Base64是网络上最常见的用于传输8Bit字节代码的编码方式之一,在发送电子邮件时,服务器认证的用户名和密码需要用Base64编码,附件也需要用Base64编码……
下面是以前扒来的Base64算法的JAVA版本,J2ME可以放心使用。
package hlib; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.OutputStream; import java.util.Vector; public class HBase64 { private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" .toCharArray(); private static Vector nodes = new Vector(); /** * Split string into multiple strings * * @param original * Original string * @param separator * Separator string in original string * @return Splitted string array */ public static String[] split(String original, String separator) { nodes.removeAllElements(); // Parse nodes into vector int index = original.indexOf(separator); while (index >= 0) { nodes.addElement(original.substring(0, index)); original = original.substring(index + separator.length()); index = original.indexOf(separator); } // Get the last node nodes.addElement(original); // Create splitted string array String[] result = new String[nodes.size()]; if (nodes.size() > 0) { for (int loop = 0; loop < nodes.size(); loop++) { result[loop] = (String) nodes.elementAt(loop); } } return result; } /* * Replace all instances of a String in a String. @param s String to alter. * @param f String to look for. @param r String to replace it with, or null * to just remove it. */ public static String replace(String s, String f, String r) { if (s == null) { return s; } if (f == null) { return s; } if (r == null) { r = ""; } int index01 = s.indexOf(f); while (index01 != -1) { s = s.substring(0, index01) + r + s.substring(index01 + f.length()); index01 += r.length(); index01 = s.indexOf(f, index01); } return s; } /** * Method removes HTML tags from given string. * * @param text * Input parameter containing HTML tags (eg. cat) * @return String without HTML tags (eg. cat) */ public static String removeHtml(String text) { try { int idx = text.indexOf("<"); if (idx == -1) { return text; } String plainText = ""; String htmlText = text; int htmlStartIndex = htmlText.indexOf("<", 0); if (htmlStartIndex == -1) { return text; } while (htmlStartIndex >= 0) { plainText += htmlText.substring(0, htmlStartIndex); int htmlEndIndex = htmlText.indexOf(">", htmlStartIndex); htmlText = htmlText.substring(htmlEndIndex + 1); htmlStartIndex = htmlText.indexOf("<", 0); } plainText = plainText.trim(); return plainText; } catch (Exception e) { System.err.println("Error while removing HTML: " + e.toString()); return text; } } /** Base64 encode the given data */ public static String encode(byte[] data) { int start = 0; int len = data.length; StringBuffer buf = new StringBuffer(data.length * 3 / 2); int end = len - 3; int i = start; int n = 0; while (i <= end) { int d = ((((int) data[i]) & 0x0ff) << 16) | ((((int) data[i + 1]) & 0x0ff) << 8) | (((int) data[i + 2]) & 0x0ff); buf.append(legalChars[(d >> 18) & 63]); buf.append(legalChars[(d >> 12) & 63]); buf.append(legalChars[(d >> 6) & 63]); buf.append(legalChars[d & 63]); i += 3; if (n++ >= 14) { n = 0; buf.append(" "); } } if (i == start + len - 2) { int d = ((((int) data[i]) & 0x0ff) << 16) | ((((int) data[i + 1]) & 255) << 8); buf.append(legalChars[(d >> 18) & 63]); buf.append(legalChars[(d >> 12) & 63]); buf.append(legalChars[(d >> 6) & 63]); buf.append("="); } else if (i == start + len - 1) { int d = (((int) data[i]) & 0x0ff) << 16; buf.append(legalChars[(d >> 18) & 63]); buf.append(legalChars[(d >> 12) & 63]); buf.append("=="); } return buf.toString(); } private static int decode(char c) { if (c >= 'A' && c <= 'Z') { return ((int) c) - 65; } else if (c >= 'a' && c <= 'z') { return ((int) c) - 97 + 26; } else if (c >= '0' && c <= '9') { return ((int) c) - 48 + 26 + 26; } else { switch (c) { case '+': return 62; case '/': return 63; case '=': return 0; default: throw new RuntimeException("unexpected code: " + c); } } } /** * Decodes the given Base64 encoded String to a new byte array. The byte * array holding the decoded data is returned. */ public static byte[] decode(String s) { ByteArrayOutputStream bos = new ByteArrayOutputStream(); try { decode(s, bos); } catch (IOException e) { throw new RuntimeException(); } byte[] decodedBytes = bos.toByteArray(); try { bos.close(); bos = null; } catch (IOException ex) { System.err.println("Error while decoding BASE64: " + ex.toString()); } return decodedBytes; } private static void decode(String s, OutputStream os) throws IOException { int i = 0; int len = s.length(); while (true) { while (i < len && s.charAt(i) <= ' ') { i++; } if (i == len) { break; } int tri = (decode(s.charAt(i)) << 18) + (decode(s.charAt(i + 1)) << 12) + (decode(s.charAt(i + 2)) << 6) + (decode(s.charAt(i + 3))); os.write((tri >> 16) & 255); if (s.charAt(i + 2) == '=') { break; } os.write((tri >> 8) & 255); if (s.charAt(i + 3) == '=') { break; } os.write(tri & 255); i += 4; } } }