MyBatis(五)：mybatis关联映射

Mybatis中表与表之间的关系分为一下4类：

1）一对一

2）一对多

3）多对一

4）多对多

创建数据Demo表

数据库表：

用户表user：记录了购买商品的用户信息。 

订单表orders：记录了用户所创建的订单（购买商品的订单）。 

订单明细表orderdetail：记录了订单的详细信息即购买商品的信息。 

商品表items：记录商品信息。

数据模型：

数据表之间的关系：

先分析数据级别之间有关系的表之间的业务关系：

• usre和orders：

user —-> orders：一个用户可以创建多个订单，一对多
orders —-> user：一个订单只由一个用户创建，一对一

• orders和orderdetail：

orders —-> orderdetail：一个订单可以包括 多个订单明细，因为一个订单可以购买多个商品，每个商品的购买信息在orderdetail记录，一对多关系。
orderdetail —-> orders：一个订单明细只能包括在一个订单中，一对一

• orderdetail和itesm：

orderdetail —-> itesms：一个订单明细只对应一个商品信息，一对一
items —-> orderdetail:一个商品可以包括在多个订单明细 ，一对多

创建Demo表

/*
Navicat MySQL Data Transfer

Source Server         : mysql1
Source Server Version : 50712
Source Host           : localhost:3306
Source Database       : relation

Target Server Type    : MYSQL
Target Server Version : 50712
File Encoding         : 65001

Date: 2019-03-24 15:57:05
*/

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for items
-- ----------------------------
DROP TABLE IF EXISTS `items`;
CREATE TABLE `items` (
  `items_id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(64) DEFAULT NULL,
  `price` double(10,2) DEFAULT NULL,
  `detail` varchar(255) DEFAULT NULL,
  `pic` varchar(255) DEFAULT NULL,
  `createtime` date DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of items
-- ----------------------------
INSERT INTO `items` VALUES ('1', '巧克力', '28.00', '黑巧克力', 'pic url', '2019-01-01');
INSERT INTO `items` VALUES ('2', '运动袜', '35.00', '运动袜', 'pic url', '2019-01-01');
INSERT INTO `items` VALUES ('3', '高跟鞋', '890.00', '高跟鞋', 'pic url', '2019-01-01');

-- ----------------------------
-- Table structure for orders
-- ----------------------------
DROP TABLE IF EXISTS `orders`;
CREATE TABLE `orders` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_id` int(11) DEFAULT NULL,
  `number` int(11) DEFAULT NULL,
  `createtime` date DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of orders
-- ----------------------------
INSERT INTO `orders` VALUES ('1', '1', '2', '2019-03-24');
INSERT INTO `orders` VALUES ('2', '2', '1', '2019-03-22');
INSERT INTO `orders` VALUES ('3', '2', '2', '2019-03-24');

-- ----------------------------
-- Table structure for ordersdetail
-- ----------------------------
DROP TABLE IF EXISTS `ordersdetail`;
CREATE TABLE `ordersdetail` (
  `ordersdetail_id` int(11) NOT NULL AUTO_INCREMENT,
  `items_id` int(11) DEFAULT NULL,
  `items_num` int(11) DEFAULT NULL,
  `orders_id` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of ordersdetail
-- ----------------------------
INSERT INTO `ordersdetail` VALUES ('1', '1', '1', '1');
INSERT INTO `ordersdetail` VALUES ('2', '2', '1', '1');
INSERT INTO `ordersdetail` VALUES ('3', '1', '1', '2');
INSERT INTO `ordersdetail` VALUES ('4', '2', '1', '3');
INSERT INTO `ordersdetail` VALUES ('5', '3', '1', '3');

-- ----------------------------
-- Table structure for user
-- ----------------------------
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(32) DEFAULT NULL,
  `birthday` date DEFAULT NULL,
  `address` varchar(255) DEFAULT NULL,
  `gender` varchar(4) DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `idx_username` (`username`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO `user` VALUES ('1', 'zhangsan', '1999-10-01', '北京市海淀区海淀黄庄', '男');
INSERT INTO `user` VALUES ('2', 'lili', '1989-02-02', '北京市朝阳区大运村', '女');

配置mybatis-generator插件，生成mapper、mapper.xml、model代码:

第一步：创建demo maven项目：

填写Group Id、Artifact Id、Packaging选择为pom：

此时项目值包含mybatie-study

然后，创建maven module-------选中mybatie-study maven项目，然后右键-》弹出菜单，菜单中选择New->选择Other...

在弹出New窗口中选择Maven->Maven Module

填写Maven Module名称

 

点击finish完成Maven Module创建。

第二步：在Maven Module项目mybatis-relation下/src/main/resources目录下，创建generatorConfig.xml文件

<?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>
    <!-- jdbc连接库jar包路径 -->
    <classPathEntry location="D:\IDE\maven\repository\mysql\mysql-connector-java\5.1.38\mysql-connector-java-5.1.38.jar" />
    <!-- eclipse tool配置 Location = E:\Java\apache-maven-3.2.3\bin\mvn.bat Working 
        Direction = ${workspace_loc:/linetoy-common} Arguments = mybatis-generator:generate -->
    <context id="DB2Tables" targetRuntime="MyBatis3">
        <!-- 去掉注释，一般都会去掉，那个注释真的不敢让人恭维 -->
        <commentGenerator>
            <property name="suppressAllComments" value="true" />
        </commentGenerator>
        <!-- jdbc连接配置 -->
        <jdbcConnection driverClass="com.mysql.jdbc.Driver"
            connectionURL="jdbc:mysql://localhost:3306/relation?characterEncoding=UTF-8" userId="root"
            password="root">
        </jdbcConnection>
        <!-- 数字字段是否强制使用BigDecimal类 -->
        <javaTypeResolver>
            <property name="forceBigDecimals" value="false" />
        </javaTypeResolver>
        <!-- entity创建后放在那个项目的哪个包路径上 -->
        
        <javaModelGenerator targetPackage="com.dx.mybatis01.model"
            targetProject="D:\git\springboot_learn01\mybatie-study\mybatis-relation\src\main\java">
            <property name="enableSubPackages" value="true" />
            <property name="trimStrings" value="true" />
        </javaModelGenerator> 
        
        <!-- dao创建后放在那个项目的哪个包路径上 -->
        <sqlMapGenerator targetPackage="com.dx.mybatis01.dao"
            targetProject="D:\git\springboot_learn01\mybatie-study\mybatis-relation\src\main\java">
            <property name="enableSubPackages" value="true" />
        </sqlMapGenerator>
        <!-- dao的.xml描述sql文件创建后放在那个项目的哪个包路径上 -->
        <javaClientGenerator type="XMLMAPPER"
            targetPackage="com.dx.mybatis01.dao"
            targetProject="D:\git\springboot_learn01\mybatie-study\mybatis-relation\src\main\java">
            <property name="enableSubPackages" value="true" />
        </javaClientGenerator>
        <!-- 要生成的表配置，可以多个 tableName：表名 domainObjectName：指定类名 -->
        <table tableName="orders" domainObjectName="Orders"
            enableCountByExample="false" enableUpdateByExample="false"
            enableDeleteByExample="false" enableSelectByExample="false"
            selectByExampleQueryId="false">
              <generatedKey column="id" sqlStatement="Mysql" identity="true" />
        </table>
    </context>
</generatorConfiguration>

该配置文件用来配置生成mybatis代码规则，以及代码生成目录，将要生成代码的table配置。

第三步：在Maven Module项目mybatis-relation中pom.xml中引入依赖包：

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.dx.mybatis01</groupId>
        <artifactId>mybatie-study</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>
    <groupId>com.dx.mybatis01.relation</groupId>
    <artifactId>mybatis-relation</artifactId>

    <dependencies>
        <!-- 配置mybatis的开发包 -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.1</version>
        </dependency>
        <!-- 配置mysql支持包 -->
        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.38</version>
        </dependency>          
        <!-- 日志 slf4j是规范/接口 日志实现:log4j,logback,common-logging 这里使用:slf4j + log4j -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.2</version>
        </dependency>
        
        <!-- https://mvnrepository.com/artifact/org.mybatis.generator/mybatis-generator-core -->
        <dependency>
            <groupId>org.mybatis.generator</groupId>
            <artifactId>mybatis-generator-core</artifactId>
            <version>1.3.5</version>
        </dependency>
                
    </dependencies>
    <build>
        <defaultGoal>compile</defaultGoal>
        <finalName>mybatis-plugin</finalName>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>2.1</version>
                <configuration>
                    <skip>true</skip>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.3.5</version>
                <configuration>   
                    <configurationFile>${basedir}/src/main/resources/generatorConfig.xml</configurationFile>
                    <verbose>true</verbose>
                    <overwrite>true</overwrite>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

第四步：选中Maven Module项目右键运行生成mybatis代码：

在Maven build.....弹出窗口中，Global参数中填写“mybatis-generator:generate”，并运行

执行日志：

Apache Maven 3.3.9 (bb52d8502b132ec0a5a3f4c09453c07478323dc5; 2015-11-11T00:41:47+08:00)
Maven home: D:\Java_Study\apache-maven-3.3.9
Java version: 1.8.0_161, vendor: Oracle Corporation
Java home: C:\Program Files\Java\jdk1.8.0_161\jre
Default locale: zh_CN, platform encoding: GBK
OS name: "windows 7", version: "6.1", arch: "amd64", family: "dos"
[DEBUG] Created new class realm maven.api
[DEBUG] Importing foreign packages into class realm maven.api
。。。。。。
[DEBUG] Populating class realm maven.api
[INFO] Error stacktraces are turned on.
[DEBUG] Reading global settings from D:\Java_Study\apache-maven-3.3.9\conf\settings.xml
[DEBUG] Reading user settings from D:\Java_Study\apache-maven-3.3.9\conf\settings.xml
[DEBUG] Reading global toolchains from D:\Java_Study\apache-maven-3.3.9\conf\toolchains.xml
[DEBUG] Reading user toolchains from C:\Users\Administrator\.m2\toolchains.xml
[DEBUG] Using local repository at D:\IDE\maven\repository
[DEBUG] Using manager EnhancedLocalRepositoryManager with priority 10.0 for D:\IDE\maven\repository
[INFO] Scanning for projects...
[DEBUG] Using mirror nexus-aliyun (http://maven.aliyun.com/nexus/content/groups/public) for central (https://repo.maven.apache.org/maven2).
[DEBUG] Extension realms for project com.dx.mybatis01.relation:mybatis-relation:jar:0.0.1-SNAPSHOT: (none)
[DEBUG] Looking up lifecyle mappings for packaging jar from ClassRealm[plexus.core, parent: null]
[DEBUG] Extension realms for project com.dx.mybatis01:mybatie-study:pom:0.0.1-SNAPSHOT: (none)
[DEBUG] Looking up lifecyle mappings for packaging pom from ClassRealm[plexus.core, parent: null]
[DEBUG] Resolving plugin prefix mybatis-generator from [org.apache.maven.plugins, org.codehaus.mojo]
[DEBUG] Using mirror nexus-aliyun (http://maven.aliyun.com/nexus/content/groups/public) for snapshots (http://snapshots.maven.codehaus.org/maven2).
[DEBUG] Resolved plugin prefix mybatis-generator to org.mybatis.generator:mybatis-generator-maven-plugin from POM com.dx.mybatis01.relation:mybatis-relation:jar:0.0.1-SNAPSHOT
[DEBUG] === REACTOR BUILD PLAN ================================================
[DEBUG] Project: com.dx.mybatis01.relation:mybatis-relation:jar:0.0.1-SNAPSHOT
[DEBUG] Tasks:   [mybatis-generator:generate]
[DEBUG] Style:   Regular
[DEBUG] =======================================================================
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building mybatis-relation 0.0.1-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[DEBUG] Resolving plugin prefix mybatis-generator from [org.apache.maven.plugins, org.codehaus.mojo]
[DEBUG] Resolved plugin prefix mybatis-generator to org.mybatis.generator:mybatis-generator-maven-plugin from POM com.dx.mybatis01.relation:mybatis-relation:jar:0.0.1-SNAPSHOT
[DEBUG] Lifecycle default -> [validate, initialize, generate-sources, process-sources, generate-resources, process-resources, compile, process-classes, generate-test-sources, process-test-sources, generate-test-resources, process-test-resources, test-compile, process-test-classes, test, prepare-package, package, pre-integration-test, integration-test, post-integration-test, verify, install, deploy]
[DEBUG] Lifecycle clean -> [pre-clean, clean, post-clean]
[DEBUG] Lifecycle site -> [pre-site, site, post-site, site-deploy]
[DEBUG] === PROJECT BUILD PLAN ================================================
[DEBUG] Project:       com.dx.mybatis01.relation:mybatis-relation:0.0.1-SNAPSHOT
[DEBUG] Dependencies (collect): []
[DEBUG] Dependencies (resolve): []
[DEBUG] Repositories (dependencies): [nexus-aliyun (http://maven.aliyun.com/nexus/content/groups/public, default, releases)]
[DEBUG] Repositories (plugins)     : [nexus-aliyun (http://maven.aliyun.com/nexus/content/groups/public, default, releases)]
[DEBUG] -----------------------------------------------------------------------
[DEBUG] Goal:          org.mybatis.generator:mybatis-generator-maven-plugin:1.3.5:generate (default-cli)
[DEBUG] Style:         Regular
[DEBUG] Configuration: <?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <configurationFile default-value="${project.basedir}/src/main/resources/generatorConfig.xml">D:\git\springboot_learn01\mybatie-study\mybatis-relation/src/main/resources/generatorConfig.xml</configurationFile>
  <contexts>${mybatis.generator.contexts}</contexts>
  <jdbcDriver>${mybatis.generator.jdbcDriver}</jdbcDriver>
  <jdbcPassword>${mybatis.generator.jdbcPassword}</jdbcPassword>
  <jdbcURL>${mybatis.generator.jdbcURL}</jdbcURL>
  <jdbcUserId>${mybatis.generator.jdbcUserId}</jdbcUserId>
  <outputDirectory default-value="${project.build.directory}/generated-sources/mybatis-generator">${mybatis.generator.outputDirectory}</outputDirectory>
  <overwrite default-value="false">true</overwrite>
  <project>${project}</project>
  <skip default-value="false">${mybatis.generator.skip}</skip>
  <sqlScript>${mybatis.generator.sqlScript}</sqlScript>
  <tableNames>${mybatis.generator.tableNames}</tableNames>
  <verbose default-value="false">true</verbose>
</configuration>
[DEBUG] =======================================================================
[INFO] 
[INFO] --- mybatis-generator-maven-plugin:1.3.5:generate (default-cli) @ mybatis-relation ---
[DEBUG] Using mirror nexus-aliyun (http://maven.aliyun.com/nexus/content/groups/public) for apache.snapshots (http://repository.apache.org/snapshots).
[DEBUG] Using mirror nexus-aliyun (http://maven.aliyun.com/nexus/content/groups/public) for sonatype-nexus-snapshots (https://oss.sonatype.org/content/repositories/snapshots).
[DEBUG] Using mirror nexus-aliyun (http://maven.aliyun.com/nexus/content/groups/public) for repository.jboss.org (http://repository.jboss.org/maven2).
[DEBUG] Using mirror nexus-aliyun (http://maven.aliyun.com/nexus/content/groups/public) for snapshots.jboss.org (http://snapshots.jboss.org/maven2).
[DEBUG] Using mirror nexus-aliyun (http://maven.aliyun.com/nexus/content/groups/public) for oss.sonatype.org/jboss-snapshots (http://oss.sonatype.org/content/repositories/jboss-snapshots).
[DEBUG] Dependency collection stats: {ConflictMarker.analyzeTime=1, ConflictMarker.markTime=0, ConflictMarker.nodeCount=17, ConflictIdSorter.graphTime=0, ConflictIdSorter.topsortTime=1, ConflictIdSorter.conflictIdCount=14, ConflictIdSorter.conflictIdCycleCount=0, ConflictResolver.totalTime=2, ConflictResolver.conflictItemCount=17, DefaultDependencyCollector.collectTime=739, DefaultDependencyCollector.transformTime=5}
[DEBUG] org.mybatis.generator:mybatis-generator-maven-plugin:jar:1.3.5:
。。。。。。
[DEBUG] Configuring mojo org.mybatis.generator:mybatis-generator-maven-plugin:1.3.5:generate from plugin realm ClassRealm[plugin>org.mybatis.generator:mybatis-generator-maven-plugin:1.3.5, parent: sun.misc.Launcher$AppClassLoader@33909752]
[DEBUG] Configuring mojo 'org.mybatis.generator:mybatis-generator-maven-plugin:1.3.5:generate' with basic configurator -->
[DEBUG]   (f) configurationFile = D:\git\springboot_learn01\mybatie-study\mybatis-relation\src\main\resources\generatorConfig.xml
[DEBUG]   (f) outputDirectory = D:\git\springboot_learn01\mybatie-study\mybatis-relation\target\generated-sources\mybatis-generator
[DEBUG]   (f) overwrite = true
[DEBUG]   (f) project = MavenProject: com.dx.mybatis01.relation:mybatis-relation:0.0.1-SNAPSHOT @ D:\git\springboot_learn01\mybatie-study\mybatis-relation\pom.xml
[DEBUG]   (f) skip = false
[DEBUG]   (f) verbose = true
[DEBUG] -- end configuration --
[INFO] Connecting to the Database
Sun Mar 24 14:42:43 CST 2019 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.
[INFO] Introspecting table orders
[DEBUG] Retrieving column information for table "orders"
[DEBUG] Found column "id", data type 4, in table "relation..orders"
[DEBUG] Found column "user_id", data type 4, in table "relation..orders"
[DEBUG] Found column "number", data type 4, in table "relation..orders"
[DEBUG] Found column "createtime", data type 91, in table "relation..orders"
[INFO] Generating Record class for table orders
[INFO] Generating Mapper Interface for table orders
[INFO] Generating SQL Map for table orders
[INFO] Saving file OrdersMapper.xml
[INFO] Saving file Orders.java
[INFO] Saving file OrdersMapper.java
[WARNING] Existing file D:\git\springboot_learn01\mybatie-study\mybatis-relation\src\main\java\com\dx\mybatis01\model\Orders.java was overwritten
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.499 s
[INFO] Finished at: 2019-03-24T14:42:44+08:00
[INFO] Final Memory: 19M/491M
[INFO] ------------------------------------------------------------------------

刷新项目，此时可以发现项目中已经包含了新的代码生成：

一对一查询

实例：查询订单信息，关联查询创建订单的用户信息。

SELECT 
orders.*,user.username,user.gender,user.address 
FROM orders,USER 
WHERE orders.user_id = user.id

主查询表：orders
关联查询表：user
联结查询：内联结

利用ResultType

1、SQL语句的书写要领：先确定查询的主表，在确定查询的关联表，关联查询是使用内联结还是外联结。
2、POVO扩展类创建。(这是由于关联查询出来的信息是多张表的综合字段，所以我们可以根据POJO创建我们的扩展类)
3、Mapper.xml和Mapper.java的代理编写
4、进行测试

在Maven Module项目mybatis-relation下src/main/resources下创建mybatis.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" 
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <settings>
        <setting name="cacheEnabled" value="true"/>
    </settings>
    <typeAliases>
        <!-- <typeAlias type="com.demo.module.News" alias="News"/> -->
    </typeAliases>
    <environments default="development"> 
        <!-- 配置数据源的相关信息 -->
        <environment id="development">
            <transactionManager type="jdbc" /> <!-- 使用JDBC方式管理 -->
            <dataSource type="POOLED"> <!-- 设置数据源类型，此时为POOLED -->
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url" value="jdbc:mysql://localhost:3306/relation" />
                <!-- 设置数据库连接的用户名和密码 -->
                <property name="username" value="root" />
                <property name="password" value="root" /> 
            </dataSource> 
        </environment>
    </environments>
    <mappers>
          <mapper resource="com/dx/mybatis01/dao/OrdersExtendsMapper.xml"></mapper>
    </mappers>
</configuration>

在com.dx.mybatis01.module下创建module：

Order.java

package com.dx.mybatis01.model;

import java.util.Date;
import java.util.List;

public class Orders {
    private Integer id;

    private Integer userId;

    private Integer number;

    private Date createtime;  
    // 用户信息
    private User user;       
    //商品信息存放集合
    private List<OrdersDetail> orderdetails;   

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

    public List<OrdersDetail> getOrderdetails() {
        return orderdetails;
    }

    public void setOrderdetails(List<OrdersDetail> orderdetails) {
        this.orderdetails = orderdetails;
    }

    public Integer getId() {
        return id;
    }

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

    public Integer getUserId() {
        return userId;
    }

    public void setUserId(Integer userId) {
        this.userId = userId;
    }

    public Integer getNumber() {
        return number;
    }

    public void setNumber(Integer number) {
        this.number = number;
    }

    public Date getCreatetime() {
        return createtime;
    }

    public void setCreatetime(Date createtime) {
        this.createtime = createtime;
    }
}

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