Android碎片的使用 _Android

智慧并不产生于学历,而是来自对于知识的终生不懈的追求。这篇文章主要讲述Android碎片的使用相关的知识，希望能为你提供帮助。
一、动态添加碎片
1》
新建三个布局

< ?xml version="1.0" encoding="utf-8"?>
< LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
< Button
android:id="@+id/b1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:text="按钮"/>
< /LinearLayout>

======================================================================

< ?xml version="1.0" encoding="utf-8"?>
< LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#00ff00">
< TextView
android:layout_gravity="center_horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="20sp"
android:text="这是右部碎片"/>
< /LinearLayout>
===========================================================================

< ?xml version="1.0" encoding="utf-8"?>
< LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#ffff00">
< TextView
android:layout_gravity="center_horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="20sp"
android:text="这是另一个右部碎片"/>
< /LinearLayout>
====================================================================================

2》新建三个类与三个布局对应
三个类的内容几乎相同重写Fragment类中的onCreateView方法使用inflater将布局引入到view中

package com.example.fragmenttest;

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 lenovo on 2019/1/27.
*/

public class LeftFragment extends Fragment {
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view=inflater.inflate(R.layout.feft_fragment,container,false);
return view;
}
}
======================================================================================

public class RightFragment extends Fragment {
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view=inflater.inflate(R.layout.rightfragment,container,false);
return view;
}
}

======================================================================================

public class AnotherRightFragment extends Fragment {
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view=inflater.inflate(R.layout.another_right_fragment,container,false);
return view;
}
}

3》编写主界面
将第二个fragment换成了FrameLayout布局

< ?xml version="1.0" encoding="utf-8"?>
< LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal" android:layout_width="match_parent"
android:layout_height="match_parent">
< fragment
android:name="com.example.fragmenttest.LeftFragment"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"
android:id="@+id/left_fragment"/>
< FrameLayout
android:name="com.example.fragmenttest.RightFragment"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"
android:id="@+id/right_fragment"/>

< /LinearLayout>

======================================================================================
下面代码中有repaceFragment函数用于往FramLayout中添加布局
（1）创建待添加布局的实例
（2）获取FragmentManager实例可用getSupportFragmentManager(); 获取
（3）开启一个事务FragmentTransaction transaction=fragmentManager.beginTransaction()
（4）向容器中添加或替换布局replace（）需要传入容器id和待添加的碎片实例
（5）提交事务，commit

package com.example.fragmenttest;

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

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button=(Button)findViewById(R.id.b1);
button.setOnClickListener(this);
repaceFragment(new RightFragment());
}

@Override
public void onClick(View view) {
switch (view.getId()){
case R.id.b1:
repaceFragment(new AnotherRightFragment());
break;
default:
break;
}
}
public void repaceFragment(Fragment fragment){
FragmentManager fragmentManager=getSupportFragmentManager();
FragmentTransaction transaction=fragmentManager.beginTransaction();
transaction.replace(R.id.right_fragment,fragment);
transaction.commit();
}
}

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二、在碎片中模拟返回栈
transaction.addToBackStack(null); 可以将事物添加到返回栈中，参数传入null即可

public void repaceFragment(Fragment fragment){
FragmentManager fragmentManager=getSupportFragmentManager();
FragmentTransaction transaction=fragmentManager.beginTransaction();
transaction.replace(R.id.right_fragment,fragment);
transaction.addToBackStack(null);
transaction.commit();
}

三、碎片之间的通信
四、限定符的使用
在res目录下新建layout—large文件夹，在该文件夹下新建activity_main.xml，
large为限定符，当分辨率较大时会调用layout—large/activity_main.xml,否则会调用activity_main.xml