Android提供了两套事件处理机制，分别是：

• 基于监听的事件处理
• 基于回调的事件处理

监听事件处理模型

• Event Source --> 任意界面组件都可作为事件源
• Event --> 系统自动产生
• Event Listener --> 程序员自己处理

主要分为以下几步：

1. 获取事件源，也就是被监听的对象
2. 实现监听器类
3. 调用事件源的setListener方法将事件监听器注册给普通组件

package com.lightless.eventqs;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
public class MainActivity extends ActionBarActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // Get App's bn button
        Button bn = (Button) findViewById(R.id.bn);
        // Bind listener to button
        bn.setOnClickListener(new MyClickListener());
    }
    // Define a Listener
    class MyClickListener implements View.OnClickListener {
        @Override
        public void onClick(View arg0) {
            EditText editText = (EditText) findViewById(R.id.txt);
            editText.setText("Button has been clicked!");
        }
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}