<?xml version="1.0" encoding="utf-8"?>
<resources>

  <declare-styleable name="test">
    <attr name="text" format="string" />
    <attr name="testAttr" format="integer" />
  </declare-styleable>

</resources>

package com.example.test;

import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;

public class MyTextView extends View {

  private static final String TAG = MyTextView.class.getSimpleName();

  public MyTextView(Context context, AttributeSet attrs) {
    super(context, attrs);

    TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.test);

    String text = ta.getString(R.styleable.test_testAttr);
    int textAttr = ta.getInteger(R.styleable.test_text, -1);

    Log.e(TAG, "text = " + text + " , textAttr = " + textAttr);

    ta.recycle();
  }

}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  xmlns:zhy="http://schemas.android.com/apk/res/com.example.test"
  android:layout_width="match_parent"
  android:layout_height="match_parent" >

  <com.example.test.MyTextView
    android:layout_width="100dp"
    android:layout_height="200dp"
    zhy:testAttr="520"
    zhy:text="helloworld" />

</RelativeLayout>

 MyTextView: text = helloworld , textAttr = 520

public MyTextView(Context context, AttributeSet attrs) {
    super(context, attrs);

    int count = attrs.getAttributeCount();
    for (int i = 0; i < count; i++) {
      String attrName = attrs.getAttributeName(i);
      String attrVal = attrs.getAttributeValue(i);
      Log.e(TAG, "attrName = " + attrName + " , attrVal = " + attrVal);
    }

    // ==>use typedarray ...

  }

MyTextView(4136): attrName = layout_width , attrVal = 100.0dip
MyTextView(4136): attrName = layout_height , attrVal = 200.0dip
MyTextView(4136): attrName = text , attrVal = helloworld
MyTextView(4136): attrName = testAttr , attrVal = 520

<com.example.test.MyTextView
    android:layout_width="@dimen/dp100"
    android:layout_height="@dimen/dp200"
    zhy:testAttr="520"
    zhy:text="@string/hello_world" />

MyTextView(4692): attrName = layout_width , attrVal = @2131165234
MyTextView(4692): attrName = layout_height , attrVal = @2131165235
MyTextView(4692): attrName = text , attrVal = @2131361809
MyTextView(4692): attrName = testAttr , attrVal = 520
>>use typedarray
MyTextView(4692): text = Hello world! , textAttr = 520

int widthDimensionId = attrs.getAttributeResourceValue(0, -1);
    Log.e(TAG, "layout_width= "+getResources().getDimension(widthDimensionId));

<declare-styleable name="test">
    <attr name="android:text" />
    <attr name="testAttr" format="integer" />
  </declare-styleable>

<?xml version="1.0" encoding="utf-8"?>
<resources>
  <attr name="testAttr" format="integer" />
</resources>

package com.example.test;

import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;

public class MyTextView extends View {

  private static final String TAG = MyTextView.class.getSimpleName();

  private static final int[] mAttr = { android.R.attr.text, R.attr.testAttr };
  private static final int ATTR_ANDROID_TEXT = 0;
  private static final int ATTR_TESTATTR = 1;

  public MyTextView(Context context, AttributeSet attrs) {
    super(context, attrs);

    // ==>use typedarray
    TypedArray ta = context.obtainStyledAttributes(attrs, mAttr);

    String text = ta.getString(ATTR_ANDROID_TEXT);
    int textAttr = ta.getInteger(ATTR_TESTATTR, -1);
    //输出 text = Hello world! , textAttr = 520
    Log.e(TAG, "text = " + text + " , textAttr = " + textAttr);

    ta.recycle();
  }

}

R.styleable.test => mAttr
R.styleable.test_text => ATTR_ANDROID_TEXT(0)
R.styleable.test_testAttr => ATTR_TESTATTR(1)

public static final class attr {
  public static final int testAttr=0x7f0100a9;
  }
public static final class styleable {
   public static final int test_android_text = 0;
   public static final int test_testAttr = 1;
   public static final int[] test = {
      0x0101014f, 0x7f0100a9
    };
  }