onCreate中的savedInstanceState有何具体作用

最近在查看OnCreate(saveInstanceState)时候，只懂得其中是为了保存当activity失去焦点的时候的状态，却不知其实如何实现的，今天发现一个好文章，和大家分享一下哦。
在activity的生命周期中，只要离开了可见阶段，或者说失去了焦点，activity就很可能被进程终止了！，被KILL掉了，，这时候，就需要有种机制，能保存当时的状态，这就是savedInstanceState的作用。       当一个Activity在PAUSE时，被kill之前，它可以调用onSaveInstanceState()来保存当前activity的状态信息。用来保存状态信息的Bundle会同时传给两个method,即onRestoreInstanceState() and onCreate(). 示例代码如下：

• package com.myandroid.test;
• import android.app.Activity;
• import android.os.Bundle;
• import android.util.Log;
• public class AndroidTest extends Activity {
• private   static  final String TAG = "MyNewLog";
• /** Called when the activity is first created. */
• @Override
• public  void onCreate(Bundle savedInstanceState) {
• super.onCreate(savedInstanceState);
• // If an instance of this activity had previously stopped, we can
• // get the original text it started with.
• if(null != savedInstanceState)
• {
• int IntTest = savedInstanceState.getInt("IntTest");
• String StrTest = savedInstanceState.getString("StrTest");
• Log.e(TAG, "onCreate get the savedInstanceState+IntTest="+IntTest+"+StrTest="+StrTest);
• }
• setContentView(R.layout.main);
• Log.e(TAG, "onCreate");
• }
• @Override
• public  void onSaveInstanceState(Bundle savedInstanceState) {
• // Save away the original text, so we still have it if the activity
• // needs to be killed while paused.
• savedInstanceState.putInt("IntTest", 0);
• savedInstanceState.putString("StrTest", "savedInstanceState test");
• super.onSaveInstanceState(savedInstanceState);
• Log.e(TAG, "onSaveInstanceState");
• }
• @Override
• public   void onRestoreInstanceState(Bundle savedInstanceState) {
• super.onRestoreInstanceState(savedInstanceState);
• int IntTest = savedInstanceState.getInt("IntTest");
• String StrTest = savedInstanceState.getString("StrTest");
• Log.e(TAG, "onRestoreInstanceState+IntTest="+IntTest+"+StrTest="+StrTest);
• }
• }