字段类型处理器

• pom.xml

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
    </dependency>
    <dependency>
        <groupId>com.h2database</groupId>
        <artifactId>h2</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>com.baomidou</groupId>
        <artifactId>mybatis-plus-boot-starter</artifactId>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
    </dependency>
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>fastjson</artifactId>
    </dependency>
    <dependency>
        <groupId>com.google.code.gson</groupId>
        <artifactId>gson</artifactId>
        <version>2.8.6</version>
    </dependency>
</dependencies>

• 数据库
  

• 配置类

@Component
public class MpJsonConfig implements CommandLineRunner {
 
    /**
     * 可以set进去自己的
     */
    @Override
    public void run(String... args) throws Exception {
        JacksonTypeHandler.setObjectMapper(new ObjectMapper());
        GsonTypeHandler.setGson(new Gson());
    }
 
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor());
        return interceptor;
    }
}

• 实体类

@Data
@Accessors(chain = true)
@TableName(autoResultMap = true)
public class User {
    private Long id;
    private String name;
    private Integer age;
    private String email;
 
    /**
     * 注意！！ 必须开启映射注解
     *
     * @TableName(autoResultMap = true)
     * <p>
     * 以下两种类型处理器，二选一 也可以同时存在
     * <p>
     * 注意！！选择对应的 JSON 处理器也必须存在对应依赖包
     */
    @TableField(typeHandler = WalletListTypeHandler.class)
    private List<Wallet> wallets;
 
    @TableField(typeHandler = FastjsonTypeHandler.class)
    private OtherInfo otherInfo;
}

• 类型处理器

public class WalletListTypeHandler extends JacksonTypeHandler {
 
    public WalletListTypeHandler(Class<?> type) {
        super(type);
    }
 
    @Override
    protected Object parse(String json) {
        try {
            return getObjectMapper().readValue(json, new TypeReference<List<Wallet>>() {
            });
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}

• 测试

/**
 * UPDATE user SET age=?, wallets=? WHERE (id = ?)
 * 99(Integer), [{"name":"Tom","currencyList":[{"type":"RMB","amount":1000.0}]}](String), 2(Long)
 * SELECT id,name,age,email,wallets,other_info FROM user WHERE id=?
 * 2(Integer)
 */
@Test
public void test2() {
    // wrapper typeHandler 测试
    LambdaUpdateWrapper<User> wrapper = Wrappers.<User>lambdaUpdate().set(User::getWallets, Arrays.asList(new Wallet("Tom",
            Arrays.asList(new Currency("RMB", 1000d)))), "typeHandler=com.baomidou.mybatisplus.samples.typehandler.WalletListTypeHandler");
    /**
     * Arrays.asList() 将数组转为list集合
     * --->[Wallet(name=Tom, currencyList=[Currency(type=RMB, amount=1000.0)])]
     */
    System.out.println("--->" + Arrays.asList(new Wallet("Tom",
            Arrays.asList(new Currency("RMB", 1000d)))));
    wrapper.eq(User::getId, 2L);
    // 更新id为2的数据
    Assertions.assertEquals(userMapper.update(new User().setAge(99), wrapper), 1);
    /**
     * 查看是否修改成功
     * User(id=2, name=Jack, age=99, email=test2@baomidou.com, wallets=[Wallet(name=Tom, currencyList=[Currency(type=RMB, amount=1000.0)])], otherInfo=OtherInfo(sex=男, city=青岛))
     */
    System.err.println(userMapper.selectById(2));
}

• 官方文档