02Android用户界面优化之（一）Android Fragment

一、使用Fragment

1.AndroidManifest.xml文件

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.shiyanshi.learningfragment">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name"
            android:theme="@style/AppTheme.NoActionBar">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

2.布局文件

(1)activity_main.xml

其中放置的是一个帧布局的布局容器，其id为container

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

(2)fragment_main.xml

主fargment布局文件，里面放置的按钮用于弹出另外一个fragment

<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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:orientation="vertical"
    tools:context="com.example.shiyanshi.learningfragment.MainActivityFragment"
    tools:showIn="@layout/activity_main">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="北京欢迎您!" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/btnShowFragmentAnother"
        android:text="显现另外一个Fragment"/>

</LinearLayout>

(3)fragment_another.xml

从fragment布局文件，里面的按钮用于支持返回到上一个fragment界面

<?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:id="@+id/fragmentAnother">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="这是另外一个Fragment"/>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/btnBackOperation"
        android:text="后退操作"/>

</LinearLayout>

3.Java源文件

（1）MainActivity.java

package com.example.shiyanshi.learningfragment;

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

if(savedInstanceState==null){
getSupportFragmentManager()
.beginTransaction()
.add(R.id.container,new MainActivityFragment()) //add的第一个参数是布局容器，第二个参数是主Fragment的类
.commit();
}

    }

}

(2)MainActivityFragment.java

package com.example.shiyanshi.learningfragment;

import android.support.v4.app.Fragment;

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

/**
 * A placeholder fragment containing a simple view.
 */
public class MainActivityFragment extends 

Fragment

 {      //注意其继承的是

import android.support.v4.app.Fragment

中的Fragment

    public MainActivityFragment() {
    }

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

View rootView=inflater.inflate(R.layout.fragment_main, container, false); //第一个参数：主fragment的布局文件，第二个：布局容器，第三个为布尔型attachToRoot

rootView.findViewById(R.id.btnShowFragmentAnother).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
getFragmentManager().beginTransaction()
.addToBackStack(null) //加入后退栈，使其支持后退的功能
.replace(R.id.container,new AnotherFragment())
.commit();
}
});

        return rootView;
    }
}

(3)AnotherFragment.java

package com.example.shiyanshi.learningfragment;

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 shiyanshi on 2016/1/25.
 */
public class AnotherFragment extends 

Fragment

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

View view = inflater.inflate(R.layout.fragment_another,container,false);

view.findViewById(R.id.btnBackOperation).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
getFragmentManager().popBackStack();
}
});

        return view;
    }
}

4.界面显示效果

二、Fragment的生命周期