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发表于 2015-07-30 14:54 |只看该作者 |倒序浏览

获取AsyncTask返回值，在Activity中使用。
代码

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>

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代码

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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代码

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

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代码

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;
}
}
};