springboot 多數據源項目demo

背景: 公司要新建一個數據項目,因為要查詢多個數據源的數據，且之前也沒有做項目搭建的筆記，這次做一個記錄。開箱即用，真香警告！

搭建過程中遇到了一些問題，會逐步說明。代碼地址：https://gitee.com/aaron_qc/multi-datasource.git

1. 先上主菜。多數據源配置步驟
   1. 引入依賴 tkmapper + druid + mysql + spring-boot-configuration-processor

      1. <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-configuration-processor</artifactId>
             <version>2.1.5.RELEASE</version>
         </dependency>
         
         <!-- mysql and mybatis etc -->
         <dependency>
             <groupId>tk.mybatis</groupId>
             <artifactId>mapper-spring-boot-starter</artifactId>
             <version>2.1.4</version>
         </dependency>
         
         <dependency>
             <groupId>mysql</groupId>
             <artifactId>mysql-connector-java</artifactId>
             <version>8.0.11</version>
         </dependency>
         
         <!-- druid -->
         <dependency>
             <groupId>com.alibaba</groupId>
             <artifactId>druid-spring-boot-starter</artifactId>
             <version>1.1.10</version>
         </dependency>

   2. 配置如下
      1. 啟動類加上@EnableConfigurationProperties。
         1. OceanApplication

            /**
             * @author QuCheng on 2019-09-16.
             * EnableConfigurationProperties 使 @ConfigurationProperties 注解的類（需要加@Component）生效。
             */
            @EnableConfigurationProperties
            @SpringBootApplication
            public class OceanApplication {
                public static void main(String[] args) {
                    SpringApplication.run(OceanApplication.class, args);
                }
            }

      2. yml配置相應屬性
         1. application.yml 屬性自定義名稱,只需要和對應java類對應即可

            druid:
              # 數據源配置
              user: root
              password: xxxx
              driverClass: com.mysql.cj.jdbc.Driver
              # 初始化 最小 最大
              initialSize: 5
              minIdle: 5
              maxActive: 20
              testOnBorrow: false
              urlIceberg: jdbc:mysql://106.12.176.120/iceberg?serverTimezone=GMT%2B8&characterEncoding=UTF-8&useSSL=false  # 設置時區
              urlOcean: jdbc:mysql://106.12.176.120/ocean?serverTimezone=GMT%2B8&characterEncoding=UTF-8&useSSL=false  # 設置時區
              urlAccount: jdbc:mysql://106.12.176.120/account?serverTimezone=GMT%2B8&characterEncoding=UTF-8&useSSL=false  # 設置時區　

      3. 自定義屬性加載父類BaseProperty
         1. 映射yml配置 。 

            package com.hb.ocean.druid;
            
            import com.alibaba.druid.pool.DruidDataSource;
            import lombok.Data;
            import org.springframework.boot.context.properties.ConfigurationProperties;
            import org.springframework.stereotype.Component;
            
            import javax.sql.DataSource;
            
            /**
             * datasource base class
             * @author qucheng
             */
            @Data
            @ConfigurationProperties(prefix = "druid")
            @Component
            class BaseProperty {
            
                protected String user;
            
                protected String password;
            
                protected String driverClass;
            
                protected int initialSize;
            
                protected int maxActive;
            
                protected int minIdle;
            
                protected boolean testOnBorrow;
            
                protected String urlAccount;
            
                protected String urlOcean;
            
                protected String urlIceberg;
            
            
                DataSource createDataSource(String url) {
                    DruidDataSource dataSource = new DruidDataSource();
                    dataSource.setDriverClassName(driverClass);
                    dataSource.setUrl(url);
                    dataSource.setUsername(user);
                    dataSource.setPassword(password);
                    dataSource.setInitialSize(initialSize);
                    dataSource.setMaxActive(maxActive);
                    dataSource.setMinIdle(minIdle);
                    dataSource.setTestOnBorrow(testOnBorrow);
                    return dataSource;
                }
            }

      4. 各數據源配置自己的映射路徑（mapper接口+xml文件）
         1. 配置路徑 -- 此處省略2個其他配置

            package com.hb.ocean.druid;
            
            import org.apache.ibatis.session.SqlSessionFactory;
            import org.mybatis.spring.SqlSessionFactoryBean;
            import org.springframework.beans.factory.annotation.Qualifier;
            import org.springframework.context.annotation.Bean;
            import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
            import org.springframework.jdbc.datasource.DataSourceTransactionManager;
            import org.springframework.stereotype.Component;
            import tk.mybatis.spring.annotation.MapperScan;
            
            import javax.sql.DataSource;
            
            /**
             * account datasource
             * MapperScan（如果要使用表名映射實體使用tk）注解用於綁定掃描的包和指定的數據源,且指定目錄下的mapper無需加注解處理
             *
             * @author qucheng
             */
            @Component
            @MapperScan(basePackages = "com.hb.ocean.mapper.account", sqlSessionFactoryRef = "accountSqlSessionFactory")
            public class AccountConfig extends BaseProperty {
            
                @Bean(name = "accountDataSource")
                public DataSource createDataSource() {
                    return createDataSource(urlAccount);
                }
            
                @Bean(name = "accountTransactionManager")
                public DataSourceTransactionManager accountTransactionManager() {
                    return new DataSourceTransactionManager(createDataSource());
                }
            
                @Bean(name = "accountSqlSessionFactory")
                public SqlSessionFactory masterSqlSessionFactory(@Qualifier("accountDataSource") DataSource accountDataSource)
                        throws Exception {
                    final SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean();
                    sessionFactory.setDataSource(accountDataSource);
                    String mapperLocation = "classpath:mapper/account/*.xml";
                    sessionFactory.setMapperLocations(new PathMatchingResourcePatternResolver()
                            .getResources(mapperLocation));
                    return sessionFactory.getObject();
                }
            }

      5. 創建相應目錄下的文件。在啟動項目時會加載。
         1. 結構如圖

             

   3. 成功之后啟動測試結果如下
      1. 測試代碼

         package com.hb.ocean.controller;
         
         import com.hb.ocean.mapper.account.UserMapper;
         import com.hb.ocean.mapper.iceberg.ItemOrderMapper;
         import org.springframework.web.bind.annotation.GetMapping;
         import org.springframework.web.bind.annotation.RequestMapping;
         import org.springframework.web.bind.annotation.RestController;
         
         import javax.annotation.Resource;
         
         /**
          * @author QuCheng on 2019-09-17.
          */
         @RestController
         @RequestMapping("/qc")
         public class TestView {
         
             /**
              * 不推薦直接在controller層引入Dao層。這里只做演示使用
              */
             @Resource
             private UserMapper userMapper;
             @Resource
             private ItemOrderMapper itemOrderMapper;
         
             @GetMapping("/test")
             public String test() {
                 System.out.println("用戶數：" + userMapper.selectCountUser(null, null));
                 System.out.println("訂單數：" + itemOrderMapper.selectCountSuccessOrder(null, null));
                 return "ok";
             }
         }

      2. 測試結果
         1. 

以上過程也出現的幾個問題

1. 多數據源共用了一個yml基礎配置，除了數據源url地址不一致之外。
2. 自定義yml屬性配置項需要
   1. 引入spring-boot-configuration-processor。
   2. 啟動類使用注解@EnableConfigurationProperties
   3. 解析類上面要引入3個注解@Data只是為了方便。@ConfigurationProperties(prefix = "druid")指明讀取的是"druid"開始的屬性。@Component表示由容器管理
3. 配置類@MapperScan注解是使用的tk.mybatis.spring.annotation.MapperScan注解。org.mybatis.spring.annotation.MapperScan也可以用但是它不能配合使用@Table注解映射表。

springboot多數據源配置的過程如上。這是demo版本，之后會出更多記錄文章。實際應用數據中還涉及

1. eureka的注冊發現。啟動類注解引入
2. feign接口調用以及失敗熔斷
3. 優雅停機簡單處理
4. swagger文檔
5. redis分布式事務