mysql和oracle数据库部分语法不相同，为了适配两种数据库（修改配置文件方式），可以先操作sql，然后通过代码级别再实现。比如oracle限制返回的条数：rownum<=1 但是mysql的语法是：limit 1,你可以通过返回所有数据，然后再get(0)去除第一条数据，
今天的重点：springcloud+tk.mybatis+oracle/mysql
1.先上依赖：
父工程部分依赖：
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.2.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<java.version>1.8</java.version>
<spring-cloud.version>Hoxton.SR1</spring-cloud.version>
<springboot.version>2.2.2.RELEASE</springboot.version>
<spring.version>5.0.9.RELEASE</spring.version>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
</properties>
子工程：
<?xml version="1.0" encoding="UTF-8"?> <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 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <parent> <groupId>com.xxx</groupId> <artifactId>xxxxxxxx</artifactId> <version>0.0.1-SNAPSHOT</version> </parent> <modelVersion>4.0.0</modelVersion> <artifactId>xxxxx-xxxx</artifactId> <description>xxxx-xxxxx</description> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> <version>${springboot.version}</version> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <version>${springboot.version}</version> <scope>test</scope> <exclusions> <exclusion> <groupId>org.junit.vintage</groupId> <artifactId>junit-vintage-engine</artifactId> </exclusion> </exclusions> </dependency> <!-- 数据库配置 start--> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>2.1.3</version> </dependency> <dependency> <groupId>tk.mybatis</groupId> <artifactId>mapper-spring-boot-starter</artifactId> <version>2.1.5</version> </dependency> <!-- <dependency>--> <!-- <groupId>com.baomidou</groupId>--> <!-- <artifactId>mybatis-plus</artifactId>--> <!-- <version>2.3</version>--> <!-- </dependency>--> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-autoconfigure</artifactId> <version>1.3.2</version> </dependency> <dependency> <groupId>com.zhdgps.oracle</groupId> <artifactId>ojdbc6</artifactId> <version>11.2.0.1.0</version> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid</artifactId> <version>1.1.9</version> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid-spring-boot-starter</artifactId> <version>1.1.9</version> </dependency> <!-- 数据库配置 end --> <!-- https://mvnrepository.com/artifact/com.github.pagehelper/pagehelper-spring-boot-starter --> <dependency> <groupId>com.github.pagehelper</groupId> <artifactId>pagehelper-spring-boot-starter</artifactId> <version>1.2.13</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.21</version> </dependency> <!-- 注册中心 start--> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId> </dependency> <!-- <dependency>--> <!-- <groupId>org.springframework.cloud</groupId>--> <!-- <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>--> <!-- <version>0.2.2.RELEASE</version>--> <!-- </dependency>--> <!-- <dependency>--> <!-- <groupId>org.springframework.cloud</groupId>--> <!-- <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>--> <!-- <version>0.2.2.RELEASE</version>--> <!-- </dependency>--> <!-- 注册中心 end--> <!-- swagger start --> <dependency> <groupId>io.springfox</groupId> <artifactId>springfox-swagger2</artifactId> <version>2.9.2</version> </dependency> <dependency> <groupId>io.springfox</groupId> <artifactId>springfox-swagger-ui</artifactId> <version>2.9.2</version> </dependency> <!-- swagger end --> <!-- jwt --> <dependency> <groupId>com.auth0</groupId> <artifactId>java-jwt</artifactId> <version>3.10.0</version> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <version>1.18.10</version> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>easyexcel</artifactId> <version>2.2.6</version> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.62</version> </dependency> <dependency> <groupId>org.springframework.data</groupId> <artifactId>spring-data-redis</artifactId> <version>${springboot.version}</version> </dependency> <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-pool2</artifactId> <version>2.9.0</version> </dependency> <!-- https://mvnrepository.com/artifact/redis.clients/jedis --> <dependency> <groupId>redis.clients</groupId> <artifactId>jedis</artifactId> <version>3.3.0</version> </dependency> <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-lang3 --> <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-lang3</artifactId> <version>3.11</version> </dependency> <!-- <dependency>--> <!-- <groupId>org.mybatis</groupId>--> <!-- <artifactId>mybatis</artifactId>--> <!-- <version>3.5.5</version>--> <!-- <scope>compile</scope>--> <!-- </dependency>--> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-tx</artifactId> <version>5.2.9.RELEASE</version> <scope>compile</scope> </dependency> <dependency> <groupId>commons-io</groupId> <artifactId>commons-io</artifactId> <version>2.8.0</version> <scope>compile</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> <version>${springboot.version}</version> <configuration><!-- 指定该Main Class为全局的唯一入口 --> <mainClass>com.zhd.eoms.EomsApplication</mainClass> <!-- <layout>ZIP</layout>--> </configuration> <executions> <execution> <goals> <goal>repackage</goal><!--可以把依赖的包都打包到生成的Jar包中--> </goals> </execution> </executions> </plugin> </plugins> </build> </project>
根据上面的依赖选择，不要都贴上，
然后使用mybatis-generator自动生成entity、mapper和xml映射文件，
略
然后就是今天的重点：怎样配置数据库id的类型
第一种：自增ID，可以这样配置：
@Id @Column(insertable = false, name = "ID") @GeneratedValue( generator = "JDBC") private Integer id;
这样oracle和mysql都适用；
自增适合哪种经常查询信息，因为id是天然有序，效率高一些，
如果是UUID：
@Id @Column(name = "ID") @KeySql(genId = UUIDGenId.class)
public class UUIDGenId implements GenId<String>{ @Override public String genId(String s, String s1) { return UUID.randomUUID().toString().replace("-",""); } }
UUIDGenId 类
public class UUIDGenId implements GenId<String>{// @Override public String genId(String s, String s1) { return UUID.randomUUID().toString().replace("-",""); } }
