Base64工具类：

package com.example.demo.util;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

import java.io.*;

public class Base64 {

    //文件转字符串
    public static String file2String(File file) {
        try {
            BufferedReader buffer = new BufferedReader(new FileReader(file));
            StringBuilder sb = new StringBuilder();
            String temp;
            while((temp = buffer.readLine()) !=null ){
                sb.append(temp);

            }
            return sb.toString();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return null;
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return null;
        }
    }
    //加密
    public static String setEncryptionBase64(String str){
        byte[] b = null;
        String s = null;
        try {
            b = str.getBytes("utf-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        if( b != null){
            s = new BASE64Encoder().encode(b);
        }
        return s;

    }

    //解密
    public static String getDecodeBase64(String str){
        byte[] b = null;
        String result = null;
        if(str != null){
            BASE64Decoder decoder = new BASE64Decoder();
            try {
                b = decoder.decodeBuffer(str);
                result = new String(b, "utf-8");
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return result;
    }

    public static void main(String[] args) {
        String phone ="15823562145";
        String base64 = Base64.setEncryptionBase64(phone);
        System.out.println("加密后:"+base64);

        String fromBase64 = Base64.getDecodeBase64(base64);
        System.out.println("解密后:"+fromBase64);
    }
}
 

测试结果如下：

加密后:MTU4MjM1NjIxNDU=
解密后:15823562145