Android:Activity+Fragment及它们之间的数据交换(一)

简介:

为什么要用Fragment?使用Fragment可以在一个Activity中实现不同的界面。Fragment与Fragment之间的动画切换,远比Activity与Activity之间的动画切换变化方式多。很多时候,我们通过使用一个Activity,切换多个Fragment。本次博客,主要列举一下Fragment与它的Activity之间进行数据交换的方式。

1.Fragment中通过getActivity()然后进行强制转化,调用Activity中的公有方法

((XXXXActivity)getActivity()).fun();

2.Activity在切换Fragment的时候,通过setArguments向Fragment传递参数,Fragment通过getArguments();获得从activity中传递过来的值

3.Activity实现一个接口,Fragment在onAttach方法中,将该Activity转化为该接口,在需要调用的时候回调。

注意:本Demo是通过FragmentManager来管理Fragment的,通过FragmentManager管理,我们创建Fragment和销毁Fragment的时候,可以通过栈的方式:

a.FragmentTransaction的add方法,添加一个Fragment

b.FragmentTransaction的popBackStack()弹出该Fragment

演示实例:

fragment1.xml

<RelativeLayout 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:background="#FFFFFFFF"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.testfragment.MainActivity$PlaceholderFragment" >
    <TextView
        android:id="@+id/tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:text="fragment1" />
    <Button
        android:id="@+id/btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/tv"
        android:text="跳转到Fragment2" />
</RelativeLayout>

MyFragment1.java

/*
 * $filename: MyFragment.java,v $
 * $Date: 2014-5-16  $
 * Copyright (C) ZhengHaibo, Inc. All rights reserved.
 * This software is Made by Zhenghaibo.
 */
package com.example.testfragment;

import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;

/*
 *@author: ZhengHaibo  
 *web:     http://blog.csdn.net/nuptboyzhb
 *mail:    [email protected]
 *2014-5-16  Nanjing,njupt,China
 */
public class MyFragment1 extends Fragment {
	
	FragmentCallBack fragmentCallBack = null;
	Button btn;
	@Override
	public View onCreateView(LayoutInflater inflater, ViewGroup container,
			Bundle savedInstanceState) {
		View rootView = inflater.inflate(R.layout.fragment1, container,
				false);
		btn = (Button)rootView.findViewById(R.id.btn);
		btn.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				fragmentCallBack.callbackFun1(null);
			}
		});
		return rootView;
	}
	
	@Override
	public void onAttach(Activity activity) {
		// TODO Auto-generated method stub
		super.onAttach(activity);
		fragmentCallBack = (MainActivity)activity;
	}
}

fragment2.xml

<RelativeLayout 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:background="#FFFFFFFF"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.testfragment.MainActivity$PlaceholderFragment" >
    <TextView
        android:id="@+id/tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:text="fragment2" />
    <Button
        android:id="@+id/btn1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/tv"
        android:text="直接调用Activity" />
    <Button
        android:id="@+id/btn2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/btn1"
        android:text="回调Activity" />
</RelativeLayout>


MyFragment2.java
/*
 * $filename: MyFragment.java,v $
 * $Date: 2014-5-16  $
 * Copyright (C) ZhengHaibo, Inc. All rights reserved.
 * This software is Made by Zhenghaibo.
 */
package com.example.testfragment;

import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.Toast;

/*
 *@author: ZhengHaibo  
 *web:     http://blog.csdn.net/nuptboyzhb
 *mail:    [email protected]
 *2014-5-16  Nanjing,njupt,China
 */
public class MyFragment2 extends Fragment {
	
	FragmentCallBack fragmentCallBack = null;
	Button btn1;
	Button btn2;
	@Override
	public View onCreateView(LayoutInflater inflater, ViewGroup container,
			Bundle savedInstanceState) {
		View rootView = inflater.inflate(R.layout.fragment2, container,
				false);
		Bundle data = getArguments();//获得从activity中传递过来的值
		Toast.makeText(getActivity(), data.getString("TEXT"), Toast.LENGTH_SHORT).show();
		btn1 = (Button)rootView.findViewById(R.id.btn1);
		btn1.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// 直接调用Activity中的方法
				((MainActivity)getActivity()).changeButtonColor();
			}
		});
		btn2 = (Button)rootView.findViewById(R.id.btn2);
		btn2.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// 回调的方式
				fragmentCallBack.callbackFun2(null);
			}
		});
		return rootView;
	}
	
	@Override
	public void onAttach(Activity activity) {
		// TODO Auto-generated method stub
		super.onAttach(activity);
		fragmentCallBack = (MainActivity)activity;
	}
}

回调接口:

/*
 * $filename: FragmentCallBack.java,v $
 * $Date: 2014-5-16  $
 * Copyright (C) ZhengHaibo, Inc. All rights reserved.
 * This software is Made by Zhenghaibo.
 */
package com.example.testfragment;

import android.os.Bundle;

/*
 *@author: ZhengHaibo  
 *web:     http://blog.csdn.net/nuptboyzhb
 *mail:    [email protected]
 *2014-5-16  Nanjing,njupt,China
 */
public interface FragmentCallBack {
	public void callbackFun1(Bundle arg);

	public void callbackFun2(Bundle arg);
}

main.xml

<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin" >
    <Button
        android:id="@+id/btn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:text="切换" />
    <RelativeLayout
        android:id="@+id/rl_container"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_above="@id/btn" />
</RelativeLayout>

MainActivity.java

package com.example.testfragment;

import android.graphics.Color;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends ActionBarActivity implements FragmentCallBack{
	
	private Button btn;
	
	private MyFragment1 fragment1;
	private MyFragment2 fragment2;
	private FragmentManager fragmentManager;
	private Fragment currentFragment;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		fragmentManager = getSupportFragmentManager();
		
		FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
		fragmentTransaction.setCustomAnimations(android.R.anim.fade_in, android.R.anim.fade_out);
		fragment1 = new MyFragment1();
		Bundle data = new Bundle();
		data.putString("TEXT", "这是Activiy通过Bundle传递过来的值");
		fragment1.setArguments(data);//通过Bundle向Activity中传递值
		fragmentTransaction.add(R.id.rl_container,fragment1);//将fragment1设置到布局上
		fragmentTransaction.addToBackStack(null);
		fragmentTransaction.commitAllowingStateLoss();
		currentFragment = fragment1;
		//初始化button控件
		btn = (Button)findViewById(R.id.btn);
		btn.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				if(currentFragment instanceof MyFragment1){
					switchFragment();
				}else{//当前是fragment2,因此,只需要将fragment2出栈即可变成fragment1
					fragmentManager.popBackStack();
					currentFragment = fragment1;
				}
			}
		});
	}
	/**
	 * 切换Fragment
	 */
	private void switchFragment(){
		if(null == fragment2){//可以避免切换的时候重复创建
			fragment2 = new MyFragment2();
		}
		Bundle data = new Bundle();
		data.putString("TEXT", "传递给fragment2");
		fragment2.setArguments(data);
		FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
		fragmentTransaction.setCustomAnimations(android.R.anim.fade_in, android.R.anim.fade_out);
		fragmentTransaction.add(R.id.rl_container,fragment2);
		fragmentTransaction.addToBackStack(null);
		fragmentTransaction.commitAllowingStateLoss();
		currentFragment = fragment2;
	}
	
	public void changeButtonColor(){
		btn.setBackgroundColor(Color.RED);
	}

	@Override
	public void callbackFun1(Bundle arg) {
		// TODO Auto-generated method stub
		switchFragment();//通过回调方式切换
	}

	@Override
	public void callbackFun2(Bundle arg) {
		// TODO Auto-generated method stub
		changeButtonColor();//通过回调方式调用Activity中的方法
	}

}


初始画面


切换到第二个Fragment之后,通过Fragment2回调,改变按钮背景后的截图。

注意:

1.直接在Fragment中通过getActivity然后强转Activity的方式调用Activity的方法,这个方式不推荐!因为这会使Fragment的适配性变差。

解决方法:在使用之前,使用instanceof 判断一下Activity的类型

2.FragmentTransaction通过使用setCustomAnimations方法,可以为Fragment的切换增添各种不同的动画。变化方式远比Activity与Activity之间的切换动画要多。

3.多个Fragment之间,可以通过Activity复用很多代码,提高效率。

4.我们还可以通过ViewPager来管理Fragment,通过Adapter添加多个Fragment,然后通过setcurrentitem进行切换。我们同样可以通过setArguments向Fragment传递数据。



Android:Activity+Fragment及它们之间的数据交换(一),,5-wow.com

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