android设备计算密度，宽高！

import android.app.Activity;
import android.os.Bundle;
import android.util.DisplayMetrics;

public class MainActivity extends Activity {

    //屏幕的宽高, 单位像素
    private int screenWidth;
    private int screenHeight;

    //屏幕的密度
    private float density;  //只有五种情况 : 0.75/ 1.0/ 1.5/ 2.0/ 3.0
    private int densityDpi; //只有五种情况 : 120/ 160/ 240/ 320/ 480

    //水平垂直精确密度
    private float xdpi; //水平方向上的准确密度, 即每英寸的像素点
    private float ydpi; //垂直方向上的准确密度, 即没音村的像素点

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

//      getPixelWindowManager();
//      getPixelDisplayMetrics();
        getPixelDisplayMetricsII();

        System.out.println("宽:" + screenWidth + ", 高:"+screenHeight);
        System.out.println("密度 density:" + density + ",densityDpi:" +densityDpi);
        System.out.println("精确密度 xdpi:" + xdpi + ", ydpi:" + ydpi);
    }

    private void getPixelWindowManager() {
        screenWidth = getWindowManager().getDefaultDisplay().getWidth();
        screenHeight = getWindowManager().getDefaultDisplay().getHeight();
    }

    private void getPixelDisplayMetrics() {
        DisplayMetrics dm = new DisplayMetrics();
        dm = getResources().getDisplayMetrics();

        screenWidth = dm.widthPixels;
        screenHeight = dm.heightPixels;

        density = dm.density;
        densityDpi = dm.densityDpi;

        xdpi = dm.xdpi;
        ydpi = dm.ydpi;
    }

    private void getPixelDisplayMetricsII() {
        DisplayMetrics dm = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(dm);

        screenWidth = dm.widthPixels;
        screenHeight = dm.heightPixels;

        density = dm.density;
        densityDpi = dm.densityDpi;

        xdpi = dm.xdpi;
        ydpi = dm.ydpi;
    }
}