利用MyBatis-Plus灵活处理JSON字段的技巧与最佳实践

import com.fasterxml.jackson.databind.JsonNode;

public class User {
    private Long id;
    private String name;
    private JsonNode additionalInfo; // JSON类型字段
    // 省略其他属性和方法
}

import org.apache.ibatis.type.JdbcType;
import org.apache.ibatis.type.TypeHandler;
import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class JsonTypeHandler extends BaseTypeHandler<JsonNode> {
    @Override
    public void setNonNullParameter(PreparedStatement ps, int i, JsonNode parameter, JdbcType jdbcType) throws SQLException {
        ps.setString(i, parameter.toString());
    }

    @Override
    public JsonNode getNullableResult(ResultSet rs, String columnName) throws SQLException {
        String sqlJson = rs.getString(columnName);
        return parseJson(sqlJson);
    }

    @Override
    public JsonNode getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
        String sqlJson = rs.getString(columnIndex);
        return parseJson(sqlJson);
    }

    @Override
    public JsonNode getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
        String sqlJson = cs.getString(columnIndex);
        return parseJson(sqlJson);
    }

    private JsonNode parseJson(String json) {
        if (json == null) return null;
        try {
            return new ObjectMapper().readTree(json);
        } catch (IOException e) {
            throw new RuntimeException("Failed to parse JSON string.", e);
        }
    }
}

<configuration>
    <typeHandlers>
        <typeHandler handler="com.yourpackage.JsonTypeHandler"/>
    </typeHandlers>
</configuration>

@Mapper
public interface UserMapper extends BaseMapper<User> {
    @Results({
        @Result(property = "additionalInfo", column = "additional_info", typeHandler = JsonTypeHandler.class)
    })
    User selectById(Long id);
}

public interface UserMapper extends BaseMapper<User> {
    @Update("UPDATE user SET additional_info = #{additionalInfo, typeHandler=com.yourpackage.JsonTypeHandler} WHERE id = #{id}")
    void updateAdditionalInfoById(@Param("additionalInfo") JsonNode additionalInfo, @Param("id") Long id);
}