android两种方式获取AsyncTask返回值

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获取AsyncTask返回值，在Activity中使用。

布局文件：<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"   >       <ImageView android:id="@+id/im1"      android:layout_width="wrap_content"       android:layout_height="wrap_content"       android:src="@drawable/ic_launcher" />        <ImageView android:id="@+id/im2"      android:layout_width="wrap_content"       android:layout_height="wrap_content"       android:src="@drawable/ic_launcher" /> </LinearLayout>

2.第一种，回调方法方式：package com.androidwallpaper; import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStream;import java.net.HttpURLConnection;import java.net.MalformedURLException;import java.net.URL;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors; import android.net.Uri;import android.os.AsyncTask;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.app.Activity;import android.app.WallpaperManager;import android.content.Intent;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.ImageView;import android.widget.ProgressBar;import android.widget.Toast; public class MainActivity extends Activity implements OnClickListener{              ImageView im1;    ImageView im2;          @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);                 im1 = (ImageView) findViewById(R.id.im1);        im2 = (ImageView) findViewById(R.id.im2);                 try {            final ImageViewAsyncTask task = new ImageViewAsyncTask("http://static.oschina.net/uploads/ad/new_banner_one_ronglianyun_WrqUs.png");            task.setOnDataFinishedListener(new OnDataFinishedListener() {                                 @Override                public void onDataSuccessfully(Object data) {                    try {                        im1.setImageBitmap((Bitmap) data);                    } catch (Exception e) {                        e.printStackTrace();                    }                }                @Override                public void onDataFailed() {                    Toast.makeText(MainActivity.this, "加载失败！", Toast.LENGTH_SHORT).show();                }            });            task.execute();        } catch (Exception e) {            e.printStackTrace();        }                               }          class ImageViewAsyncTask extends AsyncTask<String, Integer, Bitmap> {                 String mUrl;        OnDataFinishedListener onDataFinishedListener;                 public ImageViewAsyncTask(String url){            this.mUrl = url;        }                           public void setOnDataFinishedListener(                OnDataFinishedListener onDataFinishedListener) {            this.onDataFinishedListener = onDataFinishedListener;        }          @Override        protected Bitmap doInBackground(String... params) {            InputStream ins = null;            Bitmap bitmap = null;            try {                URL url = new URL(mUrl);                HttpURLConnection connection = (HttpURLConnection) url.openConnection();                if(connection.getResponseCode()==HttpURLConnection.HTTP_OK){                    ins = connection.getInputStream();                    bitmap = BitmapFactory.decodeStream(ins);                    return bitmap;                }            } catch (MalformedURLException e) {                e.printStackTrace();            } catch (IOException e) {                e.printStackTrace();            }finally{                if(ins!=null){                    try {                        ins.close();                    } catch (IOException e) {                        e.printStackTrace();                    }                }            }            return null;        }         @Override        protected void onPreExecute() {            super.onPreExecute();            progressBar.setVisibility(View.VISIBLE);        }         @Override        protected void onPostExecute(Bitmap result) {            progressBar.setVisibility(View.GONE);            if(result!=null){                onDataFinishedListener.onDataSuccessfully(result);            }else{                onDataFinishedListener.onDataFailed();            }        }         @Override        protected void onProgressUpdate(Integer... values) {            super.onProgressUpdate(values);        }             }}

回调接口：public interface OnDataFinishedListener {         public void onDataSuccessfully(Object data);         public void onDataFailed();     }

第二种：使用handler: 1.修改ImageViewAsyncTask:public class ImageViewAsyncTask extends AsyncTask<String, Integer, Bitmap> {         String mUrl;    Handler mHandler;         public ImageViewAsyncTask(String url,Handler handler){        this.mUrl = url;        this.mHandler = handler;    }     @Override    protected Bitmap doInBackground(String... params) {        InputStream ins = null;        Bitmap bitmap = null;        try {            URL url = new URL(mUrl);            HttpURLConnection connection = (HttpURLConnection) url.openConnection();            if(connection.getResponseCode()==HttpURLConnection.HTTP_OK){                ins = connection.getInputStream();                bitmap = BitmapFactory.decodeStream(ins);                return bitmap;            }        } catch (MalformedURLException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }finally{            if(ins!=null){                try {                    ins.close();                } catch (IOException e) {                    e.printStackTrace();                }            }        }        return null;    }     @Override    protected void onPreExecute() {        super.onPreExecute();    }     @Override    protected void onPostExecute(Bitmap result) {        super.onPostExecute(result);        Message msg = mHandler.obtainMessage();        if(result!=null){            msg.what = 1;            msg.obj = result;        }else{            msg.what = 2;        }        mHandler.sendMessage(msg);    }     @Override    protected void onProgressUpdate(Integer... values) {        super.onProgressUpdate(values);    }           }2.调用方式：ImageViewAsyncTask task2 = new ImageViewAsyncTask("http://static.oschina.net/uploads/ad/new_banner_one_ronglianyun_WrqUs.png", handler);        task2.execute(); Handler handler = new Handler(){         @Override        public void handleMessage(Message msg) {            switch (msg.what) {            case 1:                Bitmap bitmap = (Bitmap) msg.obj;                im2.setImageBitmap(bitmap);                break;             default:                break;            }        }             };

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