SpringBoot+MyBatis实现动态字段更新的三种方法

void updateUserSelective(User user);

<update id="updateUserSelective" parameterType="User">
    UPDATE user
    <set>
        <if test="name != null">name = #{name},</if>
        <if test="age != null">age = #{age},</if>
        <if test="address != null">address = #{address},</if>
        <if test="phone != null">phone = #{phone},</if>
    </set>
    WHERE id = #{id}
</update>

public void updateUser(Long id, Map<String, Object> updates) {
    Set<String> allowedFields = Set.of("name", "age", "address", "phone");
    updates.keySet().retainAll(allowedFields); // 过滤非法字段
    userMapper.updateUserSelective(id, updates);
}

void updateUserSelective(@Param("id") Long id, @Param("updates") Map<String, Object> updates);

<update id="updateUserSelective">
    UPDATE user
    <set>
        <foreach collection="updates" index="key" item="value" separator=",">
            ${key} = #{value}
        </foreach>
    </set>
    WHERE id = #{id}
</update>

public class UserSqlProvider {
    public String updateSelective(Map<String, Object> params) {
        Long id = (Long) params.get("id");
        Map<String, Object> updates = (Map<String, Object>) params.get("updates");
        Set<String> allowedFields = Set.of("name", "age", "address", "phone");
        
        StringBuilder sql = new StringBuilder("UPDATE user SET ");
        allowedFields.forEach(field -> {
            if (updates.containsKey(field)) {
                sql.append(field).append(" = #{updates.").append(field).append("}, ");
            }
        });
        sql.setLength(sql.length() - 2); // 移除末尾逗号
        sql.append(" WHERE id = #{id}");
        return sql.toString();
    }
}

@UpdateProvider(type = UserSqlProvider.class, method = "updateSelective")
void updateUserSelective(@Param("id") Long id, @Param("updates") Map<String, Object> updates);