springcloud适配mysql和oracle数据库

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("-","");
    }
}