Android自定义控件单位尺寸实现代码

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent" >
 <Button
   android:id="@+id/button"
   android:layout_width="200px"
   android:layout_height="wrap_content"
   android:text="Button"
   />
</RelativeLayout>

package com.example.uisizetest;
import android.app.Activity;
import android.util.Log;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
public class MainActivity extends Activity {
	 @Override
	 protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		float xdpi = getResources().getDisplayMetrics().xdpi;
		float ydpi = getResources().getDisplayMetrics().ydpi;
		Log.d("MainActivity","xdpi is "+xdpi);
		Log.d("MainActivity","ydpi is "+ydpi);
	}
}