nacos支持配置文件热部署

1.原理

  @RefreshScope注解实现的原理，是刷新bean

2.定义的变量，在代码中用变量来接，直接在代码块里面使用

示例 ：
1.在配置文件定义一个share.config的属性，

share:
  config: 测试配置2
                 

2.代码中需要在本类上增加 @RefreshScope，@Value下的属性就会自动刷新

@RestController
@RequestMapping("/app")
@RefreshScope
public class AppController {
   
   @Value("${share.config}")
   private String shareConfig;

   @GetMapping("/shareConfig")
   public String shareConfig() {
       return shareConfig;
   }
}  

3.工具类中的，定义的静态变量，调用静态方法（简单的）

 原理：静态变量无法使用注解刷新，我们在调用静态方法时，重新获取变量最新的值，然后进行赋值

示例 ：
1.在配置文件增加一个rabbitmq的属性

spring:
  # rabbitmq 配置
  rabbitmq:
    username: user123
    # 密码
    password: 123456    

2.在类上增加@RefreshScope 注解，用@Value 注入，在调用静态方法getMessageConnect()时，重新获取该bean，该类下的静态属性就会刷新

@Component
@RefreshScope
public class MessageUtil {

    private static AuthorizeImpl AUTHORIZE;

    private static String RABBITMQ_USERNAME;

    private static String RABBITMQ_PASSWORD;

    private static String MESSAGE_URL;

    @Value("${spring.rabbitmq.username}")
    public void setUsername(String username) {
        MessageUtil.RABBITMQ_USERNAME = username;
    }

    @Value("${spring.rabbitmq.password}")
    public void setPassword(String password) {
        MessageUtil.RABBITMQ_PASSWORD = password;
    }

    @Value("${spring.message.url:null}")
    public void setMessageUrl(String messageUrl) {
        MessageUtil.MESSAGE_URL = messageUrl;
    }

    @Autowired
    public void setAuthorizeImpl(AuthorizeImpl authorize) {
        MessageUtil.AUTHORIZE = authorize;
    }

    public static MessageConnectVO getMessageConnect(String tokenId) {
        MessageConnectVO messageConnectVO = new MessageConnectVO();
        //这里重新获取一次Bean，取到最新的配置属性，因为静态方法里面不会自动刷新
        BeanUtil.getInstanceByClassName(MessageUtil.class);
        UserInfoDTO tokenInfo = AUTHORIZE.getUserInfoByTokenId(tokenId);
        messageConnectVO.setUserId(tokenInfo.getUserId().toString());
        messageConnectVO.setOrganizationId(tokenInfo.getOrganizationId().toString());
        messageConnectVO.setPasscode(MessageUtil.RABBITMQ_PASSWORD);
        messageConnectVO.setLogin(MessageUtil.RABBITMQ_USERNAME);
        messageConnectVO.setUrl(MessageUtil.MESSAGE_URL);
        return messageConnectVO;
    }
}

4.框架通过配置文件读取之后，自动注入的属性相关配置，如数据源

示例：
1.这是配置文件里面的数据源：

spring: 
datasource: 
  driver-class-name: com.mysql.cj.jdbc.Driver
  url: jdbc:mysql://localhost:3306/test?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=UTF-8&useSSL=true&autoReconnect=true&failOverReadOnly=false
  username: root
  password: 123456          

2.代码适配：需要再重新写一个数据源配置类，并在使用的类，和调用到数据源的bean上增加@RefreshScope注解

@Configuration
@MapperScan(basePackages = {"com.lzmispt.core.dao", "com.lzmispt.monitor.web.mapper"}, sqlSessionFactoryRef = "monitorSqlSessionFactory")
@RefreshScope
public class MonitorSourceConfig {

    @Value("${spring.datasource.driver-class-name}")
    private String driverClassName;

    @Value("${spring.datasource.url}")
    private String url;

    @Value("${spring.datasource.username}")
    private String username;

    @Value("${spring.datasource.password}")
    private String password;

    @Bean("monitorDataSource")
    @RefreshScope
    public DataSource dataSource() {
        DruidDataSource druidDataSource = new DruidDataSource();
        druidDataSource.setDriverClassName(driverClassName);
        druidDataSource.setUrl(url);
        druidDataSource.setUsername(username);
        druidDataSource.setPassword(password);
        return druidDataSource;
    }

    @Bean("monitorTransactionManager")
    @RefreshScope
    public PlatformTransactionManager platformTransactionManager() {
        return new DataSourceTransactionManager(dataSource());
    }

    @Bean("monitorSqlSessionFactory")
    @RefreshScope
    public SqlSessionFactory sqlSessionFactory() throws Exception {
        SqlSessionFactoryBean factoryBean = new SqlSessionFactoryBean();
        DataSource dataSource = dataSource();
        factoryBean.setDataSource(dataSource);
        ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        List<Resource> resources = new ArrayList<>();

        getAdaptResources(resolver, resources, dataSource);
        Resource[] resourceArr = new Resource[resources.size()];
        factoryBean.setMapperLocations(resources.toArray(resourceArr));
        return factoryBean.getObject();
    }

    private void getAdaptResources(ResourcePatternResolver resolver, List<Resource> resources, DataSource dataSource) throws Exception {
        resources.addAll(Arrays.asList(resolver.getResources("classpath*:mapper/*.xml")));
    }
}