@PostConstruct、@Autowired以及構造函數的執行順序

結論先行：構造函數 -> PostConstruct -> @Autowired 依次執行

由於項目需要啟動時加載一個配置信息，所以想到了用@PostConstruct，如下所示：

@Configuration
public class BUserCenterConfig {

    @Value("${b.user.url}")
    public String userCenterUrl;

    @Value("${b.user.appId}")
    public String userCenterAppId;

    @PostConstruct
    public void setDefaultConfig() {
        UserCenterConfig.SetInterfaceUrl(userCenterUrl);
        UserCenterConfig.SetDefaultAppId(userCenterAppId);
    }
}

BeanTest.java

@Service
public class BeanTest {

    @Autowired
    private BeanTest2 beanTest2;

    public BeanTest() {
        System.out.println("this is BeanTest construct. ");
    }

    @PostConstruct
    private void init() {
        System.out.println("this is BeanTest init function. ");
        beanTest2.test2();
    }
}

BeanTest2.java

@Service
public class BeanTest2 {

    @PostConstruct
    private void init() {
        System.out.println("this is BeanTest2 init function. ");
    }

    public BeanTest2() {
        System.out.println("this is BeanTest2 construct. ");
    }

    void test2() {
        System.out.println("this is BeanTest2 test2 function. ");
    }
}

啟動項目，輸出結果如下：

this is BeanTest construct. 
this is BeanTest2 construct. 
this is BeanTest2 init function. 
this is BeanTest init function. 
this is BeanTest2 test2 function.