安卓学习：碎片切换

最新推荐文章于 2023-07-02 10:37:17 发布

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本文介绍了如何在安卓应用中进行碎片(Fragment)切换。首先，创建了一个碎片集合类FragmentList，接着分别详细讲述了FirstFragment、SecondFragment和ThirdFragment的创建过程。每个碎片对应的XML布局文件和Java代码部分都有涉及，包括activity_main.xml、fragment_frist.xml等。最后，提到了字符串资源string.xml和MainActivity.java的重要作用，它们是整个碎片切换功能实现的关键。

文章目录

效果：

实现：
项目结构图
在这里插入图片描述

1.创建碎片集合类FragmentList

import androidx.fragment.app.Fragment;

import java.util.ArrayList;
import java.util.List;

public class FragmentList {
    public static List<Fragment> fragments = new ArrayList<>();
}

2.分别创建三个碎片FirstFragment、SecondFragment、ThirdFragment

在这里插入图片描述

3.代码

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical"
    tools:context=".MainActivity">
</FrameLayout>

fragment_frist.xml

<?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:background="@drawable/img01"
    android:gravity="center"
    android:orientation="vertical"
    tools:context=".FirstFragment">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="20dp"
        android:text="@string/first_fragment"
        android:textColor="#ff0000"
        android:textSize="25sp" />

    <Button
        android:id="@+id/btnNextFragment"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/next_fragment" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/champion"
        android:onClick="doChampion"/>
</LinearLayout>

FirstFragment.java

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.Toast;

import androidx.fragment.app.Fragment;

public class FirstFragment extends Fragment {

    private Button btnNextFragment;

    public FirstFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        // 获取碎片视图
        View view = inflater.inflate(R.layout.fragment_first, container, false);
        // 通过资源标识获得控件实例
        btnNextFragment = view.findViewById(R.id.btnNextFragment);
        // 给按钮注册监听器
        btnNextFragment.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                getFragmentManager().beginTransaction()
                        .addToBackStack("next")
                        .replace(R.id.container,FragmentList.fragments.get(1))
                        .commit();
            }
        });
        // 返回视图
        return view;
    }
}

fragment_second.xml

<?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:background="@drawable/img02"
    android:gravity="center"
    android:orientation="vertical"
    tools:context=".FirstFragment">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="20dp"
        android:text="@string/second_fragment"
        android:textColor="#00ff00"
        android:textSize="25sp" />

    <Button
        android:id="@+id/btnNextFragment"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/next_fragment" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/runner_up"
        android:onClick="doRunner_up"/>
</LinearLayout>

SecondFragment.java

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import androidx.fragment.app.Fragment;

public class SecondFragment extends Fragment {

    private Button btnNextFragment;

    public SecondFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // 获取碎片视图
        View view = inflater.inflate(R.layout.fragment_second, container, false);
        // 通过资源标识获得控件实例
        btnNextFragment = view.findViewById(R.id.btnNextFragment);
        // 给按钮注册监听器
        btnNextFragment.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                getFragmentManager().beginTransaction()
                        .addToBackStack("next")
                        .replace(R.id.container, FragmentList.fragments.get(2))
                        .commit();
            }
        });

        // 返回视图
        return view;
    }
}

fragment_third.xml

<?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:background="@drawable/img03"
    android:gravity="center"
    android:orientation="vertical"
    tools:context=".FirstFragment">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="20dp"
        android:text="@string/third_fragment"
        android:textColor="#0000ff"
        android:textSize="25sp" />

    <Button
        android:id="@+id/btnNextFragment"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/next_fragment" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/third_winner"
        android:onClick="doThird_winner"/>
</LinearLayout>

ThirdFragment.java

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;

import androidx.fragment.app.Fragment;

public class ThirdFragment extends Fragment {

    private Button btnNextFragment;

    public ThirdFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        // 获取碎片视图
        View view = inflater.inflate(R.layout.fragment_third, container, false);
        // 通过资源标识获得控件实例
        btnNextFragment = view.findViewById(R.id.btnNextFragment);
        // 给按钮注册监听器
        btnNextFragment.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                getFragmentManager().beginTransaction()
                        .addToBackStack("next")
                        .replace(R.id.container, FragmentList.fragments.get(0))
                        .commit();
            }
        });

        // 返回视图
        return view;
    }
}

字符串资源string.xml

<resources>
    <string name="app_name">碎片切换(碎片数组)</string>
    <string name="first_fragment">第一个碎片</string>
    <string name="second_fragment">第二个碎片</string>
    <string name="third_fragment">第三个碎片</string>
    <string name="next_fragment">下一个碎片</string>
    <string name="champion">冠军</string>
    <string name="runner_up">亚军</string>
    <string name="third_winner">季军</string>
</resources>

MainActivity.java

import android.os.Bundle;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.FragmentManager;

public class MainActivity extends AppCompatActivity {

    private GestureDetector detector;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // 利用布局资源文件设置用户界面
        setContentView(R.layout.activity_main);

        // 获取碎片管理器
        FragmentManager fm = getSupportFragmentManager();

        // 创建三个碎片，添加到碎片列表
        FragmentList.fragments.add(new FirstFragment());
        FragmentList.fragments.add(new SecondFragment());
        FragmentList.fragments.add(new ThirdFragment());

        // 在主容器里添加第一个碎片
        fm.beginTransaction().add(R.id.container, FragmentList.fragments.get(0)).commit();

        // 实例化手势侦测器
        detector = new GestureDetector(new GestureDetector.OnGestureListener() {
            @Override
            public boolean onDown(MotionEvent motionEvent) {
                return false;
            }

            @Override
            public void onShowPress(MotionEvent motionEvent) {

            }

            @Override
            public boolean onSingleTapUp(MotionEvent motionEvent) {
                return false;
            }

            @Override
            public boolean onScroll(MotionEvent motionEvent, MotionEvent motionEvent1, float v, float v1) {
                return false;
            }

            @Override
            public void onLongPress(MotionEvent motionEvent) {

            }

            @Override
            public boolean onFling(MotionEvent e1, MotionEvent e2, float v, float v1) {
                // 手势往左滑动10个像素，切换到下一个碎片
                if (e1.getX() - e2.getX() > 10) {
                    // 获取返回栈条目个数
                    int count = getSupportFragmentManager().getBackStackEntryCount();
                    // 获取碎片索引
                    int index = ++count % 3;
                    // 切换碎片
                    getSupportFragmentManager().beginTransaction()
                            .addToBackStack("" + index)
                            .replace(R.id.container, FragmentList.fragments.get(index))
                            .commit();
                }
                return true;
            }
        });
    }

    /**
     * 将窗口的触摸事件交给收拾侦测器来处理
     *
     * @param event
     * @return
     */
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        return detector.onTouchEvent(event);
    }

    public void doChampion(View view) {
        Toast.makeText(MainActivity.this,"冠军",Toast.LENGTH_SHORT).show();
    }
    public void doRunner_up(View view) {
        Toast.makeText(MainActivity.this,"亚军",Toast.LENGTH_SHORT).show();
    }
    public void doThird_winner(View view) {
        Toast.makeText(MainActivity.this,"季军",Toast.LENGTH_SHORT).show();
    }
}