android两种方式获取AsyncTask返回值

获取AsyncTask返回值，在Activity中使用。

引用链接：https://www.oschina.net/code/snippet_725438_49858#72630

[1].[代码] [Java]代码跳至 [1] [2] [3] [4]

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);

}

[3].[代码] [Java]代码跳至 [1] [2] [3] [4]

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]

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;

}

};