Mybatis实现JsonObject对象与JSON之间交互

MyBatis与数据库字段交互

基础mysql类型与MyBatis数据进行交互

JavaType	JDBCType	mysql
Char	CHAR	char
String	VARCHAR	varchar
int	INTEGER	int
float	FLOAT	float
Long	BITINT	bitint
double	DOUBLE	double
Date	TIMESTAMP	datetime
LocalDateTime	TIMESTAMP	datetime

除去这些基本的字段对应，如果我们有一个JSONObject属性的字段需要与数据库中json格式的数据进行交互，此时我们就需要新创建一个类，将数据库中json格式的对象映射为Java对象，也可以使用Mybatis对JSONObject对象进行映射，将其在数据库中以json格式保存。

交互操作

import com.alibaba.fastjson.JSONObject;
import lombok.Data;

@Data
public class TestJsonDO {
    private Long id;

    private JSONObject jsonObject;
}

1. 导入fastjson包

    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>fastjson</artifactId>
    </dependency>

2. 编写JSONTypeHandler类

import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;

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

public class JsonTypeHandler<T> extends BaseTypeHandler<T> {
    private static final ObjectMapper mapper = new ObjectMapper();
    private Class<T> clazz;

    public JsonTypeHandler(Class<T> clazz) {
        if (clazz == null) throw new IllegalArgumentException("Type argument cannot be null");
        this.clazz = clazz;
    }

    @Override
    public void setNonNullParameter(PreparedStatement ps, int i, T parameter, JdbcType jdbcType) throws SQLException {
        ps.setString(i, this.toJson(parameter));
    }

    @Override
    public T getNullableResult(ResultSet rs, String columnName) throws SQLException {
        return this.toObject(rs.getString(columnName), clazz);
    }

    @Override
    public T getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
        return this.toObject(rs.getString(columnIndex), clazz);
    }

    @Override
    public T getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
        return this.toObject(cs.getString(columnIndex), clazz);
    }

    private String toJson(T object) {
        try {
            return mapper.writeValueAsString(object);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    private T toObject(String content, Class<?> clazz) {
        if (content != null && !content.isEmpty()) {
            try {
                return (T) mapper.readValue(content, clazz);
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        } else {
            return null;
        }
    }
}

3. 在mybatis映射中加入调用类并编写insert方法

<resultMap id="TestJsonMapper" type="com.xxx.xxx.xxx.dao.DO.TestJsonDO">
    <id column="id" jdbcType="BIGINT" property="id"/>
    <result column="json_object" property="jsonObject" javaType="com.alibaba.fastjson.JSONObject" typeHandler="com.xxx.xxx.xxx.dao.jsonHandler.JsonTypeHandler"/>
</resultMap>
    <insert id="insert" parameterType="com.xxx.xxx.xxx.dao.DO.TestJsonDO">
        insert into `test` (`id`, `json_object`)
        values (#{id,jdbcType=BIGINT}, #{jsonObject,typeHandler=com.xunxu.cloudcontrol.admin.dao.jsonHandler.JsonTypeHandler});
    </insert>

4. 最终调用insert接口，功能正常