StringUtils-判斷收到的參數(shù)是否為空

StringUtils.isEmpty(per)

        List<String> permissions = sysMenuDao.findPermissions(menuIds.toArray(new Integer[] {}));
        // 封裝權(quán)限信息
        SimpleAuthorizationInfo info=
                new SimpleAuthorizationInfo();
        Set<String> perSet=new HashSet<String>();
        for (String per : permissions) {
            if(!StringUtils.isEmpty(per))
                perSet.add(per);
            System.out.println("permission"+per);
        }
        info.setStringPermissions(perSet);

package org.springframework.util;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Locale;
import java.util.Properties;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.TimeZone;


public abstract class StringUtils {

    private static final String FOLDER_SEPARATOR = "/";

    private static final String WINDOWS_FOLDER_SEPARATOR = "\\";

    private static final String TOP_PATH = "..";

    private static final String CURRENT_PATH = ".";

    private static final char EXTENSION_SEPARATOR = '.';


    
    public static boolean isEmpty(Object str) {
        return (str == null || "".equals(str));
    }

    
    public static boolean hasLength(CharSequence str) {
        return (str != null && str.length() > 0);
    }

    
    public static boolean hasLength(String str) {
        return hasLength((CharSequence) str);
    }

    public static boolean hasText(CharSequence str) {
        if (!hasLength(str)) {
            return false;
        }

        int strLen = str.length();
        for (int i = 0; i < strLen; i++) {
            if (!Character.isWhitespace(str.charAt(i))) {
                return true;
            }
        }
        return false;
    }

    
    public static boolean hasText(String str) {
        return hasText((CharSequence) str);
    }

    
    public static boolean containsWhitespace(CharSequence str) {
        if (!hasLength(str)) {
            return false;
        }

        int strLen = str.length();
        for (int i = 0; i < strLen; i++) {
            if (Character.isWhitespace(str.charAt(i))) {
                return true;
            }
        }
        return false;
    }

    
    public static boolean containsWhitespace(String str) {
        return containsWhitespace((CharSequence) str);
    }

    
    public static String trimWhitespace(String str) {
        if (!hasLength(str)) {
            return str;
        }

        StringBuilder sb = new StringBuilder(str);
        while (sb.length() > 0 && Character.isWhitespace(sb.charAt(0))) {
            sb.deleteCharAt(0);
        }
        while (sb.length() > 0 && Character.isWhitespace(sb.charAt(sb.length() - 1))) {
            sb.deleteCharAt(sb.length() - 1);
        }
        return sb.toString();
    }


    public static String trimAllWhitespace(String str) {
        if (!hasLength(str)) {
            return str;
        }

        int len = str.length();
        StringBuilder sb = new StringBuilder(str.length());
        for (int i = 0; i < len; i++) {
            char c = str.charAt(i);
            if (!Character.isWhitespace(c)) {
                sb.append(c);
            }
        }
        return sb.toString();
    }

    
    public static String trimLeadingWhitespace(String str) {
        if (!hasLength(str)) {
            return str;
        }

        StringBuilder sb = new StringBuilder(str);
        while (sb.length() > 0 && Character.isWhitespace(sb.charAt(0))) {
            sb.deleteCharAt(0);
        }
        return sb.toString();
    }

    
    public static String trimTrailingWhitespace(String str) {
        if (!hasLength(str)) {
            return str;
        }

        StringBuilder sb = new StringBuilder(str);
        while (sb.length() > 0 && Character.isWhitespace(sb.charAt(sb.length() - 1))) {
            sb.deleteCharAt(sb.length() - 1);
        }
        return sb.toString();
    }

    
    public static String trimLeadingCharacter(String str, char leadingCharacter) {
        if (!hasLength(str)) {
            return str;
        }

        StringBuilder sb = new StringBuilder(str);
        while (sb.length() > 0 && sb.charAt(0) == leadingCharacter) {
            sb.deleteCharAt(0);
        }
        return sb.toString();
    }

    
    public static String trimTrailingCharacter(String str, char trailingCharacter) {
        if (!hasLength(str)) {
            return str;
        }

        StringBuilder sb = new StringBuilder(str);
        while (sb.length() > 0 && sb.charAt(sb.length() - 1) == trailingCharacter) {
            sb.deleteCharAt(sb.length() - 1);
        }
        return sb.toString();
    }


    
    public static boolean startsWithIgnoreCase(String str, String prefix) {
        if (str == null || prefix == null) {
            return false;
        }
        if (str.startsWith(prefix)) {
            return true;
        }
        if (str.length() < prefix.length()) {
            return false;
        }

        String lcStr = str.substring(0, prefix.length()).toLowerCase();
        String lcPrefix = prefix.toLowerCase();
        return lcStr.equals(lcPrefix);
    }

    
    public static boolean endsWithIgnoreCase(String str, String suffix) {
        if (str == null || suffix == null) {
            return false;
        }
        if (str.endsWith(suffix)) {
            return true;
        }
        if (str.length() < suffix.length()) {
            return false;
        }

        String lcStr = str.substring(str.length() - suffix.length()).toLowerCase();
        String lcSuffix = suffix.toLowerCase();
        return lcStr.equals(lcSuffix);
    }


    public static boolean substringMatch(CharSequence str, int index, CharSequence substring) {
        for (int j = 0; j < substring.length(); j++) {
            int i = index + j;
            if (i >= str.length() || str.charAt(i) != substring.charAt(j)) {
                return false;
            }
        }
        return true;
    }

    
    public static int countOccurrencesOf(String str, String sub) {
        if (!hasLength(str) || !hasLength(sub)) {
            return 0;
        }

        int count = 0;
        int pos = 0;
        int idx;
        while ((idx = str.indexOf(sub, pos)) != -1) {
            ++count;
            pos = idx + sub.length();
        }
        return count;
    }

    
    public static String replace(String inString, String oldPattern, String newPattern) {
        if (!hasLength(inString) || !hasLength(oldPattern) || newPattern == null) {
            return inString;
        }
        int index = inString.indexOf(oldPattern);
        if (index == -1) {
            // no occurrence -> can return input as-is
            return inString;
        }

        int capacity = inString.length();
        if (newPattern.length() > oldPattern.length()) {
            capacity += 16;
        }
        StringBuilder sb = new StringBuilder(capacity);

        int pos = 0;  // our position in the old string
        int patLen = oldPattern.length();
        while (index >= 0) {
            sb.append(inString.substring(pos, index));
            sb.append(newPattern);
            pos = index + patLen;
            index = inString.indexOf(oldPattern, pos);
        }

        // append any characters to the right of a match
        sb.append(inString.substring(pos));
        return sb.toString();
    }


    public static String delete(String inString, String pattern) {
        return replace(inString, pattern, "");
    }


    public static String deleteAny(String inString, String charsToDelete) {
        if (!hasLength(inString) || !hasLength(charsToDelete)) {
            return inString;
        }

        StringBuilder sb = new StringBuilder(inString.length());
        for (int i = 0; i < inString.length(); i++) {
            char c = inString.charAt(i);
            if (charsToDelete.indexOf(c) == -1) {
                sb.append(c);
            }
        }
        return sb.toString();
    }


    
    public static String quote(String str) {
        return (str != null ? "'" + str + "'" : null);
    }


    public static Object quoteIfString(Object obj) {
        return (obj instanceof String ? quote((String) obj) : obj);
    }

    
    public static String unqualify(String qualifiedName) {
        return unqualify(qualifiedName, '.');
    }

    public static String unqualify(String qualifiedName, char separator) {
        return qualifiedName.substring(qualifiedName.lastIndexOf(separator) + 1);
    }

    
    public static String capitalize(String str) {
        return changeFirstCharacterCase(str, true);
    }

    
    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, 0, chars.length);
    }


    public static String getFilename(String path) {
        if (path == null) {
            return null;
        }

        int separatorIndex = path.lastIndexOf(FOLDER_SEPARATOR);
        return (separatorIndex != -1 ? path.substring(separatorIndex + 1) : path);
    }

    
    public static String getFilenameExtension(String path) {
        if (path == null) {
            return null;
        }

        int extIndex = path.lastIndexOf(EXTENSION_SEPARATOR);
        if (extIndex == -1) {
            return null;
        }

        int folderIndex = path.lastIndexOf(FOLDER_SEPARATOR);
        if (folderIndex > extIndex) {
            return null;
        }

        return path.substring(extIndex + 1);
    }

    /**
     * Strip the filename extension from the given Java resource path,
     * e.g. "mypath/myfile.txt" -> "mypath/myfile".
     * @param path the file path (may be {@code null})
     * @return the path with stripped filename extension,
     * or {@code null} if none
     */
    public static String stripFilenameExtension(String path) {
        if (path == null) {
            return null;
        }

        int extIndex = path.lastIndexOf(EXTENSION_SEPARATOR);
        if (extIndex == -1) {
            return path;
        }

        int folderIndex = path.lastIndexOf(FOLDER_SEPARATOR);
        if (folderIndex > extIndex) {
            return path;
        }

        return path.substring(0, extIndex);
    }

    
    public static String applyRelativePath(String path, String relativePath) {
        int separatorIndex = path.lastIndexOf(FOLDER_SEPARATOR);
        if (separatorIndex != -1) {
            String newPath = path.substring(0, separatorIndex);
            if (!relativePath.startsWith(FOLDER_SEPARATOR)) {
                newPath += FOLDER_SEPARATOR;
            }
            return newPath + relativePath;
        }
        else {
            return relativePath;
        }
    }


    public static String cleanPath(String path) {
        if (path == null) {
            return null;
        }
        String pathToUse = replace(path, WINDOWS_FOLDER_SEPARATOR, FOLDER_SEPARATOR);

        // Strip prefix from path to analyze, to not treat it as part of the
        // first path element. This is necessary to correctly parse paths like
        // "file:core/../core/io/Resource.class", where the ".." should just
        // strip the first "core" directory while keeping the "file:" prefix.
        int prefixIndex = pathToUse.indexOf(":");
        String prefix = "";
        if (prefixIndex != -1) {
            prefix = pathToUse.substring(0, prefixIndex + 1);
            if (prefix.contains("/")) {
                prefix = "";
            }
            else {
                pathToUse = pathToUse.substring(prefixIndex + 1);
            }
        }
        if (pathToUse.startsWith(FOLDER_SEPARATOR)) {
            prefix = prefix + FOLDER_SEPARATOR;
            pathToUse = pathToUse.substring(1);
        }

        String[] pathArray = delimitedListToStringArray(pathToUse, FOLDER_SEPARATOR);
        List<String> pathElements = new LinkedList<String>();
        int tops = 0;

        for (int i = pathArray.length - 1; i >= 0; i--) {
            String element = pathArray[i];
            if (CURRENT_PATH.equals(element)) {
                // Points to current directory - drop it.
            }
            else if (TOP_PATH.equals(element)) {
                // Registering top path found.
                tops++;
            }
            else {
                if (tops > 0) {
                    // Merging path element with element corresponding to top path.
                    tops--;
                }
                else {
                    // Normal path element found.
                    pathElements.add(0, element);
                }
            }
        }

        // Remaining top paths need to be retained.
        for (int i = 0; i < tops; i++) {
            pathElements.add(0, TOP_PATH);
        }

        return prefix + collectionToDelimitedString(pathElements, FOLDER_SEPARATOR);
    }

    public static boolean pathEquals(String path1, String path2) {
        return cleanPath(path1).equals(cleanPath(path2));
    }

    public static Locale parseLocaleString(String localeString) {
        String[] parts = tokenizeToStringArray(localeString, "_ ", false, false);
        String language = (parts.length > 0 ? parts[0] : "");
        String country = (parts.length > 1 ? parts[1] : "");

        validateLocalePart(language);
        validateLocalePart(country);

        String variant = "";
        if (parts.length > 2) {
            // There is definitely a variant, and it is everything after the country
            // code sans the separator between the country code and the variant.
            int endIndexOfCountryCode = localeString.indexOf(country, language.length()) + country.length();
            // Strip off any leading '_' and whitespace, what's left is the variant.
            variant = trimLeadingWhitespace(localeString.substring(endIndexOfCountryCode));
            if (variant.startsWith("_")) {
                variant = trimLeadingCharacter(variant, '_');
            }
        }
        return (language.length() > 0 ? new Locale(language, country, variant) : null);
    }

    private static void validateLocalePart(String localePart) {
        for (int i = 0; i < localePart.length(); i++) {
            char ch = localePart.charAt(i);
            if (ch != ' ' && ch != '_' && ch != '#' && !Character.isLetterOrDigit(ch)) {
                throw new IllegalArgumentException(
                        "Locale part \"" + localePart + "\" contains invalid characters");
            }
        }
    }

    
    public static String toLanguageTag(Locale locale) {
        return locale.getLanguage() + (hasText(locale.getCountry()) ? "-" + locale.getCountry() : "");
    }

    /**
     * Parse the given {@code timeZoneString} value into a {@link TimeZone}.
     * @param timeZoneString the time zone {@code String}, following {@link TimeZone#getTimeZone(String)}
     * but throwing {@link IllegalArgumentException} in case of an invalid time zone specification
     * @return a corresponding {@link TimeZone} instance
     * @throws IllegalArgumentException in case of an invalid time zone specification
     */
    public static TimeZone parseTimeZoneString(String timeZoneString) {
        TimeZone timeZone = TimeZone.getTimeZone(timeZoneString);
        if ("GMT".equals(timeZone.getID()) && !timeZoneString.startsWith("GMT")) {
            // We don't want that GMT fallback...
            throw new IllegalArgumentException("Invalid time zone specification '" + timeZoneString + "'");
        }
        return timeZone;
    }


    
    public static String[] addStringToArray(String[] array, String str) {
        if (ObjectUtils.isEmpty(array)) {
            return new String[] {str};
        }

        String[] newArr = new String[array.length + 1];
        System.arraycopy(array, 0, newArr, 0, array.length);
        newArr[array.length] = str;
        return newArr;
    }


    public static String[] concatenateStringArrays(String[] array1, String[] array2) {
        if (ObjectUtils.isEmpty(array1)) {
            return array2;
        }
        if (ObjectUtils.isEmpty(array2)) {
            return array1;
        }

        String[] newArr = new String[array1.length + array2.length];
        System.arraycopy(array1, 0, newArr, 0, array1.length);
        System.arraycopy(array2, 0, newArr, array1.length, array2.length);
        return newArr;
    }

    
    public static String[] mergeStringArrays(String[] array1, String[] array2) {
        if (ObjectUtils.isEmpty(array1)) {
            return array2;
        }
        if (ObjectUtils.isEmpty(array2)) {
            return array1;
        }

        List<String> result = new ArrayList<String>();
        result.addAll(Arrays.asList(array1));
        for (String str : array2) {
            if (!result.contains(str)) {
                result.add(str);
            }
        }
        return toStringArray(result);
    }

    
    public static String[] sortStringArray(String[] array) {
        if (ObjectUtils.isEmpty(array)) {
            return new String[0];
        }

        Arrays.sort(array);
        return array;
    }


    public static String[] toStringArray(Collection<String> collection) {
        if (collection == null) {
            return null;
        }

        return collection.toArray(new String[collection.size()]);
    }

    
    public static String[] toStringArray(Enumeration<String> enumeration) {
        if (enumeration == null) {
            return null;
        }

        List<String> list = Collections.list(enumeration);
        return list.toArray(new String[list.size()]);
    }

    
    public static String[] trimArrayElements(String[] array) {
        if (ObjectUtils.isEmpty(array)) {
            return new String[0];
        }

        String[] result = new String[array.length];
        for (int i = 0; i < array.length; i++) {
            String element = array[i];
            result[i] = (element != null ? element.trim() : null);
        }
        return result;
    }

    
    public static String[] removeDuplicateStrings(String[] array) {
        if (ObjectUtils.isEmpty(array)) {
            return array;
        }

        Set<String> set = new LinkedHashSet<String>();
        for (String element : array) {
            set.add(element);
        }
        return toStringArray(set);
    }

    
    public static String[] split(String toSplit, String delimiter) {
        if (!hasLength(toSplit) || !hasLength(delimiter)) {
            return null;
        }
        int offset = toSplit.indexOf(delimiter);
        if (offset < 0) {
            return null;
        }

        String beforeDelimiter = toSplit.substring(0, offset);
        String afterDelimiter = toSplit.substring(offset + delimiter.length());
        return new String[] {beforeDelimiter, afterDelimiter};
    }


    public static Properties splitArrayElementsIntoProperties(String[] array, String delimiter) {
        return splitArrayElementsIntoProperties(array, delimiter, null);
    }


    public static Proerties splitArrayElementsIntoProperties(
            String[] array, String delimiter, String charsToDelete) {

        if (ObjectUtils.isEmpty(array)) {
            return null;
        }

        Properties result = new Properties();
        for (String element : array) {
            if (charsToDelete != null) {
                element = deleteAny(element, charsToDelete);
            }
            String[] splittedElement = split(element, delimiter);
            if (splittedElement == null) {
                continue;
            }
            result.setProperty(splittedElement[0].trim(), splittedElement[1].trim());
        }
        return result;
    }


    public static String[] tokenizeToStringArray(String str, String delimiters) {
        return tokenizeToStringArray(str, delimiters, true, true);
    }


    public static String[] tokenizeToStringArray(
            String str, String delimiters, boolean trimTokens, boolean ignoreEmptyTokens) {

        if (str == null) {
            return null;
        }

        StringTokenizer st = new StringTokenizer(str, delimiters);
        List<String> tokens = new ArrayList<String>();
        while (st.hasMoreTokens()) {
            String token = st.nextToken();
            if (trimTokens) {
                token = token.trim();
            }
            if (!ignoreEmptyTokens || token.length() > 0) {
                tokens.add(token);
            }
        }
        return toStringArray(tokens);
    }


    public static String[] delimitedListToStringArray(String str, String delimiter) {
        return delimitedListToStringArray(str, delimiter, null);
    }


    public static String[] delimitedListToStringArray(String str, String delimiter, String charsToDelete) {
        if (str == null) {
            return new String[0];
        }
        if (delimiter == null) {
            return new String[] {str};
        }

        List<String> result = new ArrayList<String>();
        if ("".equals(delimiter)) {
            for (int i = 0; i < str.length(); i++) {
                result.add(deleteAny(str.substring(i, i + 1), charsToDelete));
            }
        }
        else {
            int pos = 0;
            int delPos;
            while ((delPos = str.indexOf(delimiter, pos)) != -1) {
                result.add(deleteAny(str.substring(pos, delPos), charsToDelete));
                pos = delPos + delimiter.length();
            }
            if (str.length() > 0 && pos <= str.length()) {
                // Add rest of String, but not in case of empty input.
                result.add(deleteAny(str.substring(pos), charsToDelete));
            }
        }
        return toStringArray(result);
    }


    public static String[] commaDelimitedListToStringArray(String str) {
        return delimitedListToStringArray(str, ",");
    }

    public static Set<String> commaDelimitedListToSet(String str) {
        Set<String> set = new LinkedHashSet<String>();
        String[] tokens = commaDelimitedListToStringArray(str);
        for (String token : tokens) {
            set.add(token);
        }
        return set;
    }


    public static String collectionToDelimitedString(Collection<?> coll, String delim, String prefix, String suffix) {
        if (CollectionUtils.isEmpty(coll)) {
            return "";
        }

        StringBuilder sb = new StringBuilder();
        Iterator<?> it = coll.iterator();
        while (it.hasNext()) {
            sb.append(prefix).append(it.next()).append(suffix);
            if (it.hasNext()) {
                sb.append(delim);
            }
        }
        return sb.toString();
    }

    public static String collectionToDelimitedString(Collection<?> coll, String delim) {
        return collectionToDelimitedString(coll, delim, "", "");
    }


    public static String collectionToCommaDelimitedString(Collection<?> coll) {
        return collectionToDelimitedString(coll, ",");
    }


    public static String arrayToDelimitedString(Object[] arr, String delim) {
        if (ObjectUtils.isEmpty(arr)) {
            return "";
        }
        if (arr.length == 1) {
            return ObjectUtils.nullSafeToString(arr[0]);
        }

        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < arr.length; i++) {
            if (i > 0) {
                sb.append(delim);
            }
            sb.append(arr[i]);
        }
        return sb.toString();
    }


    public static String arrayToCommaDelimitedString(Object[] arr) {
        return arrayToDelimitedString(arr, ",");
    }

}