Android新手开发之旅-Fragment的用法

liu

Fragment的用法




本篇说一下怎么将Fragment添加到Activity中，有两种方法：


先新建两个Fragment（LeftFragment,RightFragment）：     

                 

LeftFragment

[Java] 纯文本查看 复制代码

package com.company.helloworld.firstapplication;


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

public class LeftFragment extends Fragment {


    public LeftFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_left, container, false);
    }

}

fragment_left.xml

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<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="@color/colorAccent"
    tools:context="com.company.helloworld.firstapplication.LeftFragment">

    <TextView
        android:id="@+id/tv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center"
        android:text="左边Fragment"
        android:textColor="@android:color/white" />

</FrameLayout>

RightFragment

[Java] 纯文本查看 复制代码

package com.company.helloworld.firstapplication;


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


/**
 * A simple {@link Fragment} subclass.
 */
public class RightFragment extends Fragment {


    public RightFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_right, container, false);
    }

}

fragment_right.xml

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<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="@color/colorPrimary"
    tools:context="com.company.helloworld.firstapplication.RightFragment">

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:id="@+id/tv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="右边Fragment"
        android:gravity="center"
        android:textColor="@android:color/white" />

</FrameLayout>

第一种方法（在布局中静态加载）：
主布局activity_main.xml中:

[XML] 纯文本查看 复制代码

<?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"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal">

    <!--android:name指定加载的Fragment-->
    <fragment
        android:id="@+id/left_fragment"
        android:name="com.company.helloworld.firstapplication.LeftFragment"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="1" />

    <fragment
        android:id="@+id/right_fragment"
        android:name="com.company.helloworld.firstapplication.RightFragment"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="1" />
</LinearLayout>

运行结果如下图：

        
        

第二种方法(动态加载):
主布局activity_main.xml:

[XML] 纯文本查看 复制代码

<?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"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal">

    <FrameLayout
        android:id="@+id/fragment_content"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</LinearLayout>

MainActivity:

[Java] 纯文本查看 复制代码

package com.company.helloworld.firstapplication;

import android.app.Activity;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.os.Bundle;

public class MainActivity extends Activity {

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

        LeftFragment leftFragment = new LeftFragment();

        FragmentManager supportFragmentManager = getFragmentManager();
        FragmentTransaction fragmentTransaction = supportFragmentManager.beginTransaction();
        fragmentTransaction.add(R.id.fragment_content, leftFragment).commit();
    }

}

运行结果：

        
        


因为android 3.0以下版本没有fragment的api,所以必须借助V4包里面的getSupportFragmentManager()方法来间接获取FragmentManager()对象,同时继承FragmentActivity
而android 3.0版本之后有了fragment的API，所以通过getFragmentManager()方法直接就可以获取到FragmentManager对象，并且继承自Activity就可以嵌入使用fragment


注意：每个Fragment和Activity导的包要保持一致,例如都是import android.app或者都是import android.support.v4.app,不然容易出错

站长苏飞

我只是路过打酱油的。

竹林风

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