Mybatis自定义类型映射处理器

前言

mybatis作为一款相当优秀的一款orm框架，不仅本身就提供了很多类型映射，还支持自定义类型映射（javaType与jdbcType之间的关系），通过TypeHandler我们可以自己在数据库类型与实体类型之间任意转换。
比如说，我现在需要讲前端传来的手机号进行脱敏入库处理，而用户查的时候，看到的得是正常的！这就涉及加密解密处理了，当然我们可以在service里处理，这里我们演示下如何通过自定义类型映射，进行处理。

运行环境

java8, springboot2.5.0,mysql8,maven3.3.9

创建表

CREATE TABLE `t_user` (`id` int(10) NOT NULL AUTO_INCREMENT,`name` varchar(255) DEFAULT NULL,`phone` varchar(255) DEFAULT NULL,`remark` varchar(255) DEFAULT NULL,PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

导入依赖

     <dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>2.1.4</version></dependency><dependency><groupId>cn.hutool</groupId><artifactId>hutool-all</artifactId><version>5.6.5</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><scope>runtime</scope></dependency>

创建实体

import java.util.List;public class User {private Integer id;private String name;private MyEncrypt phone;private List<String> remark;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public MyEncrypt getPhone() {return phone;}public void setPhone(MyEncrypt phone) {this.phone = phone;}public String getName() {return name;}public void setName(String name) {this.name = name;}public List<String> getRemark() {return remark;}public void setRemark(List<String> remark) {this.remark = remark;}
}

public class MyEncrypt {private String realPhone;public MyEncrypt(String realPhone) {this.realPhone = realPhone;}public String getRealPhone() {return realPhone;}public void setRealPhone(String realPhone) {this.realPhone = realPhone;}
}

数据库手机号设置的varchar类型，而我定义的是一个MyEncrypt实体类，所以我需要将他与jdbcType关联起来，并且完成加密解密的过程！

建立TypeHandler

import cn.hutool.crypto.SecureUtil;
import cn.hutool.crypto.symmetric.AES;
import com.jcl.mybatistypehandler.model.MyEncrypt;
import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;
import org.apache.ibatis.type.MappedJdbcTypes;
import org.apache.ibatis.type.MappedTypes;import java.nio.charset.StandardCharsets;
import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;@MappedJdbcTypes(JdbcType.VARCHAR)
@MappedTypes(MyEncrypt.class)
public class MyEncryptTypeHandler extends BaseTypeHandler<MyEncrypt> {private static final byte[] KEYS = "12345678abcdefgh".getBytes(StandardCharsets.UTF_8);/*** 设置参数,默认从前端传来是源手机号，加密处理后，又重新塞回* preparedStatement: 预执行句柄*/@Overridepublic void setNonNullParameter(PreparedStatement preparedStatement, int i, MyEncrypt myEncrypt, JdbcType jdbcType) throws SQLException {if (myEncrypt == null || myEncrypt.getRealPhone() == null) {preparedStatement.setString(i, null);return;}String phone = myEncrypt.getRealPhone();AES aes = SecureUtil.aes(KEYS);String encrypt = aes.encryptHex(phone);preparedStatement.setString(i, encrypt);}@Overridepublic MyEncrypt getNullableResult(ResultSet resultSet, String s) throws SQLException {return decrypt(resultSet.getString(s));}@Overridepublic MyEncrypt getNullableResult(ResultSet resultSet, int i) throws SQLException {return decrypt(resultSet.getString(i));}@Overridepublic MyEncrypt getNullableResult(CallableStatement callableStatement, int i) throws SQLException {return decrypt(callableStatement.getString(i));}/*** 解密** @param value 手机号* @return 返回解密对象*/public MyEncrypt decrypt(String value) {if (null == value) {return null;}return new MyEncrypt(SecureUtil.aes(KEYS).decryptStr(value));}
}

以上就是全文核心，看的就是这里！

@MappedJdbcTypes和@MappedTypes干什么用的

我认为表面上是对jdbcType和javaType做了个绑定，更像是做了个筛选。比如我上面

@MappedJdbcTypes(JdbcType.VARCHAR)
@MappedTypes(MyEncrypt.class)

就是将MyEncrypt和varchar建立了联系，你的参数里有MyEncrypt这个类型且是要转成varchar的，他才会起作用！

BaseTypeHandler要实现的方法是干什么的

他要实现一个set方法和三个get方法。
setNonNullParameter是塞值，我理解成把javaType转成jdbcType的过程（通俗点是把让你把传的对象转成你能放进数据库类型）
getNullableResult被重载了两次，但是在我眼里他就是和上面反过来，是把jdbcType转成javaType的过程，也就是把数据库里的数据转成你约定的对象。

写好的TypeHandler怎么使用

个人建议全局配在配置文件里，写在xml里，不仅麻烦，还报各种错误，麻烦死了。而且一般写这个，大概率是为了全局使用的！

# 包名
mybatis.type-handlers-package=com.jcl.mybatistypehandler.handler

写在xml里的话，那可就麻烦了

高度建议全局配

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.jcl.mybatistypehandler.dao.UserDao"><resultMap id="BaseResultMapper" type="com.jcl.mybatistypehandler.model.User"><id column="id" property="id"/><result column="name" property="name"/><result column="phone" property="phone" typeHandler="com.jcl.mybatistypehandler.handler.MyEncryptTypeHandler"/><result column="remark" property="remark" typeHandler="com.jcl.mybatistypehandler.handler.ListTypeHandler"/></resultMap><insert id="add">insert into t_user(name, phone, remark)values (#{name}, #{phone,typeHandler=com.jcl.mybatistypehandler.handler.MyEncryptTypeHandler},#{remark,typeHandler=com.jcl.mybatistypehandler.handler.ListTypeHandler})</insert><select id="findByPhone" resultMap="BaseResultMapper">select *from t_userwhere phone = #{phone,typeHandler=com.jcl.mybatistypehandler.handler.MyEncryptTypeHandler}</select>
</mapper>

创建dao

import com.jcl.mybatistypehandler.model.MyEncrypt;
import com.jcl.mybatistypehandler.model.User;
import org.apache.ibatis.annotations.Param;public interface UserDao {int add(@Param("name") String name,@Param("phone") MyEncrypt phone, @Param("remark") String remark);User findByPhone(@Param("phone") MyEncrypt phone);
}

xml上面已给！

ListTypeHandler是我设定的一个字符串转List的一个转换器！
可以不写，所以xml里面也就别配了！

package com.jcl.mybatistypehandler.handler;import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;
import org.apache.ibatis.type.MappedJdbcTypes;
import org.apache.ibatis.type.MappedTypes;
import org.springframework.util.StringUtils;import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Arrays;
import java.util.List;@MappedJdbcTypes(JdbcType.VARCHAR)
@MappedTypes(List.class)
public class ListTypeHandler extends BaseTypeHandler<List<String>> {@Overridepublic void setNonNullParameter(PreparedStatement ps, int i, List<String> parameter, JdbcType jdbcType) throws SQLException {if (null == parameter || parameter.isEmpty()) {ps.setString(i, null);return;}ps.setString(i, String.join(",", parameter));}@Overridepublic List<String> getNullableResult(ResultSet rs, String columnName) throws SQLException {final String value = rs.getString(columnName);if (StringUtils.hasText(value)) {return Arrays.asList(value.split(","));}return null;}@Overridepublic List<String> getNullableResult(ResultSet rs, int columnIndex) throws SQLException {final String value = rs.getString(columnIndex);if (StringUtils.hasText(value)) {return Arrays.asList(value.split(","));}return null;}@Overridepublic List<String> getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {final String value = cs.getString(columnIndex);if (StringUtils.hasText(value)) {return Arrays.asList(value.split(","));}return null;}
}

控制层

import com.jcl.mybatistypehandler.dao.UserDao;
import com.jcl.mybatistypehandler.model.MyEncrypt;
import com.jcl.mybatistypehandler.model.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;@RestController
public class UserController {@Autowiredprivate UserDao userDao;@GetMapping("add")public String addUser(@RequestParam("name") String name,@RequestParam("phone") String phone,@RequestParam("remark") String remark) {MyEncrypt myEncrypt = new MyEncrypt(phone);int result = userDao.add(name, myEncrypt, remark);return "添加结果: " + result;}@GetMapping("findByPhone")public User findCustomer(@RequestParam("phone") String phone) {return userDao.findByPhone(new MyEncrypt(phone));}
}