SpringBoot使用sharding-jdbc分库分表

> 

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<groupId>org.springframework.boot</groupId> 

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<artifactId>spring-boot-starter-parent</artifactId> 

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<version>1.5.16.RELEASE</version> 

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<relativePath/> <!-- lookup parent from repository --> 

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</parent> 

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<properties> 

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<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> 

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<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> 

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<java.version>1.8</java.version> 

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</properties> 

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<dependencies> 

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<dependency> 

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<groupId>org.springframework.boot</groupId> 

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<artifactId>spring-boot-starter-data-jpa</artifactId> 

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</dependency> 

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<dependency> 

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<groupId>org.springframework.boot</groupId> 

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<artifactId>spring-boot-starter-web</artifactId> 

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</dependency> 

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<dependency> 

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<groupId>mysql</groupId> 

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<artifactId>mysql-connector-java</artifactId> 

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<scope>runtime</scope> 

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</dependency> 

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<dependency> 

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<groupId>org.springframework.boot</groupId> 

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<artifactId>spring-boot-starter-test</artifactId> 

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<scope>test</scope> 

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</dependency> 

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<dependency> 

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<groupId>com.dangdang</groupId> 

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<artifactId>sharding-jdbc-core</artifactId> 

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<version>1.4.2</version> 

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</dependency> 

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<dependency> 

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<groupId>com.alibaba</groupId> 

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<artifactId>druid</artifactId> 

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<version>1.0.12</version> 

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</dependency> 

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<dependency> 

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<groupId>com.dangdang</groupId> 

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<artifactId>sharding-jdbc-self-id-generator</artifactId> 

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<version>1.4.2</version> 

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</dependency> 

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</dependencies> 

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目前好像不支持SpringBoot2.0以上的版本。

2.2编写实体类及建库建表

目标：
db0
├── t_order_0 user_id为偶数 order_id为偶数
├── t_order_1 user_id为偶数 order_id为奇数
db1
├── t_order_0 user_id为奇数 order_id为偶数
├── t_order_1 user_id为奇数 order_id为奇数

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1. 创建两个数据库 ds_0 和 ds_1，编码类型UTF-8。
2. 每个库分表创建两个表t_order_0和t_order_1,sql语句如下：
   
   DROP TABLE IF EXISTS t_order_0;
   CREATE TABLE t_order_0 (
   order_id bigint(20) NOT NULL,
   user_id bigint(20) NOT NULL,
   PRIMARY KEY (order_id)
   ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin;
3. 新建类Order，代码如下

1. package cn.sp.bean; 

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2.  

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3. import javax.persistence.Entity; 

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4. import javax.persistence.Id; 

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5. import javax.persistence.Table; 

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6.  

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7. /** 

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8. * Created by 2YSP on 2018/9/23. 

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9. */ 

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10. @Entity 

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11. @Table(name="t_order") 

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12. public class Order { 

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13. @Id 

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14. private Long orderId; 

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15.  

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16. private Long userId; 

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17.  

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18. public Long getOrderId() { 

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19. return orderId; 

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20. } 

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21.  

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22. public void setOrderId(Long orderId) { 

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23. this.orderId = orderId; 

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24. } 

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25.  

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26. public Long getUserId() { 

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27. return userId; 

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28. } 

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29.  

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30. public void setUserId(Long userId) { 

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31. this.userId = userId; 

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32. } 

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33. } 

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34.  

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这里需要注意 @Id注解不要导错包，之前我就遇到过这个问题。
4.配置文件application.yml

1. server: 

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2. port: 8000 

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3. spring: 

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4. jpa: 

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5. database: mysql 

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6. show-sql: true 

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7. hibernate: 

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8. ## 自己建表 

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9. ddl-auto: none 

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10. application: 

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11. name: sharding-jdbc-first 

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这里要注意的是spring-data-jpa默认会自己建表，这里我们要手动建立，所以需要将ddl-auto属性设置为none。

2.3自定义分库分表算法

1.分库算法类需要实现SingleKeyDatabaseShardingAlgorithm<T>接口，这是一个泛型接口，T代表分库依据的字段的类型，比如我们根据userId%2来分库，userId是Long型的，这里的T就是Long。

1. public cl