Android使用HttpClient下載圖片

在前一章中講的是Android使用HttpURLConnection下載圖片，這一章使用HttpClient下載圖片

HttpURLConnection與HttpClient的區別：

HttpClient是個很不錯的開源框架（org.appache.http），封裝了訪問http的請求頭，參數，內容體，響應等等，使用起來更方面更強大。
HttpURLConnection是java的標准類，可以實現簡單的基於URL請求、響應功能，什麼都沒封裝，用起來太原始，比如重訪問的自定義，以及一些高級功能等。

還是在上一章的基礎上添加HttpClient

關鍵下載代碼<喎?/kf/ware/vc/" target="_blank" class="keylink">vcD4KPHA+PHByZSBjbGFzcz0="brush:java;">/** * 通過Get獲取網頁內容 * * @param url * 如：http://preview.quanjing.com/is002/ev601-025.jpg * @return * @throws ClientProtocolException * @throws IOException * @date 2014.05.10 */ public static Bitmap getHttpGetBitmap(String url) throws ClientProtocolException, IOException { Bitmap bitmap = null; // 新建一個默認的連接 HttpClient client = new DefaultHttpClient(); // 新建一個Get方法 HttpGet get = new HttpGet(url); // 得到網絡的回應 HttpResponse response = client.execute(get); // 如果服務器響應的是OK的話！ if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) { InputStream is = response.getEntity().getContent(); bitmap = BitmapFactory.decodeStream(is); is.close(); } return bitmap; }

訪問互聯網權限

Activity下載代碼

package com.dzt.downloadimage;

import java.io.IOException;
import java.net.MalformedURLException;

import org.apache.http.client.ClientProtocolException;

import android.app.Activity;
import android.graphics.Bitmap;
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;

import com.dzt.downloadimage.utils.HttpUtils;

public class MainActivity extends Activity implements OnClickListener {

	private Bitmap mDownloadImage = null;
	private ImageView image = null;
	private downloadImageTask task;
	private boolean _isExe = false;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		initWidgets();
		task = new downloadImageTask();
	}

	@Override
	protected void onStop() {
		// TODO Auto-generated method stub
		super.onStop();
		if (_isExe) {
			task.cancel(true); // 取消操作
		}
	}

	private void initWidgets() {
		image = (ImageView) findViewById(R.id.img);
		Button btn = (Button) findViewById(R.id.download_btn);
		btn.setOnClickListener(this);
	}

	@Override
	public void onClick(View v) {
		// TODO Auto-generated method stub
		switch (v.getId()) {
		case R.id.download_btn:
			if (!_isExe) {
				task.execute("http://preview.quanjing.com/is002/ev601-025.jpg"); // 執行異步操作
				_isExe = true;
			}
			break;

		default:
			break;
		}
	}

	class downloadImageTask extends AsyncTask {

		@Override
		protected Boolean doInBackground(String... params) {
			// TODO Auto-generated method stub
			System.out.println("[downloadImageTask->]doInBackground "
					+ params[0]);
			// try {
			// mDownloadImage = HttpUtils.getNetWorkBitmap(params[0]);
			// } catch (MalformedURLException e) {
			// // TODO Auto-generated catch block
			// e.printStackTrace();
			// } catch (IOException e) {
			// // TODO Auto-generated catch block
			// e.printStackTrace();
			// }
			try {
				mDownloadImage = HttpUtils.getHttpGetBitmap(params[0]);
			} catch (ClientProtocolException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			return true;
		}

		// 下載完成回調
		@Override
		protected void onPostExecute(Boolean result) {
			// TODO Auto-generated method stub
			image.setImageBitmap(mDownloadImage);
			System.out.println("result = " + result);
			super.onPostExecute(result);
		}

		// 更新進度回調
		@Override
		protected void onProgressUpdate(Integer... values) {
			// TODO Auto-generated method stub
			super.onProgressUpdate(values);
		}

	}
}

如果圖片較大可能會下載失敗

Demo：http://download.csdn.net/detail/deng0zhaotai/7326167