Android应用中Back键的监听及处理实例

MainActivity如下:
复制代码 代码如下:
package cn.testnbackpressed;
import android.os.Bundle;
import android.view.KeyEvent;
import android.app.Activity;

public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}

@Override
public void onBackPressed() {
super.onBackPressed();
System.out.println("按下了back键 onBackPressed()");
}

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if ((keyCode == KeyEvent.KEYCODE_BACK)) {
System.out.println("按下了back键 onKeyDown()");
return false;
}else {
return super.onKeyDown(keyCode, event);
}

}

@Override
protected void onDestroy() {
super.onDestroy();
System.out.println("执行 onDestroy()");
}
}

main.xml如下:
复制代码 代码如下:
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="对于Back键的两种处理方法"
android:layout_centerInParent="true"
android:textSize="20sp"
/>