Android基础总结篇之一：Activity生命周期(3)

为应用中的Activity设置特定的方向是经常用到的办法，可以为我们省去不少不必要的麻烦。不过，我们今天讲的是屏幕方向改变时的生命周期，所以我们并不采用固定屏幕方向这种办法。

下面我们就结合实例讲解一下屏幕转换的生命周期，我们新建一个Activity命名为OrientationActivity，如下：

package com.scott.lifecycle;

import Android.app.Activity;
import android.content.res.Configuration;
import android.os.Bundle;
import android.util.Log;

public class OrientationActivity extends Activity {
 
 private static final String TAG = "OrientationActivity";
 private int param = 1;
 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.orientation_portrait);
  Log.i(TAG, "onCreate called.");
 }
 
 @Override
 protected void onStart() {
  super.onStart();
  Log.i(TAG, "onStart called.");
 }
 
 @Override
 protected void onRestart() {
  super.onRestart();
  Log.i(TAG, "onRestart called.");
 }
 
 @Override
 protected void onResume() {
  super.onResume();
  Log.i(TAG, "onResume called.");
 }
 
 @Override
 protected void onPause() {
  super.onPause();
  Log.i(TAG, "onPause called.");
 }
 
 @Override
 protected void onStop() {
  super.onStop();
  Log.i(TAG, "onStop called.");
 }
 
 @Override
 protected void onDestroy() {
  super.onDestroy();
  Log.i(TAG, "onDestory called.");
 }

@Override
 protected void onSaveInstanceState(Bundle outState) {
  outState.putInt("param", param);
  Log.i(TAG, "onSaveInstanceState called. put param: " + param);
  super.onSaveInstanceState(outState);
 }
 
 @Override
 protected void onRestoreInstanceState(Bundle savedInstanceState) {
  param = savedInstanceState.getInt("param");
  Log.i(TAG, "onRestoreInstanceState called. get param: " + param);
  super.onRestoreInstanceState(savedInstanceState);
 }
 
 //当指定了android:configChanges="orientation"后,方向改变时onConfigurationChanged被调用
 @Override
 public void onConfigurationChanged(Configuration newConfig) {
  super.onConfigurationChanged(newConfig);
  Log.i(TAG, "onConfigurationChanged called.");
  switch (newConfig.orientation) {
  case Configuration.ORIENTATION_PORTRAIT:
   setContentView(R.layout.orientation_portrait);
   break;
  case Configuration.ORIENTATION_LANDSCAPE:
   setContentView(R.layout.orientation_landscape);
   break;
  }
 }
}