本文将会介绍SpringBoot集成Mybatis，主要关注DataSource的配置

然后引入Druid数据库连接池，最后使用Zookeeper实现数据源的动态配置

3.1.SpringBoot集成Mybatis

3.1.1.添加依赖包

添加项目依赖包；SpringBoot、Mybatis、Mysql连接等

    
        spring-boot-starter-parent
        org.springframework.boot
        2.3.12.RELEASE
        
    
    4.0.0

    org.poiuy
    1.0-SNAPSHOT
    springboot-datasource-mybatis

    
        11
        11
    

    
        
            org.springframework.boot
            spring-boot-starter-web
            2.3.12.RELEASE
            
                
                    spring-boot-starter-logging
                    org.springframework.boot
                
            
        

        
            org.springframework.boot
            spring-boot-starter-log4j2
            2.5.2
        

        
            mysql
            mysql-connector-java
            8.0.26
        

        
            org.mybatis.spring.boot
            mybatis-spring-boot-starter
            2.1.3
        

        
            org.mybatis
            mybatis-typehandlers-jsr310
            1.0.2
        

        
            org.springframework.boot
            spring-boot-starter-validation
            2.3.11.RELEASE
        
    

3.1.2.添加SpringBoot配置文件

SpringBoot配置文件，添加datasource和mybatis的配置

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    username: root
    password: xxx
    url: jdbc:mysql://192.168.1.208:9906/poiuy_study?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai

mybatis:
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: org.poiuy.springboot.datasource.mybatis.domain

3.1.3.添加Domain类

添加数据对象

public class MybatisUser {
    private Integer userId;

    @NotNull(message = "用户名不能为空")
    private String username;
    private String secure;

    public Integer getUserId() {
        return userId;
    }

    public void setUserId(Integer userId) {
        this.userId = userId;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getSecure() {
        return secure;
    }

    public void setSecure(String secure) {
        this.secure = secure;
    }
}

3.1.4.添加Mapper

mapper接口中添加一个查询用户方法

@Mapper
public interface MybatisUserMapper {
    MybatisUser selectByUsername(@Param("username") String username);
}

对应的xml文件

    
        
        
        
    

    
    
        SELECT user_id,username FROM mybatis_user WHERE username = #{username}
    

3.1.5.Service接口

service接口直接调用mapper方法

@Service("mybatisUserService")
public class MybatisUserServiceImpl implements MybatisUserService {
    private final MybatisUserMapper mybatisUserMapper;

    @Autowired
    public MybatisUserServiceImpl(MybatisUserMapper mybatisUserMapper) {
        this.mybatisUserMapper = mybatisUserMapper;
    }

    @Override
    public MybatisUser getUserByUsername(String username) {
        return mybatisUserMapper.selectByUsername(username);
    }
}

3.1.6.Controller控制器

user控制器

@RestController
@RequestMapping("/user")
public class UserController {
    private final Logger logger = LogManager.getLogger(getClass());
    private final MybatisUserService mybatisUserService;

    @Autowired
    public UserController(MybatisUserService mybatisUserService){
        this.mybatisUserService = mybatisUserService;
    }

    @PostMapping
    public R getByUsername(@RequestBody @Valid MybatisUser mybatisUser){
        String username = mybatisUser.getUsername();
        logger.debug("获取到参数：{}",username);
        MybatisUser dbUser = mybatisUserService.getUserByUsername(username);
        return R.ok().put("data",dbUser);
    }
}

3.1.7.测试

运行SpringBoot程序，在PostMan中调用请求

3.2.增加Druid连接池

3.2.1.添加依赖包

添加Druid的依赖包

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

    4.0.0

    1.0-SNAPSHOT
    org.poiuy
    springboot-datasource-druid

    
        11
        11
    

    
        
            org.springframework.boot
            spring-boot-starter-web
            2.3.12.RELEASE
            
                
                    spring-boot-starter-logging
                    org.springframework.boot
                
            
        

        
            org.springframework.boot
            spring-boot-starter-log4j2
            2.5.2
        

        
            mysql
            mysql-connector-java
            8.0.26
        

        
            org.mybatis.spring.boot
            mybatis-spring-boot-starter
            2.1.3
        

        
            com.alibaba
            druid-spring-boot-starter
            1.2.5
        

        
            org.springframework.boot
            spring-boot-starter-validation
            2.4.0
        
    

3.2.2.修改SpringBoot配置文件

SpringBoot配置文件，删除原来的Datasource配置，并增加Druid

Druid分为基础配置、监控配置和连接池参数配置。可根据需要进行配置

spring:
  datasource:
    # 切换数据源
    type: com.alibaba.druid.pool.DruidDataSource
    druid:
      # Druid基础配置 ， 与DataSource配置等同的效果
      username: root
      password: xxx
      url: jdbc:mysql://192.168.1.208:9906/poiuy_study?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
      driver-class-name: com.mysql.cj.jdbc.Driver

      # Druid监控
      filter:
        stat:
          log-slow-sql: true
          slow-sql-millis: 1000
          merge-sql: false
        wall:
          config:
            multi-statement-allow: true
      web-stat-filter:
        enabled: true
        url-pattern: /*
        exclusions: /druid/*,*.js,*.gif,*.jpg,*.bmp,*.png,*.css,*.ico
        session-stat-enable: true
        session-stat-max-count: 10
        principal-session-name: session_name
        principal-cookie-name: cookie_name
        profile-enable:
      stat-view-servlet:
        enabled: true
        url-pattern: /druid/*
        reset-enable: false
        login-username: poiuy
        login-password: 123456
        allow: 127.0.0.1,192.168.1.111
        deny:
      aop-patterns:

      #连接池配置
      name: testDruidDataSource
      initial-size: 10
      max-active: 20
      min-idle: 10
      max-wait: 60000
      pool-prepared-statements: true
      max-pool-prepared-statement-per-connection-size: 20
      validation-query: SELECT 1 FROM DUAL
      validation-query-timeout: 3000
      test-on-borrow: false
      test-on-return: false
      test-while-idle: true
      time-between-eviction-runs-millis: 5000
      min-evictable-idle-time-millis: 5000
      max-evictable-idle-time-millis: 5000

mybatis:
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: org.poiuy.springboot.datasource.mybatis.domain

3.2.3.测试

运行SpringBoot程序，在PostMan中调用请求

另外如果配置了Druid监控配置项，那么在浏览器输入
http://localhost:8080/druid/index.html

可以进入Druid的监控界面

3.3.Zookeeper实现数据源的动态配置

3.3.1.添加依赖包

在pom.xml中新增curator依赖包

    
        spring-boot-starter-parent
        org.springframework.boot
        2.3.12.RELEASE
        
    
    4.0.0

    org.poiuy
    1.0-SNAPSHOT
    springboot-datasource-dynamic

    
        11
        11
    

    
        
            org.springframework.boot
            spring-boot-starter-web
            2.3.12.RELEASE
            
                
                    spring-boot-starter-logging
                    org.springframework.boot
                
            
        

        
            org.springframework.boot
            spring-boot-starter-log4j2
            2.5.2
        

        
            org.mybatis.spring.boot
            mybatis-spring-boot-starter
            2.1.3
        

        
            mysql
            mysql-connector-java
            8.0.26
        

        
            com.alibaba
            druid-spring-boot-starter
            1.2.5
        

        
            org.apache.curator
            curator-recipes
            2.11.0
        

        
            org.springframework.boot
            spring-boot-starter-validation
            2.3.12.RELEASE
        

        
            com.google.code.gson
            gson
            2.8.8
        
    

3.3.2.SpringBoot配置文件

修改SpringBoot配置文件，将Druid的基础配置进行注释，并添加Zookeeper配置项

spring:
  datasource:
    # 切换数据源
    type: com.alibaba.druid.pool.DruidDataSource
    druid:
      # Druid基础配置 ， 与DataSource配置等同的效果
      # username: root
      # password: xxx
      # url: jdbc:mysql://192.168.1.208:9906/poiuy_study?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
      # driver-class-name: com.mysql.cj.jdbc.Driver

      # Druid监控
      filter:
        stat:
          log-slow-sql: true
          slow-sql-millis: 1000
          merge-sql: false
        wall:
          config:
            multi-statement-allow: true
      web-stat-filter:
        enabled: true
        url-pattern: /*
        exclusions: /druid/*,*.js,*.gif,*.jpg,*.bmp,*.png,*.css,*.ico
        session-stat-enable: true
        session-stat-max-count: 10
        principal-session-name: session_name
        principal-cookie-name: cookie_name
        profile-enable:
      stat-view-servlet:
        enabled: true
        url-pattern: /druid/*
        reset-enable: false
        login-username: poiuy
        login-password: 123456
        allow: 127.0.0.1,192.168.1.111
        deny:
      aop-patterns:

      #连接池配置
      name: testDruidDataSource
      initial-size: 10
      max-active: 20
      min-idle: 10
      max-wait: 60000
      pool-prepared-statements: true
      max-pool-prepared-statement-per-connection-size: 20
      validation-query: SELECT 1 FROM DUAL
      validation-query-timeout: 3000
      test-on-borrow: false
      test-on-return: false
      test-while-idle: true
      time-between-eviction-runs-millis: 5000
      min-evictable-idle-time-millis: 5000
      max-evictable-idle-time-millis: 5000

mybatis:
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: org.poiuy.springboot.datasource.mybatis.domain

zookeeper:
  connectString: 192.168.1.208:2181
  connectionTimeoutMs: 5000
  maxRetries: 3
  baseSleepTimeMs: 1000
  listenerPath: /zookeeper/datasource

3.3.3.集成Zookeeper

创建ZookeeperConfig，将CuratorFramework注入到Spring中，用来操作Zookeeper

@Configuration
public class ZookeeperConfig {
    @Value("${zookeeper.connectString}")
    private String connectString;
    @Value("${zookeeper.connectionTimeoutMs}")
    private Integer connectionTimeoutMs;
    @Value("${zookeeper.maxRetries}")
    private Integer maxRetries;
    @Value("${zookeeper.baseSleepTimeMs}")
    private Integer baseSleepTimeMs;

    private CuratorFramework client;

    @PostConstruct
    public void init(){
        client = CuratorFrameworkFactory.builder()
                .connectString(connectString)
                .connectionTimeoutMs(connectionTimeoutMs)
                .retryPolicy(new ExponentialBackoffRetry(baseSleepTimeMs, maxRetries))
                .build();
        //连接
        client.start();
    }

    @Bean
    public CuratorFramework curatorFramework(){
        return this.client;
    }
}

3.3.4.定义DataSource配置

此时需要重新构建DruidDataSource对象，在生成dataSource时从zookeeper中获取配置信息，并赋值到DataSource

这里只写了基本的4个参数，注意此时需要将Spring配置文件中相同的属性删除，否则会被Spring配置文件中的值覆盖掉

@Configuration
public class DruidConfig {
    private final Logger logger = LogManager.getLogger(getClass());

    @Resource
    private CuratorFramework curatorFramework;

    @Value("${zookeeper.listenerPath}")
    private String datasourceParh;

    @ConfigurationProperties(prefix = "spring.datasource.druid")
    @Bean
    public DataSource dataSource(){
        DruidDataSource druidDataSource = new DruidDataSource();

        try {
            byte[] datasourceData = curatorFramework.getData().forPath(datasourceParh);
            String datasourceJson = new String(datasourceData);
            logger.debug("获取到zookeeper的数据：{}",datasourceJson);
            Gson gson = new GsonBuilder().serializeNulls().create();
            ZookeeperDataSource zookeeperDataSource = gson.fromJson(datasourceJson,ZookeeperDataSource.class);
            if(zookeeperDataSource == null) {
                return druidDataSource;
            }
            druidDataSource.setUrl(zookeeperDataSource.getUrl());
            druidDataSource.setUsername(zookeeperDataSource.getUsername());
            druidDataSource.setPassword(zookeeperDataSource.getPassword());
            druidDataSource.setDriverClassName(zookeeperDataSource.getDriver());
        } catch (Exception e) {
            e.printStackTrace();
        }

        return druidDataSource;
    }
}

Zookeeper上配置的数据源信息，直接存储了json数据

此时启动项目，在PostMan中调用接口测试

虽然SpringBoot的配置文件中没有配置数据源基本信息，但程序依旧运行正常

3.3.5.动态修改数据源

添加Zookeeper监听器，当数据节点的值发生变化时重新启动DataSource并设置修改后的值

@Component
public class ZookeeperListener {
    private static Logger logger = LogManager.getLogger(ZookeeperListener.class);

    @Value("${zookeeper.listenerPath}")
    private String listenerPath;

    @Resource
    private CuratorFramework client;

    @Resource
    private DruidDataSource dataSource;

    @PostConstruct
    public void start() throws Exception {
        //创建监听
        PathChildrenCache cache = new PathChildrenCache(client, "/zookeeper",true);
        cache.start();
        cache.rebuild();
        cache.getListenable().addListener((CuratorFramework curatorFramework, PathChildrenCacheEvent pathChildrenCacheEvent) -> {
            PathChildrenCacheEvent.Type type = pathChildrenCacheEvent.getType();
            ChildData data = pathChildrenCacheEvent.getData();
            List initialData = pathChildrenCacheEvent.getInitialData();
            logger.debug("节点发生变化,type = {} data = {} initialData = {}",type,data,initialData);

            if(data != null && listenerPath.equals(data.getPath())) {
                    byte[] datasourceData = data.getData();
                    String datasourceJson = new String(datasourceData);
                    logger.debug("获取到zookeeper的数据：{}",datasourceJson);
                    Gson gson = new GsonBuilder().serializeNulls().create();
                    ZookeeperDataSource zookeeperDataSource = gson.fromJson(datasourceJson,ZookeeperDataSource.class);
                    if(zookeeperDataSource != null) {
                        dataSource.restart();
                        dataSource.setUrl(zookeeperDataSource.getUrl());
                        dataSource.setUsername(zookeeperDataSource.getUsername());
                        dataSource.setPassword(zookeeperDataSource.getPassword());
                        dataSource.setDriverClassName(zookeeperDataSource.getDriver());
                    }
            }
        });
    }
}

这里为了测试，新建了一个数据库，测试动态数据库的变更

重新启动程序，调用接口，程序运行正常（注意此时返回的id为1）

然后通过Zookeeper客户端修改datasource的值（此处仅修改了database）

set /zookeeper/datasource {"username":"xxx","password":"xxx","url":"jdbc:mysql://192.168.1.208:9906/poiuy_study_bak?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai","driver":"com.mysql.cj.jdbc.Driver"}

在程序后台console中可以看到Zookeeper监听到数据变化后重新获取数据源配置并重启DruidDataSource

此时再次调用接口可以看到获取的值是更换后的数据库的数据