Android：自定义View

MyCustomView

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Color;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.view.View;

import com.tencent.formalandroid.R;

public class MyCustomView extends View {

    private int mBackgroudColor;

    // 仿照Scrollview去书写
    public MyCustomView(Context context) {
        this(context, null);
    }

    public MyCustomView(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public MyCustomView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);

        init(context, attrs);
    }

    private void init(Context context, AttributeSet attributeSets) {

        // 获取自定义属性的数组
        TypedArray typedArray = context.obtainStyledAttributes(attributeSets, R.styleable.MyCustomView);
        // 拿到自定义的颜色
        mBackgroudColor = typedArray.getColor(R.styleable.MyCustomView_backgroundColor, Color.RED);
        // 给自身赋值
        this.setBackgroundColor(mBackgroudColor);
    }
}

attrs.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="MyCustomView">
        <attr name="backgroundColor" format="color"/>
    </declare-styleable>
</resources>

使用：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    // 注意：这里一定要加上这句话，引入新的命名空间
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    // 这里，需要加上包名+路径
    <com.tencent.formalandroid.view.MyCustomView
        android:layout_width="200dp"
        android:layout_height="100dp"/>

</LinearLayout>