drawable,通过xml去生成图片

layer-list：两张图片和成一张图片

state-list：状态图，如button按钮的点击，点击前与点击时的状态颜色不一样。

level-list：打分图片

shape：绘制形状图片

布局代码：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <ImageView
        android:id="@+id/iv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/layerlist"/>

    <Button 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="onClick"
        android:text="    下             一                张"
        android:background="@drawable/shape"/>
</LinearLayout>

MainActivity：

package com.android.hzy.drawable;
import android.app.Activity;
import android.graphics.drawable.LayerDrawable;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;

public class MainActivity extends Activity {

    private ImageView iv;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        iv = (ImageView) findViewById(R.id.iv);
    }

    public void onClick(View v){
        LayerDrawable layerDrawable = (LayerDrawable) getResources().getDrawable(R.drawable.layerlist);
        // 替换图片
        layerDrawable.setDrawableByLayerId(R.id.user, getResources().getDrawable(R.drawable.ic_launcher));
        // 将图片复制给imageview
        iv.setImageDrawable(layerDrawable);
    }
}

res/drawable下创建与之对应的xml

layerlist.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >

    <item android:drawable="@drawable/faceback"/>
    <item
        android:id="@+id/user"
        android:bottom="22dp"
        android:drawable="@drawable/user"
        android:left="18dp"
        android:right="18dp"
        android:top="68dp"/>

</layer-list>

statelist.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android" >
    <!-- 按下采用的是什么图片 -->
    <item android:state_pressed="true" android:drawable="@drawable/bg_selected"></item>
    <!-- 默认状态就是个正常状态，因此默认状态的条目要放在最后写 -->
    <item android:drawable="@drawable/bg_normal"></item>

</selector>

levellist.xml

<?xml version="1.0" encoding="utf-8"?>
<level-list xmlns:android="http://schemas.android.com/apk/res/android" >

    <item
        android:drawable="@drawable/faceback"
        android:maxLevel="10"
        android:minLevel="0"/>
    <item
        android:drawable="@drawable/faceback"
        android:maxLevel="20"
        android:minLevel="11"/>

</level-list>

shape.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- 
android:shape=["rectangle" | "oval" | "line" | "ring"]：表示图形的形状
corners ：代表圆角
gradient : 渐变色
padding：内边距
size：图片的大小
solid：内填充色     和  gradient 只能使用一个
stroke：边线 (虚线图片)
 -->
<shape
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <corners
        android:radius="3dp" />
    <gradient
        android:centerColor="#D0F4F9"
        android:endColor="#4BED23"
        android:startColor="#5FF2FA" />
    <padding
        android:left="2dp"
        android:top="2dp"
        android:right="2dp"
        android:bottom="2dp" />

    <stroke
        android:width="1dp"
        android:color="#f00"
        android:dashWidth="10dp"
        android:dashGap="2dp" />
</shape>