Android实战简易教程-第四十九枪（两种方式实现网络图片异步加载）

<RelativeLayout 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" >

    <ImageView
        android:id="@+id/img"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true" />

</RelativeLayout>

package com.example.imageloaderdemo;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.ProtocolException;
import java.net.URL;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;

public class MainActivity extends Activity {
	private ImageView mImageView;
	private static String URLSTRING;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		mImageView = (ImageView) findViewById(R.id.img);
		URLSTRING="http://photocdn.sohu.com/20110927/Img320705637.jpg";//图片地址
		MyAsyncTask myAsyncTask=new MyAsyncTask();
		myAsyncTask.execute(URLSTRING);
		
	}

	class MyAsyncTask extends AsyncTask<String, Void, Bitmap> {
		

		@Override
		protected void onPostExecute(Bitmap result) {
			super.onPostExecute(result);
			mImageView.setImageBitmap(result);
		}

		@Override
		protected Bitmap doInBackground(String... params) {
			Bitmap bitmap=null;
			try {
				URL url=new URL(params[0]);
				HttpURLConnection connection=(HttpURLConnection) url.openConnection();
				connection.setRequestMethod("GET");
				connection.setConnectTimeout(5000);
				if(connection.getResponseCode()==200){
					InputStream inputStream=connection.getInputStream();
					bitmap=BitmapFactory.decodeStream(inputStream);
				}
				
			} catch (MalformedURLException e) {
				e.printStackTrace();
			} catch (ProtocolException e) {
				e.printStackTrace();
			} catch (IOException e) {
				e.printStackTrace();
			}

			return bitmap;
		}

	}

}

mImageView.setImageBitmap(result);可以直接设置

package com.example.imageloaderdemo;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.ProtocolException;
import java.net.URL;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.ImageView;

public class MainActivity extends Activity {
	private ImageView mImageView;
	private static String URLSTRING;

	private Handler handler = new Handler() {
		public void handleMessage(Message msg) {
			Bitmap bitmap = (Bitmap) msg.obj;
			mImageView.setImageBitmap(bitmap);
		};
	};

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		mImageView = (ImageView) findViewById(R.id.img);
		URLSTRING = "http://photocdn.sohu.com/20110927/Img320705637.jpg";// 图片地址

		MyThread myThread = new MyThread();
		myThread.start();// 调用线程

	}

	class MyThread extends Thread {
		@Override
		public void run() {
			super.run();
			Bitmap bitmap = null;
			try {
				URL url = new URL(URLSTRING);
				HttpURLConnection connection = (HttpURLConnection) url
						.openConnection();
				connection.setRequestMethod("GET");
				connection.setConnectTimeout(5000);
				if (connection.getResponseCode() == 200) {
					InputStream inputStream = connection.getInputStream();
					bitmap = BitmapFactory.decodeStream(inputStream);
					Message message = new Message();
					message.obj = bitmap;
					handler.sendMessage(message);

				}

			} catch (MalformedURLException e) {
				e.printStackTrace();
			} catch (ProtocolException e) {
				e.printStackTrace();
			} catch (IOException e) {
				e.printStackTrace();
			}

		}
	}

}

class MyThread extends Thread{}

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