屏幕大小及单位计算的工具类
ScreenUtil.java

import android.content.Context;
import android.content.res.Resources;
import android.util.DisplayMetrics;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.ListAdapter;
import android.widget.ListView;

public class ScreenUtil {
    /**
     * 获取屏幕的大小
     * 
     * @param context
     *            当前上下文
     * @return 屏幕尺寸对象
     */
    public static Screen getScreenPix(Context context) {
        DisplayMetrics dm = new DisplayMetrics();
        WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        windowManager.getDefaultDisplay().getMetrics(dm);
        return new Screen(dm.widthPixels, dm.heightPixels);
    }

    /**
     * 获取屏幕的宽
     * 
     * @param context
     *            当前上下文
     * @return 屏幕宽
     */
    public static int getScreenWidthPix(Context context) {
        DisplayMetrics dm = new DisplayMetrics();
        WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        windowManager.getDefaultDisplay().getMetrics(dm);
        return dm.widthPixels;
    }

    /**
     * 获取屏幕的高
     * 
     * @param context
     *            当前上下文
     * @return 屏幕高
     */
    public static int getScreenHeightPix(Context context) {
        DisplayMetrics dm = new DisplayMetrics();
        WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        windowManager.getDefaultDisplay().getMetrics(dm);
        return dm.heightPixels;
    }

    /**
     * 屏幕信息
     * 
     * @author wangyang
     * 
     */
    public static class Screen {
        // 屏幕宽
        public int widthPixels;
        // 屏幕高
        public int heightPixels;

        public Screen() {
        }

        public Screen(int widthPixels, int heightPixels) {
            this.widthPixels = widthPixels;
            this.heightPixels = heightPixels;
        }
    }

    /**
     * 获取屏幕密度
     * 
     * @return float
     * @throws
     */
    public static float getDensity(Context context) {
        DisplayMetrics dm = new DisplayMetrics();
        dm = context.getResources().getDisplayMetrics();
        return dm.density;
    }

    /**
     * dp转px
     * 
     * @param dpValue
     *            dp
     * @return int px
     * @throws
     */
    public static int dp2px(Context context, float dpValue) {
        return (int) (dpValue * getDensity(context) + 0.5f);
    }

    /**
     * px 转 dp
     * 
     * @param pxValue
     *            px
     * @return int dp
     * @throws
     */
    public static int px2dp(Context context, float pxValue) {
        return (int) (pxValue / getDensity(context) + 0.5f);
    }

    /**
     * 获取状态栏高度
     * 
     * @return
     * @return int
     * @throws
     */
    public static int getStatusBarHeight() {
        return Resources.getSystem().getDimensionPixelSize(Resources.getSystem().getIdentifier("status_bar_height", "dimen", "android"));
    }
    
    /**
     * 动态设置ListView的高度
     * @param listView
     */
    public static void setListViewHeightBasedOnChildren(ListView listView) { 
        if(listView == null) return;

        ListAdapter listAdapter = listView.getAdapter(); 
        if (listAdapter == null) { 
            // pre-condition 
            return; 
        } 

        int totalHeight = 0; 
        for (int i = 0; i < listAdapter.getCount(); i++) { 
            View listItem = listAdapter.getView(i, null, listView); 
            listItem.measure(0, 0); 
            totalHeight += listItem.getMeasuredHeight(); 
        } 

        ViewGroup.LayoutParams params = listView.getLayoutParams(); 
        params.height = totalHeight + (listView.getDividerHeight() * (listAdapter.getCount() - 1)); 
        System.out.println("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"+params.height);
        listView.setLayoutParams(params); 
    }
}