不多说，直接上代码，对称加密只有一个密钥。用他来加密，也用它来解密。

package com.example.shirotest.utils;

import org.apache.tomcat.util.codec.binary.Base64;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.security.SecureRandom;

public class AESKeyPairUtils {
    public static void main(String[] args) {
        String content = "www.baidu.com";
        String password = "123";
        System.out.println("加密之前：" + content);

        // 加密
        byte[] encrypt = AESKeyPairUtils.encrypt(content, password);
        System.out.println("加密后的内容：" + new String(encrypt));

        // 解密
        String msg = AESKeyPairUtils.decrypt(encrypt, password);
        System.out.println("解密后的内容：" + new String(msg));
    }

    /**
     * AES加密字符串
     * @param content 需要被加密的字符串
     * @param password 加密需要的密码
     * @return 密文字符串
     */
    public static byte[] encrypt(String content,String password){
        try {
            SecretKeySpec secretKeySpec = getSecretKeySpec(password);
            Cipher cipher = Cipher.getInstance("AES");//创建密码器
            cipher.init(Cipher.ENCRYPT_MODE,secretKeySpec);
            byte[] bytes = cipher.doFinal(content.getBytes("UTF-8"));
            return bytes;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static String decrypt(byte[] content,String password){
        String msg = "";
        try {
            SecretKeySpec secretKeySpec = getSecretKeySpec(password);
            Cipher cipher = Cipher.getInstance("AES");
            cipher.init(Cipher.DECRYPT_MODE,secretKeySpec);
            byte[] bytes = cipher.doFinal(content);
            msg = new String(bytes);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return msg;
    }

    /**
     * 获取cipher
     * @param password 密码
     * @return
     */
    public static SecretKeySpec getSecretKeySpec(String password){
        try {
            KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
            keyGenerator.init(128,new SecureRandom(password.getBytes()));
            SecretKey secretKey = keyGenerator.generateKey();
            System.out.println("secretkey:"+ Base64.encodeBase64String(secretKey.getEncoded()));
            SecretKeySpec secretKeySpec = new SecretKeySpec(secretKey.getEncoded(),"AES");
            return secretKeySpec;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
}