NormalCode/Utils.java at patch-1 · SolveBugs/NormalCode · GitHub

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/**

* Created by zhen on 2016/8/19.

/**

* 常用代码片段

public class Utils {

1.给当前界面添加一个透明度

/**

* 给界面添加透明度

* @param activity

* @param bgAlpha

public static void backgroundAlpha(Activity activity, float bgAlpha) {

activity.getWindow().addFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);

WindowManager.LayoutParams lp = activity.getWindow().getAttributes();

lp.alpha = bgAlpha; //0.0-1.0

activity.getWindow().setAttributes(lp);

}

2.一键添加qq群

//http://qun.qq.com/join.html 选择需要添加的群，然后选择手机平台，即可生成相应的代码。

3.得到当前版本号

public static int getVersionCode(Context context) {

int code = 0;

if (context == null) {

return code;

}

try {

PackageInfo info = context.getPackageManager().getPackageInfo(context.getPackageName(), 0);

code = info.versionCode;

} catch (PackageManager.NameNotFoundException e) {

}

return code;

}

4.判断当前网络是否可用

public static boolean isNetworkConnected(Context context) {

if (context != null) {

ConnectivityManager mConnectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);

NetworkInfo mNetworkInfo = mConnectivityManager.getActiveNetworkInfo();

if (mNetworkInfo != null) {

return mNetworkInfo.isAvailable()

&& mNetworkInfo.isConnectedOrConnecting();

}

return false;

}

5.当前是否是移动网络

public static boolean isMobileConnected(Context context) {

if (context != null) {

ConnectivityManager mConnectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);

NetworkInfo mMobileNetworkInfo = mConnectivityManager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);

if (mMobileNetworkInfo != null) {

return mMobileNetworkInfo.isAvailable()

&& mMobileNetworkInfo.isConnectedOrConnecting();

}

return false;

}

6.当前是否是wifi

public static boolean isWifi(Context context) {

if (context != null) {

ConnectivityManager mConnectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);

NetworkInfo mNetworkInfo = mConnectivityManager.getActiveNetworkInfo();

if (mNetworkInfo != null) {

return mNetworkInfo.getType() == ConnectivityManager.TYPE_WIFI;

}

return false;

}

7.ListView根据item计算出实际的高度

public static void setListViewHeightBasedOnChildren(ListView listView) {

// 获取ListView对应的Adapter

ListAdapter listAdapter = listView.getAdapter();

if (listAdapter == null) {

return;

}

int totalHeight = 0;

for (int i = 0; i < listAdapter.getCount(); i++) {

View listItem = listAdapter.getView(i, null, listView);

listItem.measure(0, 0); // 计算子项View 的宽高

totalHeight += listItem.getMeasuredHeight(); // 统计所有子项的总高度

}

ViewGroup.LayoutParams params = listView.getLayoutParams();

params.height = totalHeight + (listView.getDividerHeight() * (listAdapter.getCount() - 1));

listView.setLayoutParams(params);

}

8.拨打电话(记得在清单文件添加权限)

/**

* @param phoneNum

public void call(String phoneNum, Context context) {

Intent intent = new Intent(Intent.ACTION_CALL, Uri.parse("tel:" + phoneNum));

context.startActivity(intent);

}

9. 字符串是否包含汉字

public static boolean checkChinese(String sequence) {

final String format = "[\\u4E00-\\u9FA5\\uF900-\\uFA2D]";

boolean result = false;

Pattern pattern = Pattern.compile(format);

Matcher matcher = pattern.matcher(sequence);

result = matcher.find();//

return result;

}

10.从assets 文件夹中读取图片

public static Drawable loadImageFromAsserts(final Context ctx, String fileName) {

try {

InputStream is = ctx.getResources().getAssets().open(fileName);

return Drawable.createFromStream(is, null);

} catch (IOException e) {

if (e != null) {

e.printStackTrace();

}

} catch (OutOfMemoryError e) {

if (e != null) {

e.printStackTrace();

}

} catch (Exception e) {

if (e != null) {

e.printStackTrace();

}

return null;

}

11.判断字符串是否为空

public static boolean isNull(String string) {

if (string != null) {

string = string.trim();

if (string.length() != 0) {

return false;

}

return true;

}

12.递归删除文件夹及里边的文件

public void deletFiles(File file) {

if (file.isFile()) {

file.delete();

return;

}

if (file.isDirectory()) {

File[] childFile = file.listFiles();

if (childFile == null || childFile.length == 0) {

file.delete();

return;

}

for (File f : childFile) {

deletFiles(f);

}

file.delete();

}

13.非常全面的一个图片库，个人开发者必看

//http://www.iconfont.cn/collections

14.各种单位转换

/**

* 获得屏幕宽度（像素）

* @param activity

* @return

public static int getDisplayWidth(Activity activity) {

DisplayMetrics metric = new DisplayMetrics();

activity.getWindowManager().getDefaultDisplay().getMetrics(metric);

int width = metric.widthPixels; // 屏幕宽度（像素）

return width;

}

/**

* 获得屏幕高度（像素）

* @param activity

* @return

public static int getDisplayHeight(Activity activity) {

DisplayMetrics metric = new DisplayMetrics();

activity.getWindowManager().getDefaultDisplay().getMetrics(metric);

int height = metric.heightPixels; // 屏幕高度（像素）

return height;

}

/**

* 将px值转换为dip或dp值，保证尺寸大小不变

* @param context 通过上下文获得显示参数中的屏幕密度

* @param pxValue 需要转换的px值

* @return

public static int px2dip(Context context, float pxValue) {

final float scale = context.getResources().getDisplayMetrics().density;

return (int) (pxValue / scale + 0.5f);

}

/**

* 将dip或dp值转换为px值，保证尺寸大小不变

* @param context 通过上下文获得显示参数中的屏幕密度

* @param dipValue 需要转换的dp值

* @return

public static int dip2px(Context context, float dipValue) {

final float scale = context.getResources().getDisplayMetrics().density;

return (int) (dipValue * scale + 0.5f);

}

/**

* 将px值转换为sp值，保证文字大小不变

* @param context 通过上下文获得显示参数中的屏幕密度

* @param pxValue 需要转换的px值

* @return

public static int px2sp(Context context, float pxValue) {

final float fontScale = context.getResources().getDisplayMetrics().scaledDensity;

return (int) (pxValue / fontScale + 0.5f);

}

/**

* 将sp值转换为px值，保证文字大小不变

* @param context 通过上下文获得显示参数中的屏幕密度

* @param spValue 需要转换的sp值

* @return

public static int sp2px(Context context, float spValue) {

final float fontScale = context.getResources().getDisplayMetrics().scaledDensity;

return (int) (spValue * fontScale + 0.5f);

}

15. 压缩图片，防止Bitmap过大导致OOM

/**

* 谷歌推荐使用方法，从资源中加载图像，并高效压缩，有效降低OOM的概率

* @param res 资源

* @param resId 图像资源的资源id

* @param reqWidth 要求图像压缩后的宽度

* @param reqHeight 要求图像压缩后的高度

* @return

public Bitmap decodeSampledBitmapFromResource(Resources res, int resId, int reqWidth, int reqHeight) {

// 设置inJustDecodeBounds = true ,表示获取图像信息，但是不将图像的像素加入内存

final BitmapFactory.Options options = new BitmapFactory.Options();

options.inJustDecodeBounds = true;

BitmapFactory.decodeResource(res, resId, options);

// 调用方法计算合适的 inSampleSize

options.inSampleSize = calculateInSampleSize(options, reqWidth,

reqHeight);

// inJustDecodeBounds 置为 false 真正开始加载图片

options.inJustDecodeBounds = false;

//将options.inPreferredConfig改成Bitmap.Config.RGB_565，

// 是默认情况Bitmap.Config.ARGB_8888占用内存的一般

options.inPreferredConfig = Bitmap.Config.RGB_565;

return BitmapFactory.decodeResource(res, resId, options);

}

// 计算 BitmapFactpry 的 inSimpleSize的值的方法

public int calculateInSampleSize(BitmapFactory.Options options,

int reqWidth, int reqHeight) {

if (reqWidth == 0 || reqHeight == 0) {

return 1;

}

// 获取图片原生的宽和高

final int height = options.outHeight;

final int width = options.outWidth;

int inSampleSize = 1;

// 如果原生的宽高大于请求的宽高,那么将原生的宽和高都置为原来的一半

if (height > reqHeight || width > reqWidth) {

final int halfHeight = height / 2;

final int halfWidth = width / 2;

// 主要计算逻辑

// Calculate the largest inSampleSize value that is a power of 2 and

// keeps both

// height and width larger than the requested height and width.

while ((halfHeight / inSampleSize) >= reqHeight && (halfWidth / inSampleSize) >= reqWidth) {

inSampleSize *= 2;

}

return inSampleSize;

}

16.请求打开蓝牙

//REQUEST_ENABLE_BT自定义requestCode

int REQUEST_ENABLE_BT = 0;

Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);

startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT) {

}

17.读取Excel文件

使用jxl jar包。

18.应用程序启动短暂白屏或者黑屏解决办法（启动页设置背景图片）

//1.自定义全屏主题

<item name="android:windowBackground">@drawable/start_app_flash</item>

</style>

//2.设置给闪屏页

android:theme="@style/FlashStyle"

19.判断是否是短时间内重复点击按钮之类的动作（防止重复打开页面等）

private static long lastClickTime;

public synchronized static boolean isDoubleClick(long time) {

long currentTime = System.currentTimeMillis();

boolean isClick2;

if (currentTime - lastClickTime > time) {

lastClickTime = currentTime;

isClick2 = false;

} else {

isClick2 = true;

}

return isClick2;

}

20.得到sd卡路径

public static String getSDCardPath() {

File sdcardDir = null;

boolean sdcardExist = Environment.getExternalStorageState().equals(

android.os.Environment.MEDIA_MOUNTED);

if (sdcardExist) {

sdcardDir = Environment.getExternalStorageDirectory();

return sdcardDir.toString();

} else {

return null;

}

21 从网络路径下载图片保存到本地，并返回本地保存路径

public static String getImageURI(String networkPath, String dirPath, String s) {

if (networkPath == null) {

return null;

}

String name = networkPath.substring(networkPath.lastIndexOf("/"));

File dirFile = new File(dirPath);

if (!dirFile.exists()) {

dirFile.mkdirs();

}

File file = new File(dirFile, name + s);

try {

// 从网络上获取图片

URL url = new URL(networkPath);

HttpURLConnection conn = (HttpURLConnection) url.openConnection();

conn.setConnectTimeout(5000);

conn.setRequestMethod("GET");

conn.setDoInput(true);

if (conn.getResponseCode() == 200) {

InputStream is = conn.getInputStream();

FileOutputStream fos = new FileOutputStream(file);

byte[] buffer = new byte[1024];

int len = 0;

while ((len = is.read(buffer)) != -1) {

fos.write(buffer, 0, len);

}

is.close();

fos.close();

// 返回一个URI对象

return dirPath + File.separator + name + s;

}

} catch (Exception e) {

e.printStackTrace();

}

return null;

}

22 改变系统语言为英文环境

public static void initLanguage() {

try {

Log.d("Appcontext", "初始化的时候设置系统语言为英文环境");

Class<?> activityManagerNative = Class.forName("android.app.ActivityManagerNative");

Log.i("amnType", activityManagerNative.toString());

Object am = activityManagerNative.getMethod("getDefault").invoke(activityManagerNative);

Log.i("amType", am.getClass().toString());

Object config = am.getClass().getMethod("getConfiguration").invoke(am);

Log.i("configType", config.getClass().toString());

config.getClass().getDeclaredField("locale").set(config, Locale.ENGLISH);

config.getClass().getDeclaredField("userSetLocale").setBoolean(config, true);

am.getClass().getMethod("updateConfiguration", android.content.res.Configuration.class).invoke(am, config);

} catch (Exception e) {

e.printStackTrace();

}

23.异或运算和校验

public static byte getXor(byte[] datas) {

byte temp = datas[0];

for (int i = 1; i < datas.length; i++) {

temp ^= datas[i];

}

return temp;

}

NormalCode/Utils.java at patch-1 · SolveBugs/NormalCode · GitHub

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