1. Activity生命周期

1.1 知识点

（1）掌握Activity的生命周期及操作方法；

1.2 具体内容

范例：

第一个配置文件

<LinearLayout 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:orientation="vertical"
    tools:context=".ActivityLifeActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="这是第一个Activity" />
    <Button 
        android:id="@+id/but_first"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="跳转到第二个Activity"
        />

</LinearLayout>

第二个配置文件：

<LinearLayout 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:orientation="vertical"
    tools:context=".ActivityLifeActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="这是第二个Activity" />
    <Button 
        android:id="@+id/but_second"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="跳转到第三个Activity"
        />

</LinearLayout>

第三个配置文件：

<LinearLayout 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:orientation="vertical"
    tools:context=".ActivityLifeActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="这是第二个Activity" />
   

</LinearLayout>

第一个Activity

package com.example.activitylifeproject;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class ActivityLifeActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_activity_life_first);
		Log.i("sign","第一个Activity的onCreate方法");
		Button but = (Button) super.findViewById(R.id.but_first);
		but.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				Intent it = new Intent(ActivityLifeActivity.this,ActivityLifeSecondActivity.class);
				startActivity(it);
			}
		});
	}
    @Override
    protected void onStart(){
    	Log.i("sign","第一个Activity的onStart方法");
    	super.onStart();
    }
    @Override
    protected void onResume(){
    	Log.i("sign","第一个Activity的onResume方法");
    	super.onResume();
    }
    @Override
    protected void onPause(){
    	Log.i("sign","第一个Activity的onPause方法");
    	super.onPause();
    }
    @Override
    protected void onStop(){
    	Log.i("sign","第一个Activity的onStop方法");
    	super.onStop();
    }
    @Override
    protected void onDestroy(){
    	Log.i("sign","第一个Activity的onDestroy方法");
    	super.onDestroy();
    }
    @Override
    protected void onRestart(){
    	Log.i("sign","第一个Activity的onRestart方法");
    	super.onRestart();
    }
}

第二个Activity

package com.example.activitylifeproject;

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class ActivityLifeSecondActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_activity_life_second);
		Log.i("sign","第二个Activity的onCreate方法");
		Button but = (Button) super.findViewById(R.id.but_second);
		but.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				Intent it = new Intent(ActivityLifeSecondActivity.this,ActivityLifeThirdActivity.class);
				startActivity(it);
			}
		});
	}

	@Override
    protected void onStart(){
    	Log.i("sign","第二个Activity的onStart方法");
    	super.onStart();
    }
    @Override
    protected void onResume(){
    	Log.i("sign","第二个Activity的onResume方法");
    	super.onResume();
    }
    @Override
    protected void onPause(){
    	Log.i("sign","第二个Activity的onPause方法");
    	super.onPause();
    }
    @Override
    protected void onStop(){
    	Log.i("sign","第二个Activity的onStop方法");
    	super.onStop();
    }
    @Override
    protected void onDestroy(){
    	Log.i("sign","第二个Activity的onDestroy方法");
    	super.onDestroy();
    }
    @Override
    protected void onRestart(){
    	Log.i("sign","第二个Activity的onRestart方法");
    	super.onRestart();
    }
}

第三个Activity

package com.example.activitylifeproject;

import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;

public class ActivityLifeThirdActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_activity_life_third);
	}

	@Override
    protected void onStart(){
    	Log.i("sign","第三个Activity的onStart方法");
    	super.onStart();
    }
    @Override
    protected void onResume(){
    	Log.i("sign","第三个Activity的onResume方法");
    	super.onResume();
    }
    @Override
    protected void onPause(){
    	Log.i("sign","第三个Activity的onPause方法");
    	super.onPause();
    }
    @Override
    protected void onStop(){
    	Log.i("sign","第三个Activity的onStop方法");
    	super.onStop();
    }
    @Override
    protected void onDestroy(){
    	Log.i("sign","第三个Activity的onDestroy方法");
    	super.onDestroy();
    }
    @Override
    protected void onRestart(){
    	Log.i("sign","第三个Activity的onRestart方法");
    	super.onRestart();
    }

}

1.3 小结

（1）Activity提供了专门的生命周期方法；

（2）在多个Activity打开的时候，会自动的进行入栈操作；