图片查看器

<pre name="code" class="java">package com.xh.tx.images;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
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.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;

public class MainActivity extends Activity implements OnClickListener{
	
	protected static final String TAG="MainActivity";
	ImageView image=null;
	EditText edit = null;
	
	Handler handler = new Handler(){
		
		//接收一个消息
		@Override
		public void handleMessage(Message msg) {
			
			super.handleMessage(msg);
			if(msg.what==1){
				Bitmap bitmap = (Bitmap) msg.obj;
				image.setImageBitmap(bitmap);
			}
		}
	};
	
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
	
		image = (ImageView) findViewById(R.id.img);
		edit = (EditText) findViewById(R.id.et_net);
		
		Button button = (Button) findViewById(R.id.bt_get);
		
		button.setOnClickListener(this);
	}

	/**
	 * 1.访问网络不能直接放在主方法里面（android.os.NetworkOnMainThreadException）,应该放在一个线程里面
	 * 2. android.view.ViewRootImpl$CalledFromWrongThreadException: 只能在主线程或者UI线程里面修改视图,应该用通信来解决
	 */

	@Override
	public void onClick(View v) {
		final String uri = edit.getText().toString();
		
		 new Thread(new Runnable(){

			@Override
			public void run() {
				
				Bitmap bitmap = getImageFromNet(uri);
				if(null != bitmap)
				{
					Message msg = new Message();
					msg.what = 1; //你是谁
					msg.obj = bitmap;
					
					handler.sendMessage(msg); //发送一个消息
					
					//image.setImageBitmap(bitmap); 
					Log.i(TAG, "========" + bitmap);
				}else
				{
					//Toast.makeText(MainActivity.this, "获取图片失败", 0).show();
				}
				
			}

			 
		 }).start();
	}
	private Bitmap getImageFromNet(String uri) {
		
		HttpURLConnection conn = null;
		//1.首先将地址转换为Uri
		//Uri net_uri = Uri.parse(uri); //这种方式是错误的
		URL url;
		try {
			url = new URL(uri);
		
		//2. 获取网络连接
		conn = (HttpURLConnection) url.openConnection(); //这个地方要转换一次，转换为你获取图片的协议连接
		
		//3. 设置请求的一些常用的参数
		conn.setConnectTimeout(30000);//设置超时
		conn.setDoInput(true); //设置请求可以放服务器写入数据
		conn.setReadTimeout(30000); //设置连接去读取数据的超时时间
		
		//4.真正请求图片,然后把从网络上请求到的二进制流保存到了inputStream里面
		conn.connect();
		
		InputStream in = conn.getInputStream();
		
		Bitmap bitmap = BitmapFactory.decodeStream(in); //BitMap的图片工厂，创建出一个图片
		
		
		
		return bitmap;
		} catch (MalformedURLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		finally
		{
			//5. 关闭连接
			if(null != conn)
			{
				conn.disconnect(); 
			}
		}
		
		return null;
	}
}