android fragment加载方式与数据通信 Android中Fragment的加载方式与数据通信详解
Joah 人气:0一、加载方式
1. 静态加载
1.1 加载步骤
(1) 创建fragment:创建自定义Fragment类继承自Fragment类,同时将自定义Fragment类与Fragment视图绑定(将layout转换成View)
View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
inflater用于绑定Fragment的布局文件,同时将该布局转换成View对象并返回;container为Fragment的UI所在的父容器。返回值为Fragment显示的UI,若不显示,则返回null。
inflate(int resource, ViewGroup root, boolean attachToRoot)
resource为Fragment需要加载的布局文件;root为加载Fragment的父ViewGroup,也就是onCreateView传递进来的container;attachToRoot为是否返回父ViewGroup。
(2) 使用fragment:在父视图中引入fragment,静态加载必须指定name属性以及一个唯一标识符,标识符可以为id或者tag
<!--指定在layout中实例化的Fragment类,需要为“包名.类名”的完整形式--> android:name <!--唯一标识,id和tag可任选其一,不可两者都没有--> android:id android:tag
(3) 监听事件:若在父视图对应的类中设置监听事件,可以直接访问fragment中的子组件;若在Fragment的类中设置,则必须通过inflate()返回的View对象访问Fragment中的子组件(view.findViewById(id))。
1.2 简单范例
MyFragment视图:
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent"> <TextView android:id="@+id/fragment_text" android:layout_width="wrap_content" android:layout_height="wrap_content" /> </LinearLayout>
MyFragment类:
public class MyFragment extends Fragment { @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { //将layout布局转换成View对象 View view = inflater.inflate(R.layout.myfragment, container, false); //必须通过view对象对其子组件进行访问 TextView textView = (TextView) view.findViewById(R.id.fragment_text); textView.setText("这里是fragment"); //返回Fragment显示UI return view; } }
引用fragment的父视图:
<?xml version="1.0" encoding="utf-8"?> <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" tools:context="com.studying.StaticFragmentActivity"> <fragment android:tag="fragment" android:name="com.joahyau.studying.MyFragment" android:layout_width="wrap_content" android:layout_height="wrap_content"/> </LinearLayout>
父视图对应的类设置事件监听:
public class StaticFragmentActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_static_fragment); //可直接通过findViewById访问 findViewById(R.id.fragment_text).setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Toast.makeText(StaticFragmentActivity.this, "点击了文本", Toast.LENGTH_SHORT).show(); } }); } }
2. 动态加载
2.1 加载步骤
(1) 获取事务管理器:对Fragment进行的添加、移除、替换等操作,均为事务。需通过以下代码获取事务管理器,从而对fragment进行动态操作。
FragmentManager fm = getFragmentManager(); FragmentTransaction ft = fm.beginTransaction();
(2) 创建Fragment对象:创建需要加载的fragment,而后通过add或replace等方法实现动态加载。
2.2 简单范例
布局:
<?xml version="1.0" encoding="utf-8"?> <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:orientation="vertical" tools:context="io.github.joahyau.studying.DynamicFragmentActivity"> <Button android:id="@+id/load" android:text="加载" android:layout_width="match_parent" android:layout_height="80dp" /> <LinearLayout android:id="@+id/container" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="horizontal" /> </LinearLayout>
Java:
public class DynamicFragmentActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_dynamic_fragment); findViewById(R.id.load).setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { //获取事务管理器 FragmentManager fragmentManager = getFragmentManager(); FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction(); //创建fragment,并将其动态加载到id位container的布局中 MyFragment myFragment = new MyFragment(); fragmentTransaction.add(R.id.container, myFragment); //提交事务 fragmentTransaction.commit(); } }); } }
二、数据通信
3. Activity向Fragment传递数据
3.1 Activity向动态加载的Fragment传递数据
(1)在Activity中获取Fragment对象;
(2)创建Bundle对象并传入数据;
(3)将Bundle对象传递给Fragment对象;
(4)在Fragment中获取Bundle对象并拆包得到数据。
范例:Activity中只有一个id为send的Button,MyFragment中只有一个TextView,这里就不再放布局代码了。
Activity:
public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); findViewById(R.id.send).setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { //创建Fragment对象 MyFragment myFragment = new MyFragment(); //创建Bundle对象并传入数据 Bundle bundle = new Bundle(); bundle.putString("info", "这里是向Fragment传递的数据"); myFragment.setArguments(bundle); //加载Fragment FragmentManager fragmentManager = getFragmentManager(); FragmentTransaction beginTransaction = fragmentManager.beginTransaction(); beginTransaction.add(R.id.layout, myFragment, "myfragment"); beginTransaction.commit(); } }); } }
Fragment:
public class MyFragment extends Fragment { @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.my_fragment, container, false); TextView tv = (TextView) view.findViewById(R.id.text); //获取数据 String text = getArguments().get("info") + ""; tv.setText(text); return view; } }
3.2 Activity向静态加载的Fragment传递数据
(1)在Fragment中创建作为容器的数据对象,并创建getter和setter;
(2)在Activity中获取FragmentManager;
(3)通过事务管理器的findFragmentById或findFragmentByTag方法,获得fragment对象;
(4)通过获得的fragment对象调用容器的setter方法进行传值。
范例:这里的布局与动态加载的布局唯一不同的就是将send按钮放在了Fragment里面,其它相同。
Fragment:
public class MyFragment extends Fragment { private Button btn; private String received;//作为容器的对象 @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.my_fragment, container, false); TextView tv = (TextView) view.findViewById(R.id.text); tv.setText("这里是Fragment"); btn = (Button) view.findViewById(R.id.send); btn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Toast.makeText(getActivity(), "成功接收\"" + getReceived() + "\"", Toast.LENGTH_SHORT).show(); } }); return view; } public String getReceived() { return received; } public void setReceived(String received) { this.received = received; } }
Activity:
public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); FragmentManager fragmentManager = getFragmentManager(); MyFragment myFragment = (MyFragment) fragmentManager.findFragmentById(R.id.my_fragment); myFragment.setReceived("this is a test."); } }
4. Fragment向Activity传递数据
(1)在Fragment中写一个回调接口;
(2)在activity中实现这个回调接口,实现的函数用于传值;
(3)重写Fragment中onAttach,在其中创建一个接口对象,得到传递过来的activity(我的理解是这个接口其实相当于传递过来的activity的一个父类,这一步是用到了多态的特性);
(4)用得到的接口对象进行传值。
Fragment:
public class MyFragment extends Fragment { private SendData sendData; @Override public void onAttach(Activity activity) { super.onAttach(activity); //获取实现的接口对象 sendData = (SendData) activity; } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.my_fragment, container, false); TextView tv = (TextView) view.findViewById(R.id.text); tv.setText("这里是Fragment"); //通过接口对象传递数据 sendData.sendMsg("this is a test."); return view; } //定义一个回调接口 public interface SendData{ void sendMsg(String str); } }
Activity:
public class MainActivity extends Activity implements MyFragment.SendData{ private Button btn; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); btn = (Button) findViewById(R.id.send); btn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { MyFragment myFragment = new MyFragment(); FragmentManager fragmentManager = getFragmentManager(); FragmentTransaction beginTransaction = fragmentManager.beginTransaction(); beginTransaction.add(R.id.layout, myFragment); beginTransaction.commit(); } }); } //实现SendData接口,接收数据 @Override public void sendMsg(String str) { Toast.makeText(this, "成功接收\"" + str + "\"", Toast.LENGTH_SHORT).show(); } }
以上就是本文的全部内容,希望本文的内容对大家的学习或者工作能带来一定的帮助,同时也希望多多支持!
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