获取AsyncTask返回值，在Activity中使用。
引用链接：https://www.oschina.net/code/snippet_725438_49858#72630
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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].[代码] [Java]代码 跳至 [1] [2] [3] [4]
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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); } }} |
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回调接口：public interface OnDataFinishedListener { public void onDataSuccessfully(Object data); public void onDataFailed(); } |
[4].[代码] [Java]代码 跳至 [1] [2] [3] [4]
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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; } } }; |