分布式ID选型对比（2）

数据库号段模式

一, 引入依赖:

java 复制代码

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.19</version>
</dependency>
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.2.2</version>
</dependency>

二, 新建表

java 复制代码

CREATE TABLE `id_generator` (
  `id` int NOT NULL,
  `max_id` bigint NOT NULL COMMENT '当前最大id',
  `step` int NOT NULL COMMENT '号段的布长',
  `biz_type` int NOT NULL COMMENT '业务类型',
  `version` int NOT NULL COMMENT '版本号',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

三, resources目录下编写自动生成代码配置文件: generatorConfig.xml

java 复制代码

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
        PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">

<generatorConfiguration>
    <!--mysql 连接数据库jar 这里选择自己本地位置;
    如果不知道maven本地仓库地址，可以使用EveryThing工具全局搜索mysql-connector-java，找到jar包位置；
    也可以手动下载一个jar放在指定位置，进行引用。
    -->
    <classPathEntry location="/Users/lizhihao/.m2/repository/mysql/mysql-connector-java/8.0.19/mysql-connector-java-8.0.19.jar"/>

    <context id="testTables" targetRuntime="MyBatis3">
        <commentGenerator>
            <!-- 是否去除自动生成的注释,true：是,false:否 -->
            <property name="suppressAllComments" value="true"/>
        </commentGenerator>

        <!--数据库连接的信息：驱动类、连接地址、用户名、密码 -->
        <jdbcConnection driverClass="com.mysql.cj.jdbc.Driver"
                        connectionURL="jdbc:mysql://localhost:3306/generate_id" userId="root"
                        password="root">
        </jdbcConnection>

        <!-- 默认false，把JDBC DECIMAL 和 NUMERIC 类型解析为 Integer，为 true时把JDBC DECIMAL 和
           NUMERIC 类型解析为java.math.BigDecimal -->
        <javaTypeResolver>
            <property name="forceBigDecimals" value="false"/>
        </javaTypeResolver>

        <!-- 指定javaBean生成的位置
            targetPackage：生成的类要放的包，真实的包受enableSubPackages属性控制；
            targetProject：目标项目，指定一个存在的目录下，生成的内容会放到指定目录中，如果目录不存在，MBG不会自动建目录
         -->
        <javaModelGenerator targetPackage="org.com.spi.model" targetProject="src/main/java">
            <!-- 在targetPackage的基础上，根据数据库的schema再生成一层package，最终生成的类放在这个package下，默认为false；如果多个数据库改为true分目录 -->
            <property name="enableSubPackages" value="false"/>
            <!-- 设置是否在getter方法中，对String类型字段调用trim()方法 -->
            <property name="trimStrings" value="true"/>
        </javaModelGenerator>

        <!--  指定mapper映射文件生成的位置
           targetPackage、targetProject同javaModelGenerator中作用一样-->
        <sqlMapGenerator targetPackage="mybatis" targetProject="src/main/resources">
            <property name="enableSubPackages" value="false"/>
        </sqlMapGenerator>

        <!-- 指定mapper接口生成的位置
         targetPackage、targetProject同javaModelGenerator中作用一样
         -->
        <javaClientGenerator type="XMLMAPPER" targetPackage="org.com.spi.dao" targetProject="src/main/java">
            <property name="enableSubPackages" value="false"/>
        </javaClientGenerator>
        <!-- 指定数据库表
        domainObjectName：生成的domain类的名字,当表名和domain类的名字有差异时一定要设置，如果不设置，直接使用表名作为domain类的名字；
        可以设置为somepck.domainName，那么会自动把domainName类再放到somepck包里面；
        -->
        <table tableName="worker_node"></table>
<!--        <table tableName="auto_generate2" domainObjectName="AutoGenerate2"></table>-->
    </context>
</generatorConfiguration>

application.properties数据库配置:

java 复制代码

#   ???url
spring.datasource.url=jdbc:mysql://localhost:3306/generate_id?characterEncoding=utf8&serverTimezone=UTC    
#  ??????
spring.datasource.username=root
#  ?????
spring.datasource.password=root
#  ?????
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
###################################### MyBatis ??######################################
# ?? mapper.xml ???
mybatis.mapper-locations=classpath:mybatis/*.xml
#????????,?????????????? mapper.xml ??????????????
mybatis.type-aliases-package=net.biancheng.www.bean
#???????????????????
mybatis.configuration.map-underscore-to-camel-case=true

四, 编写层级代码

1, 对象 IdGenerator

java 复制代码

package org.com.spi.model;

public class IdGenerator {
    private Integer id;

    private Long maxId;

    private Integer step;

    private Integer bizType;

    private Integer version;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public Long getMaxId() {
        return maxId;
    }

    public void setMaxId(Long maxId) {
        this.maxId = maxId;
    }

    public Integer getStep() {
        return step;
    }

    public void setStep(Integer step) {
        this.step = step;
    }

    public Integer getBizType() {
        return bizType;
    }

    public void setBizType(Integer bizType) {
        this.bizType = bizType;
    }

    public Integer getVersion() {
        return version;
    }

    public void setVersion(Integer version) {
        this.version = version;
    }
}

IdGeneratorExample:

java 复制代码

package org.com.spi.model;

import java.util.ArrayList;
import java.util.List;

public class IdGeneratorExample {
    protected String orderByClause;

    protected boolean distinct;

    protected List<Criteria> oredCriteria;

    public IdGeneratorExample() {
        oredCriteria = new ArrayList<Criteria>();
    }

    public void setOrderByClause(String orderByClause) {
        this.orderByClause = orderByClause;
    }

    public String getOrderByClause() {
        return orderByClause;
    }

    public void setDistinct(boolean distinct) {
        this.distinct = distinct;
    }

    public boolean isDistinct() {
        return distinct;
    }

    public List<Criteria> getOredCriteria() {
        return oredCriteria;
    }

    public void or(Criteria criteria) {
        oredCriteria.add(criteria);
    }

    public Criteria or() {
        Criteria criteria = createCriteriaInternal();
        oredCriteria.add(criteria);
        return criteria;
    }

    public Criteria createCriteria() {
        Criteria criteria = createCriteriaInternal();
        if (oredCriteria.size() == 0) {
            oredCriteria.add(criteria);
        }
        return criteria;
    }

    protected Criteria createCriteriaInternal() {
        Criteria criteria = new Criteria();
        return criteria;
    }

    public void clear() {
        oredCriteria.clear();
        orderByClause = null;
        distinct = false;
    }

    protected abstract static class GeneratedCriteria {
        protected List<Criterion> criteria;

        protected GeneratedCriteria() {
            super();
            criteria = new ArrayList<Criterion>();
        }

        public boolean isValid() {
            return criteria.size() > 0;
        }

        public List<Criterion> getAllCriteria() {
            return criteria;
        }

        public List<Criterion> getCriteria() {
            return criteria;
        }

        protected void addCriterion(String condition) {
            if (condition == null) {
                throw new RuntimeException("Value for condition cannot be null");
            }
            criteria.add(new Criterion(condition));
        }

        protected void addCriterion(String condition, Object value, String property) {
            if (value == null) {
                throw new RuntimeException("Value for " + property + " cannot be null");
            }
            criteria.add(new Criterion(condition, value));
        }

        protected void addCriterion(String condition, Object value1, Object value2, String property) {
            if (value1 == null || value2 == null) {
                throw new RuntimeException("Between values for " + property + " cannot be null");
            }
            criteria.add(new Criterion(condition, value1, value2));
        }

        public Criteria andIdIsNull() {
            addCriterion("id is null");
            return (Criteria) this;
        }

        public Criteria andIdIsNotNull() {
            addCriterion("id is not null");
            return (Criteria) this;
        }

        public Criteria andIdEqualTo(Integer value) {
            addCriterion("id =", value, "id");
            return (Criteria) this;
        }

        public Criteria andIdNotEqualTo(Integer value) {
            addCriterion("id <>", value, "id");
            return (Criteria) this;
        }

        public Criteria andIdGreaterThan(Integer value) {
            addCriterion("id >", value, "id");
            return (Criteria) this;
        }

        public Criteria andIdGreaterThanOrEqualTo(Integer value) {
            addCriterion("id >=", value, "id");
            return (Criteria) this;
        }

        public Criteria andIdLessThan(Integer value) {
            addCriterion("id <", value, "id");
            return (Criteria) this;
        }

        public Criteria andIdLessThanOrEqualTo(Integer value) {
            addCriterion("id <=", value, "id");
            return (Criteria) this;
        }

        public Criteria andIdIn(List<Integer> values) {
            addCriterion("id in", values, "id");
            return (Criteria) this;
        }

        public Criteria andIdNotIn(List<Integer> values) {
            addCriterion("id not in", values, "id");
            return (Criteria) this;
        }

        public Criteria andIdBetween(Integer value1, Integer value2) {
            addCriterion("id between", value1, value2, "id");
            return (Criteria) this;
        }

        public Criteria andIdNotBetween(Integer value1, Integer value2) {
            addCriterion("id not between", value1, value2, "id");
            return (Criteria) this;
        }

        public Criteria andMaxIdIsNull() {
            addCriterion("max_id is null");
            return (Criteria) this;
        }

        public Criteria andMaxIdIsNotNull() {
            addCriterion("max_id is not null");
            return (Criteria) this;
        }

        public Criteria andMaxIdEqualTo(Long value) {
            addCriterion("max_id =", value, "maxId");
            return (Criteria) this;
        }

        public Criteria andMaxIdNotEqualTo(Long value) {
            addCriterion("max_id <>", value, "maxId");
            return (Criteria) this;
        }

        public Criteria andMaxIdGreaterThan(Long value) {
            addCriterion("max_id >", value, "maxId");
            return (Criteria) this;
        }

        public Criteria andMaxIdGreaterThanOrEqualTo(Long value) {
            addCriterion("max_id >=", value, "maxId");
            return (Criteria) this;
        }

        public Criteria andMaxIdLessThan(Long value) {
            addCriterion("max_id <", value, "maxId");
            return (Criteria) this;
        }

        public Criteria andMaxIdLessThanOrEqualTo(Long value) {
            addCriterion("max_id <=", value, "maxId");
            return (Criteria) this;
        }

        public Criteria andMaxIdIn(List<Long> values) {
            addCriterion("max_id in", values, "maxId");
            return (Criteria) this;
        }

        public Criteria andMaxIdNotIn(List<Long> values) {
            addCriterion("max_id not in", values, "maxId");
            return (Criteria) this;
        }

        public Criteria andMaxIdBetween(Long value1, Long value2) {
            addCriterion("max_id between", value1, value2, "maxId");
            return (Criteria) this;
        }

        public Criteria andMaxIdNotBetween(Long value1, Long value2) {
            addCriterion("max_id not between", value1, value2, "maxId");
            return (Criteria) this;
        }

        public Criteria andStepIsNull() {
            addCriterion("step is null");
            return (Criteria) this;
        }

        public Criteria andStepIsNotNull() {
            addCriterion("step is not null");
            return (Criteria) this;
        }

        public Criteria andStepEqualTo(Integer value) {
            addCriterion("step =", value, "step");
            return (Criteria) this;
        }

        public Criteria andStepNotEqualTo(Integer value) {
            addCriterion("step <>", value, "step");
            return (Criteria) this;
        }

        public Criteria andStepGreaterThan(Integer value) {
            addCriterion("step >", value, "step");
            return (Criteria) this;
        }

        public Criteria andStepGreaterThanOrEqualTo(Integer value) {
            addCriterion("step >=", value, "step");
            return (Criteria) this;
        }

        public Criteria andStepLessThan(Integer value) {
            addCriterion("step <", value, "step");
            return (Criteria) this;
        }

        public Criteria andStepLessThanOrEqualTo(Integer value) {
            addCriterion("step <=", value, "step");
            return (Criteria) this;
        }

        public Criteria andStepIn(List<Integer> values) {
            addCriterion("step in", values, "step");
            return (Criteria) this;
        }

        public Criteria andStepNotIn(List<Integer> values) {
            addCriterion("step not in", values, "step");
            return (Criteria) this;
        }

        public Criteria andStepBetween(Integer value1, Integer value2) {
            addCriterion("step between", value1, value2, "step");
            return (Criteria) this;
        }

        public Criteria andStepNotBetween(Integer value1, Integer value2) {
            addCriterion("step not between", value1, value2, "step");
            return (Criteria) this;
        }

        public Criteria andBizTypeIsNull() {
            addCriterion("biz_type is null");
            return (Criteria) this;
        }

        public Criteria andBizTypeIsNotNull() {
            addCriterion("biz_type is not null");
            return (Criteria) this;
        }

        public Criteria andBizTypeEqualTo(Integer value) {
            addCriterion("biz_type =", value, "bizType");
            return (Criteria) this;
        }

        public Criteria andBizTypeNotEqualTo(Integer value) {
            addCriterion("biz_type <>", value, "bizType");
            return (Criteria) this;
        }

        public Criteria andBizTypeGreaterThan(Integer value) {
            addCriterion("biz_type >", value, "bizType");
            return (Criteria) this;
        }

        public Criteria andBizTypeGreaterThanOrEqualTo(Integer value) {
            addCriterion("biz_type >=", value, "bizType");
            return (Criteria) this;
        }

        public Criteria andBizTypeLessThan(Integer value) {
            addCriterion("biz_type <", value, "bizType");
            return (Criteria) this;
        }

        public Criteria andBizTypeLessThanOrEqualTo(Integer value) {
            addCriterion("biz_type <=", value, "bizType");
            return (Criteria) this;
        }

        public Criteria andBizTypeIn(List<Integer> values) {
            addCriterion("biz_type in", values, "bizType");
            return (Criteria) this;
        }

        public Criteria andBizTypeNotIn(List<Integer> values) {
            addCriterion("biz_type not in", values, "bizType");
            return (Criteria) this;
        }

        public Criteria andBizTypeBetween(Integer value1, Integer value2) {
            addCriterion("biz_type between", value1, value2, "bizType");
            return (Criteria) this;
        }

        public Criteria andBizTypeNotBetween(Integer value1, Integer value2) {
            addCriterion("biz_type not between", value1, value2, "bizType");
            return (Criteria) this;
        }

        public Criteria andVersionIsNull() {
            addCriterion("version is null");
            return (Criteria) this;
        }

        public Criteria andVersionIsNotNull() {
            addCriterion("version is not null");
            return (Criteria) this;
        }

        public Criteria andVersionEqualTo(Integer value) {
            addCriterion("version =", value, "version");
            return (Criteria) this;
        }

        public Criteria andVersionNotEqualTo(Integer value) {
            addCriterion("version <>", value, "version");
            return (Criteria) this;
        }

        public Criteria andVersionGreaterThan(Integer value) {
            addCriterion("version >", value, "version");
            return (Criteria) this;
        }

        public Criteria andVersionGreaterThanOrEqualTo(Integer value) {
            addCriterion("version >=", value, "version");
            return (Criteria) this;
        }

        public Criteria andVersionLessThan(Integer value) {
            addCriterion("version <", value, "version");
            return (Criteria) this;
        }

        public Criteria andVersionLessThanOrEqualTo(Integer value) {
            addCriterion("version <=", value, "version");
            return (Criteria) this;
        }

        public Criteria andVersionIn(List<Integer> values) {
            addCriterion("version in", values, "version");
            return (Criteria) this;
        }

        public Criteria andVersionNotIn(List<Integer> values) {
            addCriterion("version not in", values, "version");
            return (Criteria) this;
        }

        public Criteria andVersionBetween(Integer value1, Integer value2) {
            addCriterion("version between", value1, value2, "version");
            return (Criteria) this;
        }

        public Criteria andVersionNotBetween(Integer value1, Integer value2) {
            addCriterion("version not between", value1, value2, "version");
            return (Criteria) this;
        }
    }

    public static class Criteria extends GeneratedCriteria {

        protected Criteria() {
            super();
        }
    }

    public static class Criterion {
        private String condition;

        private Object value;

        private Object secondValue;

        private boolean noValue;

        private boolean singleValue;

        private boolean betweenValue;

        private boolean listValue;

        private String typeHandler;

        public String getCondition() {
            return condition;
        }

        public Object getValue() {
            return value;
        }

        public Object getSecondValue() {
            return secondValue;
        }

        public boolean isNoValue() {
            return noValue;
        }

        public boolean isSingleValue() {
            return singleValue;
        }

        public boolean isBetweenValue() {
            return betweenValue;
        }

        public boolean isListValue() {
            return listValue;
        }

        public String getTypeHandler() {
            return typeHandler;
        }

        protected Criterion(String condition) {
            super();
            this.condition = condition;
            this.typeHandler = null;
            this.noValue = true;
        }

        protected Criterion(String condition, Object value, String typeHandler) {
            super();
            this.condition = condition;
            this.value = value;
            this.typeHandler = typeHandler;
            if (value instanceof List<?>) {
                this.listValue = true;
            } else {
                this.singleValue = true;
            }
        }

        protected Criterion(String condition, Object value) {
            this(condition, value, null);
        }

        protected Criterion(String condition, Object value, Object secondValue, String typeHandler) {
            super();
            this.condition = condition;
            this.value = value;
            this.secondValue = secondValue;
            this.typeHandler = typeHandler;
            this.betweenValue = true;
        }

        protected Criterion(String condition, Object value, Object secondValue) {
            this(condition, value, secondValue, null);
        }
    }
}

2, dao层接口: IdGeneratorMapper

java 复制代码

package org.com.spi.dao;

import java.util.List;

import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.com.spi.model.IdGenerator;
import org.com.spi.model.IdGeneratorExample;

@Mapper
public interface IdGeneratorMapper {
    int countByExample(IdGeneratorExample example);

    int deleteByExample(IdGeneratorExample example);

    int deleteByPrimaryKey(Integer id);

    int insert(IdGenerator record);

    int insertSelective(IdGenerator record);

    List<IdGenerator> selectByExample(IdGeneratorExample example);

    IdGenerator selectByPrimaryKey(Integer id);

    int updateByExampleSelective(@Param("record") IdGenerator record, @Param("example") IdGeneratorExample example);

    int updateByExample(@Param("record") IdGenerator record, @Param("example") IdGeneratorExample example);

    int updateByPrimaryKeySelective(IdGenerator record);

    int updateByPrimaryKey(IdGenerator record);

    IdGenerator selectMaxId(int bizType);

    int updateMaxId(IdGenerator idGenerator);
}

3, controller层: GenerateIdController

java 复制代码

@Autowired
IdGeneratorMapper idGeneratorMapper;
@PutMapping("/save1")
public int save1(@RequestBody AutoGenerate1 autoGenerate){
    IdGenerator idGenerator = idGeneratorMapper.selectMaxId(BizTypeEnum.GENERATE_ONE.getType());
    int count = 0;
    if(idGenerator == null){
        idGenerator = new IdGenerator();
        idGenerator.setId(1);
        idGenerator.setStep(4);
        idGenerator.setVersion(1);
        idGenerator.setMaxId(1L);
        idGenerator.setBizType(BizTypeEnum.GENERATE_ONE.getType());
        count = idGeneratorMapper.insertSelective(idGenerator);
        autoGenerate.setId(1L);
    }else{
        Long currentId = idGenerator.getMaxId() + idGenerator.getStep();
        autoGenerate.setId(currentId);
        idGenerator.setMaxId(currentId);
        count = idGeneratorMapper.updateMaxId(idGenerator);
    }
    if(count > 0){//id生成后才能算成功进行新增
        return autoGenerateMapper1.insert(autoGenerate);
    }
    return 0;
}

4, resources/mybatis目录下建: IdGeneratorMapper.xml

java 复制代码

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="org.com.spi.dao.IdGeneratorMapper" >
  <resultMap id="BaseResultMap" type="org.com.spi.model.IdGenerator" >
    <id column="id" property="id" jdbcType="INTEGER" />
    <result column="max_id" property="maxId" jdbcType="BIGINT" />
    <result column="step" property="step" jdbcType="INTEGER" />
    <result column="biz_type" property="bizType" jdbcType="INTEGER" />
    <result column="version" property="version" jdbcType="INTEGER" />
  </resultMap>
  <sql id="Example_Where_Clause" >
    <where >
      <foreach collection="oredCriteria" item="criteria" separator="or" >
        <if test="criteria.valid" >
          <trim prefix="(" suffix=")" prefixOverrides="and" >
            <foreach collection="criteria.criteria" item="criterion" >
              <choose >
                <when test="criterion.noValue" >
                  and ${criterion.condition}
                </when>
                <when test="criterion.singleValue" >
                  and ${criterion.condition} #{criterion.value}
                </when>
                <when test="criterion.betweenValue" >
                  and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
                </when>
                <when test="criterion.listValue" >
                  and ${criterion.condition}
                  <foreach collection="criterion.value" item="listItem" open="(" close=")" separator="," >
                    #{listItem}
                  </foreach>
                </when>
              </choose>
            </foreach>
          </trim>
        </if>
      </foreach>
    </where>
  </sql>
  <sql id="Update_By_Example_Where_Clause" >
    <where >
      <foreach collection="example.oredCriteria" item="criteria" separator="or" >
        <if test="criteria.valid" >
          <trim prefix="(" suffix=")" prefixOverrides="and" >
            <foreach collection="criteria.criteria" item="criterion" >
              <choose >
                <when test="criterion.noValue" >
                  and ${criterion.condition}
                </when>
                <when test="criterion.singleValue" >
                  and ${criterion.condition} #{criterion.value}
                </when>
                <when test="criterion.betweenValue" >
                  and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
                </when>
                <when test="criterion.listValue" >
                  and ${criterion.condition}
                  <foreach collection="criterion.value" item="listItem" open="(" close=")" separator="," >
                    #{listItem}
                  </foreach>
                </when>
              </choose>
            </foreach>
          </trim>
        </if>
      </foreach>
    </where>
  </sql>
  <sql id="Base_Column_List" >
    id, max_id, step, biz_type, version
  </sql>
  <select id="selectMaxId" parameterType="int" resultMap="BaseResultMap">
    select * from id_generator where biz_type = #{bizType} limit 1;
  </select>
  <select id="selectByExample" resultMap="BaseResultMap" parameterType="org.com.spi.model.IdGeneratorExample" >
    select
    <if test="distinct" >
      distinct
    </if>
    <include refid="Base_Column_List" />
    from id_generator
    <if test="_parameter != null" >
      <include refid="Example_Where_Clause" />
    </if>
    <if test="orderByClause != null" >
      order by ${orderByClause}
    </if>
  </select>
  <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
    select 
    <include refid="Base_Column_List" />
    from id_generator
    where id = #{id,jdbcType=INTEGER}
  </select>
  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
    delete from id_generator
    where id = #{id,jdbcType=INTEGER}
  </delete>
  <delete id="deleteByExample" parameterType="org.com.spi.model.IdGeneratorExample" >
    delete from id_generator
    <if test="_parameter != null" >
      <include refid="Example_Where_Clause" />
    </if>
  </delete>
  <insert id="insert" parameterType="org.com.spi.model.IdGenerator" >
    insert into id_generator (id, max_id, step, 
      biz_type, version)
    values (#{id,jdbcType=INTEGER}, #{maxId,jdbcType=BIGINT}, #{step,jdbcType=INTEGER}, 
      #{bizType,jdbcType=INTEGER}, #{version,jdbcType=INTEGER})
  </insert>
  <insert id="insertSelective" parameterType="org.com.spi.model.IdGenerator" >
    insert into id_generator
    <trim prefix="(" suffix=")" suffixOverrides="," >
      <if test="id != null" >
        id,
      </if>
      <if test="maxId != null" >
        max_id,
      </if>
      <if test="step != null" >
        step,
      </if>
      <if test="bizType != null" >
        biz_type,
      </if>
      <if test="version != null" >
        version,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides="," >
      <if test="id != null" >
        #{id,jdbcType=INTEGER},
      </if>
      <if test="maxId != null" >
        #{maxId,jdbcType=BIGINT},
      </if>
      <if test="step != null" >
        #{step,jdbcType=INTEGER},
      </if>
      <if test="bizType != null" >
        #{bizType,jdbcType=INTEGER},
      </if>
      <if test="version != null" >
        #{version,jdbcType=INTEGER},
      </if>
    </trim>
  </insert>
  <select id="countByExample" parameterType="org.com.spi.model.IdGeneratorExample" resultType="java.lang.Integer" >
    select count(*) from id_generator
    <if test="_parameter != null" >
      <include refid="Example_Where_Clause" />
    </if>
  </select>
  <update id="updateByExampleSelective" parameterType="map" >
    update id_generator
    <set >
      <if test="record.id != null" >
        id = #{record.id,jdbcType=INTEGER},
      </if>
      <if test="record.maxId != null" >
        max_id = #{record.maxId,jdbcType=BIGINT},
      </if>
      <if test="record.step != null" >
        step = #{record.step,jdbcType=INTEGER},
      </if>
      <if test="record.bizType != null" >
        biz_type = #{record.bizType,jdbcType=INTEGER},
      </if>
      <if test="record.version != null" >
        version = #{record.version,jdbcType=INTEGER},
      </if>
    </set>
    <if test="_parameter != null" >
      <include refid="Update_By_Example_Where_Clause" />
    </if>
  </update>
  <update id="updateByExample" parameterType="map" >
    update id_generator
    set id = #{record.id,jdbcType=INTEGER},
      max_id = #{record.maxId,jdbcType=BIGINT},
      step = #{record.step,jdbcType=INTEGER},
      biz_type = #{record.bizType,jdbcType=INTEGER},
      version = #{record.version,jdbcType=INTEGER}
    <if test="_parameter != null" >
      <include refid="Update_By_Example_Where_Clause" />
    </if>
  </update>
  <update id="updateMaxId" parameterType="org.com.spi.model.IdGenerator" >
    update id_generator set max_id = #{maxId},version = version + 1
    where biz_type = #{bizType} and version = #{version}
  </update>
  <update id="updateByPrimaryKeySelective" parameterType="org.com.spi.model.IdGenerator" >
    update id_generator
    <set >
      <if test="maxId != null" >
        max_id = #{maxId,jdbcType=BIGINT},
      </if>
      <if test="step != null" >
        step = #{step,jdbcType=INTEGER},
      </if>
      <if test="bizType != null" >
        biz_type = #{bizType,jdbcType=INTEGER},
      </if>
      <if test="version != null" >
        version = #{version,jdbcType=INTEGER},
      </if>
    </set>
    where id = #{id,jdbcType=INTEGER}
  </update>
  <update id="updateByPrimaryKey" parameterType="org.com.spi.model.IdGenerator" >
    update id_generator
    set max_id = #{maxId,jdbcType=BIGINT},
      step = #{step,jdbcType=INTEGER},
      biz_type = #{bizType,jdbcType=INTEGER},
      version = #{version,jdbcType=INTEGER}
    where id = #{id,jdbcType=INTEGER}
  </update>
</mapper>

特点: 相较于数据库自增,扩展性更好,但缺点是每次取ID都需要加锁,性能较低.