getWidth()和getMeasuredWidth()两个方法在写法上非常相似，但是在用法上却大不相同。首先先总结一下：getWidth（）代表的是view布局结束之后view所代表的宽度；getMeasuredWidth()代表的是view中内容的宽度。听起来有点绕口，我们直接从源码开始说起：

对于android源码中的getWidth（）方法的源码如下：

public final int getWidth() {

return mRight - mLeft;

}

那么mRight和mLeft属性代表的又是什么呢？查看文档，我们可以发现在View类中有getLeft和getRight两个方法：

public final int getLeft() {

return mLeft;

}

public final int getRight() {

return mRight;

}

查看帮助文档，文档对于这两个方法的解释如下：

Left position of this view relative to its parent.

Right position of this view relative to its parent.

所以getWidth的宽度正好是view右边边框距离父组件的距离减去左边边框距离父组件的距离。正好就是view布局好之后的宽度。

对于getMeasuredWidth( ),我们查看源码，如下：

public final int getMeasuredWidth() {

return mMeasuredWidth & MEASURED_SIZE_MASK;

}

属性mMeasuredWidth使我们需要的，但是是在什么地方设置的这个属性呢？查阅源码，如下：

*/

protected final void setMeasuredDimension(int measuredWidth, int measuredHeight) {

boolean optical = isLayoutModeOptical(this);

if (optical != isLayoutModeOptical(mParent)) {

Insets insets = getOpticalInsets();

int opticalWidth = insets.left + insets.right;

int opticalHeight = insets.top + insets.bottom;

measuredWidth += optical ? opticalWidth : -opticalWidth;

measuredHeight += optical ? opticalHeight : -opticalHeight;

}

mMeasuredWidth = measuredWidth;

mMeasuredHeight = measuredHeight;

mPrivateFlags |= PFLAG_MEASURED_DIMENSION_SET;

}

mMeasuredWidth是在setMeasuredDimension()方法中设置的，而调用该方法是在onMeasure()方法中调用的，源码如下：

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

setMeasuredDimension(getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec),

getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec));

}

所以mMeasuredWidth属性的设置是在measure阶段，通过widthMeasureSpec中的sieze值，经过一些判断（setMeasuredDimension中的optical的true or false），对size值进行一些操作，最后赋值给mMeasuredWidth,所以这个值就是measure阶段测量的view的内容宽度。

下面通过一个例子，设置TextView宽度为match_parent,观察getWidth和getMeasuredWidth值的变化。

package com.example.measuredwidthheight;

import android.R.color;

import android.app.Activity;

import android.content.Context;

import android.graphics.Canvas;

import android.os.Bundle;

import android.util.AttributeSet;

import android.util.Log;

import android.widget.LinearLayout;

import android.widget.TextView;

public class Main extends Activity {

public static final String TAG = "tag";

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

LinearLayout ll = new LinearLayout(this);

MyTextView tv = new MyTextView(this);

LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(

LinearLayout.LayoutParams.MATCH_PARENT,

LinearLayout.LayoutParams.WRAP_CONTENT);

tv.setLayoutParams(lp);

tv.setText("aaaa");

ll.addView(tv);

this.setContentView(ll);

}

}

class MyTextView extends TextView {

public static final String TAG = "tag";

public MyTextView(Context context, AttributeSet attrs) {

super(context, attrs);

}

public MyTextView(Context context) {

super(context);

}

@Override

protected void onDraw(Canvas canvas) {

super.onDraw(canvas);

Log.v(TAG, "draw_width:" + this.getWidth());

Log.v(TAG, "draw_height:" + this.getHeight());

Log.v(TAG, "draw_measured_width:" + this.getMeasuredWidth());

Log.v(TAG, "draw_measured_height:" + this.getMeasuredHeight());

}

}

从结果可以看到：因为设置了textview的宽度为match_parent,所有getWidth的长度为屏幕宽度，而getMeasuredWidth返回的方法是textview内容的宽度60。