<p>当需要扩展android原生TextView的时候，比如需要给TextView默认加上10像素的颜色边框时，当设置宽高为wrap_content时，高度并不好处理。网上大部分人云亦云的说设置一个默认值，然后根据测量模式，取 MeasureSpec.getSize(widthMeasureSpec)和默认值中的较小值，我想说就是扯淡。比如说我需要的宽度是200px,默认值是50px，此时宽度肯定不够。先看如下代码</p>    <pre>  <code class="language-java">  package com.example.customview.view;    import android.content.Context;  import android.graphics.Canvas;  import android.graphics.Color;  import android.graphics.Paint;  import android.util.AttributeSet;  import android.util.Log;  import android.view.View.MeasureSpec;  import android.view.WindowManager;  import android.widget.TextView;    public class CustomTextView extends TextView {        private Paint paint1;      private Paint paint2;        public CustomTextView(Context context) {          super(context, null);      }        public CustomTextView(Context context, AttributeSet attrs) {          super(context, attrs);          initView(context, attrs);          // TODO Auto-generated constructor stub      }        private void initView(Context context, AttributeSet attrs) {          paint1 = new Paint();          paint1.setColor(getResources().getColor(android.R.color.holo_blue_dark));          paint1.setStyle(Paint.Style.FILL);          paint2 = new Paint();          paint2.setStyle(Paint.Style.FILL);          paint2.setColor(Color.GREEN);        }        @Override      protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {          // // TODO Auto-generated method stub          super.onMeasure(widthMeasureSpec, heightMeasureSpec);          int widthMode = MeasureSpec.getMode(widthMeasureSpec);          int widthSize = MeasureSpec.getSize(widthMeasureSpec);          int heightMode = MeasureSpec.getMode(heightMeasureSpec);          int heightSize = MeasureSpec.getSize(heightMeasureSpec);          if(heightMode == MeasureSpec.AT_MOST&&widthMode == MeasureSpec.AT_MOST){              //高度宽度为wrap_content时              setMeasuredDimension(getMeasuredWidth()+20, getMeasuredHeight()+20);          }        }        @Override      protected void onDraw(Canvas canvas) {          Log.e("CustomTextView", "widthSize" + getMeasuredWidth() + "heightSize"                  + getMeasuredHeight());          canvas.drawRect(0, 0, getMeasuredWidth(), getMeasuredWidth(), paint1);          canvas.drawRect(10, 10, getMeasuredWidth() - 10,                  getMeasuredHeight() - 10, paint2);          canvas.translate(10, 10);          super.onDraw(canvas);      }  }    View Code</code></pre>    <p>注意：</p>    <pre>  <code class="language-java">if(heightMode == MeasureSpec.AT_MOST&&widthMode == MeasureSpec.AT_MOST){              //高度宽度为wrap_content时              setMeasuredDimension(getMeasuredWidth()+20, getMeasuredHeight()+20);          }  </code></pre>    <p>通过调用TextView的getMeasuredWidth()，getMeasuredHeight()的方法获取获取不加边框时的宽高，在加上适当的偏移量，就能实现了。</p>    <p><strong>用法如下：</strong></p>    <pre>  <code class="language-java"><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"      xmlns:tools="http://schemas.android.com/tools"      xmlns:app="http://schemas.android.com/apk/res-auto"      android:layout_width="match_parent"      android:layout_height="match_parent"      android:gravity="center"      android:orientation="vertical" >        <com.example.customview.view.CustomTextView          android:layout_width="wrap_content"          android:layout_height="wrap_content"          android:text="参与人数"/>    </LinearLayout>  </code></pre>    <p style="text-align:center">运行结果如下：</p>    <p style="text-align:center"><img src="https://simg.open-open.com/show/98a81322be8530dafd018cd758fbcd89.png"></p>    <p> </p>    <p>来自：http://www.cnblogs.com/sharkli/p/5974909.html</p>    <p> </p>