Liferay7 BPM门户开发之30: 通用帮助类Validator、ArrayUtil、StringUtil等使用

废话不多说，直接上代码。

验证类Validator

主要是空验证、数字、格式验证

调用的例子：

protected void validateEmailFrom(ActionRequest actionRequest){

    String emailFromName = getParameter(actionRequest, "emailFromName");
    String emailFromAddress = getParameter(
        actionRequest, "emailFromAddress");

    if (Validator.isNull(emailFromName)) {
        SessionErrors.add(actionRequest, "emailFromName");
    }
    else if (!Validator.isEmailAddress(emailFromAddress) &&
             !Validator.isVariableTerm(emailFromAddress)) {

        SessionErrors.add(actionRequest, "emailFromAddress");
    }
}

数组工具类，ArrayUtil

主要的操作是：

源代码实现分析1、去除重复值，如

　　  public static String[] distinct(String[] array) {
         return distinct(array, null);
     }
 
     public static String[] distinct(
         String[] array, Comparator<String> comparator) {
 
         if ((array == null) || (array.length == 0)) {
             return array;
         }
 
         Set<String> set = null;
 
         if (comparator == null) {
             set = new TreeSet<String>();
         }
         else {
             set = new TreeSet<String>(comparator);
         }
 
         for (int i = 0; i < array.length; i++) {
             String s = array[i];
 
             if (!set.contains(s)) {
                 set.add(s);
             }
         }
 
         return set.toArray(new String[set.size()]);
     }
     

源代码实现分析2、尾部增加项，比如：

public static Float[] append(Float[] array, Float obj) {
　　Float[] newArray = new Float[array.length + 1];

　　System.arraycopy(array, 0, newArray, 0, array.length);

　　newArray[newArray.length - 1] = obj;

　　return newArray;
}

3、JSONArray、Object和Array转换，如：

static String[]    toStringArray(JSONArray array) 

static String[]    toStringArray(Object[] array)

字符串工具StringUtil

一个例子，用于字符替换，同时也使用了StringPool

protected Map<String, String> getJSONValues(
    JSONArray data, String namespace, String id) {

    Map<String, String> values = new HashMap<String, String>(data.length());

    for (int i = 0; i < data.length(); i++) {
        JSONObject jsonObject = data.getJSONObject(i);

        String name = jsonObject.getString("name");

        name = StringUtil.replace(
            name, new String[] {namespace, id},
            new String[] {StringPool.BLANK, StringPool.BLANK});

        values.put(name, jsonObject.getString("value"));
    }

    return values;
}

StringUtil源代码，有兴趣可以研究

package com.liferay.portal.kernel.util;

import com.liferay.portal.kernel.log.Log;
import com.liferay.portal.kernel.log.LogFactoryUtil;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.StringReader;

import java.net.URL;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Enumeration;
import java.util.List;
import java.util.Map;
import java.util.StringTokenizer;

public class StringUtil {

    public static String add(String s, String add) {
        return add(s, add, StringPool.COMMA);
    }

    public static String add(String s, String add, String delimiter) {
        return add(s, add, delimiter, false);
    }

    public static String add(
        String s, String add, String delimiter, boolean allowDuplicates) {

        if ((add == null) || (delimiter == null)) {
            return null;
        }

        if (s == null) {
            s = StringPool.BLANK;
        }

        if (allowDuplicates || !contains(s, add, delimiter)) {
            StringBuilder sb = new StringBuilder();

            sb.append(s);

            if (Validator.isNull(s) || s.endsWith(delimiter)) {
                sb.append(add);
                sb.append(delimiter);
            }
            else {
                sb.append(delimiter);
                sb.append(add);
                sb.append(delimiter);
            }

            s = sb.toString();
        }

        return s;
    }

    public static String bytesToHexString(byte[] bytes) {
        StringBuilder sb = new StringBuilder(bytes.length * 2);

        for (int i = 0; i < bytes.length; i++) {
            String hex = Integer.toHexString(
                0x0100 + (bytes[i] & 0x00FF)).substring(1);

            if (hex.length() < 2) {
                sb.append("0");
            }

            sb.append(hex);
        }

        return sb.toString();
    }

    public static boolean contains(String s, String text) {
        return contains(s, text, StringPool.COMMA);
    }

    public static boolean contains(String s, String text, String delimiter) {
        if ((s == null) || (text == null) || (delimiter == null)) {
            return false;
        }

        StringBuilder sb = null;

        if (!s.endsWith(delimiter)) {
            sb = new StringBuilder();

            sb.append(s);
            sb.append(delimiter);

            s = sb.toString();
        }

        sb = new StringBuilder();

        sb.append(delimiter);
        sb.append(text);
        sb.append(delimiter);

        String dtd = sb.toString();

        int pos = s.indexOf(dtd);

        if (pos == -1) {
            sb = new StringBuilder();

            sb.append(text);
            sb.append(delimiter);

            String td = sb.toString();

            if (s.startsWith(td)) {
                return true;
            }

            return false;
        }

        return true;
    }

    public static int count(String s, String text) {
        if ((s == null) || (text == null)) {
            return 0;
        }

        int count = 0;

        int pos = s.indexOf(text);

        while (pos != -1) {
            pos = s.indexOf(text, pos + text.length());

            count++;
        }

        return count;
    }

    public static boolean endsWith(String s, char end) {
        return endsWith(s, (new Character(end)).toString());
    }

    public static boolean endsWith(String s, String end) {
        if ((s == null) || (end == null)) {
            return false;
        }

        if (end.length() > s.length()) {
            return false;
        }

        String temp = s.substring(s.length() - end.length(), s.length());

        if (temp.equalsIgnoreCase(end)) {
            return true;
        }
        else {
            return false;
        }
    }

    public static String extractChars(String s) {
        if (s == null) {
            return StringPool.BLANK;
        }

        StringBuilder sb = new StringBuilder();

        char[] c = s.toCharArray();

        for (int i = 0; i < c.length; i++) {
            if (Validator.isChar(c[i])) {
                sb.append(c[i]);
            }
        }

        return sb.toString();
    }

    public static String extractDigits(String s) {
        if (s == null) {
            return StringPool.BLANK;
        }

        StringBuilder sb = new StringBuilder();

        char[] c = s.toCharArray();

        for (int i = 0; i < c.length; i++) {
            if (Validator.isDigit(c[i])) {
                sb.append(c[i]);
            }
        }

        return sb.toString();
    }

    public static String extractFirst(String s, String delimiter) {
        if (s == null) {
            return null;
        }
        else {
            String[] array = split(s, delimiter);

            if (array.length > 0) {
                return array[0];
            }
            else {
                return null;
            }
        }
    }

    public static String extractLast(String s, String delimiter) {
        if (s == null) {
            return null;
        }
        else {
            String[] array = split(s, delimiter);

            if (array.length > 0) {
                return array[array.length - 1];
            }
            else {
                return null;
            }
        }
    }

    public static String highlight(String s, String keywords) {
        return highlight(s, keywords, "<span class="highlight">", "</span>");
    }

    public static String highlight(
        String s, String keywords, String highlight1, String highlight2) {

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

        // The problem with using a regexp is that it searches the text in a
        // case insenstive manner but doens't replace the text in a case
        // insenstive manner. So the search results actually get messed up. The
        // best way is to actually parse the results.

        //return s.replaceAll(
        //  "(?i)" + keywords, highlight1 + keywords + highlight2);

        StringBuilder sb = new StringBuilder(StringPool.SPACE);

        StringTokenizer st = new StringTokenizer(s);

        while (st.hasMoreTokens()) {
            String token = st.nextToken();

            if (token.equalsIgnoreCase(keywords)) {
                sb.append(highlight1);
                sb.append(token);
                sb.append(highlight2);
            }
            else {
                sb.append(token);
            }

            if (st.hasMoreTokens()) {
                sb.append(StringPool.SPACE);
            }
        }

        return sb.toString();
    }

    public static String lowerCase(String s) {
        if (s == null) {
            return null;
        }
        else {
            return s.toLowerCase();
        }
    }

    public static String merge(boolean[] array) {
        return merge(array, StringPool.COMMA);
    }

    public static String merge(boolean[] array, String delimiter) {
        if (array == null) {
            return null;
        }

        StringBuilder sb = new StringBuilder();

        for (int i = 0; i < array.length; i++) {
            sb.append(String.valueOf(array[i]).trim());

            if ((i + 1) != array.length) {
                sb.append(delimiter);
            }
        }

        return sb.toString();
    }

    public static String merge(double[] array) {
        return merge(array, StringPool.COMMA);
    }

    public static String merge(double[] array, String delimiter) {
        if (array == null) {
            return null;
        }

        StringBuilder sb = new StringBuilder();

        for (int i = 0; i < array.length; i++) {
            sb.append(String.valueOf(array[i]).trim());

            if ((i + 1) != array.length) {
                sb.append(delimiter);
            }
        }

        return sb.toString();
    }

    public static String merge(float[] array) {
        return merge(array, StringPool.COMMA);
    }

    public static String merge(float[] array, String delimiter) {
        if (array == null) {
            return null;
        }

        StringBuilder sb = new StringBuilder();

        for (int i = 0; i < array.length; i++) {
            sb.append(String.valueOf(array[i]).trim());

            if ((i + 1) != array.length) {
                sb.append(delimiter);
            }
        }

        return sb.toString();
    }

    public static String merge(int[] array) {
        return merge(array, StringPool.COMMA);
    }

    public static String merge(int[] array, String delimiter) {
        if (array == null) {
            return null;
        }

        StringBuilder sb = new StringBuilder();

        for (int i = 0; i < array.length; i++) {
            sb.append(String.valueOf(array[i]).trim());

            if ((i + 1) != array.length) {
                sb.append(delimiter);
            }
        }

        return sb.toString();
    }

    public static String merge(long[] array) {
        return merge(array, StringPool.COMMA);
    }

    public static String merge(long[] array, String delimiter) {
        if (array == null) {
            return null;
        }

        StringBuilder sb = new StringBuilder();

        for (int i = 0; i < array.length; i++) {
            sb.append(String.valueOf(array[i]).trim());

            if ((i + 1) != array.length) {
                sb.append(delimiter);
            }
        }

        return sb.toString();
    }

    public static String merge(short[] array) {
        return merge(array, StringPool.COMMA);
    }

    public static String merge(short[] array, String delimiter) {
        if (array == null) {
            return null;
        }

        StringBuilder sb = new StringBuilder();

        for (int i = 0; i < array.length; i++) {
            sb.append(String.valueOf(array[i]).trim());

            if ((i + 1) != array.length) {
                sb.append(delimiter);
            }
        }

        return sb.toString();
    }

    public static String merge(Collection<?> col) {
        return merge(col, StringPool.COMMA);
    }

    public static String merge(Collection<?> col, String delimiter) {
        return merge(col.toArray(new Object[col.size()]), delimiter);
    }

    public static String merge(Object[] array) {
        return merge(array, StringPool.COMMA);
    }

    public static String merge(Object[] array, String delimiter) {
        if (array == null) {
            return null;
        }

        StringBuilder sb = new StringBuilder();

        for (int i = 0; i < array.length; i++) {
            sb.append(String.valueOf(array[i]).trim());

            if ((i + 1) != array.length) {
                sb.append(delimiter);
            }
        }

        return sb.toString();
    }

    public static String randomize(String s) {
        return Randomizer.getInstance().randomize(s);
    }

    public static String read(ClassLoader classLoader, String name)
        throws IOException {

        return read(classLoader, name, false);
    }

    public static String read(ClassLoader classLoader, String name, boolean all)
        throws IOException {

        if (all) {
            StringBuilder sb = new StringBuilder();

            Enumeration<URL> enu = classLoader.getResources(name);

            while (enu.hasMoreElements()) {
                URL url = enu.nextElement();

                InputStream is = url.openStream();

                String s = read(is);

                if (s != null) {
                    sb.append(s);
                    sb.append(StringPool.NEW_LINE);
                }

                is.close();
            }

            return sb.toString().trim();
        }
        else {
            InputStream is = classLoader.getResourceAsStream(name);

            String s = read(is);

            is.close();

            return s;
        }
    }

    public static String read(InputStream is) throws IOException {
        StringBuilder sb = new StringBuilder();

        BufferedReader br = new BufferedReader(new InputStreamReader(is));

        String line = null;

        while ((line = br.readLine()) != null) {
            sb.append(line).append('
');
        }

        br.close();

        return sb.toString().trim();
    }

    public static String remove(String s, String remove) {
        return remove(s, remove, StringPool.COMMA);
    }

    public static String remove(String s, String remove, String delimiter) {
        if ((s == null) || (remove == null) || (delimiter == null)) {
            return null;
        }

        if (Validator.isNotNull(s) && !s.endsWith(delimiter)) {
            s += delimiter;
        }

        StringBuilder sb = new StringBuilder();

        sb.append(delimiter);
        sb.append(remove);
        sb.append(delimiter);

        String drd = sb.toString();

        sb = new StringBuilder();

        sb.append(remove);
        sb.append(delimiter);

        String rd = sb.toString();

        while (contains(s, remove, delimiter)) {
            int pos = s.indexOf(drd);

            if (pos == -1) {
                if (s.startsWith(rd)) {
                    int x = remove.length() + delimiter.length();
                    int y = s.length();

                    s = s.substring(x, y);
                }
            }
            else {
                int x = pos + remove.length() + delimiter.length();
                int y = s.length();

                sb = new StringBuilder();

                sb.append(s.substring(0, pos));
                sb.append(s.substring(x, y));

                s =  sb.toString();
            }
        }

        return s;
    }

    public static String replace(String s, char oldSub, char newSub) {
        if (s == null) {
            return null;
        }

        return s.replace(oldSub, newSub);
    }

    public static String replace(String s, char oldSub, String newSub) {
        if ((s == null) || (newSub == null)) {
            return null;
        }

        // The number 5 is arbitrary and is used as extra padding to reduce
        // buffer expansion

        StringBuilder sb = new StringBuilder(s.length() + 5 * newSub.length());

        char[] charArray = s.toCharArray();

        for (char c : charArray) {
            if (c == oldSub) {
                sb.append(newSub);
            }
            else {
                sb.append(c);
            }
        }

        return sb.toString();
    }

    public static String replace(String s, String oldSub, String newSub) {
        if ((s == null) || (oldSub == null) || (newSub == null)) {
            return null;
        }

        int y = s.indexOf(oldSub);

        if (y >= 0) {

            // The number 5 is arbitrary and is used as extra padding to reduce
            // buffer expansion

            StringBuilder sb = new StringBuilder(
                s.length() + 5 * newSub.length());

            int length = oldSub.length();
            int x = 0;

            while (x <= y) {
                sb.append(s.substring(x, y));
                sb.append(newSub);

                x = y + length;
                y = s.indexOf(oldSub, x);
            }

            sb.append(s.substring(x));

            return sb.toString();
        }
        else {
            return s;
        }
    }

    public static String replace(String s, String[] oldSubs, String[] newSubs) {
        if ((s == null) || (oldSubs == null) || (newSubs == null)) {
            return null;
        }

        if (oldSubs.length != newSubs.length) {
            return s;
        }

        for (int i = 0; i < oldSubs.length; i++) {
            s = replace(s, oldSubs[i], newSubs[i]);
        }

        return s;
    }

    public static String replace(
        String s, String[] oldSubs, String[] newSubs, boolean exactMatch) {

        if ((s == null) || (oldSubs == null) || (newSubs == null)) {
            return null;
        }

        if (oldSubs.length != newSubs.length) {
            return s;
        }

        if (!exactMatch) {
            replace(s, oldSubs, newSubs);
        }
        else {
            for (int i = 0; i < oldSubs.length; i++) {
                s = s.replaceAll("\b" + oldSubs[i] + "\b" , newSubs[i]);
            }
        }

        return s;
    }

    /**
     * Returns a string with replaced values. This method will replace all text
     * in the given string, between the beginning and ending delimiter, with new
     * values found in the given map. For example, if the string contained the
     * text <code>[$HELLO$]</code>, and the beginning delimiter was
     * <code>[$]</code>, and the ending delimiter was <code>$]</code>, and the
     * values map had a key of <code>HELLO</code> that mapped to
     * <code>WORLD</code>, then the replaced string will contain the text
     * <code>[$WORLD$]</code>.
     *
     * @param       s the original string
     * @param       begin the beginning delimiter
     * @param       end the ending delimiter
     * @param       values a map of old and new values
     * @return      a string with replaced values
     */
    public static String replaceValues(
        String s, String begin, String end, Map<String, String> values) {

        if ((s == null) || (begin == null) || (end == null) ||
            (values == null) || (values.size() == 0)) {

            return s;
        }

        StringBuilder sb = new StringBuilder(s.length());

        int pos = 0;

        while (true) {
            int x = s.indexOf(begin, pos);
            int y = s.indexOf(end, x + begin.length());

            if ((x == -1) || (y == -1)) {
                sb.append(s.substring(pos, s.length()));

                break;
            }
            else {
                sb.append(s.substring(pos, x + begin.length()));

                String oldValue = s.substring(x + begin.length(), y);

                String newValue = values.get(oldValue);

                if (newValue == null) {
                    newValue = oldValue;
                }

                sb.append(newValue);

                pos = y;
            }
        }

        return sb.toString();
    }

    public static String reverse(String s) {
        if (s == null) {
            return null;
        }

        char[] c = s.toCharArray();
        char[] reverse = new char[c.length];

        for (int i = 0; i < c.length; i++) {
            reverse[i] = c[c.length - i - 1];
        }

        return new String(reverse);
    }

    public static String safePath(String path) {
        return replace(path, StringPool.DOUBLE_SLASH, StringPool.SLASH);
    }

    public static String shorten(String s) {
        return shorten(s, 20);
    }

    public static String shorten(String s, int length) {
        return shorten(s, length, "...");
    }

    public static String shorten(String s, String suffix) {
        return shorten(s, 20, suffix);
    }

    public static String shorten(String s, int length, String suffix) {
        if ((s == null) || (suffix == null)) {
            return null;
        }

        if (s.length() > length) {
            for (int j = length; j >= 0; j--) {
                if (Character.isWhitespace(s.charAt(j))) {
                    length = j;

                    break;
                }
            }

            StringBuilder sb = new StringBuilder();

            sb.append(s.substring(0, length));
            sb.append(suffix);

            s =  sb.toString();
        }

        return s;
    }

    public static String[] split(String s) {
        return split(s, StringPool.COMMA);
    }

    public static String[] split(String s, String delimiter) {
        if (s == null || delimiter == null) {
            return new String[0];
        }

        s = s.trim();

        if (!s.endsWith(delimiter)) {
            StringBuilder sb = new StringBuilder();

            sb.append(s);
            sb.append(delimiter);

            s = sb.toString();
        }

        if (s.equals(delimiter)) {
            return new String[0];
        }

        List<String> nodeValues = new ArrayList<String>();

        if (delimiter.equals("
") || delimiter.equals("
")) {
            try {
                BufferedReader br = new BufferedReader(new StringReader(s));

                String line = null;

                while ((line = br.readLine()) != null) {
                    nodeValues.add(line);
                }

                br.close();
            }
            catch (IOException ioe) {
                _log.error(ioe.getMessage());
            }
        }
        else {
            int offset = 0;
            int pos = s.indexOf(delimiter, offset);

            while (pos != -1) {
                nodeValues.add(new String(s.substring(offset, pos)));

                offset = pos + delimiter.length();
                pos = s.indexOf(delimiter, offset);
            }
        }

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

    public static boolean[] split(String s, boolean x) {
        return split(s, StringPool.COMMA, x);
    }

    public static boolean[] split(String s, String delimiter, boolean x) {
        String[] array = split(s, delimiter);
        boolean[] newArray = new boolean[array.length];

        for (int i = 0; i < array.length; i++) {
            boolean value = x;

            try {
                value = Boolean.valueOf(array[i]).booleanValue();
            }
            catch (Exception e) {
            }

            newArray[i] = value;
        }

        return newArray;
    }

    public static double[] split(String s, double x) {
        return split(s, StringPool.COMMA, x);
    }

    public static double[] split(String s, String delimiter, double x) {
        String[] array = split(s, delimiter);
        double[] newArray = new double[array.length];

        for (int i = 0; i < array.length; i++) {
            double value = x;

            try {
                value = Double.parseDouble(array[i]);
            }
            catch (Exception e) {
            }

            newArray[i] = value;
        }

        return newArray;
    }

    public static float[] split(String s, float x) {
        return split(s, StringPool.COMMA, x);
    }

    public static float[] split(String s, String delimiter, float x) {
        String[] array = split(s, delimiter);
        float[] newArray = new float[array.length];

        for (int i = 0; i < array.length; i++) {
            float value = x;

            try {
                value = Float.parseFloat(array[i]);
            }
            catch (Exception e) {
            }

            newArray[i] = value;
        }

        return newArray;
    }

    public static int[] split(String s, int x) {
        return split(s, StringPool.COMMA, x);
    }

    public static int[] split(String s, String delimiter, int x) {
        String[] array = split(s, delimiter);
        int[] newArray = new int[array.length];

        for (int i = 0; i < array.length; i++) {
            int value = x;

            try {
                value = Integer.parseInt(array[i]);
            }
            catch (Exception e) {
            }

            newArray[i] = value;
        }

        return newArray;
    }

    public static long[] split(String s, long x) {
        return split(s, StringPool.COMMA, x);
    }

    public static long[] split(String s, String delimiter, long x) {
        String[] array = split(s, delimiter);
        long[] newArray = new long[array.length];

        for (int i = 0; i < array.length; i++) {
            long value = x;

            try {
                value = Long.parseLong(array[i]);
            }
            catch (Exception e) {
            }

            newArray[i] = value;
        }

        return newArray;
    }

    public static short[] split(String s, short x) {
        return split(s, StringPool.COMMA, x);
    }

    public static short[] split(String s, String delimiter, short x) {
        String[] array = split(s, delimiter);
        short[] newArray = new short[array.length];

        for (int i = 0; i < array.length; i++) {
            short value = x;

            try {
                value = Short.parseShort(array[i]);
            }
            catch (Exception e) {
            }

            newArray[i] = value;
        }

        return newArray;
    }

    public static boolean startsWith(String s, char begin) {
        return startsWith(s, (new Character(begin)).toString());
    }

    public static boolean startsWith(String s, String start) {
        if ((s == null) || (start == null)) {
            return false;
        }

        if (start.length() > s.length()) {
            return false;
        }

        String temp = s.substring(0, start.length());

        if (temp.equalsIgnoreCase(start)) {
            return true;
        }
        else {
            return false;
        }
    }

    /**
     * Return the number of starting letters that s1 and s2 have in common
     * before they deviate.
     *
     * @param       s1 the first string
     * @param       s2 the second string
     *
     * @return      the number of starting letters that s1 and s2 have in common
     *              before they deviate
     */
    public static int startsWithWeight(String s1, String s2) {
        if ((s1 == null) || (s2 == null)) {
            return 0;
        }

        char[] charArray1 = s1.toCharArray();
        char[] charArray2 = s2.toCharArray();

        int i = 0;

        for (; (i < charArray1.length) && (i < charArray2.length); i++) {
            if (charArray1[i] != charArray2[i]) {
                break;
            }
        }

        return i;
    }

    public static String stripBetween(String s, String begin, String end) {
        if ((s == null) || (begin == null) || (end == null)) {
            return s;
        }

        StringBuilder sb = new StringBuilder(s.length());

        int pos = 0;

        while (true) {
            int x = s.indexOf(begin, pos);
            int y = s.indexOf(end, x + begin.length());

            if ((x == -1) || (y == -1)) {
                sb.append(s.substring(pos, s.length()));

                break;
            }
            else {
                sb.append(s.substring(pos, x));

                pos = y + end.length();
            }
        }

        return sb.toString();
    }

    public static String trim(String s) {
        return trim(s, null);
    }

    public static String trim(String s, char c) {
        return trim(s, new char[] {c});
    }

    public static String trim(String s, char[] exceptions) {
        if (s == null) {
            return null;
        }

        char[] charArray = s.toCharArray();

        int len = charArray.length;

        int x = 0;
        int y = charArray.length;

        for (int i = 0; i < len; i++) {
            char c = charArray[i];

            if (_isTrimable(c, exceptions)) {
                x = i + 1;
            }
            else {
                break;
            }
        }

        for (int i = len - 1; i >= 0; i--) {
            char c = charArray[i];

            if (_isTrimable(c, exceptions)) {
                y = i;
            }
            else {
                break;
            }
        }

        if ((x != 0) || (y != len)) {
            return s.substring(x, y);
        }
        else {
            return s;
        }
    }

    public static String trimLeading(String s) {
        return trimLeading(s, null);
    }

    public static String trimLeading(String s, char c) {
        return trimLeading(s, new char[] {c});
    }

    public static String trimLeading(String s, char[] exceptions) {
        if (s == null) {
            return null;
        }

        char[] charArray = s.toCharArray();

        int len = charArray.length;

        int x = 0;
        int y = charArray.length;

        for (int i = 0; i < len; i++) {
            char c = charArray[i];

            if (_isTrimable(c, exceptions)) {
                x = i + 1;
            }
            else {
                break;
            }
        }

        if ((x != 0) || (y != len)) {
            return s.substring(x, y);
        }
        else {
            return s;
        }
    }

    public static String trimTrailing(String s) {
        return trimTrailing(s, null);
    }

    public static String trimTrailing(String s, char c) {
        return trimTrailing(s, new char[] {c});
    }

    public static String trimTrailing(String s, char[] exceptions) {
        if (s == null) {
            return null;
        }

        char[] charArray = s.toCharArray();

        int len = charArray.length;

        int x = 0;
        int y = charArray.length;

        for (int i = len - 1; i >= 0; i--) {
            char c = charArray[i];

            if (_isTrimable(c, exceptions)) {
                y = i;
            }
            else {
                break;
            }
        }

        if ((x != 0) || (y != len)) {
            return s.substring(x, y);
        }
        else {
            return s;
        }
    }

    public static String upperCase(String s) {
        if (s == null) {
            return null;
        }
        else {
            return s.toUpperCase();
        }
    }

    public static String upperCaseFirstLetter(String s) {
        char[] chars = s.toCharArray();

        if ((chars[0] >= 97) && (chars[0] <= 122)) {
            chars[0] = (char)(chars[0] - 32);
        }

        return new String(chars);
    }

    public static String wrap(String text) {
        return wrap(text, 80, StringPool.NEW_LINE);
    }

    public static String wrap(String text, int width, String lineSeparator) {
        if (text == null) {
            return null;
        }

        StringBuilder sb = new StringBuilder();

        try {
            BufferedReader br = new BufferedReader(new StringReader(text));

            String s = StringPool.BLANK;

            while ((s = br.readLine()) != null) {
                if (s.length() == 0) {
                    sb.append(lineSeparator);
                }
                else {
                    String[] tokens = s.split(StringPool.SPACE);
                    boolean firstWord = true;
                    int curLineLength = 0;

                    for (int i = 0; i < tokens.length; i++) {
                        if (!firstWord) {
                            sb.append(StringPool.SPACE);
                            curLineLength++;
                        }

                        if (firstWord) {
                            sb.append(lineSeparator);
                        }

                        sb.append(tokens[i]);

                        curLineLength += tokens[i].length();

                        if (curLineLength >= width) {
                            firstWord = true;
                            curLineLength = 0;
                        }
                        else {
                            firstWord = false;
                        }
                    }
                }
            }
        }
        catch (IOException ioe) {
            _log.error(ioe.getMessage());
        }

        return sb.toString();
    }

    private static boolean _isTrimable(char c, char[] exceptions) {
        if ((exceptions != null) && (exceptions.length > 0)) {
            for (int i = 0; i < exceptions.length; i++) {
                if (c == exceptions[i]) {
                    return false;
                }
            }
        }

        return Character.isWhitespace(c);
    }

    private static Log _log = LogFactoryUtil.getLog(StringUtil.class);

}

其他工具类

 

• 集合的泛型帮助类：MapUtil、ListUtil
• Base64的转换：Base64
• http参数帮助，编解码工具：HttpUtil
• 文件操作：FileUtil
• 类型工具：ClassUtil：
• 常用字符串静态类：StringPool

其中StringPool定义了一些final值，可以利用起来：

package com.liferay.portal.kernel.util;

public class StringPool {

public static final String AMPERSAND = "&";

public static final String AMPERSAND_ENCODED = "&";

public static final String APOSTROPHE = "'";

public static final String AT = "@";

public static final String BACK_SLASH = "\";

public static final String BETWEEN = "BETWEEN";

public static final String BLANK = "";

public static final String CDATA_OPEN = "<![CDATA[";

public static final String CDATA_CLOSE = "]]>";

public static final String CLOSE_BRACKET = "]";

public static final String CLOSE_CURLY_BRACE = "}";

public static final String CLOSE_PARENTHESIS = ")";

public static final String COLON = ":";

public static final String COMMA = ",";

public static final String COMMA_AND_SPACE = ", ";

public static final String DASH = "-";

public static final String DOUBLE_APOSTROPHE = "''";

public static final String DOUBLE_CLOSE_BRACKET = "]]";

public static final String DOUBLE_OPEN_BRACKET = "[[";

public static final String DOUBLE_SLASH = "//";

public static final String EQUAL = "=";

public static final String GREATER_THAN = ">";

public static final String GREATER_THAN_OR_EQUAL = ">=";

public static final String FALSE = "false";

public static final String FORWARD_SLASH = "/";

public static final String FOUR_SPACES = " ";

public static final String IS_NOT_NULL = "IS NOT NULL";

public static final String IS_NULL = "IS NULL";

public static final String LESS_THAN = "<";

public static final String LESS_THAN_OR_EQUAL = "<=";

public static final String LIKE = "LIKE";

public static final String MINUS = "-";

public static final String NBSP = "&nbsp;";

public static final String NEW_LINE = "
";

public static final String NOT_EQUAL = "!=";

public static final String NOT_LIKE = "NOT LIKE";

public static final String NULL = "null";

public static final String OPEN_BRACKET = "[";

public static final String OPEN_CURLY_BRACE = "{";

public static final String OPEN_PARENTHESIS = "(";

public static final String PERCENT = "%";

public static final String PERIOD = ".";

public static final String PIPE = "|";

public static final String PLUS = "+";

public static final String POUND = "#";

public static final String QUESTION = "?";

public static final String QUOTE = """;

public static final String RETURN = "
";

public static final String RETURN_NEW_LINE = "
";

public static final String SEMICOLON = ";";

public static final String SLASH = FORWARD_SLASH;

public static final String SPACE = " ";

public static final String STAR = "*";

public static final String TILDE = "~";

public static final String TRUE = "true";

public static final String UNDERLINE = "_";

public static final String UTF8 = "UTF-8";

}

 简单、优雅、有序才是真的美。