一：对象转json, 存入数据库

也就是在对象中加几个注解,例如我写的这个例子:

public class Situation {
    @TableId(type = IdType.AUTO)
    private Integer id;

    
    private String name;

    @TableField(typeHandler = JacksonTypeHandler.class)
    private List<Switch> switches;

    @TableField(typeHandler = JacksonTypeHandler.class)
    private List<TerminalInfo> terminals;

    @TableField(typeHandler = JacksonTypeHandler.class)
    private List<Link> links;
}

加了@TableField(typeHandler = JacksonTypeHandler.class)注解, 就可以存入对象为json格式

二：json转对象(从数据库中读取数据)

1. mybatis

我用的是注解形式,再Mapper里面加入注解，举个例子:

@Select("select * from situation_info where name = #{name}")
    @Results({
            @Result(column = "switches", property = "switches", typeHandler = JacksonTypeHandler.class),
            @Result(column = "terminals", property = "terminals", typeHandler = JacksonTypeHandler.class),
            @Result(column = "links", property = "links", typeHandler = JacksonTypeHandler.class)
    })
    Situation getSituationByName(String name);

加个@Results注解 就ok了

2. mybatis-plus

在所需对象上面加入一个注解即可 如：

@TableName(value = "situation_info",autoResultMap = true)
public class Situation {
    @TableId(type = IdType.AUTO)
    private Integer id;
}

这种就行