android 中FragmentActivity中模拟返回键返回上一个Activity效果

FragmentTransaction中先加入一个Fragment，这个Fragment就是当前要显示的Fragment，

当通过事件触发显示第二个Fragment时，在加入第二个Fragment并调用fragmentTransaction.addToBackStack(null);

在onBackPressed方法中调用mFragmentManager.popBackStack();回到第一个Fragment

package com.example.fragmentdemo;

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

public class MainActivity extends Activity {
	private FragmentManager mFragmentManager;
	private Fragment1 fragment1;
	private Fragment2 fragment2;
	private Button button1;
	private FragmentTransaction fragmentTransaction;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		//新建两个Fragment
		fragment1 = new Fragment1();
		fragment2 = new Fragment2();
		mFragmentManager = getFragmentManager();
		//Fragment事务
		fragmentTransaction = mFragmentManager.beginTransaction();
		//增加执行的动画效果 动画不能用我们的Tween动画，后面会有代码
		fragmentTransaction.setCustomAnimations(R.anim.animation_view, R.anim.animation_view_exit);
		//加入1个Fragment
		fragmentTransaction.add(R.id.myFrameLayout, fragment1);
		fragmentTransaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
		fragmentTransaction.commit();
		button1 = (Button)findViewById(R.id.button1);
		button1.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				fragmentTransaction = mFragmentManager.beginTransaction();
				//执行动画，显示fragment2
				fragmentTransaction.setCustomAnimations(R.anim.animation_view, R.anim.animation_view_exit);
				if (fragment2.isAdded()) {
					fragmentTransaction.commit();
				}else{
					fragmentTransaction.add(R.id.myFrameLayout, fragment2);
					fragmentTransaction.addToBackStack(null);
					fragmentTransaction.commit();
				}
			}
		});
		
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}
	
	@Override
	protected void onResume() {
		
		super.onResume();
	}

	@Override
	public void onBackPressed() {
		super.onBackPressed();
		mFragmentManager.popBackStack();
		
	}
	
	
}