base64 加密 解密 Java代码实现 【尝试 博客园 用Markdown 编写】

原理链接

https://www.cnblogs.com/qianjinyan/p/9541368.html

Java代码 base64 加密代码实现 最后

@Test
    public void Test2() {

        String base64Code = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
        String abc = "Jasmine";
        char[] chars = abc.toCharArray();
        System.out.println(chars);//char
        System.out.println(chars.toString());//char 2 String
        System.out.println("chars is"+chars);//char 2! String
        String Binary =null;
        //将字符串转化为字符数组
        StringBuilder asciiBinStrA = new StringBuilder();
        StringBuilder asciiBinStrB = new StringBuilder();
        for (int i = 0; i < chars.length; i++) {
            System.out.println("第"+(i+1)+"个数对应的ASCII码十进制是："+(byte) chars[i]);
            Binary = Integer.toBinaryString(chars[i]);
            while (Binary.length()<8){
                Binary="0"+Binary;
            }

            asciiBinStrB.append(Integer.toBinaryString(chars[i]));
            asciiBinStrA.append(Binary);
            //将字符数组中每一个字符转化为ascii值
        }
        System.out.println(asciiBinStrA);
        System.out.println(asciiBinStrB);
        if(asciiBinStrA.length()%6==1)
            asciiBinStrA.append("00000");
                else if(asciiBinStrA.length()%6==2)
            asciiBinStrA.append("0000");
        else if(asciiBinStrA.length()%6==3)
            asciiBinStrA.append("000");
        else if(asciiBinStrA.length()%6==4)
            asciiBinStrA.append("00");
        else if(asciiBinStrA.length()%6==5)
            asciiBinStrA.append("0");
        else asciiBinStrA=asciiBinStrA;
        System.out.println(asciiBinStrA.length());
        System.out.println(asciiBinStrA);

        char[] codeCh = new char[asciiBinStrA.length() / 6];

        String bbb = String.valueOf(asciiBinStrA);
        System.out.println(bbb);
        System.out.println(asciiBinStrA);

        int index = 0;
        for (int i = 0; i < codeCh.length; i++) {
            index = parseInt(bbb.substring(0, 6), 2);
            System.out.println("第"+(i+1)+"ge index是："+(int) index);
            bbb = bbb.substring(6);
            codeCh[i] = base64Code.charAt(index);
            System.out.println("第"+(i+1)+"："+codeCh[i]);}
        System.out.println(codeCh);
        StringBuilder code = new StringBuilder(String.valueOf(codeCh));

        while(code.length()%3!=0)
            code.append("=");
            System.out.println(code.toString());
    }

Java代码 base64 加密和解密方法的代码实现

public class base64Util {
    
    private static final String base64Code = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

    public static String encode(String srcStr) {
        //有效值检查
        if (srcStr == null || srcStr.length() == 0) {
            return srcStr;
        }
        //将明文的ASCII码转为二进制位字串
        char[] srcStrCh = srcStr.toCharArray();

        StringBuilder asciiBinStrB = new StringBuilder();
        String asciiBin = null;
        for (int i = 0; i < srcStrCh.length; i++) {
            asciiBin = Integer.toBinaryString((int) srcStrCh[i]);
            while (asciiBin.length() < 8) {
                asciiBin = "0" + asciiBin;
            }
            asciiBinStrB.append(asciiBin);
        }

        //根据明文长度在二进制位字串尾部补“0”
        while (asciiBinStrB.length() % 6 != 0) {
            asciiBinStrB.append("0");
        }

        String asciiBinStr = String.valueOf(asciiBinStrB);
        //将上面得到的二进制位字串转为Value，再跟据Base64编码表将之转为Encoding
        char[] codeCh = new char[asciiBinStr.length() / 6];
        int index = 0;
        for (int i = 0; i < codeCh.length; i++) {
            index = Integer.parseInt(asciiBinStr.substring(0, 6), 2);
            asciiBinStr = asciiBinStr.substring(6);
            codeCh[i] = base64Code.charAt(index);
        }
        StringBuilder code = new StringBuilder(String.valueOf(codeCh));
        //跟据需要在尾部添加“=”
        if (srcStr.length() % 3 == 1) {
            code.append("==");
        } else if (srcStr.length() % 3 == 2) {
            code.append("=");
        }
        //每76个字符加一个回车换行符（CRLF） ??
        int i = 76;
        while (i < code.length()) {
            code.insert(i, "
");
            i += 76;
        }
        code.append("
");
        return String.valueOf(code);
    }

    public static String decode(String srcStr) {
        //有效值检查
        if (srcStr == null || srcStr.length() == 0) {
            return srcStr;
        }

        //检测密文中“=”的个数后将之删除，同时删除换行符
        int eqCounter = 0;
        if (srcStr.endsWith("==")) {
            eqCounter = 2;
        } else if (srcStr.endsWith("=")) {
            eqCounter = 1;
        }
        srcStr = srcStr.replaceAll("=", "");
        srcStr = srcStr.replaceAll("
", "");
        //跟据Base64编码表将密文（Encoding）转为对应Value，然后转为二进制位字串
        char[] srcStrCh = srcStr.toCharArray();
        StringBuilder indexBinStr = new StringBuilder();
        String indexBin = null;
        for (int i = 0; i < srcStrCh.length; i++) {
            indexBin = Integer.toBinaryString(base64Code.indexOf((int) srcStrCh[i]));
            while (indexBin.length() < 6) {
                indexBin = "0" + indexBin;
            }
            indexBinStr.append(indexBin);
        }
        //删除因编码而在尾部补位的“0”后得到明文的ASCII码的二进制位字串
        if (eqCounter == 1) {
            indexBinStr.delete(indexBinStr.length() - 2, indexBinStr.length());
        } else if (eqCounter == 2) {
            indexBinStr.delete(indexBinStr.length() - 4, indexBinStr.length());
        }
        String asciiBinStr = String.valueOf(indexBinStr);
        //将上面得到的二进制位字串分隔成字节后还原成明文
        String asciiBin = null;
        char[] ascii = new char[asciiBinStr.length() / 8];
        for (int i = 0; i < ascii.length; i++) {
            asciiBin = asciiBinStr.substring(0, 8);
            asciiBinStr = asciiBinStr.substring(8);
            ascii[i] = (char) Integer.parseInt(asciiBin, 2);
        }
        return String.valueOf(ascii);
    }

}