stringutils.java

velocity官方工具包 包括各种JAR包 示例 文档等

                    }

                    if (nameBuf.length() > 0)
                    {
                        String value =
                                (String) vars.get(nameBuf.toString());

                        if (value != null)
                        {
                            argBuf.append(value);
                        }
                    }
                    break;

                default:
                    argBuf.append(ch);
                    ++cIdx;
                    break;
            }
        }

        return argBuf;
    }

    /**
     * Read the contents of a file and place them in
     * a string object.
     *
     * @param file path to file.
     * @return String contents of the file.
     */
    public static String fileContentsToString(String file)
    {
        String contents = "";

        File f = null;
        try
        {
            f = new File(file);

            if (f.exists())
            {
                FileReader fr = null;
                try
                {
                    fr = new FileReader(f);
                    char[] template = new char[(int) f.length()];
                    fr.read(template);
                    contents = new String(template);
                }
                catch (Exception e)
                {
                    e.printStackTrace();
                }
                finally
                {
                    if (fr != null)
                    {
                        fr.close();
                    }
                }
            }
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
        return contents;
    }

    /**
     * Remove/collapse multiple newline characters.
     *
     * @param argStr string to collapse newlines in.
     * @return String
     */
    public static String collapseNewlines(String argStr)
    {
        char last = argStr.charAt(0);
        StringBuffer argBuf = new StringBuffer();

        for (int cIdx = 0 ; cIdx < argStr.length(); cIdx++)
        {
            char ch = argStr.charAt(cIdx);
            if (ch != '\n' || last != '\n')
            {
                argBuf.append(ch);
                last = ch;
            }
        }

        return argBuf.toString();
    }

    /**
     * Remove/collapse multiple spaces.
     *
     * @param argStr string to remove multiple spaces from.
     * @return String
     */
    public static String collapseSpaces(String argStr)
    {
        char last = argStr.charAt(0);
        StringBuffer argBuf = new StringBuffer();

        for (int cIdx = 0 ; cIdx < argStr.length(); cIdx++)
        {
            char ch = argStr.charAt(cIdx);
            if (ch != ' ' || last != ' ')
            {
                argBuf.append(ch);
                last = ch;
            }
        }

        return argBuf.toString();
    }

    /**
      * Replaces all instances of oldString with newString in line.
      * Taken from the Jive forum package.
      *
      * @param line original string.
      * @param oldString string in line to replace.
      * @param newString replace oldString with this.
      * @return String string with replacements.
      */
    public static final String sub(String line, String oldString,
            String newString)
    {
        int i = 0;
        if ((i = line.indexOf(oldString, i)) >= 0)
        {
            char [] line2 = line.toCharArray();
            char [] newString2 = newString.toCharArray();
            int oLength = oldString.length();
            StringBuffer buf = new StringBuffer(line2.length);
            buf.append(line2, 0, i).append(newString2);
            i += oLength;
            int j = i;
            while ((i = line.indexOf(oldString, i)) > 0)
            {
                buf.append(line2, j, i - j).append(newString2);
                i += oLength;
                j = i;
            }
            buf.append(line2, j, line2.length - j);
            return buf.toString();
        }
        return line;
    }

    /**
     * Returns the output of printStackTrace as a String.
     *
     * @param e A Throwable.
     * @return A String.
     */
    public static final String stackTrace(Throwable e)
    {
        String foo = null;
        try
        {
            // And show the Error Screen.
            ByteArrayOutputStream ostr = new ByteArrayOutputStream();
            e.printStackTrace( new PrintWriter(ostr,true) );
            foo = ostr.toString();
        }
        catch (Exception f)
        {
            // Do nothing.
        }
        return foo;
    }

    /**
     * Return a context-relative path, beginning with a "/", that represents
     * the canonical version of the specified path after ".." and "." elements
     * are resolved out.  If the specified path attempts to go outside the
     * boundaries of the current context (i.e. too many ".." path elements
     * are present), return <code>null</code> instead.
     *
     * @param path Path to be normalized
     * @return String normalized path
     */
    public static final String normalizePath(String path)
    {
        // Normalize the slashes and add leading slash if necessary
        String normalized = path;
        if (normalized.indexOf('\\') >= 0)
        {
            normalized = normalized.replace('\\', '/');
        }

        if (!normalized.startsWith("/"))
        {
            normalized = "/" + normalized;
        }

        // Resolve occurrences of "//" in the normalized path
        while (true)
        {
            int index = normalized.indexOf("//");
            if (index < 0)
                break;
            normalized = normalized.substring(0, index) +
            normalized.substring(index + 1);
        }

        // Resolve occurrences of "%20" in the normalized path
        while (true)
        {
            int index = normalized.indexOf("%20");
            if (index < 0)
                break;
            normalized = normalized.substring(0, index) + " " +
            normalized.substring(index + 3);
        }

        // Resolve occurrences of "/./" in the normalized path
        while (true)
        {
            int index = normalized.indexOf("/./");
            if (index < 0)
                break;
            normalized = normalized.substring(0, index) +
            normalized.substring(index + 2);
        }

        // Resolve occurrences of "/../" in the normalized path
        while (true)
        {
            int index = normalized.indexOf("/../");
            if (index < 0)
                break;
            if (index == 0)
                return (null);  // Trying to go outside our context
            int index2 = normalized.lastIndexOf('/', index - 1);
            normalized = normalized.substring(0, index2) +
            normalized.substring(index + 3);
        }

        // Return the normalized path that we have completed
        return (normalized);
    }

    /**
     * If state is true then return the trueString, else
     * return the falseString.
     *
     * @param state
     * @param trueString
     * @param falseString
     * @return Selected result.
     */
    public String select(boolean state, String trueString, String falseString)
    {
        if (state)
        {
            return trueString;
        }
        else
        {
            return falseString;
        }
    }

    /**
     * Check to see if all the string objects passed
     * in are empty.
     *
     * @param list A list of {@link java.lang.String} objects.
     * @return     Whether all strings are empty.
     */
    public boolean allEmpty(List list)
    {
        int size = list.size();

        for (int i = 0; i < size; i++)
        {
            if (list.get(i) != null && list.get(i).toString().length() > 0)
            {
                return false;
            }
        }
        return true;
    }

    /**
     * Trim all strings in a List.  Changes the strings in the existing list.
     * @param list
     * @return List of trimmed strings.
     */
    public static List trimStrings(List list)
    {
        if (list == null)
            return null;

        int sz = list.size();
        for (int i = 0; i < sz; i++)
            list.set(i,nullTrim((String) list.get(i)));
        return list;
    }

    /**
     * Trim the string, but pass a null through.
     * @param s
     * @return List of trimmed Strings.
     */
    public static String nullTrim(String s)
    {
        if (s == null)
        {
            return null;
        }
        else
        {
            return s.trim();
        }
    }
}