;
import java.util.Map;

public class UploadFileActivity extends AppCompatActivity {
    private static final String TAG = "UploadFileActivity";
    ImageView imageViewResult ;
    TextView  tvUploadStatus;
    Button    btnReturn;
    Bitmap    bitmap; 
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_upload_file); 
        imageViewResult = (ImageView)findViewById(R.id.ivCameraResult);
        btnReturn       = (Button)findViewById(R.id.btnReturn);
        tvUploadStatus  = (TextView)findViewById(R.id.tvUploadStatus);

        String PhotoFileName = AppData.getPhotoFileName(this);  
        try {
            if (!PhotoFileName.isEmpty()) { 
                bitmap = getLoacalBitmap(PhotoFileName);
                imageViewResult.setImageBitmap(bitmap); 
                handlerUpdateUI.sendEmptyMessageDelayed(0, 500);
            } else {
                tvUploadStatus.setText("照片讀取錯誤！");
            }
        }catch (Exception e){
            Log.d(TAG, "onCreate: Load bitmap error   #################"+e.getMessage());
        }
    }

    protected void onStop(){
        super.onStop();
        if (bitmap != null) { //&& bitmap.isRecycled() == false
            bitmap.recycle();
            System.gc();
            Log.d(TAG, "onStop: bitmap.recycle ^^^^^^^^^^^^^^^^^^^^^^^^^");
        }
    }

    protected void onDestroy(){
        super.onDestroy();
        if (bitmap != null) { //&& bitmap.isRecycled() == false
            bitmap.recycle();
            System.gc();
            Log.d(TAG, "onDestroy: bitmap.recycle ^^^^^^^^^^^^^^^^^^^^^^^^^");
        }
    } 

    public static Bitmap getLoacalBitmap(String url) {
        try {
            FileInputStream fis = new FileInputStream(url);
            return BitmapFactory.decodeStream(fis);
        }catch (FileNotFoundException e) {
            e.printStackTrace();
            Log.d(TAG, "getLoacalBitmap: --------->   " + e.getMessage());
            return null;
        }  
    }  
    }

}