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

<!-- sdCard增加删除与读写权限 -->
<uses-permission android:name="android.permission.INTERNET" />

<!-- sdCard增加删除与读写权限 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />