Android中Fragment的简单应用

这个学期的短学期要求我们在移动平台上进行开发，虽然自己断断续续已经写了大半年的Android了，但是暑假的时候一直在刷PAT，开学了之后也在写HDUOJ，eclipse也好久没打开过了，现在趁这个机会重新捡起Android。

这是第二个小作业，要求我们使用Fragment，我还一直没接触过这个，所以借鉴着网上大牛们的介绍写了一个小DEMO。

Fragment的出现是因为在不同的屏幕大小下，我们的APP无法同时满足不同大小，所以出现了Fragment。（你可以把Fragment当成Activity的一个界面的一个组成部分，甚至Activity的界面可以完全有不同的Fragment组成，更帅气的是Fragment拥有自己的生命周期和接收、处理用户的事件，这样就不必在Activity写一堆控件的事件处理的代码了。更为重要的是，你可以动态的添加、替换和移除某个Fragment。）（摘自大牛的Blog）

activity_main.xml

<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:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.whisker.fragmenttest.MainActivity" >

<LinearLayout
android:layout_width="match_parent"
android:layout_height="36dp"
android:orientation="horizontal"
android:weightSum="3">

<LinearLayout
android:id="@+id/tab1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:background="@color/tab_down"
android:gravity="center">

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="NO.1"
android:textColor="#ffffff"/>

</LinearLayout>

<ImageView
android:layout_width="2dp"
android:layout_height="match_parent"
android:background="#ffffff" />

<LinearLayout
android:id="@+id/tab2"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:background="@color/tab"
android:gravity="center">

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="NO.2"
android:textColor="#ffffff"/>

</LinearLayout>

<ImageView
android:layout_width="2dp"
android:layout_height="match_parent"
android:background="#ffffff" />

<LinearLayout
android:id="@+id/tab3"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:background="@color/tab"
android:gravity="center">

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="NO.3"
android:textColor="#ffffff"/>
</LinearLayout>

</LinearLayout>

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

</FrameLayout>

</LinearLayout>

MainActivity.java

package com.whisker.fragmenttest;

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.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.LinearLayout;

public class MainActivity extends FragmentActivity {
<span style="white-space:pre">	</span>
<span style="white-space:pre">	</span>private LinearLayout tabLayout1,tabLayout2,tabLayout3;
<span style="white-space:pre">	</span>private Fragment tabFragment1,tabFragment2,tabFragment3;
<span style="white-space:pre">	</span>private FragmentManager fragmentManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        fragmentManager = getSupportFragmentManager();
        
        tabLayout1 = (LinearLayout) findViewById(R.id.tab1);
        tabLayout2 = (LinearLayout) findViewById(R.id.tab2);
        tabLayout3 = (LinearLayout) findViewById(R.id.tab3);
        
        clickListener clickListener = new clickListener();
        
<span style="white-space:pre">		</span>tabLayout1.setOnClickListener(clickListener);
        tabLayout2.setOnClickListener(clickListener);
        tabLayout3.setOnClickListener(clickListener);
        
        setDefaultFragment();
    }
    
    /*初始化默认的Fragment*/
    
    private void setDefaultFragment() {
    <span style="white-space:pre">	</span>FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
    <span style="white-space:pre">	</span>tabFragment1 = new TabFragment1();
    <span style="white-space:pre">	</span>fragmentTransaction.replace(R.id.content_layout, tabFragment1);
    <span style="white-space:pre">	</span>fragmentTransaction.commit();
    }
    
    public void replaceFragment(Fragment fragment) {
    <span style="white-space:pre">	</span>FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
    <span style="white-space:pre">	</span>if(!fragment.isAdded()){
    <span style="white-space:pre">		</span>fragmentTransaction.replace(R.id.content_layout, fragment);
    <span style="white-space:pre">		</span>fragmentTransaction.commit();
    <span style="white-space:pre">	</span>}
    <span style="white-space:pre">	</span>else{
    <span style="white-space:pre">		</span>fragmentTransaction.show(fragment);
    <span style="white-space:pre">	</span>}
    }
    
    private class clickListener implements OnClickListener{

<span style="white-space:pre">		</span>@Override
<span style="white-space:pre">		</span>public void onClick(View v) {
<span style="white-space:pre">			</span>switch (v.getId()) {
<span style="white-space:pre">			</span>case R.id.tab1:
<span style="white-space:pre">				</span>if(tabFragment1 == null)
<span style="white-space:pre">					</span>tabFragment1 = new TabFragment1();
<span style="white-space:pre">				</span>
<span style="white-space:pre">				</span>replaceFragment(tabFragment1);
<span style="white-space:pre">				</span>tabLayout1.setBackgroundColor(getResources().getColor(R.color.tab_down));
<span style="white-space:pre">				</span>tabLayout2.setBackgroundColor(getResources().getColor(R.color.tab));
<span style="white-space:pre">				</span>tabLayout3.setBackgroundColor(getResources().getColor(R.color.tab));
<span style="white-space:pre">				</span>break;
<span style="white-space:pre">				</span>
<span style="white-space:pre">			</span>case R.id.tab2:
<span style="white-space:pre">				</span>if(tabFragment2 == null)
<span style="white-space:pre">					</span>tabFragment2 = new TabFragment2();
<span style="white-space:pre">				</span>replaceFragment(tabFragment2);
<span style="white-space:pre">				</span>tabLayout2.setBackgroundColor(getResources().getColor(R.color.tab_down));
<span style="white-space:pre">				</span>tabLayout1.setBackgroundColor(getResources().getColor(R.color.tab));
<span style="white-space:pre">				</span>tabLayout3.setBackgroundColor(getResources().getColor(R.color.tab));
<span style="white-space:pre">				</span>break;
<span style="white-space:pre">				</span>
<span style="white-space:pre">			</span>case R.id.tab3:
<span style="white-space:pre">				</span>if(tabFragment3 == null)
<span style="white-space:pre">					</span>tabFragment3 = new TabFragment3();
<span style="white-space:pre">				</span>
<span style="white-space:pre">				</span>replaceFragment(tabFragment3);
<span style="white-space:pre">				</span>tabLayout1.setBackgroundColor(getResources().getColor(R.color.tab));
<span style="white-space:pre">				</span>tabLayout2.setBackgroundColor(getResources().getColor(R.color.tab));
<span style="white-space:pre">				</span>tabLayout3.setBackgroundColor(getResources().getColor(R.color.tab_down));
<span style="white-space:pre">				</span>break;

<span style="white-space:pre">			</span>}
<span style="white-space:pre">		</span>}
    <span style="white-space:pre">	</span>
    }
}

TabFragment1.java

package com.whisker.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;

public class TabFragment1 extends Fragment{

@Override
@Nullable
public View onCreateView(LayoutInflater inflater,
@Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_tab1, null);
return view;
}

}

fragment_tab1.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="match_parent"
android:layout_gravity="center"
android:gravity="center"
android:text="Tab1"
android:textColor="#000000"/>

</LinearLayout>

TabFragment2,TabFragment3同上。

效果图：