stringutil.java

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/*
 * 	This program is free software; you can redistribute it and/or modify it under the terms of 
 * the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, 
 * or (at your option) any later version. 
 * 
 * 	This program is distributed in the hope that it will be useful, 
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  
 * See the GNU General Public License for more details. 
 * 	You should have received a copy of the GNU General Public License along with this program; 
 * if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */
package com.meidusa.amoeba.util;

import java.io.ByteArrayOutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class StringUtil {

	private static final String[] EMPTY_STRING_ARRAY = new String[0];

	private final static char[] c = { '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', 'q',
        'w', 'e', 'r', 't', 'y', 'u', 'i', 'o', 'p', 'a', 's', 'd',
        'f', 'g', 'h', 'j', 'k', 'l', 'z', 'x', 'c', 'v', 'b', 'n', 'm', 'Q',
        'W', 'E', 'R', 'T', 'Y', 'U', 'I', 'O', 'P', 'A', 'S', 'D',
        'F', 'G', 'H', 'J', 'K', 'L', 'Z', 'X', 'C', 'V', 'B', 'N', 'M' };
	
	public static String getRandomString(int size){
        Random random = new Random();
        StringBuffer sb = new StringBuffer(size);
        for (int i = 0; i < size; i++){
            sb.append(c[Math.abs(random.nextInt()) % c.length]);
        }
        return sb.toString();
    }
	
	/**
	 * Attempts to generate a string representation of the object using
	 * {@link Object#toString}, but catches any exceptions that are thrown and
	 * reports them in the returned string instead. Useful for situations where
	 * you can't trust the rat bastards that implemented the object you're
	 * toString()ing.
	 */
	public static String safeToString(Object object) {
		try {
			return object.toString();
		} catch (Throwable t) {
			// We catch any throwable, even Errors. Someone is just trying to
			// debug something,
			// probably inside another catch block.
			return "<toString() failure: " + t + ">";
		}
	}
	
	public static boolean isEmpty(String str) {
        return ((str == null) || (str.length() == 0));
    }

	/**
	 * Used to convert a time interval to a more easily human readable string of
	 * the form: <code>1d
	 * 15h 4m 15s 987m</code>.
	 */
	public static String intervalToString(long millis) {
		StringBuilder buf = new StringBuilder();
		boolean started = false;

		long days = millis / (24 * 60 * 60 * 1000);
		if (days != 0) {
			buf.append(days).append("d ");
			started = true;
		}

		long hours = (millis / (60 * 60 * 1000)) % 24;
		if (started || hours != 0) {
			buf.append(hours).append("h ");
		}

		long minutes = (millis / (60 * 1000)) % 60;
		if (started || minutes != 0) {
			buf.append(minutes).append("m ");
		}

		long seconds = (millis / (1000)) % 60;
		if (started || seconds != 0) {
			buf.append(seconds).append("s ");
		}

		buf.append(millis % 1000).append("ms");

		return buf.toString();
	}

	/**
	 * Dumps the given bytes to STDOUT as a hex dump (up to length bytes).
	 * 
	 * @param byteBuffer
	 *            the data to print as hex
	 * @param length
	 *            the number of bytes to print
	 * 
	 * @return ...
	 */
	public static final String dumpAsHex(byte[] byteBuffer, int length) {
		StringBuffer outputBuf = new StringBuffer(length * 4);

		int p = 0;
		int rows = length / 8;

		for (int i = 0; (i < rows) && (p < length); i++) {
			int ptemp = p;

			for (int j = 0; j < 8; j++) {
				String hexVal = Integer.toHexString(byteBuffer[ptemp] & 0xff);

				if (hexVal.length() == 1) {
					hexVal = "0" + hexVal; //$NON-NLS-1$
				}

				outputBuf.append(hexVal + " "); //$NON-NLS-1$
				ptemp++;
			}

			outputBuf.append("    "); //$NON-NLS-1$

			for (int j = 0; j < 8; j++) {
				int b = 0xff & byteBuffer[p];

				if (b > 32 && b < 127) {
					outputBuf.append((char) b + " "); //$NON-NLS-1$
				} else {
					outputBuf.append(". "); //$NON-NLS-1$
				}

				p++;
			}

			outputBuf.append("\n"); //$NON-NLS-1$
		}

		int n = 0;

		for (int i = p; i < length; i++) {
			String hexVal = Integer.toHexString(byteBuffer[i] & 0xff);

			if (hexVal.length() == 1) {
				hexVal = "0" + hexVal; //$NON-NLS-1$
			}

			outputBuf.append(hexVal + " "); //$NON-NLS-1$
			n++;
		}

		for (int i = n; i < 8; i++) {
			outputBuf.append("   "); //$NON-NLS-1$
		}

		outputBuf.append("    "); //$NON-NLS-1$

		for (int i = p; i < length; i++) {
			int b = 0xff & byteBuffer[i];

			if (b > 32 && b < 127) {
				outputBuf.append((char) b + " "); //$NON-NLS-1$
			} else {
				outputBuf.append(". "); //$NON-NLS-1$
			}
		}

		outputBuf.append("\n"); //$NON-NLS-1$

		return outputBuf.toString();
	}
	
	
	/**
	 * Unfortunately, SJIS has 0x5c as a high byte in some of its double-byte
	 * characters, so we need to escape it.
	 * 
	 * @param origBytes
	 *            the original bytes in SJIS format
	 * @param origString
	 *            the string that had .getBytes() called on it
	 * @param offset
	 *            where to start converting from
	 * @param length
	 *            how many characters to convert.
	 * 
	 * @return byte[] with 0x5c escaped
	 */
	public static byte[] escapeEasternUnicodeByteStream(byte[] origBytes,
			String origString, int offset, int length) {
		if ((origBytes == null) || (origBytes.length == 0)) {
			return origBytes;
		}

		int bytesLen = origBytes.length;
		int bufIndex = 0;
		int strIndex = 0;

		ByteArrayOutputStream bytesOut = new ByteArrayOutputStream(bytesLen);

		while (true) {
			if (origString.charAt(strIndex) == '\\') {
				// write it out as-is
				bytesOut.write(origBytes[bufIndex++]);

				// bytesOut.write(origBytes[bufIndex++]);
			} else {
				// Grab the first byte
				int loByte = origBytes[bufIndex];

				if (loByte < 0) {
					loByte += 256; // adjust for signedness/wrap-around
				}

				// We always write the first byte
				bytesOut.write(loByte);

				//
				// The codepage characters in question exist between
				// 0x81-0x9F and 0xE0-0xFC...
				//
				// See:
				//
				// http://www.microsoft.com/GLOBALDEV/Reference/dbcs/932.htm
				//
				// Problematic characters in GBK
				//
				// U+905C : CJK UNIFIED IDEOGRAPH
				//
				// Problematic characters in Big5
				//
				// B9F0 = U+5C62 : CJK UNIFIED IDEOGRAPH
				//
				if (loByte >= 0x80) {
					if (bufIndex < (bytesLen - 1)) {
						int hiByte = origBytes[bufIndex + 1];

						if (hiByte < 0) {
							hiByte += 256; // adjust for signedness/wrap-around
						}

						// write the high byte here, and increment the index
						// for the high byte
						bytesOut.write(hiByte);
						bufIndex++;

						// escape 0x5c if necessary
						if (hiByte == 0x5C) {
							bytesOut.write(hiByte);
						}
					}
				} else if (loByte == 0x5c) {
					if (bufIndex < (bytesLen - 1)) {
						int hiByte = origBytes[bufIndex + 1];

						if (hiByte < 0) {
							hiByte += 256; // adjust for signedness/wrap-around
						}

						if (hiByte == 0x62) {
							// we need to escape the 0x5c
							bytesOut.write(0x5c);
							bytesOut.write(0x62);
							bufIndex++;
						}
					}
				}

				bufIndex++;
			}

			if (bufIndex >= bytesLen) {
				// we're done
				break;
			}

			strIndex++;
		}

		return bytesOut.toByteArray();
	}
	
	public static String toString(byte[] bytes){
		if(bytes == null || bytes.length == 0) return "";
		StringBuffer buffer = new StringBuffer();
		for(byte byt: bytes){
			buffer.append((char)byt);
		}
		return buffer.toString();
	}
	

    /**
     * 比较两个字符串（大小写敏感）。
     * <pre>
     * StringUtil.equals(null, null)   = true
     * StringUtil.equals(null, "abc")  = false
     * StringUtil.equals("abc", null)  = false
     * StringUtil.equals("abc", "abc") = true
     * StringUtil.equals("abc", "ABC") = false
     * </pre>
     *
     * @param str1 要比较的字符串1
     * @param str2 要比较的字符串2
     *
     * @return 如果两个字符串相同，或者都是<code>null</code>，则返回<code>true</code>
     */
    public static boolean equals(String str1, String str2) {
        if (str1 == null) {
            return str2 == null;
        }

        return str1.equals(str2);
    }

    /**
     * 比较两个字符串（大小写不敏感）。
     * <pre>
     * StringUtil.equalsIgnoreCase(null, null)   = true
     * StringUtil.equalsIgnoreCase(null, "abc")  = false
     * StringUtil.equalsIgnoreCase("abc", null)  = false
     * StringUtil.equalsIgnoreCase("abc", "abc") = true
     * StringUtil.equalsIgnoreCase("abc", "ABC") = true
     * </pre>
     *
     * @param str1 要比较的字符串1
     * @param str2 要比较的字符串2
     *
     * @return 如果两个字符串相同，或者都是<code>null</code>，则返回<code>true</code>
     */
    public static boolean equalsIgnoreCase(String str1, String str2) {
        if (str1 == null) {
            return str2 == null;
        }

        return str1.equalsIgnoreCase(str2);
    }

    /* ============================================================================ */
    /*  字符串分割函数。                                                            */
    /*                                                                              */
    /*  将字符串按指定分隔符分割。                                                  */
    /* ============================================================================ */

    /**
     * 将字符串按空白字符分割。
     * 
     * <p>
     * 分隔符不会出现在目标数组中，连续的分隔符就被看作一个。如果字符串为<code>null</code>，则返回<code>null</code>。
     * <pre>
     * StringUtil.split(null)       = null
     * StringUtil.split("")         = []
     * StringUtil.split("abc def")  = ["abc", "def"]
     * StringUtil.split("abc  def") = ["abc", "def"]
     * StringUtil.split(" abc ")    = ["abc"]
     * </pre>
     * </p>
     *
     * @param str 要分割的字符串
     *
     * @return 分割后的字符串数组，如果原字符串为<code>null</code>，则返回<code>null</code>
     */
    public static String[] split(String str) {
        return split(str, null, -1);
    }

    /**
     * 将字符串按指定字符分割。
     * 
     * <p>
     * 分隔符不会出现在目标数组中，连续的分隔符就被看作一个。如果字符串为<code>null</code>，则返回<code>null</code>。
     * <pre>
     * StringUtil.split(null, *)         = null
     * StringUtil.split("", *)           = []
     * StringUtil.split("a.b.c", '.')    = ["a", "b", "c"]
     * StringUtil.split("a..b.c", '.')   = ["a", "b", "c"]
     * StringUtil.split("a:b:c", '.')    = ["a:b:c"]
     * StringUtil.split("a b c", ' ')    = ["a", "b", "c"]
     * </pre>
     * </p>
     *
     * @param str 要分割的字符串
     * @param separatorChar 分隔符
     *