com.gitee.l0km.common.spring.util.StringUtils Maven / Gradle / Ivy
/*
* Copyright 2002-2021 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.gitee.l0km.common.spring.util;
import java.util.Arrays;
import com.google.common.base.Function;
import com.google.common.base.Joiner;
import com.google.common.collect.Iterables;
/**
* Miscellaneous {@link String} utility methods.
*
* Mainly for internal use within the framework; consider
* Apache's Commons Lang
* for a more comprehensive suite of {@code String} utilities.
*
*
This class delivers some simple functionality that should really be
* provided by the core Java {@link String} and {@link StringBuilder}
* classes. It also provides easy-to-use methods to convert between
* delimited strings, such as CSV strings, and collections and arrays.
*
* @author Rod Johnson
* @author Juergen Hoeller
* @author Keith Donald
* @author Rob Harrop
* @author Rick Evans
* @author Arjen Poutsma
* @author Sam Brannen
* @author Brian Clozel
* @since 16 April 2001
*/
public abstract class StringUtils {
//---------------------------------------------------------------------
// General convenience methods for working with Strings
//---------------------------------------------------------------------
/**
* Check that the given {@code CharSequence} is neither {@code null} nor
* of length 0.
*
Note: this method returns {@code true} for a {@code CharSequence}
* that purely consists of whitespace.
*
* StringUtils.hasLength(null) = false
* StringUtils.hasLength("") = false
* StringUtils.hasLength(" ") = true
* StringUtils.hasLength("Hello") = true
*
* @param str the {@code CharSequence} to check (may be {@code null})
* @return {@code true} if the {@code CharSequence} is not {@code null} and has length
* @see #hasLength(String)
* @see #hasText(CharSequence)
*/
public static boolean hasLength(CharSequence str) {
return (str != null && str.length() > 0);
}
/**
* Check that the given {@code String} is neither {@code null} nor of length 0.
* Note: this method returns {@code true} for a {@code String} that
* purely consists of whitespace.
* @param str the {@code String} to check (may be {@code null})
* @return {@code true} if the {@code String} is not {@code null} and has length
* @see #hasLength(CharSequence)
* @see #hasText(String)
*/
public static boolean hasLength(String str) {
return (str != null && !str.isEmpty());
}
/**
* Check whether the given {@code CharSequence} contains actual text.
*
More specifically, this method returns {@code true} if the
* {@code CharSequence} is not {@code null}, its length is greater than
* 0, and it contains at least one non-whitespace character.
*
* StringUtils.hasText(null) = false
* StringUtils.hasText("") = false
* StringUtils.hasText(" ") = false
* StringUtils.hasText("12345") = true
* StringUtils.hasText(" 12345 ") = true
*
* @param str the {@code CharSequence} to check (may be {@code null})
* @return {@code true} if the {@code CharSequence} is not {@code null},
* its length is greater than 0, and it does not contain whitespace only
* @see #hasText(String)
* @see #hasLength(CharSequence)
* @see Character#isWhitespace
*/
public static boolean hasText(CharSequence str) {
return (str != null && str.length() > 0 && containsText(str));
}
/**
* Check whether the given {@code String} contains actual text.
* More specifically, this method returns {@code true} if the
* {@code String} is not {@code null}, its length is greater than 0,
* and it contains at least one non-whitespace character.
* @param str the {@code String} to check (may be {@code null})
* @return {@code true} if the {@code String} is not {@code null}, its
* length is greater than 0, and it does not contain whitespace only
* @see #hasText(CharSequence)
* @see #hasLength(String)
* @see Character#isWhitespace
*/
public static boolean hasText(String str) {
return (str != null && !str.isEmpty() && containsText(str));
}
private static boolean containsText(CharSequence str) {
int strLen = str.length();
for (int i = 0; i < strLen; i++) {
if (!Character.isWhitespace(str.charAt(i))) {
return true;
}
}
return false;
}
/**
* Capitalize a {@code String}, changing the first letter to
* upper case as per {@link Character#toUpperCase(char)}.
* No other letters are changed.
* @param str the {@code String} to capitalize
* @return the capitalized {@code String}
*/
public static String capitalize(String str) {
return changeFirstCharacterCase(str, true);
}
//---------------------------------------------------------------------
// Convenience methods for working with formatted Strings
//---------------------------------------------------------------------
/**
* Uncapitalize a {@code String}, changing the first letter to
* lower case as per {@link Character#toLowerCase(char)}.
* No other letters are changed.
* @param str the {@code String} to uncapitalize
* @return the uncapitalized {@code String}
*/
public static String uncapitalize(String str) {
return changeFirstCharacterCase(str, false);
}
private static String changeFirstCharacterCase(String str, boolean capitalize) {
if (!hasLength(str)) {
return str;
}
char baseChar = str.charAt(0);
char updatedChar;
if (capitalize) {
updatedChar = Character.toUpperCase(baseChar);
}
else {
updatedChar = Character.toLowerCase(baseChar);
}
if (baseChar == updatedChar) {
return str;
}
char[] chars = str.toCharArray();
chars[0] = updatedChar;
return new String(chars);
}
/**
* Convert a {@code String} array into a delimited {@code String} (e.g. CSV).
*
Useful for {@code toString()} implementations.
* @param arr the array to display (potentially {@code null} or empty)
* @param delim the delimiter to use (typically a ",")
* @return the delimited {@code String}
*/
public static String arrayToDelimitedString(Object[] arr, String delim) {
if (ObjectUtils.isEmpty(arr)) {
return "";
}
if (arr.length == 1) {
return ObjectUtils.nullSafeToString(arr[0]);
}
return Joiner.on(delim).join(Iterables.transform(Arrays.asList(arr), STRING_VALUEOF_FUN));
}
/**
* Convert a {@code String} array into a comma delimited {@code String}
* (i.e., CSV).
*
Useful for {@code toString()} implementations.
* @param arr the array to display (potentially {@code null} or empty)
* @return the delimited {@code String}
*/
public static String arrayToCommaDelimitedString(Object[] arr) {
return arrayToDelimitedString(arr, ",");
}
public static final Function STRING_VALUEOF_FUN = new Function() {
@Override
public String apply(Object input) {
return String.valueOf(input);
}
};
}