package lizhen.download;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
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 android.os.AsyncTask;
public class DownloadAsyncTask extends AsyncTask<String, Integer, Boolean> {
protected int size;
protected String errorMessage;
@Override
protected Boolean doInBackground(String... params) {
String url = params[0];
String path = params[1];
try {
InputStream source = requestInputStream(url);
/**
* 创建文件写入数据，并更新进度
*/
fileWrite(source, path, new OnProgressUpdateListener() {
@Override
public void onProgressUpdate(int progress) {
publishProgress(progress);
}
});
} catch (ClientProtocolException e) {
errorMessage = e.getMessage();
cancel(true);
return false;
} catch (IOException e) {
errorMessage = e.getMessage();
cancel(true);
return false;
}
return true;
}
/**
* 文件写入
*
* @param in
* 数据源输出流
* @param path
* 文件路径
* @param listener
* 下载进度监听器
* */
private void fileWrite(InputStream in, String path,
OnProgressUpdateListener listener) throws IOException {
File file = createFile(path);
FileOutputStream fileOutputStream = new FileOutputStream(file);
byte buffer[] = new byte[1024];
int progress = 0;
int readBytes = 0;
while ((readBytes = in.read(buffer)) != -1) {
progress += readBytes;
fileOutputStream.write(buffer, 0, readBytes);
if (listener != null) {
listener.onProgressUpdate(progress);
}
}
in.close();
fileOutputStream.close();
}
/**
* 下载进度监听器
* */
private interface OnProgressUpdateListener {
/**
* 下载进度更新
*
* @param progress
* 进度
* */
public void onProgressUpdate(int progress);
}
/**
* 根据资源URL地址取得资源输入流
*
* @param url
* URL地址
* @return 资源输入流
* @throws ClientProtocolException
* @throws IOException
* */
private InputStream requestInputStream(String url)
throws ClientProtocolException, IOException {
InputStream result = null;
HttpGet httpGet = new HttpGet(url);
HttpClient httpClient = new DefaultHttpClient();
HttpResponse httpResponse = httpClient.execute(httpGet);
int httpStatusCode = httpResponse.getStatusLine().getStatusCode();
if (httpStatusCode == HttpStatus.SC_OK) {
HttpEntity httpEntity = httpResponse.getEntity();
size = (int) httpEntity.getContentLength();
result = httpEntity.getContent();
}
return result;
}
/**
* 根据文件路径创建文件
*
* @param path
* 文件路径
* @return 文件File实例
* @return IOException
* */
private File createFile(String path) throws IOException {
File file = new File(path);
file.createNewFile();
return file;
}
/**
* 返回错误信息
*
* @return 错误信息
* */
public String getErrorString() {
return this.errorMessage;
}
}
