android下圖片

 如果每下載一張圖片，就得重寫一次Http協議，多線程的啓動和handler的信息傳遞就顯得太麻煩了，我們直接來封裝一個工具類，便於我們以後在開發時隨時可以調用。

 （1）在清單文件添加權限

<uses-permission android:name="android.permission.INTERNET"/>

（2）編輯工具類

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);
    }
}

    （3）調用該工具類

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;
    }

}