Android Fragment实现按钮间的切换

朱雀 2022-08-24 00:53 274阅读 0赞

**Fragment****要点**

Fragment是activity的界面中的一部分或一种行为。你可以把多个Fragment们组合到一个activity中来创建一个多面界面并且你可以在多个activity中重用一个Fragment。你可以把Fragment认为模块化的一段activity，它具有自己的生命周期，接收它自己的事件，并可以在activity运行时被添加或删除。

Fragment不能独立存在，它必须嵌入到activity中，而且Fragment的生命周期直接受所在的activity的影响。例如：当activity暂停时，它拥有的所有的Fragment们都暂停了，当activity销毁时，它拥有的所有Fragment们都被销毁。然而，当activity运行时（在onResume()之后，onPause()之前），你可以单独地操作每个Fragment，比如添加或删除或替代(add(),remove(),replace())它们。当你在执行上述针对Fragment的事务时，你可以将事务添加到一个棧中，这个栈被activity管理，栈中的每一条都是一个Fragment的一次事务。有了这个栈，就可以反向执行Fragment的事务，这样就可以在Fragment级支持“返回”键（向后导航）。

而本文简单介绍主要通过点击不同按钮实现切换对应的fragment的效果，类似用Tab的切换：

主要代码如下：

1.工程源代码显示：

![Center][]

2.编译后效果图

![Center 1][]![Center 2][]

3.切换按钮布局：activity\_bottom\_bts.xml切换的按钮显示在底部

<?xmlversion="1.0" encoding="utf-8"?>
 <LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="horizontal">
 
 <Button
 android:id="@+id/movie_btn"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_weight="1"
 android:gravity="center"
 android:text="@string/movie"/>
 
 <Button
 android:id="@+id/tv_btn"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_weight="1"
 android:gravity="center"
 android:text="@string/tv"/>
 
 <Button
 android:id="@+id/anime_btn"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_weight="1"
 android:gravity="center"
 android:text="@string/anime"/>
 
 <Button
 android:id="@+id/variety_btn"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_weight="1"
 android:gravity="center"
 android:text="@string/variety" />
 
 </LinearLayout>

4.主界面activity\_main.xml

<RelativeLayoutxmlns: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:paddingBottom="@dimen/activity_vertical_margin"
 android:paddingLeft="@dimen/activity_horizontal_margin"
 android:paddingRight="@dimen/activity_horizontal_margin"
 android:paddingTop="@dimen/activity_vertical_margin"
 tools:context="com.example.switchfragmentdemo.MainActivity$PlaceholderFragment">
 
 <LinearLayout
 android:id="@+id/button_view_include"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 android:layout_alignParentBottom="true"
 >
 
 <includelayout="@layout/activity_bottom_btns" />
 </LinearLayout>
 
 <FrameLayout
 android:id="@+id/fragment_content"
 android:layout_width="match_parent"
 android:layout_height="fill_parent"
 android:layout_alignParentTop="true"
 android:layout_marginBottom="50dp"
 android:layout_below="@id/button_view_include"
 >
 </FrameLayout>
 
 </RelativeLayout>

5.strings.xml

<?xmlversion="1.0" encoding="utf-8"?>
 <resources>
 <stringname="app_name">SwitchFragmentDemo</string>
 <stringname="hello_world">Hello world!</string>
 <stringname="action_settings">Settings</string>
 
 <string name="movie">电影</string>
 <string name="tv">电视剧</string>
 <string name="anime">动漫</string>
 <string name="variety">综艺</string>
 
 <stringname="movie_view">这是一个电影界面</string>
 <string name="tv_view">这是一个电视剧界面</string>
 <stringname="anime_view">这是一个动漫界面</string>
 <stringname="variety_view">这是一个综艺界面</string>
 </resources>

6.主界面实现代码：MainActivity.java

packagecom.example.myandroidswitchbtndemo;
 
 importjava.util.ArrayList;
 importjava.util.List;
 
 importandroid.annotation.SuppressLint;
 importandroid.app.Activity;
 importandroid.app.FragmentManager;
 importandroid.app.FragmentTransaction;
 importandroid.graphics.Color;
 importandroid.os.Bundle;
 importandroid.view.Menu;
 importandroid.view.MenuItem;
 importandroid.view.View;
 importandroid.view.View.OnClickListener;
 importandroid.widget.Button;
 
 @SuppressLint("NewApi")
 public classMainActivity extends Activity implements OnClickListener {
 
 private Button movieBtn, tvBtn,animeBtn, varietyBtn;
 private List<Button> btnList = newArrayList<Button>();
 private FragmentManager fm;
 private FragmentTransaction ft;
 
 @Override
 protected void onCreate(BundlesavedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 
 findById();
 
 // 進入系統默認為movie
 fm = getFragmentManager();
 ft = fm.beginTransaction();
 
 setBackgroundColorById(R.id.movie_btn);
 ft.replace(R.id.fragment_content,new MovieFragment());
 ft.commit();
 }
 
 private void findById() {
 movieBtn = (Button)this.findViewById(R.id.movie_btn);
 tvBtn = (Button)this.findViewById(R.id.tv_btn);
 animeBtn = (Button) this.findViewById(R.id.anime_btn);
 varietyBtn = (Button)this.findViewById(R.id.variety_btn);
 movieBtn.setOnClickListener(this);
 tvBtn.setOnClickListener(this);
 animeBtn.setOnClickListener(this);
 varietyBtn.setOnClickListener(this);
 
 btnList.add(movieBtn);
 btnList.add(tvBtn);
 btnList.add(animeBtn);
 btnList.add(varietyBtn);
 }
 
 private void setBackgroundColorById(intbtnId) {
 for (Button btn : btnList) {
 if (btn.getId() == btnId){
 btn.setBackgroundColor(Color.GREEN);
 }else {
 btn.setBackgroundColor(Color.BLUE);
 }
 }
 }
 
 @Override
 public boolean onCreateOptionsMenu(Menumenu) {
 
 // Inflate the menu; this addsitems to the action bar if it is present.
 getMenuInflater().inflate(R.menu.main,menu);
 return true;
 }
 
 @Override
 public booleanonOptionsItemSelected(MenuItem item) {
 // Handle action bar item clickshere. The action bar will
 // automatically handle clicks onthe Home/Up button, so long
 // as you specify a parentactivity in AndroidManifest.xml.
 int id = item.getItemId();
 if (id == R.id.action_settings) {
 return true;
 }
 returnsuper.onOptionsItemSelected(item);
 }
 
 @Override
 public void onClick(View v) {
 // TODO Auto-generated methodstub
 fm = getFragmentManager();
 ft = fm.beginTransaction();
 switch (v.getId()) {
 
 case R.id.movie_btn:
 setBackgroundColorById(R.id.movie_btn);
 
 ft.replace(R.id.fragment_content,new MovieFragment());
 break;
 
 case R.id.tv_btn:
 setBackgroundColorById(R.id.tv_btn);
 
 ft.replace(R.id.fragment_content,new TVFragment());
 break;
 
 case R.id.anime_btn:
 setBackgroundColorById(R.id.anime_btn);
 
 ft.replace(R.id.fragment_content,new AnimeFragment());
 break;
 
 case R.id.variety_btn:
 setBackgroundColorById(R.id.variety_btn);
 
 ft.replace(R.id.fragment_content,new VarietyFragment());
 break;
 
 default:
 break;
 }
 // 不要忘记提交
 ft.commit();
 }
 
 }

7.电影界面：fragment\_movie.xml和MovieFragment.java

packagecom.example.myandroidswitchbtndemo;
 import android.app.Fragment;
 importandroid.os.Bundle;
 importandroid.view.LayoutInflater;
 importandroid.view.View;
 importandroid.view.ViewGroup;
 
 public classMovieFragment extends Fragment {
 <spanstyle="white-space:pre"> @Override 
 public View onCreateView(LayoutInflater inflater, ViewGroup container, 
 Bundle savedInstanceState) { 
 return inflater.inflate(R.layout.fragment_movie, null); 
 } 
 }

8.电视剧界面：fragment\_tv.xml和TVFragment.java

packagecom.example.myandroidswitchbtndemo;
 importandroid.os.Bundle;
 importandroid.app.Fragment;
 importandroid.view.LayoutInflater;
 importandroid.view.View;
 importandroid.view.ViewGroup;
 
 public classTVFragment extends Fragment {
 <spanstyle="white-space:pre"> @Override 
 public View onCreateView(LayoutInflater inflater, ViewGroup container, 
 Bundle savedInstanceState) { 
 return inflater.inflate(R.layout.fragment_tv, null); 
 } 
 }

9.动漫界面：fragment\_anime和AnimeFragment.java

packagecom.example.myandroidswitchbtndemo;
 importandroid.os.Bundle;
 importandroid.annotation.SuppressLint;
 importandroid.app.Fragment;
 importandroid.view.LayoutInflater;
 importandroid.view.View;
 importandroid.view.ViewGroup;
 
 @SuppressLint("NewApi")
 public classAnimeFragment extends Fragment {
 <spanstyle="white-space:pre"> @Override 
 public View onCreateView(LayoutInflater inflater, ViewGroup container, 
 Bundle savedInstanceState) { 
 return inflater.inflate(R.layout.fragment_anime, null); 
 } 
 }

10.综艺界面：fragment\_variety和VarietyFragment

packagecom.example.myandroidswitchbtndemo;
 importandroid.os.Bundle;
 importandroid.app.Fragment;
 importandroid.view.LayoutInflater;
 importandroid.view.View;
 importandroid.view.ViewGroup;
 
 public classVarietyFragment extends Fragment {
 <spanstyle="white-space:pre"> @Override 
 public View onCreateView(LayoutInflater inflater, ViewGroup container, 
 Bundle savedInstanceState) { 
 return inflater.inflate(R.layout.fragment_variety, null); 
 } 
 }

上面为代码的具体实现。

源代码下载地址：[http://download.csdn.net/detail/a123demi/7524047][http_download.csdn.net_detail_a123demi_7524047]

[Center]: /images/20220823/6dfafe2dd6df4a92b60a5f8ee59b1d51.png
[Center 1]: https://img-blog.csdn.net/20140620090546250?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvYTEyM2RlbWk=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center
[Center 2]: /images/20220823/e453e84d47254878ae939bb6571a5708.png
[http_download.csdn.net_detail_a123demi_7524047]: http://download.csdn.net/detail/a123demi/7524047