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：

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org.springframework.boot
spring-boot-starter-parent
2.2.2.RELEASE

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<?xml version="1.0" encoding="UTF-8"?>

com.xxx
xxxxxxxx
0.0.1-SNAPSHOT

4.0.0
xxxxx-xxxx
xxxx-xxxxx

<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>

    <!--            <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>

    <!-- 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.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>

            </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>

复制代码 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)

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public class UUIDGenId implements GenId{
@Override
public String genId(String s, String s1) {
return UUID.randomUUID().toString().replace(“-”,“”);
}
}
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UUIDGenId 类
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public class UUIDGenId implements GenId{//
@Override
public String genId(String s, String s1) {
return UUID.randomUUID().toString().replace(“-”,“”);
}
}