Android開發之使用Handler封裝下載圖片工具類

    package com.example.g05_handler;  

    import java.io.IOException;  

    import org.apache.http.HttpResponse;  
    import org.apache.http.client.ClientProtocolException;  
    import org.apache.http.client.HttpClient;  
    import org.apache.http.client.methods.HttpGet;  
    import org.apache.http.impl.client.DefaultHttpClient;  
    import org.apache.http.util.EntityUtils;  

    import android.annotation.SuppressLint;  
    import android.app.ProgressDialog;  
    import android.content.Context;  
    import android.os.Handler;  
    import android.os.Message;  
    import android.util.Log;  

    public class DownLoad {  

        private ProgressDialog dialog;  

        public DownLoad(Context context) {  
            // TODO Auto-generated constructor stub  
            dialog = new ProgressDialog(context);  
            dialog.setTitle("提示");  
            dialog.setMessage("玩命加載中");  

        }  

        @SuppressLint("HandlerLeak")  
        public void Down(final String path, final DownLoadCallback callback) {  
            final Handler handler = new Handler() {  
                @Override  
                public void handleMessage(Message msg) {  
                    // TODO Auto-generated method stub  
                    super.handleMessage(msg);  
                    byte[] result = (byte[]) msg.obj;  

                    callback.download(result);  

                    if (msg.what == 1) {  
                        dialog.dismiss();  
                    }  
                }  
            };  
            class MyThread implements Runnable {  
                @Override  
                public void run() {  
                    // TODO Auto-generated method stub  
                    HttpClient client = new DefaultHttpClient();  
                    HttpGet httpGet = new HttpGet(path);  
                    try {  
                        HttpResponse httpResponse = client.execute(httpGet);  
                        Log.i("TAG", "------>"  
                                + httpResponse.getStatusLine().getStatusCode());  
                        if (httpResponse.getStatusLine().getStatusCode() == 200) {  
                            byte[] result = EntityUtils.toByteArray(httpResponse  
                                    .getEntity());  
                            Message message = Message.obtain();  
                            message.obj = result;  
                            message.what = 1;  
                            handler.sendMessage(message);  
                        }  
                    } catch (ClientProtocolException e) {  
                        // TODO Auto-generated catch block  
                        e.printStackTrace();  
                    } catch (IOException e) {  
                        // TODO Auto-generated catch block  
                        e.printStackTrace();  
                    } finally {  
                        if (client != null) {  
                            client.getConnectionManager().shutdown();  
                        }  
                    }  
                };  
            }  
            new Thread(new MyThread()).start();  
            dialog.show();  
        }  

        public interface DownLoadCallback {  
            public void download(byte[] data);  
        }  
    }  

package com.example.g05_handler;  

import com.example.g05_handler.DownLoad.DownLoadCallback;  

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

public class MainActivity extends Activity {  
    private Button button;  
    private ImageView imageView;  
    private final String path="http://avatar.csdn.net/D/7/5/1_u013900875.jpg";  
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  
        button=(Button)this.findViewById(R.id.button1);  
        imageView=(ImageView)this.findViewById(R.id.imageView1);  
        button.setOnClickListener(new View.OnClickListener() {  

            @Override  
            public void onClick(View v) {  
                // TODO Auto-generated method stub  
                DownLoad downLoad=new DownLoad(MainActivity.this);  
                downLoad.Down(path, new DownLoadCallback() {  

                    @Override  
                    public void download(byte[] data) {  
                        // TODO Auto-generated method stub  
                        Bitmap bitmap=BitmapFactory.decodeByteArray(data, 0, data.length);  
                        imageView.setImageBitmap(bitmap);  
                    }  
                });  
            }  
        });  
    }  

    @Override  
    public boolean onCreateOptionsMenu(Menu menu) {  
        // Inflate the menu; this adds items to the action bar if it is present.  
        getMenuInflater().inflate(R.menu.main, menu);  
        return true;  
    }  

}