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A simple but powerful web server framework
package io.muserver;
import io.netty.handler.codec.DateFormatter;
import java.io.*;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.Date;
import java.util.Objects;
import java.util.stream.Stream;
public class Mutils {
/**
* The new-line character for the current platform, e.g. \n in Linux or \r\n on Windows.
*/
public static final String NEWLINE = String.format("%n");
/**
* @param value the value to encode
* @return Returns the UTF-8 URL encoded value
*/
public static String urlEncode(String value) {
try {
return URLEncoder.encode(value, "UTF-8").replace("+", "%20");
} catch (UnsupportedEncodingException e) {
throw new MuException("Error encoding " + value, e);
}
}
/**
* @param value the value to decode
* @return Returns the UTF-8 URL decoded value
*/
public static String urlDecode(String value) {
try {
return URLDecoder.decode(value, "UTF-8");
} catch (UnsupportedEncodingException e) {
throw new MuException("Error encoding " + value, e);
}
}
private Mutils() {}
/**
* Copies an input stream to another stream
* @param from The source of the bytes
* @param to The destination of the bytes
* @param bufferSize The size of the byte buffer to use as bytes are copied
* @throws IOException Thrown if there is a problem reading from or writing to either stream
*/
public static void copy(InputStream from, OutputStream to, int bufferSize) throws IOException {
byte[] buffer = new byte[bufferSize];
int read;
while ((read = from.read(buffer)) > -1) {
to.write(buffer, 0, read);
}
}
/**
* Reads the given input stream into a byte array and closes the input stream
* @param source The source of the bytes
* @param bufferSize The size of the byte buffer to use when copying streams
* @return Returns a byte array
* @throws IOException If there is an error reading from the stream
*/
public static byte[] toByteArray(InputStream source, int bufferSize) throws IOException {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
copy(source, baos, bufferSize);
source.close();
return baos.toByteArray();
}
/**
* Checks for a null string or string with a length of 9
* @param val The value to check
* @return True if the value is null or a zero-length string.
*/
public static boolean nullOrEmpty(String val) {
return val == null || val.length() == 0;
}
/**
* Checks that a string is not null and has a length greater than 0.
* @param val The value to check
* @return True if the string is 1 or more characters.
*/
public static boolean hasValue(String val) {
return !nullOrEmpty(val);
}
/**
* Joins two strings with the given separator, unless the first string ends with the separator, or the second
* string begins with it. For example, the output one/two would be returned from join("one", "two", "/")
* or join("one/", "/two", "/") or join("one/", "two", "/") or
* join("one", "/two", "/")
* @param one The prefix
* @param sep The separator to put between the two strings, if it is not there already
* @param two The suffix
* @return The joined strings
*/
public static String join(String one, String sep, String two) {
one = one == null ? "" : one;
two = two == null ? "" : two;
boolean oneEnds = one.endsWith(sep);
boolean twoStarts = two.startsWith(sep);
if (oneEnds && twoStarts) {
return one + two.substring(sep.length());
} else if (oneEnds || twoStarts) {
return one + two;
} else {
return one + sep + two;
}
}
/**
* Trims the given string from the given value
* @param value The value to be trimmed
* @param toTrim The string to trim
* @return The value with any occurrences of toTrim removed from the start and end of the value
*/
public static String trim(String value, String toTrim) {
int len = toTrim.length();
while (value.startsWith(toTrim)) {
value = value.substring(len);
}
while (value.endsWith(toTrim)) {
value = value.substring(0, value.length() - len);
}
return value;
}
/**
* Throws an {@link IllegalArgumentException} if the given value is null
* @param name The name of the variable to check
* @param value The value to check
*/
public static void notNull(String name, Object value) {
if (value == null) {
throw new IllegalArgumentException(name + " cannot be null");
}
}
/**
* Gets the canonical path of the given file, or if that throws an exception then gets the absolute path.
* @param file The file to check
* @return The canonical or absolute path of the given file
*/
public static String fullPath(File file) {
notNull("file", file);
try {
return file.getCanonicalPath();
} catch (IOException e) {
return file.getAbsolutePath();
}
}
/**
* Converts a date into a date string as used in HTTP headers (defined in RFC 7321), for example Tue, 15 Nov 1994 08:12:31 GMT
* @param date A date to format
* @return The date as a formatted string
* @throws IllegalArgumentException If the date is null
*/
public static String toHttpDate(Date date) {
notNull("date", date);
return DateFormatter.format(date);
}
/**
* Very basic HTML encoding, converting characters such as < to <lt;
* Important: HTML encoding is a complex topic, and different schemes are needed depending on whether the string
* is destined for a tag name, attribute, the contents of a tag, CSS, or JavaScript etc. It is recommended that
* a fully featured text encoding library is used rather than this method.
* @param value A value
* @return A value that can be safely included inside HTML tags.
*/
public static String htmlEncode(String value) {
if (value == null) {
return "";
}
return value
.replace("&", "&")
.replace("<", "<")
.replace(">", ">")
.replace("\"", """)
.replace("'", "'")
.replace("/", "/")
;
}
/**
* Returns the first non-null value from the given values (or null if all values are null)
* @param values An array of values
* @param The type of the value
* @return The first object in the list that is not null (or null, if all are null)
*/
public static T coalesce(T... values) {
return Stream.of(values).filter(Objects::nonNull).findFirst().orElse(null);
}
}