Android通信：Handler和runOnUiThread()

1、Handler类，主要用于复杂的通信，但操作相对复杂

public class MainActivity extends Activity {

	private static final int SET_TEXT = 1;
	private static final int ERROR = 2;
	private EditText metPath, metShow;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		initView();
		setListener();
	}

	Handler handler = new Handler() {
		public void handleMessage(Message msg) {
			String result = (String) msg.obj;
			switch (msg.what) {
			case SET_TEXT:
				metShow.setText(result);
				break;
			case ERROR:
				Toast.makeText(MainActivity.this, "操作失败", Toast.LENGTH_LONG).show();
				break;
			}
		};
	};

	private void setListener() {

		findViewById(R.id.btnComfire).setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {

				new ChildThread().start();
			}
		});
	}

	private void initView() {

		metPath = (EditText) findViewById(R.id.evPath);
		metShow = (EditText) findViewById(R.id.etShow);
	}

	/**
	 * 连接网络属于耗时操作，放到子线程中进行相应操作
	 * @author CHJ
	 * 
	 */
	class ChildThread extends Thread {
		public void run() {
			String path = metPath.getText().toString().trim();
			try {

				URL url = new URL(path);
				HttpURLConnection conn = (HttpURLConnection) url.openConnection();
				// 设置请求参数, 这里为了简单只设置两种
				conn.setRequestMethod("GET");
				conn.setConnectTimeout(5000);

				int code = conn.getResponseCode();
				if (200 == code) {// 建立连接成功
					// 获取网页源代码并且转换成字符串
					InputStream is = conn.getInputStream();
					String result = new UtilTools().streamToString(is);
					if (result == null) {
						new UtilTools().sendInfoToMainThread(handler, ERROR,null);
					} else {
						new UtilTools().sendInfoToMainThread(handler, SET_TEXT,result);
					}

				} else {
					new UtilTools().sendInfoToMainThread(handler, ERROR, null);
				}
			} catch (Exception e) {
				e.printStackTrace();
				new UtilTools().sendInfoToMainThread(handler, ERROR, null);
			}
		};
	}

}

class UtilTools {

	/**
	 * 将一个输出流转换成字符串
	 * @param is
	 * @return 字符串
	 */
	public String streamToString(InputStream is) {
		// 在这个方法中还可以处理乱码，这里就不操作了。思路是通过解析
		// 网页的源码，可以得到网页的编码格式，然后进行相应操作
		BufferedReader br = new BufferedReader(new InputStreamReader(is));
		StringBuilder sb = new StringBuilder();
		String result = null;
		try {

			String temp = null;
			while ((temp = br.readLine()) != null) {
				sb.append(temp);
			}
			result = sb.toString().trim();
			is.close();
			return result;

		} catch (Exception e) {

			e.printStackTrace();
			try {
				is.close();
			} catch (IOException e1) {
				e1.printStackTrace();
			}

			return null;
		}
	}

	/**
	 * 往主线程发送消息，这里主要是考虑代码的复用
	 * @param handler
	 */
	public void sendInfoToMainThread(Handler handler, int tag, String obj) {
		Message msg = new Message();
		msg.what = tag;
		msg.obj = obj;
		handler.sendMessage(msg);
	}
}

2、runOnUiThread()主要用于简单的通信，操作简单。
	runOnUiThread(new Runnable() {
		public void run() {
		// 操作主线程的UI
		}
	});

public class MainActivity extends Activity {

	private EditText metPath, metShow;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		initView();
		setListener();
	}

	private void setListener() {

		findViewById(R.id.btnComfire).setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {

				new Thread() {

					public void run() {
						String path = metPath.getText().toString().trim();
						try {

							URL url = new URL(path);
							HttpURLConnection conn = (HttpURLConnection) url.openConnection();
							// 设置请求参数, 这里为了简单只设置两种
							conn.setRequestMethod("GET");
							conn.setConnectTimeout(5000);

							int code = conn.getResponseCode();
							if (200 == code) {// 建立连接成功
								// 获取网页源代码并且转换成字符串
								InputStream is = conn.getInputStream();
								final String result = new UtilTools()
										.streamToString(is);
								if (result == null) {
									
									runOnUiThread(new Runnable() {

										@Override
										public void run() {
											Toast.makeText(MainActivity.this,"操作失败", Toast.LENGTH_LONG).show();
										}
									});
								} else {

									runOnUiThread(new Runnable() {
										public void run() {
										
											metShow.setText(result);
										}
									});
								}

							} else {

								runOnUiThread(new Runnable() {

									@Override
									public void run() {
										Toast.makeText(MainActivity.this,"操作失败", Toast.LENGTH_LONG).show();
									}
								});
							}
						} catch (Exception e) {
							e.printStackTrace();
							runOnUiThread(new Runnable() {

								@Override
								public void run() {
									Toast.makeText(MainActivity.this,"操作失败", Toast.LENGTH_LONG).show();
								}
							});
						}
					};

				}.start();
			}
		});
	}

	private void initView() {

		metPath = (EditText) findViewById(R.id.evPath);
		metShow = (EditText) findViewById(R.id.etShow);
	}
}

class UtilTools {

	/**
	 * 将一个输出流转换成字符串
	 * 
	 * @param is
	 * @return 字符串
	 */
	public String streamToString(InputStream is) {
		// 在这个方法中还可以处理乱码，这里就不操作了。思路是通过解析
		// 网页的源码，可以得到网页的编码格式，然后进行相应操作
		BufferedReader br = new BufferedReader(new InputStreamReader(is));
		StringBuilder sb = new StringBuilder();
		String result = null;
		try {

			String temp = null;
			while ((temp = br.readLine()) != null) {
				sb.append(temp);
			}
			result = sb.toString().trim();
			is.close();
			return result;

		} catch (Exception e) {

			e.printStackTrace();
			try {
				is.close();
			} catch (IOException e1) {
				e1.printStackTrace();
			}

			return null;
		}
	}

}