Android工具类——处理网络、内存、屏幕等操作

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转载最新推荐文章于 2026-07-26 09:05:54 发布 1.9k 阅读 AI 写同款· GEO 优化 ›

【Android】性能优化之内存、网络、布局、卡顿、安装包、启动速度优化欢迎来到 Android 开发老生常谈的性能优化篇，本文将性能优化划分为内存、网络、电量、布局、卡顿、安装包、启动速度七块，从这七块优化出发，阐述优化的 Application 的方式。阅读详情

public class CommonUtil {


public static boolean hasSDCard() {


String status = Environment.getExternalStorageState();
return status.equals(Environment.MEDIA_MOUNTED);
}


/**
* 获取最大内存
* 
* @return
*/
public static long getMaxMemory() {


return Runtime.getRuntime().maxMemory() / 1024;
}


/**
* 检查网络
* 
* @param context
* @return
*/
public static boolean checkNetState(Context context) {


boolean netstate = false;
ConnectivityManager connectivity = (ConnectivityManager) context
.getSystemService(Context.CONNECTIVITY_SERVICE);
if (connectivity != null) {


NetworkInfo[] info = connectivity.getAllNetworkInfo();
if (info != null) {
for (int i = 0; i < info.length; i++) {


if (info[i].getState() == NetworkInfo.State.CONNECTED) {


netstate = true;
break;
}
}
}
}
return netstate;
}


public static void showToast(Context context, String tip) {


Toast.makeText(context, tip, Toast.LENGTH_SHORT).show();
}


public static DisplayMetrics metric = new DisplayMetrics();


/**
* 得到屏幕高度
* 
* @param context
* @return
*/
public static int getScreenHeight(Activity context) {


context.getWindowManager().getDefaultDisplay().getMetrics(metric);
return metric.heightPixels;
}


/**
* 得到屏幕宽度
* 
* @param context
* @return
*/
public static int getScreenWidth(Activity context) {


context.getWindowManager().getDefaultDisplay().getMetrics(metric);
return metric.widthPixels;
}


/**
* 根据手机的分辨率从 dp 的单位 转成为 px(像素)
*/


public static int dip2px(Context context, float dpValue) {
final float scale = context.getResources().getDisplayMetrics().density;
return (int) (dpValue * scale + 0.5f);
}


/**
* 根据手机的分辨率从 px(像素) 的单位 转成为 dp
*/
public static int px2dip(Context context, float pxValue) {


final float scale = context.getResources().getDisplayMetrics().density;
return (int) (pxValue / scale + 0.5f);
}


/**
* 查询手机内非系统应用
* 
* @param context
* @return
*/
public static List<PackageInfo> getAllApps(Context context) {


List<PackageInfo> apps = new ArrayList<PackageInfo>();
PackageManager pManager = context.getPackageManager();
// 获取手机内所有应用
List<PackageInfo> paklist = pManager.getInstalledPackages(0);
for (int i = 0; i < paklist.size(); i++) {
PackageInfo pak = (PackageInfo) paklist.get(i);
// 判断是否为非系统预装的应用程序
if ((pak.applicationInfo.flags & ApplicationInfo.FLAG_SYSTEM) <= 0) {
// customs applications
apps.add(pak);
}
}
return apps;
}


public static Bitmap zoomBitmap(Bitmap bitmap, int width, int height) {
int w = bitmap.getWidth();
int h = bitmap.getHeight();
Matrix matrix = new Matrix();
float scaleWidth = ((float) width / w);
float scaleHeight = ((float) height / h);
matrix.postScale(scaleWidth, scaleHeight);
Bitmap newbmp = Bitmap.createBitmap(bitmap, 0, 0, w, h, matrix, true);
return newbmp;
}


/**
* 获取版本号和版本次数
* 
* @param context
* @return
*/
public static String getVersionCode(Context context, int type) {


try {


PackageInfo pi = context.getPackageManager().getPackageInfo(
context.getPackageName(), 0);
if (type == 1) {


return String.valueOf(pi.versionCode);
} else {


return pi.versionName;
}
} catch (NameNotFoundException e) {


e.printStackTrace();
return null;
}
}


// 通过Service的类名来判断是否启动某个服务
public static boolean messageServiceIsStart(
List<ActivityManager.RunningServiceInfo> mServiceList,
String className) {


for (int i = 0; i < mServiceList.size(); i++) {
if (className.equals(mServiceList.get(i).service.getClassName())) {


return true;
}
}
return false;
}
}

转自【http://www.open-open.com/lib/view/open1394788968947.html】

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