Fragment

最新推荐文章于 2024-06-25 10:30:00 发布

原创最新推荐文章于 2024-06-25 10:30:00 发布 · 366 阅读

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本文详细介绍了Fragment的概念及其在Android应用开发中的作用。Fragment作为一种可重用的UI组件，能够帮助开发者更好地应对不同屏幕尺寸的问题。文中通过实例展示了Fragment的静态加载与动态加载方法，并介绍了如何结合ViewPager实现流畅的页面切换效果。

                       **## Fragment ##**

什么是Fragment
fragment意为碎片，多个fragment进行组合可以做成多窗的UI界面。他有着自己的生命周期。
用Fragment能解决什么问题
能解决多种产品之间分辨率不同的问题。
Fragment静态加载方法
首先我们得建两个fragment布局文件，这两个布局我们只需要简单设定一下颜色和文字意思一下就好了。

<FrameLayout 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="#90ff55"
    tools:context="com.example.pc.fragment.fragment.Fragmentone">

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="Fragment_one"
        android:textSize="30sp"/>

</FrameLayout>

<FrameLayout 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="#605555"
    tools:context="com.example.pc.fragment.fragment.Fragmenttwo">

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="Fragment_two"
        android:textSize="30sp"/>

</FrameLayout>

 然后建两个类分别继承上面两个布局文件，然后我们在主Activity的布局文件里添上简单的布局。Fragment的用法也如下。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.example.pc.fragment.MainActivity">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:text="Hello World!"
        android:textSize="30sp"
        android:gravity="center"
    />
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal">
        <fragment
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="match_parent"
            android:id="@+id/f_one"
            android:name="com.example.pc.fragment.fragment.Fragmentone"
            />
        <fragment

            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="match_parent"
            android:id="@+id/f_two"
            android:name="com.example.pc.fragment.fragment.Fragmenttwo"
            />
    </LinearLayout>


</LinearLayout>

最后显示如下效果
这里写图片描述

Fragment动态加载方法
动态的加载方法大部分与静态一样，使用除了主的布局和activity不一样代码如下。

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.pc.fragment.TianMaoActivity">
    <LinearLayout
        android:id="@+id/lb"
        android:layout_width="100dp"
        android:layout_height="match_parent"
        android:orientation="vertical">
        <Button
            android:id="@+id/nvzhuang_btn"
            android:layout_width="match_parent"
            android:layout_height="50dp"
            android:text="女装"/>
        <Button
            android:id="@+id/nanzhuang_btn"
            android:layout_width="match_parent"
            android:layout_height="50dp"
            android:text="男装"/>
    </LinearLayout>
<FrameLayout
    android:id="@+id/yemian"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_toRightOf="@id/lb"
    android:layout_marginLeft="5dp"
    >
</FrameLayout>

</RelativeLayout>

package com.example.pc.fragment;

import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

import com.example.pc.fragment.fragment.NanzhuangFragment;
import com.example.pc.fragment.fragment.NvzhuangFragment;

public class TianMaoActivity extends AppCompatActivity implements View.OnClickListener{

    private Button nanBtn;
    private Button nvBtn;

    private NanzhuangFragment nanzhuangFragment;
    private NvzhuangFragment nvzhuangFragment;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_tian_mao);

        bindId();
    }
    private void bindId(){
        nanBtn = findViewById(R.id.nanzhuang_btn);
        nvBtn = findViewById(R.id.nvzhuang_btn);
        nanBtn.setOnClickListener(this);
        nvBtn.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        FragmentManager manager = getFragmentManager();
        FragmentTransaction transaction = manager.beginTransaction();
        switch (view.getId()){
            case R.id.nanzhuang_btn:
                if(nanzhuangFragment==null){
                    nanzhuangFragment = new NanzhuangFragment();
                }
                transaction.replace(R.id.yemian,nanzhuangFragment);
                break;
            case  R.id.nvzhuang_btn:
                if(nvzhuangFragment==null){
                    nvzhuangFragment = new NvzhuangFragment();
                }
                transaction.replace(R.id.yemian,nvzhuangFragment);
                break;
                default:
                    break;
        }
        transaction.commit();
    }
}

这里写图片描述
5. Viewpager+Fragment实现页卡滑动切换

package com.example.pc.fragment.adapter;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;

import java.util.List;

/**
 * Created by pc on 2018/3/6.
 */

public class MypagerAdapter extends FragmentPagerAdapter{
    private List<Fragment> mFragmentList;
    public MypagerAdapter(FragmentManager fm,List<Fragment> fragmentList) {
        super(fm);
        this.mFragmentList = fragmentList;
    }

    @Override
    public Fragment getItem(int position) {
        return mFragmentList.get(position);
    }

    @Override
    public int getCount() {
        return mFragmentList.size();
    }
}

package com.example.pc.fragment;

import android.support.v4.app.Fragment;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

import com.example.pc.fragment.adapter.MypagerAdapter;
import com.example.pc.fragment.fragment.ContactFragment;
import com.example.pc.fragment.fragment.FriendFragment;
import com.example.pc.fragment.fragment.NewsFragment;

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

public class WxActivity extends AppCompatActivity implements View.OnClickListener{
    private Button contactBtn;
    private Button friendBtn;
    private Button newsBtn;

    private ViewPager viewPager;

    private ContactFragment contactFragment;
    private FriendFragment friendFragment;
    private NewsFragment newsFragment;

    private List<Fragment> fragmentList = new ArrayList<>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_wx);

        bindID();

        contactFragment = new ContactFragment();
        friendFragment = new FriendFragment();
        newsFragment = new NewsFragment();

        fragmentList.add(contactFragment);
        fragmentList.add(friendFragment);
        fragmentList.add(newsFragment);

        MypagerAdapter adapter = new MypagerAdapter(getSupportFragmentManager(),fragmentList);
        viewPager.setAdapter(adapter);
    }

    private void bindID() {
        contactBtn = findViewById(R.id.contact_btn);
        friendBtn = findViewById(R.id.friend_btn);
        newsBtn = findViewById(R.id.news_btn);
        viewPager = findViewById(R.id.wx_vp);

        contactBtn.setOnClickListener(this);
        friendBtn.setOnClickListener(this);
        newsBtn.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()){
            case R.id.contact_btn:
                viewPager.setCurrentItem(0);
                break;
            case R.id.friend_btn:
                viewPager.setCurrentItem(1);
                break;
            case R.id.news_btn:
                viewPager.setCurrentItem(2);
                break;

        }

    }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.pc.fragment.WxActivity">

    <LinearLayout
        android:id="@+id/wx_bottom"
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true">
        <Button
            android:id="@+id/contact_btn"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="50dp"
        android:text="联系人"/>
        <Button
            android:id="@+id/friend_btn"
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="50dp"
            android:text="朋友圈"/>
        <Button
            android:id="@+id/news_btn"
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="50dp"
            android:text="动态"/>
    </LinearLayout>
    <android.support.v4.view.ViewPager
        android:id="@+id/wx_vp"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@id/wx_bottom">

    </android.support.v4.view.ViewPager>
</RelativeLayout>