onCreate中的savedInstanceState有何具体作用

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（在paused状态时，要被KILLED的时候）。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);  
        }  
    }