編輯:關於android開發
Android3.0引入了Fragment,主要目的是用在大屏幕設備上,支持更加動態和靈活的UI設計。Fragment在你的應用中應當是一個模塊化和可重用的組件,因為Fragment定義了它自己的布局,以及通過使用它自己的聲明周期回調回調方法定義了它自己的行為,可以將Fragment包含到多個Activity中。
(1)Fragment可以作為Activity界面的一部分組成出現;
(2)可以在一個Activity中同時出現多個Fragment,並且一個Fragment也可以在多個Activity中使用;
(3)在Activity運行過程中,可以添加、移除或替換Fragment;
(4)Fragment可以響應自己的輸入事件,並且有自己的聲明周期,它們的生命周期受宿主Activity的生命周期影響;
(5)Fragment在第一次繪制它的用戶界面時,系統會調用onCreateView()方法,此方法返回一個View。(如果不顯示UI,返回null);
Fragment兩種加載方式:靜態加載、動態加載。
本文以及後續將使用一個APP來講解關於Fragment的知識,大致布局如下:
values添加color.xml:
<!--{cke_protected}{C}%3C!%2D%2D%3Fxml%20version%3D%221.0%22%20encoding%3D%22utf-8%22%3F%2D%2D%3E--> <resources> <color name="gray">#88000000</color> <color name="white">#ffffff</color> </resources>drawable中添加radio_pressed.xml
<?xml version="1.0" encoding="utf-8"?> <selector xmlns:android="http://schemas.android.com/apk/res/android"> <item android:drawable="@color/gray" android:state_checked="true"></item> <item android:drawable="@color/white" android:state_pressed="true"></item> <item android:drawable="@color/white"></item> </selector>main主布局:
<!--{cke_protected}{C}%3C!%2D%2D%3Fxml%20version%3D%221.0%22%20encoding%3D%22utf-8%22%3F%2D%2D%3E--> <relativelayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent"> <linearlayout android:id="@+id/frame" android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical"> </linearlayout> <radiogroup android:id="@+id/radiogroup" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_alignparentbottom="true" android:gravity="center_horizontal" android:orientation="horizontal"> <radiobutton android:id="@+id/first" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:background="@drawable/radio_pressed" android:button="@null" android:drawabletop="@drawable/ic_launcher" android:gravity="center_horizontal" android:text="靜態加載"> <radiobutton android:id="@+id/second" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:background="@drawable/radio_pressed" android:button="@null" android:drawabletop="@drawable/ic_launcher" android:gravity="center_horizontal" android:text="動態加載"> <radiobutton android:id="@+id/thrid" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:background="@drawable/radio_pressed" android:button="@null" android:drawabletop="@drawable/ic_launcher" android:gravity="center_horizontal" android:text="生命周期"> <radiobutton android:id="@+id/fourth" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:background="@drawable/radio_pressed" android:button="@null" android:drawabletop="@drawable/ic_launcher" android:gravity="center_horizontal" android:text="傳值通信"> </radiobutton></radiobutton></radiobutton></radiobutton></radiogroup> </relativelayout>MainActivity加載main:
package com.example.fragment; import android.os.Bundle; import android.app.Activity; import android.view.Menu; import android.widget.RadioGroup; import android.widget.RadioGroup.OnCheckedChangeListener; public class MainActivity extends Activity implements OnCheckedChangeListener { private RadioGroup group; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); group=(RadioGroup) findViewById(R.id.radiogroup); group.setOnCheckedChangeListener(this); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } @Override public void onCheckedChanged(RadioGroup group, int checkedId) { // TODO Auto-generated method stub switch (checkedId) { case R.id.first: //演示靜態加載 break; case R.id.second: //演示動態加載 break; case R.id.thrid: //演示生命周期 break; case R.id.fourth: //演示傳值通信 break; } } }
在Activity的layout文件中聲明Fragment(特別注意:在
添加fragment.xml:
<!--{cke_protected}{C}%3C!%2D%2D%3Fxml%20version%3D%221.0%22%20encoding%3D%22utf-8%22%3F%2D%2D%3E--> <linearlayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <textview android:id="@+id/text" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="我的Fragment"><button android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/button"></button></textview></linearlayout>添加MyFragment類,並加載fragment布局:
package com.example.fragment; import android.app.Fragment; import android.os.Bundle; 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; public class MyFragment extends Fragment { @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { // layout布局文件轉換成View對象 /** * inflater.inflate(resource, root, attachToRoot) * resource:Fragment需要加載的布局文件 * root:加載layout的父ViewGroup * attactToRoot:false,不返回父ViewGroup */ View view = inflater.inflate(R.layout.fragment, container, false); TextView text = (TextView) view.findViewById(R.id.text); Button button = (Button) view.findViewById(R.id.button); text.setText("靜態加載Fragment"); button.setText("獲取內容"); button.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub // String value = getAaa(); // Toast.makeText(getActivity(), "value="+value, // Toast.LENGTH_SHORT).show(); } }); return view; } }添加jigntai.xml:
<!--{cke_protected}{C}%3C!%2D%2D%3Fxml%20version%3D%221.0%22%20encoding%3D%22utf-8%22%3F%2D%2D%3E--> <linearlayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <!--{cke_protected}{C}%3C!%2D%2D%20android%3Aid%EF%BC%9A%E9%9D%99%E6%80%81%E5%8A%A0%E8%BD%BD%E5%BF%85%E9%A1%BB%E6%8C%87%E5%AE%9A%E4%B8%80%E4%B8%AAID%20%2D%2D%3E--> <!--{cke_protected}{C}%3C!%2D%2D%20android%3Aname%EF%BC%9A%E5%AE%8C%E6%95%B4%E5%8C%85%E5%90%8D%20%2D%2D%3E--> <fragment android:id="@+id/fragment" android:layout_width="wrap_content" android:layout_height="wrap_content" android:name="com.example.fragment.MyFragment"> </fragment></linearlayout>
添加JingTaiActivity類:
public class JingTaiActivity extends Activity { private TextView tv; @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.jingtai); Button button=(Button) findViewById(R.id.button); tv=(TextView) findViewById(R.id.text); button.setText("改變"); button.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub tv.setText("TextView改變了"); } }); } }
主MainActivity中演示靜態加載部分添加:
case R.id.first: //演示靜態加載 Intent jingtaiIntent=new Intent(MainActivity.this,JingTaiActivity.class); startActivity(jingtaiIntent); break;
也就是說,當一個布局文件中通過靜態加載Fragment加載到Activity中來,Fragment中的布局文件對Activity也是共享的。
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