Android圆形按钮实现

<Button
android:id="@+id/btn_5"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="@string/general_consulting"
android:textColor="@color/white"
android:textSize="@dimen/text_size18"
android:background="@drawable/bg_special_disease_circle"/>

"1.0" encoding="utf-8"?>
"http://schemas.android.com/apk/res/android">
    
    
        "oval" >
            "@dimen/size90"/>
            "@color/white" />
            170dp" android:170dp"/>
        
    
    
    "8dp" android:right="8dp" android:top="8dp" android:left="8dp" >
        "http://schemas.android.com/apk/res/android">
            "true">
                "oval" >
                    "@dimen/size90"/>
                    "#e66b4f" />
                    162dp" android:162dp"/>
                
            
            
            
                "oval" >
                    "@dimen/size90"/>
                    "#f3876f" />
                    162dp" android:162dp"/>