java使用mybatis拦截器对数据库敏感字段进行加密存储并解密

记录业务中遇到的使用场景：灵活对数据库敏感字段进行加密和解密

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前言

项目中遇到一个需求，要对指定的数据库表中的敏感字段进行加密存储，读取的时候再进行解密返回给前端，以下对具体的实现过程进行记录和解释。

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一、创建数据库表和实体类

数据库表：

CREATE TABLE `sys_user` (
  `user_id` bigint(20) NOT NULL AUTO_INCREMENT,
  `username` varchar(60) DEFAULT NULL,
  `password` varchar(80) DEFAULT NULL,
  `address` varchar(80) DEFAULT NULL,
  `hobby` varchar(80) DEFAULT NULL,
  PRIMARY KEY (`user_id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8mb4;

实体类：

@Data
@Accessors(chain = true)
@ToString
@SensitiveClass
public class SysUser {
    private Long userId;
    private String username;
    @EncryptField
    private String password;
    @EncryptField
    private String address;
    private String hobby;
}

二、Mapper、Service、Controller等

SysUserMapper.java

public interface SysUserMapper {

    List<SysUser> listAll();

    SysUser getById(Long userId);

    int insert(SysUser sysUser);

    int update(SysUser sysUser);

}

SysUserMapper.xml

DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.fanchen.mapper.SysUserMapper">

    <insert id="insert" parameterType="SysUser">
        insert into sys_user
        <trim prefix="(" suffix=")" suffixOverrides=",">
            <if test="username != null and username != ''">username,if>
            <if test="password != null and password != ''">password,if>
            <if test="address != null and address != ''">address,if>
            <if test="hobby != null and hobby != ''">hobby,if>
        trim>
        <trim prefix="values (" suffix=")" suffixOverrides=",">
            <if test="username != null and username != ''">#{username},if>
            <if test="password != null and password != ''">#{password},if>
            <if test="address != null and address != ''">#{address},if>
            <if test="hobby != null and hobby != ''">#{hobby},if>
        trim>
    insert>

    <update id="update" parameterType="SysUser">
        update sys_user
        <trim prefix="SET" suffixOverrides=",">
            <if test="username != null and username != ''">username = #{username},if>
            <if test="password != null and password != ''">password = #{password},if>
            <if test="address != null and address != ''">address = #{address},if>
            <if test="hobby != null and hobby != ''">hobby = #{hobby},if>
        trim>
        where user_id = #{userId}
    update>

    <select id="listAll" resultType="SysUser">
        select user_id, username, password, address, hobby from sys_user
    select>

    <select id="getById" resultType="SysUser" parameterType="long">
        select user_id, username, password, address, hobby from sys_user where user_id = #{userId}
    select>

mapper>

这里省略Service和Controller，没啥好写的。

三、自定义注解

EncryptField表示需要加密的字段，加在实体类参数上

@Inherited
@Target({ElementType.FIELD,ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
public @interface EncryptField {
}

SensitiveClass标识需要加密的实体类，加载实体类上

@Inherited
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
public @interface SensitiveClass {
}

四、加密工具类

编写拦截器中需要用到的加密解密的工具类

public class EncryptUtil {

    public static Object encrypt(Object param) throws Exception {
        Class<?> paramClass = param.getClass();
        if (String.class == paramClass) {
            return AESUtil.aesDecrypt((String) param);
        } else {
            Field[] fields = paramClass.getDeclaredFields();
            for (Field field : fields) {
                EncryptField encryptField = field.getAnnotation(EncryptField.class);
                if (Objects.nonNull(encryptField)) {
                    field.setAccessible(true);
                    Object fieldInstance = field.get(param);
                    if (fieldInstance instanceof String) {
                        field.set(param, AESUtil.aesEncrypt((String) fieldInstance));
                    }
                }
            }
        }
        return param;
    }

    public static Object decrypt(Object result) throws Exception {
        Class<?> resultClass = result.getClass();
        Field[] fields = resultClass.getDeclaredFields();
        for (Field field : fields) {
            EncryptField annotation = field.getAnnotation(EncryptField.class);
            if (Objects.nonNull(annotation)){
                field.setAccessible(true);
                Object fieldInstance = field.get(result);
                if (fieldInstance instanceof String){
                    field.set(result, AESUtil.aesDecrypt((String) fieldInstance));
                }
            }
        }
        return result;
    }

}

五、参数拦截器和结果集拦截器

参数拦截器，对敏感参数进行加密存储，目前只针对String类型进行加密解密

@Intercepts({
        @Signature(type = ParameterHandler.class, method = "setParameters", args = PreparedStatement.class),
})
@Component
@Slf4j
public class ParameterInterceptor implements Interceptor {

    @Override
    public Object intercept(Invocation invocation) throws Throwable {
        //@Signature 指定了 type= parameterHandler 后，这里的 invocation.getTarget() 便是parameterHandler
        // 若指定ResultSetHandler，这里则能强转为ResultSetHandler
        DefaultParameterHandler parameterHandler = (DefaultParameterHandler) invocation.getTarget();
        // 获取参数对像，即 mapper 中 paramsType 的实例
        Field parameterField = parameterHandler.getClass().getDeclaredField("parameterObject");
        parameterField.setAccessible(true);
        // 取出实例
        Object parameterObject = parameterField.get(parameterHandler);
        try {
            // 搜索该方法中是否有需要加密的字段
            List<String> paramNames = searchParamAnnotation(parameterHandler);
            if (parameterObject != null) {
                if (!CollectionUtils.isEmpty(paramNames)) {
                    PreparedStatement ps = (PreparedStatement) invocation.getArgs()[0];
                    //改写参数
                    processParam(parameterObject, paramNames);
                    //改写的参数设置到原parameterHandler对象
                    parameterField.set(parameterHandler, parameterObject);
                    parameterHandler.setParameters(ps);
                }
            }
        } catch (Exception e) {
            log.error(e.getMessage());
        }
        return invocation.proceed();
    }

    private List<String> searchParamAnnotation(ParameterHandler parameterHandler) throws Exception {
        Class<DefaultParameterHandler> handlerClass = DefaultParameterHandler.class;
        Field mappedStatementFiled = handlerClass.getDeclaredField("mappedStatement");
        mappedStatementFiled.setAccessible(true);
        MappedStatement mappedStatement = (MappedStatement) mappedStatementFiled.get(parameterHandler);
        String methodName = mappedStatement.getId();
        // 获取Mapper类对象
        Class<?> mapperClass = Class.forName(methodName.substring(0, methodName.lastIndexOf('.')));
        methodName = methodName.substring(methodName.lastIndexOf('.') + 1);
        Method[] methods = mapperClass.getDeclaredMethods();
        Method method = null;
        for (Method m : methods) {
            if (m.getName().equals(methodName)) {
                method = m;
                break;
            }
        }
        List<String> paramList = new ArrayList<>();
        if (method != null) {
            Annotation[][] pa = method.getParameterAnnotations();
            Parameter[] parameters = method.getParameters();
            for (int i = 0; i < pa.length; i++) {
                Parameter parameter = parameters[i];
                String typeName = parameter.getParameterizedType().getTypeName();
                // 去除泛型导致的ClassNotFoundException
                Class<?> parameterClass = Class.forName(typeName.contains("<") ? typeName.substring(0, typeName.indexOf("<")) : typeName);
                SensitiveClass sensitiveClass = AnnotationUtils.findAnnotation(parameterClass, SensitiveClass.class);
                if (Objects.nonNull(sensitiveClass)) { // 该类有字段需要被加密
                    // 多个参数时 parameterObject 为 MapperMethod.ParamMap，其中的参数key为param1、param2...
                    paramList.add("param" + (i + 1));
                } else {
                    // 如果类上没有注解，那么就判断参数是否有注解
                    for (Annotation annotation : pa[i]) {
                        if (annotation instanceof EncryptField) {
                            if (parameterClass == String.class) {
                                // 目前只针对String加密
                                paramList.add("param" + (i + 1));
                            }
                        }
                    }
                }
            }
        }
        return paramList;
    }

    private void processParam(Object parameterObject, List<String> params) throws Exception {
        if (parameterObject instanceof MapperMethod.ParamMap) { //多个参数
            MapperMethod.ParamMap paramMap = (MapperMethod.ParamMap) parameterObject;
            for (String paramName : params) {
                Object param = paramMap.get(paramName);
                paramMap.put(paramName, EncryptUtil.encrypt(param));
            }
        } else { //单个参数
            parameterObject = EncryptUtil.encrypt(parameterObject);
        }
    }

}

结果集拦截器，对敏感参数进行解密，目前只针对String类型进行加密解密

@Intercepts({
        @Signature(type = ResultSetHandler.class, method = "handleResultSets", args = {Statement.class})
})
@Component
public class ResultSetInterceptor implements Interceptor {

    @Override
    public Object intercept(Invocation invocation) throws Throwable {
        // 取出查询的结果
        Object resultObject = invocation.proceed();
        if (Objects.isNull(resultObject)) {
            return null;
        }
        // 基于selectList
        if (resultObject instanceof List<?>) {
            List<?> resultList = (List<?>) resultObject;
            if (!CollectionUtils.isEmpty(resultList) && needToDecrypt(resultList.get(0))) {
                for (Object obj : resultList) {
                    EncryptUtil.decrypt(obj);
                }
            }
        } else {
            if (needToDecrypt(resultObject)) {
                EncryptUtil.decrypt(resultObject);
            }
        }
        return resultObject;
    }

    private boolean needToDecrypt(Object object) {
        Class<?> objectClass = object.getClass();
        SensitiveClass sensitiveClass = AnnotationUtils.findAnnotation(objectClass, SensitiveClass.class);
        return Objects.nonNull(sensitiveClass);
    }

}

六、运行结果

以上为添加结果

以上为查询结果

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总结

以上就是使用mybatis拦截器对指定敏感字段进行加密解密的过程。