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Fragment与Activity之间的通信

 

  我个人将Fragment与Activity间的通信比喻为JSP与Servlet间的通信,fragment中用接口的方式来进行与Activity的通信。通信的结果可以作为数据传入另一个Fragment中。当然两个Fragment之间也是可以进行通信的~

注意加载或者切换Fragment时,必须new一个FragmentTransaction对象,不能用同一个FragmentTransaction对象进行对容器进行替换、增加fragment。将fragment填充进容器的方式是(这里分别给两个容器填充了两个fragment对象):

     FragmentManager fragmentManager = getSupportFragmentManager();        FragmentTransaction ft = fragmentManager.beginTransaction();              ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);        ft.add(R.id.container_fragment, new MyFragment())        .commit();                //不能用同个FragmentTransaction来加载两个fragment        fragmentManager.beginTransaction()        .add(R.id.container_fragment02, new MyFragment02())        .commit();

 

更换fragment的方式是:

        getSupportFragmentManager().beginTransaction().        replace(R.id.container_fragment02, fragment)        .addToBackStack(null)        .commit();

 

  本实例完成的是点击一个Fragment中的按钮后,fragment给activity传值,activity接受到值后给另一个fragment(右边的)传值,以此改变textview中的内容。

activity_main.xml (定义了2个布局来作为fragment的容器)

<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:background="#000000"    android:orientation="horizontal" >    <FrameLayout        android:id="@+id/container_fragment"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:layout_weight="1"        android:background="#ffffff"        android:layout_marginRight="1dp" />    <FrameLayout        android:id="@+id/container_fragment02"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:layout_weight="1"        android:background="#ffffff"        android:layout_marginLeft="1dp" >    </FrameLayout></LinearLayout>

 

fragment.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"    tools:context="${relativePackage}.${activityClass}" >    <Button        android:id="@+id/fragment_button"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerHorizontal="true"        android:layout_centerVertical="true"        android:layout_marginBottom="41dp"        android:text="kale" />    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_above="@+id/fragment_button"        android:layout_centerHorizontal="true"        android:layout_marginBottom="46dp"        android:text="点击后传值"        android:textAppearance="?android:attr/textAppearanceLarge" /></RelativeLayout>

 

MyFragment

package com.kale.activity;import android.app.Activity;import android.os.Bundle;import android.support.annotation.Nullable;import android.support.v4.app.Fragment;import android.util.Log;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.view.View.OnClickListener;import android.widget.Button;public class MyFragment extends Fragment{    private MyCallback mCallback;    //定义一个调用接口}    public interface MyCallback {        public void onBtnClick(View v);    }    String TAG = getClass().getName();    @Override    public void onAttach(Activity activity) {        super.onAttach(activity);        Log.e(TAG, "F------------onAttach->");        if(!(activity instanceof MyCallback)) {            throw new IllegalStateException("fragment所在的Activity必须实现Callbacks接口");        }        //把绑定的activity当成callback对象        mCallback = (MyCallback)activity;    }    @Override    public void onActivityCreated(@Nullable Bundle savedInstanceState) {        super.onActivityCreated(savedInstanceState);        Log.e(TAG, "F------------onActivityCreated->");        //一定要在定义好视图后才来初始化控件,不能放在onCreat()里面        Button btn = (Button)getActivity().findViewById(R.id.fragment_button);        btn.setOnClickListener(new OnClickListener() {                        @Override            public void onClick(View v) {                mCallback.onBtnClick(v);            }        });    }    @Override    public void onDetach() {        super.onDetach();        Log.e(TAG, "F------------onDetach->");        mCallback = null;//移除前幅值为空    }}

 

fragment02.xml

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent">    <TextView        android:id="@+id/fragment_textView"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerHorizontal="true"        android:layout_centerVertical="true"        android:text="null"        android:textAppearance="?android:attr/textAppearanceLarge" />    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_above="@+id/fragment_textView"        android:layout_centerHorizontal="true"        android:layout_marginBottom="40dp"        android:textAppearance="?android:attr/textAppearanceLarge"         android:text="传来的信息" /></RelativeLayout>

 

MyFragment02

package com.kale.activity;import android.app.Activity;import android.os.Bundle;import android.support.annotation.Nullable;import android.support.v4.app.Fragment;import android.util.Log;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.TextView;public class MyFragment02 extends Fragment{    public static final String KEY = "key";    String TAG = getClass().getName();    @Override    public View onCreateView(LayoutInflater inflater,            @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {        Log.e(TAG, "F------------onCreateView->");        return inflater.inflate(R.layout.fragment02, container, false);    }    @Override    public void onActivityCreated(@Nullable Bundle savedInstanceState) {        super.onActivityCreated(savedInstanceState);        Log.e(TAG, "F------------onActivityCreated->");        //一定要在定义好视图后才来初始化控件,不能放在onCreat()里面        TextView tv = (TextView)getActivity().findViewById(R.id.fragment_textView);        tv.setText("haha");          Bundle bundle = getArguments();          if (bundle == null) {            tv.setText("默认值01");        }          else {              tv.setText(bundle.getString(KEY, "默认值02"));        }    }}

 

源码下载:http://download.csdn.net/detail/shark0017/7709315