使用Fragment实现动态布局

接着Fragment的简单使用一文继续探讨Fragment的使用，本文主要介绍使用Fragment实现动态UI布局，包括动态添加、替换、移除某个Fragment，至于Fragment之间的交互，后面在讨论。

MainActivity：

package com.home.testfragment;import android.os.Bundle;import android.support.v4.app.FragmentActivity;import android.support.v4.app.FragmentTransaction;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;public class MainActivity extends FragmentActivity implements OnClickListener {private Button addFirstFragmentBtn;private Button replaceFirstFragmentBtn;private Button removeFirstFragmentBtn;private FirstFragment firstFragment;@Overrideprotected void onCreate(Bundle arg0) {super.onCreate(arg0);setContentView(R.layout.main);addFirstFragmentBtn = (Button) findViewById(R.id.main_btn_add);replaceFirstFragmentBtn = (Button) findViewById(R.id.main_btn_replace);removeFirstFragmentBtn = (Button) findViewById(R.id.main_btn_remove);addFirstFragmentBtn.setOnClickListener(this);replaceFirstFragmentBtn.setOnClickListener(this);removeFirstFragmentBtn.setOnClickListener(this);addFirstFragmentBtn.setEnabled(true);removeFirstFragmentBtn.setEnabled(false);}@Overridepublic void onClick(View v) {if (v == addFirstFragmentBtn) {addFirstFragmentBtn.setEnabled(false);removeFirstFragmentBtn.setEnabled(true);if (findViewById(R.id.main_container) != null) {firstFragment = new FirstFragment();FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();transaction.add(R.id.main_container, firstFragment);// 把当前Fragment添加至回退栈，通过返回键返回时可以导航到上一个Fragment状态transaction.addToBackStack(null);// 提交transaction.commit();}}if (v == replaceFirstFragmentBtn) {addFirstFragmentBtn.setEnabled(true);removeFirstFragmentBtn.setEnabled(false);SecondFragment secondFragment = new SecondFragment();FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();transaction.replace(R.id.main_container, secondFragment);transaction.addToBackStack(null);transaction.commit();}if (v == removeFirstFragmentBtn) {addFirstFragmentBtn.setEnabled(true);removeFirstFragmentBtn.setEnabled(false);FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();transaction.remove(firstFragment);// 如果移除的时候也添加到回退栈，表示当前Fragment只是被停止而没有被摧毁，返回时它将恢复；// 那么如果不添加到回退栈则表示完全摧毁// transaction.addToBackStack(null);transaction.commit();}}}

FirstFragment：

package com.home.testfragment;import android.os.Bundle;import android.support.v4.app.Fragment;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;public class FirstFragment extends Fragment {@Overridepublic View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {return inflater.inflate(R.layout.fragment_first, container, false);}}

SecondFragment：

package com.home.testfragment;import android.os.Bundle;import android.support.v4.app.Fragment;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;public class SecondFragment extends Fragment{@Overridepublic View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {return inflater.inflate(R.layout.fragment_second, container, false);}}

main.xml：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent" >    <FrameLayout        android:id="@+id/main_container"        android:layout_width="match_parent"        android:layout_height="wrap_content" />    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_alignParentBottom="true"        android:orientation="horizontal" >        <Button            android:id="@+id/main_btn_add"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_weight="1"            android:text="添加" />        <Button            android:id="@+id/main_btn_replace"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_weight="1"            android:text="替换" />        <Button            android:id="@+id/main_btn_remove"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_weight="1"            android:text="移除" />    </LinearLayout></RelativeLayout>

fragment_first.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" >    <TextView        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="MyFirstFragment"        android:textSize="20sp" /></LinearLayout>

fragment_second.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" >    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="MySecondFragment"        android:textSize="20sp" /></LinearLayout>