Fragment跟Activity之间的通信（互相调用方法）

今天用到viewPager嵌套fragment，需要fragment调用activity的方法，还需要activity调用fragment的方法，一时间不知道该怎么做了。后来看到别人这样实现：在Activity定义接口和一个Handler,接口的作用是让碎片接收Activity的指令,而Handler用于接收碎片传来的指令,Activity在执行操作.

如下所示:

package com.example.fragmentactivity;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentTransaction;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.FrameLayout;

public class MainActivity extends FragmentActivity implements OnClickListener {
private Button button1;
private String fragmentName;
private OnButtonClickedListener buttonClickedListener;
/**
* 定义一个Handler用于接收黄色碎片给Activity发出来的指令
*/
public Handler handler=new Handler(){
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
if(msg!=null){
switch (msg.what) {
case 100:
/**
* 接收到黄色碎片发来的指令,Activity执行替换操作
*/
fragmentName=Fragment2.class.getName();
replaceFragment(R.id.FrameLayout1, fragmentName);
break;

default:
break;
}
}
}

};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button1=(Button) findViewById(R.id.button1);
button1.setOnClickListener(this);
/**
* 加载黄色碎片
*/
fragmentName=Fragment1.class.getName();
replaceFragment(R.id.FrameLayout1, fragmentName);
}

@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.button1:
if(buttonClickedListener!=null){
buttonClickedListener.onclicked("Activity:我不想要这个黄色碎片了,点击下面的按钮给我换个绿色的碎片");
}
break;
default:
break;
}

}
/*
*
* 加载碎片
*/
protected void replaceFragment(int viewResource, String fragmentName) {
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
Fragment fragment = Fragment.instantiate(this, fragmentName);
ft.replace(viewResource, fragment);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
ft.commit();
getSupportFragmentManager().executePendingTransactions();
}
/**
* 定义一个接口
* @author zqy
*
*/
public  interface OnButtonClickedListener{
/**
* 里面传个值
* @param s
*/
public void onclicked(String s);
}
/**
*
* @param buttonClickedListener
* 写一个对外公开的方法
*/
public void setButtonClickedListener(OnButtonClickedListener buttonClickedListener){
this.buttonClickedListener=buttonClickedListener;
}

}

这就是Activity里面的代码,我们在去写两个碎片如下所示:

Fragment1:

package com.example.fragmentactivity;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
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.TextView;
import android.widget.Toast;

import com.example.fragmentactivity.MainActivity.OnButtonClickedListener;

public class Fragment1 extends Fragment implements OnClickListener {
private TextView textView;
private Button button;
private Handler handler;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
MainActivity activity=(MainActivity) getActivity();
/**
* 得到Activity的Handler
*/
handler=activity.handler;
/**
* 加监听
*/
activity.setButtonClickedListener(new OnButtonClickedListener() {

@Override
public void onclicked(String s) {
/*
* 显示Activity传来的内容
*/
textView.setText(s);
button.setVisibility(View.VISIBLE);
}
});
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.item1, null);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
textView=(TextView) getActivity().findViewById(R.id.textView1);
button=(Button) getActivity().findViewById(R.id.button2);
button.setOnClickListener(this);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.button2:
/**
* 发送指令到Activity
*/
handler.sendEmptyMessage(100);
break;

default:
break;
}
}

这个碎片让它的Activity实现这个接口,在把接口里面的值显示到页面上,在点击这个碎片里面的Button给它的Activity发送一个消息.这里面我发的是100.

Fragment2:

package com.example.fragmentactivity;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class Fragment2 extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
return inflater.inflate(R.layout.item2, null);
}
}

这就写完了.以后的项目在也不怕碎片跟Activity通信了。