网络图片加载

加载Internet图片并显示在ImageView上。不可以在子线程中更改界面布局。

需要使用连接网络的权限： <uses-permission android:name="android.permission.INTERNET"/>

布局文件：

<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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="45dp"
        android:layout_marginTop="16dp"
        android:text="Button" />

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/button1"
        android:layout_below="@+id/button1"
        android:layout_marginLeft="24dp"
        android:layout_marginTop="80dp"
        android:src="@drawable/ic_launcher" />

</RelativeLayout>

Activity类：

package com.example.netdemo;

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

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

public class MainActivity extends Activity {
    private Button button;
    private ImageView imageView;
    private Handler handler=new Handler(){
        @Override
        public void handleMessage(Message msg) {
            //根据msg.what的值判断是哪个子线程
            if(msg.what==11){
                Bitmap mBitmap=(Bitmap) msg.obj;
                imageView.setImageBitmap(mBitmap);
            }
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button=(Button) findViewById(R.id.button1);
        imageView=(ImageView) findViewById(R.id.imageView1);
        button.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View arg0) {
                //开启子线程
                Thread thread=new Thread(new MyRunnable());
                thread.start();
            }
        });
    }

class MyRunnable implements Runnable{

    @Override
    public void run() {
        String urlString="http://amorypepelu.github.io/shell/src/8eea0ecdd3c83d2.jpg";
        InputStream is=null;
        try {
            //配置网络连接
            URL url=new URL(urlString);
            HttpURLConnection connection=(HttpURLConnection) url.openConnection();
            connection.setConnectTimeout(5*1000);
            connection.setRequestMethod("GET");
            connection.setRequestProperty("", "");
            is=connection.getInputStream();
            //解析图片
            Bitmap bitmap=BitmapFactory.decodeStream(is);
            //配置消息
            Message msg=handler.obtainMessage();
            msg.what=11;
            msg.obj=bitmap;
            //发送
            handler.sendMessage(msg);
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally{
            if (is!=null) {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        
    }
    
}

}