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/* ---------------------------------------------------------- * 文件名称:Base64.java * * 作者:秦建辉 * * MSN:splashcn@msn.com * QQ:36748897 * * 博客:http://www.firstsolver.com/wordpress/ * * 开发环境: * Eclipse Juno * Java SE 7u5 * * 版本历史: * V1.1 2012年08月19日 * 改进解码算法,字符串中允许任意的空白字符、回车换行符、连字符 * * V1.0 2012年05月30日 * Base64编解码 * * 参考资料: * http://www.openssl.org/ ------------------------------------------------------------ */ package com.firstsolver.util; import java.io.ByteArrayOutputStream; import java.io.IOException; public class Base64 { private final static String DATA_BIN2ASCII = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; // 将字节数组转换成Base64编码字符串 public static String encodeBase64String(byte[] binaryData) { if(binaryData == null) return null; // 每3个字节转换成4个字符 int Length = ((binaryData.length + 2) / 3) << 2; StringBuilder sb = new StringBuilder(Length); int Index = 0; for(int i = binaryData.length; i > 0; i -= 3) { if(i >= 3) { // 将3字节数据转换成4个ASCII字符 int b0 = binaryData[Index++] & 0xFF; int b1 = binaryData[Index++] & 0xFF; int b2 = binaryData[Index++] & 0xFF; sb.append(DATA_BIN2ASCII.charAt(b0 >> 2)); sb.append(DATA_BIN2ASCII.charAt(((b0 << 4) | (b1 >> 4)) & 0x3F)); sb.append(DATA_BIN2ASCII.charAt(((b1 << 2) | (b2 >> 6)) & 0x3F)); sb.append(DATA_BIN2ASCII.charAt(b2 & 0x3F)); } else { int b0 = binaryData[Index++] & 0xFF; int b1; if(i == 2) b1 = binaryData[Index++] & 0xFF; else b1 = 0; sb.append(DATA_BIN2ASCII.charAt(b0 >> 2)); sb.append(DATA_BIN2ASCII.charAt(((b0 << 4) | (b1 >> 4)) & 0x3F)); if(i == 1) sb.append('='); else sb.append(DATA_BIN2ASCII.charAt((b1 << 2) & 0x3F)); sb.append('='); } } return sb.toString(); } // private final static int B64_ERROR = -1; // 0xFF 错误字符 // private final static int B64_EOLN = -16; // 0xF0 换行\n // private final static int B64_CR = -15; // 0xF1 回车\r // private final static int B64_EOF = -14; // 0xF2 连字符- // private final static int B64_WS = -32; // 0xE0 跳格或者空格(\t、space) private final static int B64_NOT_BASE64 = -13; // 0xF3 空白字符、回车换行字符、连字符 private final static byte[] DATA_ASCII2BIN = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -32, -16, -1, -1, -15, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -32, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,0x3E, -1, -14, -1,0x3F, 0x34,0x35,0x36,0x37,0x38,0x39,0x3A,0x3B,0x3C,0x3D, -1, -1, -1,0x00, -1, -1, -1,0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0A,0x0B,0x0C,0x0D,0x0E, 0x0F,0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19, -1, -1, -1, -1, -1, -1,0x1A,0x1B,0x1C,0x1D,0x1E,0x1F,0x20,0x21,0x22,0x23,0x24,0x25,0x26,0x27,0x28, 0x29,0x2A,0x2B,0x2C,0x2D,0x2E,0x2F,0x30,0x31,0x32,0x33, -1, -1, -1, -1, -1 }; // 将Base64编码字符串复原为字节数组。字符串中允许任意的空白字符、回车换行符、连字符 public static byte[] decodeBase64(String base64String) throws IOException { if(base64String == null || base64String.isEmpty()) return null; ByteArrayOutputStream memoryStream = null; try { int length = base64String.length(); memoryStream = new ByteArrayOutputStream(((length + 3) >> 2) * 3); int index = 0; int previous = 0; for(int i = 0; i < length; i++) { int charValue = base64String.charAt(i); if(charValue >= 0x80) throw new IllegalArgumentException(); // 错误字符 int orderValue = DATA_ASCII2BIN[charValue]; if(orderValue == -1) throw new IllegalArgumentException(); // 错误字符 // 跳过空白字符、回车换行字符、连字符 if((orderValue | 0x13) == B64_NOT_BASE64) continue; if(index == 0) { if(charValue == '=') throw new IllegalArgumentException(); previous = orderValue; index++; } else if(index == 1) { if(charValue == '=') throw new IllegalArgumentException(); memoryStream.write((previous << 2) | (orderValue >> 4)); previous = orderValue; index++; } else if(index == 2) { if(charValue == '=') { // 简化处理,不再判断第二个'=' index = 0; break; } memoryStream.write((previous << 4) | (orderValue >> 2)); previous = orderValue; index++; } else { index = 0; if(charValue == '=')break; memoryStream.write((previous << 6) | orderValue); } } // End for // 有效字符个数必须是4的倍数 if(index == 0) return memoryStream.toByteArray(); else throw new IllegalArgumentException(); } finally { if(memoryStream != null) memoryStream.close(); } } }