上次写过 App界面Tab选项卡之ViewPager ，今天就谈谈另一种实现方式，采用Fragment的方式，关于Fragment有篇非常好的文章，不太熟悉的先自行前往get 点我点我 。
今天只是Fragment初探，目的还是实现ViewPager一样的界面，但是由于Fragment自身并不支持左右滑动，须自行实现，所以这次只能靠点击下面的bottom_bar进行页面切换。在后面我会写一个综合版的，让Fragment也可以滑起来。
title_bar和bottom_bar都是采用的ViewPager那一篇中的，唯一值得注意的主界面，activity_main.xml：
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <include layout="@layout/title_bar" /> <FrameLayout android:id="@+id/frame_layout" android:layout_width="fill_parent" android:layout_height="0dp" android:layout_weight="1" /> <include layout="@layout/bottom_bar" /> </LinearLayout>
本该显示切换页面的位置由ViewPager换成的FrameLayout，上篇中内容布局不是以inflate动态加载出来的么，然后放在views中，这次就不这样做了，新建4个类，都继承自Fragment，因为大同小异，我就贴一个代码了，Fragment_0.java：
package com.cjt_pc.fragment; import android.os.Bundle; import android.support.annotation.Nullable; import android.support.v4.app.Fragment; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; /** * Created by cjt-pc on 2015/8/21. * Email:879309896@qq.com */ public class Fragment_0 extends Fragment { @Nullable @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.content_0, null); return view; } } 后面就相应的改类的名称和加载的布局id就可以了，最重要的MainActivity.java：
package com.cjt_pc.fragment; import android.os.Bundle; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentActivity; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentTransaction; import android.view.View; import android.widget.ImageView; import android.widget.LinearLayout; public class MainActivity extends FragmentActivity implements View.OnClickListener { private Fragment fragment_0, fragment_1, fragment_2, fragment_3; // ViewPager指示器布局 private LinearLayout llIndicator0, llIndicator1, llIndicator2, llIndicator3; private ImageView ivImg0, ivImg1, ivImg2, ivImg3; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initWidget(); setSelector(0); } private void initWidget() { llIndicator0 = (LinearLayout) findViewById(R.id.tab_0); llIndicator0.setOnClickListener(this); llIndicator1 = (LinearLayout) findViewById(R.id.tab_1); llIndicator1.setOnClickListener(this); llIndicator2 = (LinearLayout) findViewById(R.id.tab_2); llIndicator2.setOnClickListener(this); llIndicator3 = (LinearLayout) findViewById(R.id.tab_3); llIndicator3.setOnClickListener(this); ivImg0 = (ImageView) findViewById(R.id.img_0); ivImg1 = (ImageView) findViewById(R.id.img_1); ivImg2 = (ImageView) findViewById(R.id.img_2); ivImg3 = (ImageView) findViewById(R.id.img_3); } @Override public void onClick(View view) { resetIndicator(); switch (view.getId()) { case R.id.tab_0: setSelector(0); break; case R.id.tab_1: setSelector(1); break; case R.id.tab_2: setSelector(2); break; case R.id.tab_3: setSelector(3); break; } } public void setSelector(int selector) { FragmentManager manager = getSupportFragmentManager(); FragmentTransaction transaction = manager.beginTransaction(); hideFragment(transaction); switch (selector) { case 0: if (fragment_0 == null) { fragment_0 = new Fragment_0(); transaction.add(R.id.frame_layout, fragment_0); } else { transaction.show(fragment_0); } ivImg0.setImageResource(R.mipmap.tab_weixin_pressed); break; case 1: if (fragment_1 == null) { fragment_1 = new Fragment_1(); transaction.add(R.id.frame_layout, fragment_1); } else { transaction.show(fragment_1); } ivImg1.setImageResource(R.mipmap.tab_find_frd_pressed); break; case 2: if (fragment_2 == null) { fragment_2 = new Fragment_2(); transaction.add(R.id.frame_layout, fragment_2); } else { transaction.show(fragment_2); } ivImg2.setImageResource(R.mipmap.tab_address_pressed); break; case 3: if (fragment_3 == null) { fragment_3 = new Fragment_3(); transaction.add(R.id.frame_layout, fragment_3); } else { transaction.show(fragment_3); } ivImg3.setImageResource(R.mipmap.tab_settings_pressed); break; } transaction.commit(); } private void hideFragment(FragmentTransaction transaction) { if (fragment_0 != null) { transaction.hide(fragment_0); } if (fragment_1 != null) { transaction.hide(fragment_1); } if (fragment_2 != null) { transaction.hide(fragment_2); } if (fragment_3 != null) { transaction.hide(fragment_3); } } private void resetIndicator() { ivImg0.setImageResource(R.mipmap.tab_weixin_normal); ivImg1.setImageResource(R.mipmap.tab_find_frd_normal); ivImg2.setImageResource(R.mipmap.tab_address_normal); ivImg3.setImageResource(R.mipmap.tab_settings_normal); } } 我要指出的就是在四个fragment并没有在onCreate中全部初始化，而是放在setSelector中，这样做的好处的是只有当使用到的时候通过if判断，若fragment为null才new一个出来，具体的用法还是参照最上面详解fragment链接。
相关代码下载： http://download.csdn.net/detail/qq_15002323/9038173
搞个gitee的项目
![[HBLOG]公众号](https://www.liuhaihua.cn/img/qrcode_gzh.jpg)
