With the update and iteration of technology, Java5.0 began to support annotations. As the leading framework in Java, spring has slowly begun to abandon xml configuration since it was updated to version 2.5, and more annotations are used to control the spring framework. There are so many annotations in spring that you may not be able to use them even if you have been working on Java for many years. Here is a summary of the 7 most commonly used annotations by type.
This annotation is used on the setter method of the bean. Indicates that this attribute is required and must be injected during the configuration phase, otherwise BeanInitializationExcepion will be thrown. This annotation is used on the field, setter method and constructor method of the bean to explicitly declare dependencies. Autowiring based on type. When you use this annotation on a field and use attributes to pass values, Spring will automatically assign the value to the field. This annotation can also be used for private properties (not recommended), as follows. @Componentpublic class User { @Autowired private Address address;}Copy after login
@Component
public class User {
private Address address;
@AutoWired
public setAddress(Address address) {
// custom code
this.address=address;
}
}Copy after login
@Component
public class User {
private Address address;
public User(Address address) {
this.address=address;
}
}
<bean id="user" class="xx.User"/>Copy after login
@Component
public class User {
@Autowired
@Qualifier("address1")
private Address address;
...
}Copy after login
@Configuration
Copy after login
@Configuartion
public class SpringCoreConfig {
@Bean
public AdminUser adminUser() {
AdminUser adminUser = new AdminUser();
return adminUser;
}
}Copy after login
此注解使用在class上声明此类是一个Spring controller，是@Component注解的一种具体形式。<br/>此注解可以用在class和method上，用来映射web请求到某一个handler类或者handler方法上。当此注解用在Class上时，就创造了一个基础url，其所有的方法上的@RequestMapping都是在此url之上的。可以使用其method属性来限制请求匹配的http method。@Controller
@RequestMapping("/users")
public class UserController {
@RequestMapping(method = RequestMethod.GET)
public String getUserList() {
return "users";
}
}Copy after login
这篇也推荐大家看下：Spring MVC常用注解。此外，Spring4.3之后引入了一系列@RequestMapping的变种。如下：
Copy after login
分别对应了相应method的RequestMapping配置。
关注微信公众号：Java技术栈，在后台回复：spring，可以获取我整理的 N 篇最新 Spring 教程，都是干货。此注解用在@RequestMapping声明的方法的参数上，可以把HTTP cookie中相应名称的cookie绑定上去。@ReuestMapping("/cookieValue")
public void getCookieValue(@CookieValue("JSESSIONID") String cookie){
}Copy after login
@CrossOrigin(maxAge = 3600)
@RestController
@RequestMapping("/users")
public class AccountController {
@CrossOrigin(origins = "http://xx.com")
@RequestMapping("/login")
public Result userLogin() {
// ...
}
}Copy after login
// GET /pets/42;q=11;r=22
@RequestMapping(value = "/pets/{petId}")
public void findPet(@PathVariable String petId, @MatrixVariable int q) {
// petId == 42
// q == 11
}Copy after login
<mvc:annotation-driven enable-matrix-variables="true" />
Copy after login
@Configuration
public class WebConfig extends WebMvcConfigurerAdapter {
@Override
public void configurePathMatch(PathMatchConfigurer configurer) {
UrlPathHelper urlPathHelper = new UrlPathHelper();
urlPathHelper.setRemoveSemicolonContent(false);
configurer.setUrlPathHelper(urlPathHelper);
}
}Copy after login
@RequestMapping("/users/{uid}")Copy after login
@RequestMapping("/users/{uid}")
public String execute(@PathVariable("uid") String uid){
}Copy after login
@ModelAttribute("user")
public PUser getUser() {}
// controller和上面的代码在同一controller中
@Controller
@SeesionAttributes(value = "user", types = {
User.class
})
public class UserController {}Copy after login
此注解通常被用在主应用class上，告诉Spring Boot自动基于当前包添加Bean、对bean的属性进行设置等。此注解用在Spring Boot项目的应用主类上（此类需要在base package中）。
This annotation is used on the class to declare a Spring component (Bean) and add it to application context. This annotation is used in class above, declare that this class is a service class that performs business logic, calculations, calls internal APIs, etc. It is a specific form of @Component annotation. This class is used to declare this class on the class to access the database, generally as a DAO role. This annotation has the feature of automatic translation. For example: when this component throws an exception, there will be a handler to handle the exception without using a try-catch block.
##@Transactional
This annotation is used on interface definitions, methods in interfaces, class definitions, or public methods in classes. It should be noted that this annotation does not activate transaction behavior, it is just metadata that will be consumed by some runtime infrastructure.
此注解使用在方法上，声明此方法被定时调度。使用了此注解的方法返回类型需要是Void，并且不能接受任何参数。@Scheduled(fixedDelay=1000)
public void schedule() {
}
@Scheduled(fixedRate=1000)
public void schedulg() {
}Copy after login
此注解使用在Class上，声明测试使用的配置文件，此外，也可以指定加载上下文的类。此注解一般需要搭配SpringJUnit4ClassRunner使用。@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = SpringCoreConfig.class)
public class UserServiceTest {
}Copy after login
The above is the detailed content of The 7 most commonly used annotations in Spring, the most powerful organization in history!. For more information, please follow other related articles on the PHP Chinese website!
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
