为自定View添加相应属性，在XML可以直接使用

首先在values下新建一个atts文件夹，添加 

declare-styleable

<?xml version="1.0" encoding="utf-8"?><resources>    <declare-styleable name="Topbar">        <attr name="title" format="string"></attr>        <attr name="titleTextSize" format="dimension"></attr>        <attr name="titleTextColor" format="color"></attr>        <attr name="leftTextColor" format="color"></attr>        <attr name="leftBackground" format="color|reference"></attr>        <attr name="leftText" format="string"></attr>        <attr name="rightText" format="string"></attr>        <attr name="rightBackground" format="color|reference"></attr>        <attr name="rightTextColor" format="color"></attr>    </declare-styleable></resources>

XML布局

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:custom="http://schemas.android.com/apk/res-auto"    android:layout_width="match_parent"    android:layout_height="match_parent"    >  <com.example.hc.mytopbar.TopBar      android:id="@+id/tp"      android:layout_width="wrap_content"      android:layout_height="wrap_content"      custom:leftText="back"      custom:leftTextColor="#ffff00"      custom:rightTextColor="#ffff00"      custom:rightText="menu"      custom:title="菜单"      custom:titleTextColor="#123412"      custom:titleTextSize="10sp">  </com.example.hc.mytopbar.TopBar></RelativeLayout>

然后在自定义View类中的构造函数中 通过
TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.Topbar); 获得这个atts文件
获得atts中自定义属性之后 将属性与相应的控件绑定
public class TopBar extends RelativeLayout {    private Button leftButton, rightButton;    private TextView tv_title;    private int leftTextColor;    private Drawable leftBackground;    private String leftText;    private int rightTextColor;    private Drawable rightBackground;    private String rightText;    private float titleTextSize;    private int titleTextColor;    private String title;    private LayoutParams leftParams, rightParams, titleParam;    private topbarClickListener listener;    public interface topbarClickListener {        public void leftClick();        public void rightClick();    }    public void setOnTopbarClickListener(topbarClickListener listner) {        this.listener = listner;    }    public TopBar(final Context context, AttributeSet attrs) {        super(context, attrs);        TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.Topbar);        leftTextColor = ta.getColor(R.styleable.Topbar_leftTextColor, 0);        leftBackground = ta.getDrawable(R.styleable.Topbar_leftBackground);        leftText = ta.getString(R.styleable.Topbar_leftText);        rightTextColor = ta.getColor(R.styleable.Topbar_rightTextColor, 0);        rightBackground = ta.getDrawable(R.styleable.Topbar_rightBackground);        rightText = ta.getString(R.styleable.Topbar_rightText);        titleTextSize = ta.getDimension(R.styleable.Topbar_titleTextSize, 0);        titleTextColor = ta.getColor(R.styleable.Topbar_titleTextColor, 0);        title = ta.getString(R.styleable.Topbar_title);        ta.recycle();        setBackgroundColor(0xfff59563);        leftButton = new Button(context);        rightButton = new Button(context);        tv_title = new TextView(context);        leftButton.setTextColor(leftTextColor);        leftButton.setText(leftText);        leftButton.setBackground(leftBackground);        rightButton.setText(rightText);        rightButton.setTextColor(rightTextColor);        rightButton.setBackground(rightBackground);        tv_title.setTextColor(titleTextColor);        tv_title.setTextSize(titleTextSize);        tv_title.setText(title);        tv_title.setGravity(Gravity.CENTER);        leftParams = new LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);        leftParams.addRule(ALIGN_PARENT_LEFT, TRUE);        addView(leftButton, leftParams);        rightParams = new LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);        rightParams.addRule(ALIGN_PARENT_RIGHT, TRUE);        addView(rightButton, rightParams);        titleParam = new LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);        titleParam.addRule(CENTER_IN_PARENT);        addView(tv_title, titleParam);