Android 下载文件至SD卡，并用progressBar显示下载进度

Android 下载文件至SD卡，并用progressBar显示下载进度

import java.io.File;
import java.io.FileOutputStream;
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.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.Toast;

public class ProgressBarActivity extends Activity {

	private final static String TAG = "MainActivity";
	private final static String downloadAddress = "http://e.hiphotos.baidu.com/image/w%3D2048/sign=96d9aaaf552c11dfded1b823571f63d0/eaf81a4c510fd9f9232a3825272dd42a2834a4b9.jpg";
	private final static String musicName = "美女.jpg";
	Button startButton = null;
	Button endButton = null;
	ProgressBar progressBar = null;
	Handler handler = null;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.progressbar);
		startButton = (Button) this.findViewById(R.id.start);
		endButton = (Button) this.findViewById(R.id.end);
		progressBar = (ProgressBar) this.findViewById(R.id.progressBar);
		progressBar.setMax(100);
		startButton.setClickable(true);
		endButton.setClickable(false);
		handler = new Handler() {

			@Override
			public void handleMessage(Message msg) {
				int progress = msg.arg1;
				if (progress >= 99) {
					Toast.makeText(ProgressBarActivity.this,
							"download is finished", Toast.LENGTH_SHORT).show();
				}
				progressBar.setProgress(progress);
				super.handleMessage(msg);
			}
		};
		startButton.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				// startOnClick();
				new Thread(runnable).start();
				Log.i(TAG, "StartButton is pressed.....");
				startButton.setClickable(false);
				endButton.setClickable(true);
			}
		});
		endButton.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				handler.removeCallbacks(runnable);
				Log.i(TAG, "EndButton is pressed.....");
				endButton.setClickable(false);
				startButton.setClickable(true);
			}
		});

	}

	Runnable runnable = new Runnable() {

		@Override
		public void run() {
			URL url = null;
			InputStream inputStream = null;
			FileOutputStream fileOutputStream = null;
			try {
				// 设置下载路径
				String path = Environment.getExternalStorageDirectory()
						.getAbsolutePath() + File.separator + musicName;
				// 检查SD卡状态
				if (Environment.getExternalStorageState().equals(
						Environment.MEDIA_MOUNTED)) {
					fileOutputStream = new FileOutputStream(path);
					url = new URL(downloadAddress);
					HttpURLConnection connection = (HttpURLConnection) url
							.openConnection();
					inputStream = connection.getInputStream();
					long total_length = connection.getContentLength();
					byte[] buf = new byte[1024];
					int len = 0;
					int now_length = 0;
					while ((len = inputStream.read(buf)) != -1) {
						fileOutputStream.write(buf, 0, len);
						now_length += len;
						Message msg = handler.obtainMessage();
						//计算下载进度
						msg.arg1 = ((int) ((now_length / (float) total_length) * 100));
						msg.sendToTarget();
					}
				} else {
					Toast.makeText(ProgressBarActivity.this,
							"Please check SD card", Toast.LENGTH_SHORT).show();
				}
			} catch (MalformedURLException e1) {
				// TODO Auto-generated catch block
				e1.printStackTrace();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} finally {
				try {
					if (inputStream != null)
						inputStream.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}
	};
}

别忘了要加上权限