汇顶科技（base64Code）

import java.util.*;

public class Main{

	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);
		}
		//跟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, "\r\n");
			i+= 76;
		}
		code.append("\r\n");
		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("\r\n", "");
		//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);
	}
	
	public static void main(String[] args) {
        
        Scanner in = new Scanner(System.in);
        String s = in.nextLine();
		System.out.print(encode(s));

	}

}