上一篇我们讲到与Fragment有关的常用函数,既然Fragment被称为是“小Activity”,现在我们来讲一下Fragment如何与Acitivity通信。如果上一篇还有不懂得,可以再看一下。传送门。
Fragment与Activity通信的方式如下:
一、通过初始化函数提供
1.在动态添加Fragment的过程中,我们在Activity中通过Fragment.setArguments()的方法为Fragment提供数据;
2.在Fragment中,在onAttach()函数中通过调用getArguments()获得一个Bundle对象,从而获取我们提供的数据。
二、创建回调接口
比如说:新闻浏览情境下,共有两个Fragment,一个是用来显示新闻标题;另外一个用来显示新闻内容。当我们点击新闻标题的时候,新闻的内容就显示到另外一个Fragment当中了。下面我们就来通过按下Fragment1中的button来传递一个消息到Fragment2中。
首先我们要做的是,在Fragment1中创建一个回调接口,并且在Activity中重写他的方法,传递信息给Fragment2(举一反三:我们也可以传递给其他的Fragment)。
下面我给出Fragment1的代码:
package com.example.fragment; import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.AttributeSet;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup; import com.example.fragmentdemo.R; public class Fragment1 extends Fragment { private static final String TAG = "FragmentDemo";
private OnButtonClickListener mListener; /**
* 这里我们创建一个回调接口
*
* @author Myp
*
*/
public interface OnButtonClickListener {
public void onButtonClicked();
} @Override
public void onAttach(Activity activity) {
Log.v(TAG, "Fragment1 onAttach");
Bundle args = getArguments();
if (null != args) {
/*
* 在这里我们可以将从Acivity收到的数据保存起来,并且显示到Fragment当中。
*/
Log.d(TAG,
"Fragment1 Get data from activity "
+ args.getString("hello"));
} try {
mListener = (OnButtonClickListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnButtonClickListener");
}
super.onAttach(activity);
} @Override
public void onInflate(Activity activity, AttributeSet attrs,
Bundle savedInstanceState) {
Log.d(TAG, "onInflate");
super.onInflate(activity, attrs, savedInstanceState);
} @Override
public void onCreate(Bundle savedInstanceState) {
Log.v(TAG, "Fragment1 onCreate");
super.onCreate(savedInstanceState);
} @Override
public void onDestroy() {
Log.v(TAG, "Fragment1 onDestroy");
super.onDestroy();
} @Override
public void onResume() {
Log.v(TAG, "Fragment1 onResume");
super.onResume();
} @Override
public void onStart() {
Log.v(TAG, "Fragment1 onStart");
super.onStart();
} @Override
public void onDetach() {
Log.v(TAG, "Fragment1 onDetach");
super.onDetach();
} @Override
public void onPause() {
Log.v(TAG, "Fragment1 onPause");
super.onPause();
} @Override
public void onStop() {
Log.v(TAG, "Fragment1 onStop");
super.onStop();
} @Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
Log.v(TAG, "Fragment1 onCreateView");
View view = inflater.inflate(R.layout.fragment1, container, false);
// 为button注册事件,并且调用回调接口,将信息返回给上层
view.findViewById(R.id.fragment1_btn).setOnClickListener(
new OnClickListener() {
@Override
public void onClick(View v) {
mListener.onButtonClicked();
}
});
return view;
} @Override
public void onDestroyView() {
Log.v(TAG, "Fragment1 onDestroyView");
super.onDestroyView();
} @Override
public void onActivityCreated(Bundle savedInstanceState) {
Log.v(TAG, "Fragment1 onActivityCreated");
super.onActivityCreated(savedInstanceState);
} }
1.创建回调接口;
2.为了确保宿主activity实现这个接口,fragment1的onAttach() 方法中通过将传入的activity强制类型转换,实例化一个OnButtonClickListener对象;
3.注册Button的Click事件,并在事件中调用回调方法。
然后我给出Activity的代码:
package com.example.fragmentdemo; import android.annotation.SuppressLint;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentTransaction;
import android.util.Log;
import android.widget.TextView; import com.example.fragment.Fragment1;
import com.example.fragment.Fragment1.OnButtonClickListener;
import com.example.fragment.Fragment2; @SuppressLint("Recycle")
public class MainActivity extends FragmentActivity implements
OnButtonClickListener { private static final String TAG = "FragmentDemo";
private Fragment1 fragment1;
private Fragment2 fragment2; @Override
protected void onCreate(Bundle savedInstanceState) {
Log.i(TAG, "onCreate");
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
fragment1 = new Fragment1();
fragment2 = new Fragment2();
addFragment1();
addFragment2();
} private void addFragment1() {
Bundle args = new Bundle();
args.putString("hello", "Hello Fragment1");
fragment1.setArguments(args);
Log.i(TAG, "create Fragment1");
FragmentTransaction transaction = getSupportFragmentManager()
.beginTransaction();
transaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
transaction.add(R.id.one, fragment1);
transaction.addToBackStack(null);
transaction.commit();
} private void addFragment2() {
Bundle args = new Bundle();
args.putString("hello", "Hello Fragment2");
fragment2.setArguments(args);
Log.i(TAG, "create Fragment2");
FragmentTransaction transaction = getSupportFragmentManager()
.beginTransaction();
transaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
transaction.replace(R.id.two, fragment2);
transaction.addToBackStack(null);
transaction.commit();
} @Override
public void onAttachFragment(Fragment fragment) {
Log.i(TAG, "onAttachFragment");
super.onAttachFragment(fragment);
} @Override
protected void onDestroy() {
Log.i(TAG, "onDestroy");
super.onDestroy();
} @Override
protected void onPause() {
Log.i(TAG, "onPause");
super.onPause();
} @Override
protected void onResume() {
Log.i(TAG, "onResume");
super.onResume();
} @Override
protected void onStart() {
Log.i(TAG, "onStart");
super.onStart();
} @Override
protected void onStop() {
Log.i(TAG, "onStop");
super.onStop();
} @Override
protected void onRestart() {
Log.i(TAG, "onRestart");
super.onRestart();
} @Override
public void onButtonClicked() {
Log.i(TAG, "onButtonClicked");
TextView tv = (TextView) fragment1.getActivity().findViewById(
R.id.fragment2_tv);
tv.setText(tv.getText() + "\n从Fragment1收到数据!");
}
}
1.通过implements实现回调接口;
2.重写回调方法,然后向Fragment2传递数据。
三、源码下载
点我下载,下载源码导入工程就可以使用了!