MybatisPlus 数组映射

字段映射处理器

类型处理器，用于 JavaType 与 JdbcType 之间的转换，用于 PreparedStatement 设置参数值和从 ResultSet 或 CallableStatement 中取出一个值，本文讲解 mybaits-plus 内置常用类型处理器如何通过TableField注解快速注入到 mybatis 容器中。

实体类

@Data
@EqualsAndHashCode
@Accessors(chain = true)
public class Label {

    @TableId(type = IdType.AUTO)
    private Integer id;
    
    private List<Integer> labelId;

    private List<String> labelName;
}

xml

DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.lm.dao.mapper.LabelMapper">

    <resultMap id="properties" type="com.lm.common.bean.Label" >
        <result column="label_id" property="labelId" typeHandler="com.lm.common.bean.handle.typehandler.ArrayTypeHandler" />
        <result column="label_name" property="labelName" typeHandler="com.lm.common.bean.handle.typehandler.ArrayTypeHandler" />
    resultMap>
    
mapper>

typeHandler

package com.lm.common.bean.handle.typehandler;


import org.apache.ibatis.type.*;

import java.sql.*;

@MappedJdbcTypes(JdbcType.ARRAY)
@MappedTypes(String[].class)
public class ArrayTypeHandler extends BaseTypeHandler<Object[]> {
    private static final String TYPE_NAME_VARCHAR = "varchar";
    private static final String TYPE_NAME_INTEGER = "integer";
    private static final String TYPE_NAME_BOOLEAN = "boolean";
    private static final String TYPE_NAME_NUMERIC = "numeric";
    private static final String TYPE_NAME_BIGINT  = "bigint";

    @Override
    public void setNonNullParameter(PreparedStatement ps, int i, Object[] parameter, JdbcType jdbcType) throws SQLException {
        String typeName = null;
        if (parameter instanceof Integer[]) {
            typeName = TYPE_NAME_INTEGER;
        } else if (parameter instanceof String[]) {
            typeName = TYPE_NAME_VARCHAR;
        } else if (parameter instanceof Boolean[]) {
            typeName = TYPE_NAME_BOOLEAN;
        } else if (parameter instanceof Double[]) {
            typeName = TYPE_NAME_NUMERIC;
        } else if (parameter instanceof Long[]) {
            typeName = TYPE_NAME_BIGINT;
        }

        if (typeName == null) {
            throw new TypeException("ArrayTypeHandler parameter typeName error, your type is " + parameter.getClass().getName());
        }

        // 这3行是关键的代码，创建Array，然后ps.setArray(i, array)就可以了
        Connection conn = ps.getConnection();
        Array array = conn.createArrayOf(typeName, parameter);
        ps.setArray(i, array);
    }

    @Override
    public Object[] getNullableResult(ResultSet resultSet, String s) throws SQLException {
        return getArray(resultSet.getArray(s));
    }

    @Override
    public Object[] getNullableResult(ResultSet resultSet, int i) throws SQLException {
        return getArray(resultSet.getArray(i));
    }

    @Override
    public Object[] getNullableResult(CallableStatement callableStatement, int i) throws SQLException {
        return getArray(callableStatement.getArray(i));
    }

    private Object[] getArray(Array array) {
        if (array == null) {
            return null;
        }
        try {
            return (Object[]) array.getArray();
        } catch (Exception e) {
        }
        return null;
    }

}