js btoa atob base64加密算法，对应java后台的btoa atob的解密算法

以下代码亲测有效，放心使用。

1、前端加密、解密算法：

//加密字符串,可以先将中文加密，然后再用btoa加密
function encryption(str){
    var encStr = encodeURIComponent(str);
    encStr = btoa(encStr);
    return encStr;
}

//解密，可以先将ascii解密，然后再将非ascii解密
function decrypt(str){
    var decStr = atob(str);
    decStr = decodeURIComponent(decStr);
    return decStr;
}

2、java后台加密、解密算法：

import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.log4j.Logger;
/**
* @author zxy
* @date 2020年8月24日 上午11:20:16
* @Description :  字符串加密类
*/
public class BtoAAtoB {

	private static Logger log = Logger.getLogger("BtoAAtoB.class");
	
	private static String base64hash = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

	public static boolean isMatcher(String inStr, String reg) {
		Pattern pattern = Pattern.compile(reg);
		Matcher matcher = pattern.matcher(inStr);
		if (matcher.matches()) {
			return true;
		}
		return false;
	}

	/**
	 * btoa method
	 * @param inStr
	 * @return
	 */
	public static String btoa(String inStr) {

		if (inStr == null || isMatcher(inStr, "([^\\u0000-\\u00ff])")) {
			return null;
		}

		StringBuilder result = new StringBuilder();
		int i = 0;
		int mod = 0;
		int ascii;
		int prev = 0;
		while (i < inStr.length()) {
			ascii = inStr.charAt(i);
			mod = i % 3;
			switch (mod) {
			case 0:
				result.append(String.valueOf(base64hash.charAt(ascii >> 2)));
				break;
			case 1:
				result.append(String.valueOf(base64hash.charAt((prev & 3) << 4 | (ascii >> 4))));
				break;
			case 2:
				result.append(String.valueOf(base64hash.charAt((prev & 0x0f) << 2 | (ascii >> 6))));
				result.append(String.valueOf(base64hash.charAt(ascii & 0x3f)));
				break;
			}
			prev = ascii;
			i++;
		}
		if (mod == 0) {
			result.append(String.valueOf(base64hash.charAt((prev & 3) << 4)));
			result.append("==");
		} else if (mod == 1) {
			result.append(String.valueOf(base64hash.charAt((prev & 0x0f) << 2)));
			result.append("=");
		}
		return result.toString();
	}

	/**
	 * atob method  逆转encode的思路即可
	 * @param inStr
	 * @return
	 */
	public static String atob(String inStr) {
		if (inStr == null)
			return null;
		inStr = inStr.replaceAll("\\s|=", "");
		StringBuilder result = new StringBuilder();
		int cur;
		int prev = -1;
		int mod;
		int i = 0;
		while (i < inStr.length()) {
			cur = base64hash.indexOf(inStr.charAt(i));
			mod = i % 4;
			switch (mod) {
			case 0:
				break;
			case 1:
				result.append(String.valueOf((char) (prev << 2 | cur >> 4)));
				break;
			case 2:

				result.append(String.valueOf((char) ((prev & 0x0f) << 4 | cur >> 2)));
				break;
			case 3:

				result.append(String.valueOf((char) ((prev & 3) << 6 | cur)));
				break;
			}
			prev = cur;
			i++;
		}
		return result.toString();
	}
	
	/**
	 * 加密字符串
	 * @return
	 */
	public static String encryption(String str) {
		String encode;
		try {
			encode = URLEncoder.encode(str,"utf-8");
			encode=encode.replaceAll("\\+", "%20");//URLEncoder.encode 会将空格解释为+号
			String btoa = BtoAAtoB.btoa(encode);
			return btoa;
		} catch (UnsupportedEncodingException e) {
			log.info("btoa加密函数出现错误。");
		}
		return str;
	}
	
	/**
	 * 解密字符串
	 * @return
	 */
	public static String decrypt(String str) {
		String atob = BtoAAtoB.atob(str);
		try {
			String decode = URLDecoder.decode(atob, "utf-8");
			return decode;
		} catch (UnsupportedEncodingException e) {
			log.info("atob加密函数出现错误。");
		}
		return str;
	}
	
}