Android美工坊：Selector选择器的使用

Android selector选择器可以让你切换自定义的背景风格，比如button、ListView、或者布局点击时候的背景切换等，都需要用到它

背景可以是自定义到颜色，或者图片资源

首先需要在你的res目录下创建drawable文件夹，然后在里面创建一个selector文件，如myselector.xml

注：不知为什么，selector里面有关focus的东西在真机上没什么效果，反而会影响使用，比如android:state_focus="true"，加上它就没有效果，去掉它就可以正常使用了

默认情况下直接用下面的布局即可实现点击后即可切换背景，其实只需要两个item标签即可，当然，item标签内部可以用shape标签自定义不同的风格

例子1：button点击效果

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android" >
    <item 
        android:state_pressed="true"
        android:drawable="@drawable/button_pressed"
        ></item>
    <item 
        android:drawable="@drawable/button_normal"
        ></item>
</selector>

res/layout/main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >
    <Button
        android:id="@+id/test"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:background="@drawable/myselectr"
        android:text="Go Home"
        />
</LinearLayout>

运行效果：

这是正常情况

这是点击后的效果

当然，针对button的selector还有很多其他的配置，但是对于一般程序来说上面的配置就够了

例子2：TextView点击效果

这个例子是网上找的，演示的是一个用TextView来定义的一个Button，实现类似TabWidget风格的选项卡。

自定义按钮，这里没有通过Button类或者子类去做派生，而是通过TextView派生出来的。

在这里三个按钮是三个TextView派生类实例，中间的白线，是1px宽的白色矩形，这样就可以做出类似上面的效果。先看图

点击后

转自：http://marshal.easymorse.com/archives/3059

/res/drawable/background_color.xml 用shape标签自定义一个渐变背景

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >
    <gradient 
        android:startColor="#FFFFFFFF"
        android:endColor="#FFFFFFFF"
        android:angle="270.0"
        android:centerY="0.3"
        android:centerColor="#FFBDBDBD"
        />
</shape>

/res/drawable/button_color.xml
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >
    <gradient 
        android:startColor="#FF7F7F7F"
        android:endColor="#FF000000"
        android:angle="270.0"
        />
</shape>

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android" 
    android:constantSize="true">
    <!-- 获得焦点时的背景图片 -->
    <item android:state_focused="true">
        <shape>
            <gradient 
                android:startColor="#FFE5CF33"
                android:endColor="#FFF1E7A2"
                android:angle="90.0"
                />
        </shape>
    </item>
    <!-- 设置相应所有事件 -->
    <item android:state_enabled="true" android:state_pressed="false">
        <shape>
            <gradient 
                android:startColor="#FF1B1B1B"
                android:endColor="#FF969696"
                android:angle="90.0"
                />
        </shape>
    </item>
    <!-- 按钮点击时的背景 -->
    <item android:state_enabled="true" android:state_pressed="true">
        <shape>
            <gradient 
                android:startColor="#FF000000"
                android:endColor="#FF474747"
                android:angle="90.0"
                />
        </shape>
    </item>
    <item android:state_enabled="false" android:state_pressed="true">
        <shape>
            <gradient 
                android:startColor="#FF000000"
                android:endColor="#FF474747"
                android:angle="90.0"
                />
        </shape>
    </item>
    <!-- 默认情况下的背景 -->
    <item>
        <shape>
            <gradient 
                android:startColor="#FF000000"
                android:endColor="#FF474747"
                android:angle="90.0"
                />
        </shape>
    </item>
</selector>

res/drawable/button_selector.xml
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android" 
    android:constantSize="true">
    <!-- 获得焦点时的背景图片 -->
    <item android:state_focused="true">
        <shape>
            <gradient 
                android:startColor="#FFE5CF33"
                android:endColor="#FFF1E7A2"
                android:angle="90.0"
                />
        </shape>
    </item>
    <!-- 设置相应所有事件 -->
    <item android:state_enabled="true" android:state_pressed="false">
        <shape>
            <gradient 
                android:startColor="#FF1B1B1B"
                android:endColor="#FF969696"
                android:angle="90.0"
                />
        </shape>
    </item>
    <!-- 按钮点击时的背景 -->
    <item android:state_enabled="true" android:state_pressed="true">
        <shape>
            <gradient 
                android:startColor="#FF000000"
                android:endColor="#FF474747"
                android:angle="90.0"
                />
        </shape>
    </item>
    <item android:state_enabled="false" android:state_pressed="true">
        <shape>
            <gradient 
                android:startColor="#FF000000"
                android:endColor="#FF474747"
                android:angle="90.0"
                />
        </shape>
    </item>
    <!-- 默认情况下的背景 -->
    <item>
        <shape>
            <gradient 
                android:startColor="#FF000000"
                android:endColor="#FF474747"
                android:angle="90.0"
                />
        </shape>
    </item>
</selector>

res/layout/main.xml，这个是主布局，由自定义的Button和1px的白色矩形组成
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@drawable/background_color"
    android:orientation="vertical" >

<LinearLayout 
        android:layout_width="fill_parent"
        android:layout_height="10dip"
        />
    <LinearLayout 
        android:layout_width="fill_parent"
        android:layout_height="40dip"
        >
        <com.loulijun.demo02.TextButton
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="饮食"
            android:gravity="center"
            android:background="@drawable/button_selector"
            android:focusable="true"
            android:clickable="true"
            />
        <View android:layout_width="2px" android:layout_height="fill_parent"
            android:background="#FFFFFFFF"/>
        <com.loulijun.demo02.TextButton
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="旅行"
            android:gravity="center"
            android:background="@drawable/button_selector"
            android:focusable="true"
            android:clickable="true"
            />
        <View android:layout_width="2px" android:layout_height="fill_parent"
            android:background="#FFFFFFFF"/>
        <com.loulijun.demo02.TextButton
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:text="体育"
            android:gravity="center"
            android:background="@drawable/button_selector"
            android:focusable="true"
            android:clickable="true"
            />
    </LinearLayout>
</LinearLayout>

继承自TextView的自定义Button

package com.loulijun.demo02;
import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;
public class TextButton extends TextView {
    public TextButton(Context context)
    {
        super(context);
    }
    public TextButton(Context context, AttributeSet attrs, int defStyle)
    {
        super(context,attrs,defStyle);
    }
    public TextButton(final Context context, AttributeSet attrs)
    {
        this(context,attrs,0);
        this.setOnTouchListener(new OnTouchListener()
        {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                if(event.getAction()==MotionEvent.ACTION_CANCEL
                        ||event.getAction()==MotionEvent.ACTION_UP
                        ||event.getAction()==MotionEvent.ACTION_OUTSIDE)
                {
                    Toast.makeText(context, "hello", Toast.LENGTH_SHORT).show();
                }
                return false;
            }
            
        });
    }
}

主程序

package com.loulijun.demo02;
import android.app.Activity;
import android.os.Bundle;
public class Demo02Activity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }
}