解决mybatis 无法映射 数据库 json字段的问题

1.前言

MySQL从5.7版本之后开始支持JSON数据类型，相比于JSON格式的字符串类型有如下优势：存储在JSON列中的JSON文档的会被自动验证。无效的文档会产生错误；最佳存储格式。存储在JSON列中的JSON文档会被转换为允许快速读取文档元素的内部格式。

2.背景

mybatis目前还不支持映射json的数据格式，需要我们自己进行增强

3.实现

对mybatis TypeHandler进行增强

3.1ListStringTypeHandler 核心代码

package com.xxx.xxx.pipeline.repository.typehandle;

import com.fasterxml.jackson.core.type.TypeReference;
import lombok.SneakyThrows;
import org.apache.ibatis.type.JdbcType;
import org.apache.ibatis.type.MappedJdbcTypes;
import org.apache.ibatis.type.MappedTypes;
import org.apache.ibatis.type.TypeHandler;

import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

@MappedJdbcTypes(JdbcType.VARCHAR)
@MappedTypes(List.class)
public class ListStringTypeHandler implements TypeHandler<List<String>> {

	@Override
	public void setParameter(PreparedStatement ps, int i, List parameter, JdbcType jdbcType) throws SQLException {
		ps.setString(i, JsonUtils.objectToJson(parameter));
	}

	@SneakyThrows
	@Override
	public List getResult(ResultSet rs, String columnName) throws SQLException {
		return JsonUtils.jsonToObject(rs.getString(columnName), new TypeReference<List>() {
		});
	}

	@SneakyThrows
	@Override
	public List getResult(ResultSet rs, int columnIndex) throws SQLException {
		return JsonUtils.jsonToObject(rs.getString(columnIndex), new TypeReference<List>() {
		});
	}

	@SneakyThrows
	@Override
	public List getResult(CallableStatement cs, int columnIndex) throws SQLException {
		return JsonUtils.jsonToObject(cs.getString(columnIndex), new TypeReference<List>() {
		});
	}
}

3.2 PO代码

package com.xxx.xx.pipeline.domain;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.SneakyThrows;
import lombok.experimental.SuperBuilder;
import org.apache.commons.compress.utils.Lists;
import org.apache.commons.lang3.StringUtils;

import java.io.IOException;
import java.time.LocalDateTime;
import java.util.List;
import java.util.Optional;

@Data
@SuperBuilder
@AllArgsConstructor
@NoArgsConstructor
public class PluginConfigPO extends BasePO {
    private static final String DEFAULT_JSON_LIST = "[]";
    private String gitUrl;
    private String name;
    private String title;
    private String version;
    private String description;
    private String commitId;
    private List<String> osTypes;
    private List<String> categories;
    private List<String> contributors;
    private String releaseNote;
    private LocalDateTime publishedAt;

3.3 mapper代码

package com.xxx.xx.pipeline.repository;

import org.apache.ibatis.annotations.*;

import java.util.List;

public interface PluginConfigDAO {
    @Options(useGeneratedKeys = true, keyProperty = "id", keyColumn = "id")
    @Insert("insert into plugin_config(git_url,name,commit_id," +
            "os_types,categories," +
            "published_at,contributors,title," +
            "version,release_note,description,operator,status," +
            "create_time,update_time) " +
            "value (#{gitUrl},#{name},#{commitId}," +
            "#{osTypes,jdbcType=OTHER ,typeHandler=com.xxx.xx.pipeline.repository.typehandle.ListStringTypeHandler}," +
            "#{categories,jdbcType=OTHER ,typeHandler=com.xxx.xx.pipeline.repository.typehandle.ListStringTypeHandler}," +
            "#{publishedAt},#{contributors,jdbcType=OTHER ,typeHandler=com.xxx.xx.pipeline.repository.typehandle.ListStringTypeHandler},#{title}," +
            "#{version},#{releaseNote},#{description},#{operator},#{status}," +
            "now(),now())")
    int create(PluginConfigPO pluginConfig);

3.4 配置文件代码

mybatis:
  configuration:
    map-underscore-to-camel-case: true
  type-handlers-package: com.xxx.xx.pipeline.repository.typehandle

原文地址：https://cloud.tencent.com/developer/article/2008492