Android AsyncTask异步处理抓取网页

Android AsyncTask异步处理抓取网页

/**
 * 
 * @author yanggang
 * @see http://blog.csdn.net/sunboy_2050
 */
public class MainActivity extends Activity {
	private EditText metURL;
	private TextView mtvPage;
	private Button mbtnConn;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        metURL = (EditText)findViewById(R.id.etURL);		// 输入网址
        mbtnConn = (Button)findViewById(R.id.btnConn);		// 连接网站
        mtvPage = (TextView)findViewById(R.id.tvPage);		// 显示网页
        
        mbtnConn.setOnClickListener(new View.OnClickListener() {
			@Override
			public void onClick(View v) {
				connURL();
			}
		});
    }
    private void connURL(){
    	URLTask urlTask = new URLTask(this);	// 实例化抽象AsyncTask
    	urlTask.execute(metURL.getText().toString().trim());	// 调用AsyncTask，传入url参数
    }
    
    /** 继承AsyncTask的子类，下载url网页内容 */
    class URLTask extends AsyncTask<String, Integer, String> {
    	ProgressDialog proDialog;
    	
    	public URLTask(Context context) {
    		proDialog = new ProgressDialog(context, 0);
    		proDialog.setButton("cancel", new DialogInterface.OnClickListener() {
				@Override
				public void onClick(DialogInterface dialog, int which) {
					dialog.cancel();
				}
			});
    		proDialog.setOnCancelListener(new DialogInterface.OnCancelListener() {
				@Override
				public void onCancel(DialogInterface dialog) {
					finish();
				}
			});
    		proDialog.setCancelable(true);
    		proDialog.setMax(100);
    		proDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
    		proDialog.show();
    	}
    	@Override
    	protected void onPreExecute(){
    		mtvPage.setText(R.string.hello_world);		// 可以与UI控件交互
    	}
    	
		@Override
		protected String doInBackground(String... params) {		// 在后台，下载url网页内容
			try {
				HttpGet get = new HttpGet(params[0]);			// url
				HttpResponse response = new DefaultHttpClient().execute(get);
				
				if(response.getStatusLine().getStatusCode() == 200) {		// 判断网络连接是否成功
//					String result = EntityUtils.toString(response.getEntity(), "gb2312");	// 获取网页内容
//					return result;
					
					HttpEntity entity = response.getEntity();
					long len = entity.getContentLength();		// 获取url网页内容总大小
					InputStream is = entity.getContent();
					
					ByteArrayOutputStream bos = new ByteArrayOutputStream();
					byte[] buffer = new byte[1024];
					int ch = -1;
					int count = 0;		// 统计已下载的url网页内容大小
					while(is != null && (ch = is.read(buffer)) != -1 ) {
						bos.write(buffer, 0, ch);
						count += ch;
						if(len > 0) {
							float ratio = count/(float)len * 100;	// 计算下载url网页内容百分比
							publishProgress((int)ratio);	// android.os.AsyncTask.publishProgress(Integer... values)
						}
						Thread.sleep(100);
					}
					String result = new String(bos.toString("gb2312"));
					return result;
				}
			} catch (Exception e) {
				e.printStackTrace();
			}
			
			return null;
		}
		
		@Override
		protected void onProgressUpdate(Integer... values) {	// 可以与UI控件交互
			mtvPage.setText("" + values[0]);	// 获取 publishProgress((int)ratio)的values
			proDialog.setProgress(values[0]);
		}
		
		@Override
		protected void onPostExecute(String result) {	// 可以与UI控件交互
			mtvPage.setText(result);
			proDialog.dismiss();
		}
    }
}