# SpringBoot 初始化 Bean、初始化静态变量

SpringBoot 初始化 Bean、初始化静态变量

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SpringBoot 初始化 Bean

@Value 方式初始化

• people.properties

people.id:1001
people.name:"张三"
people.address:"北京大兴亦庄区"

• 使用 Value取值，用Bean注解将Bean添加到容器中

@Configuration
@PropertySource(value="classpath:/test/people.properties",encoding = "UTF-8")
public class PeopleBeanOne {

    private static final Logger logger = LoggerFactory.getLogger(PeopleBeanOne.class);

    @Value("${people.id}")
    private String id;

    @Value("${people.name}")
    private String userName;

    @Value("${people.address}")
    private String address;


    @Bean
    public PeopleBeanOne initPeopleBean() {
        PeopleBeanOne people = new PeopleBeanOne();
        people.setId(id);
        people.setUserName(userName);
        people.setAddress(address);
        logger.info("peoplebean info :{}", people);
        return people;
    }
    
    // 省略 set、get 方法
}

prefix 方式初始化

• application.yml中添加bean的信息

# 测试 prefix 方式注入 bean
people:
  id: 1004
  name: "李四"
  address: "青海省"

• 配置 属性的前缀（"people"）

@Configuration
@ConfigurationProperties(prefix = "people")
public class PeopleBeanThree {

    private String id;

    private String userName;

    private String address;
    
    // 省略 set、get 方法
}

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参数的方式拿到Spring 中的 Bean set方法中初始化静态变量

• set()方法中初始化静态变量

@Component
public class RedisClient {

    private static RedissonClient redissonClient;

    @Autowired(required = true)
    public void setRedissonClient(RedissonClient redissonClient){
        RedisClient.redissonClient=redissonClient;
        logger.info("redisclinet注入完成！");
    }

    public static void setList(){
        redissonClient.getList("one").add("two");
    }
}

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构造方法 参数的方式拿到Spring 中的 Bean 构造方法中初始化静态变量

private static RedissonClient redissonClientOne;

/**
  * 作为参数拿到 redissonClient 的 Bean
  *
  * @param redissonClient
  */
public InitStaticVariableOne(RedissonClient redissonClient) {
    // 初始化类变量
    redissonClientOne = redissonClient;
}

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@PostConstruct方式实现

• @PostConstruct 注解的方法在加载类的构造函数之后执行，也就是在加载了构造函数之后，执行init方法。这种方式和在xml中配置 init-method和 destory-method方法差不多，定义spring 容器在初始化bean和容器销毁之前的所做的操作。

@Component
public class InitStaticVariableThree {

    private static final Logger logger = LoggerFactory.getLogger(InitStaticVariableThree.class);

    @Autowired
    private RedissonClient redissonClient;

    public static RedissonClient redissonClientOne;

    @PostConstruct
    public void init() {
        redissonClientOne = redissonClient;
        logger.info(String.valueOf(redissonClient));
        logger.info(String.valueOf(redissonClientOne));
    }
}