<?xml version="1.0" encoding="utf-8"?>
<resources>
  <declare-styleable name="CustomViewStyle">
    <attr name="customText" format="string" />
    <attr name="customTextColor" format="color" />
    <attr name="customTextSize" format="dimension" />
  </declare-styleable>
</resources>

xmlns:xr="http://schemas.android.com/apk/res/com.rong.test"

xmlns:xr="http://schemas.android.com/apk/res-auto"

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:xr="http://schemas.android.com/apk/res/com.rong.test"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:background="@android:color/black"
  android:orientation="vertical" >
  <com.rong.activity.CustomView
    android:layout_width="300dp"
    android:layout_height="300dp"
    android:layout_centerInParent="true"
    android:background="#ff0000"
    xr:customText="自定义控件"
    xr:customTextColor="#000000"
    xr:customTextSize="40sp" />
</RelativeLayout>

package com.rong.activity;
import com.rong.test.R;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.View;
/**
 * 自定义控件
 * 
 * @author 徐荣
 *
 */
public class CustomView extends View {
  /**
   * 自定义画笔
   */
  private Paint mPaint;
  /**
   * 文字范围
   */
  private Rect mBounds;
  /**
   * 自定义文字
   */
  private String customText;
  /**
   * 自定义大小
   */
  private int customTextSize;
  /**
   * 自定义颜色
   */
  private int customTextColor;
  public CustomView(Context context, AttributeSet attrs) {
    super(context, attrs);
    TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.CustomViewStyle);
    // 获取自定义文字
    customText = typedArray.getString(R.styleable.CustomViewStyle_customText);
    // 获取自定义文字大小
    customTextSize = typedArray.getDimensionPixelSize(R.styleable.CustomViewStyle_customTextSize, 28);
    // 或者自定义文字颜色
    customTextColor = typedArray.getColor(R.styleable.CustomViewStyle_customTextColor, Color.WHITE);
    // 要回收这个typedArray对象
    typedArray.recycle();
    initView();
  }
  public void initView() {
    // 初始化画笔
    mPaint = new Paint();
    mPaint.setAntiAlias(true);
    mPaint.setStyle(Paint.Style.FILL);
    mPaint.setColor(customTextColor);
    mPaint.setTextSize(customTextSize);
    // 生成文字区域
    mBounds = new Rect();
  }
  @Override
  protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    // 获取文字显示区域mBounds
    mPaint.getTextBounds(customText, 0, customText.length(), mBounds);
    //使文字宽居中显示=控件的宽度/2 -文字的宽度/2
    float helfWidth = getWidth() / 2 - mBounds.width() / 2;
    //使文字高居中显示=控件的宽度/2 +文字的宽度/2
    float helfHeight = getHeight() / 2+mBounds.height()/2;
    //绘制文字
    canvas.drawText(customText, helfWidth, helfHeight, mPaint);
  }
}