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记录一些常用的函数

程序员文章站 2024-02-22 15:21:10
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public static String convertInputStreamToString(InputStream is) {

StringBuilder result = new StringBuilder();

if (is != null)
try {
InputStreamReader inputReader = new InputStreamReader(is);
BufferedReader bufReader = new BufferedReader(inputReader);
String line = "";
while ((line = bufReader.readLine()) != null)
result.append(line);

bufReader.close();
inputReader.close();

} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}

return result.toString();
}


public static boolean isEmpty(String string) {
return string == null || string.length() == 0;
}


public static boolean isNumeric(String strNumeric) {
if (isEmpty(strNumeric))
return false;

String patternStr = "^[-+]?\\d+(\\.\\d+)?$";

if (Pattern.matches(patternStr, strNumeric))
return true;
else
return false;
}


public static float getDistance(double lat1, double lon1, double lat2, double lon2) {

int EARTH_RADIUS_KM = 6371;

// if there's unavailable location (0,0), return 0
if (lat1 == 0 || lon1 == 0 || lat2 == 0 || lon2 == 0)
return 0;

double lat1Rad = Math.toRadians(lat1);
double lat2Rad = Math.toRadians(lat2);
double deltaLonRad = Math.toRadians(lon2 - lon1);

double km = Math.acos(Math.sin(lat1Rad) * Math.sin(lat2Rad) + Math.cos(lat1Rad)
* Math.cos(lat2Rad) * Math.cos(deltaLonRad))
* EARTH_RADIUS_KM;

return km;
}


public static String getMD5(String val) {
try {
byte[] source = val.getBytes("UTF-8");
MessageDigest md5 = MessageDigest.getInstance("MD5");
md5.update(source);
StringBuffer buf = new StringBuffer();
for (byte b : md5.digest())
buf.append(String.format("%02x", b & 0xff));
return buf.toString();
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
return "";
}
}
相关标签: java