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This article is to share with you what the JavaConfig notes on Java Spring are like. The editor thinks it is very practical, so I share it with you to learn. I hope you can get something after reading this article.

Order

Traditional spring is generally based on xml configuration, but a lot of JavaConfig annotations have been added later. Springboot, in particular, is basically the same java config, do not understand, really do not adapt. Make a note here.

@ RestController

In order to support the development of restfull applications more conveniently, spring4 has added RestController annotations. The more function than Controller annotations is to add ResponseBody annotations to the following RequestMapping methods by default, so that you don't have to add the annotations to each.

@ Configuration

This annotation class is the configuration class of spring and comes with Component annotations.

@ ImportResource

Corresponding xml

The necessity of existence

This is compatible with traditional xml configurations. After all, JavaConfig is not yet *. For example, JavaConfig does not support aop:advisor and tx:advice very well, Introduce @ EnableAspectJAutoProxy (equivalent to aop:aspectj-autoproxy), Introduce @ Configuration-based equivalent to aop:config XML element

@ ComponentScan

Corresponding xml

This configuration automatically includes the following configured features:

It is to register AutowiredAnnotationBeanPostProcessor with the Spring container (you must register for @ Autowired), CommonAnnotationBeanPostProcessor (you must register for @ Resource, @ PostConstruct, @ PreDestroy, etc.), PersistenceAnnotationBeanPostProcessor (you must register for @ PersistenceContext), and RequiredAnnotationBeanPostProcessor (you must register for @ Required).

It is worth noting that the Spring3.1RC2 version does not allow annotated Configuration classes within the package specified by ComponentScan, otherwise an error will be reported.

@ Bean

The corresponding xml is as follows:

@ EnableWebMvc

The corresponding xml is as follows:

This configuration automatically registers DefaultAnnotationHandlerMapping (to register the mapping relationship between handler method and request) and AnnotationMethodHandlerAdapter (to process its parameters before actually calling handler method) to support the use of the @ Controller annotation.

The main functions are as follows:

Configurable ConversionService (to facilitate custom type conversion)

Support for formatting numeric type fields with @ NumberFormat

Support for formatting Date,Calendar and Joda Time fields with @ DateTimeFormat (if classpath has Joda Time)

Parameter verification of @ Valid is supported (if JSR-303-related provider is available in classpath)

Support for XML reading and writing of @ RequestBody/@ResponseBody annotations (if JAXB is in classpath)

Support for JSON reading and writing of @ RequestBody/@ResponseBody annotations (if Jackson is in classpath)

@ ContextConfiguration

Specify java config primarily during junit testing

RunWith (SpringJUnit4ClassRunner.class) @ ContextConfiguration ({"classpath*:spring/*.xml", "classpath:applicationContext.xml", "classpath:applicationContext-rabbitmq.xml", "classpath:applicationContext-mail.xml", "classpath:applicationContext-medis.xml", "classpath:applicationContext-mybatis.xml"}) @ TransactionConfiguration (transactionManager = "mybatisTransactionManager", defaultRollback = false) public class AppBaseTest {/. }

@ ResponseStatus

It is mainly used for rest development. Note the returned http return code. For specific values, see org.springframework.http.HttpStatus enumeration. The general post method returns HttpStatus.CREATED,DELETE and the PUT method returns HttpStatus.OK. You can also configure exception handling, as shown in @ ExceptionHandler and @ ControllerAdvice

@ ExceptionHandler

It is mainly used to handle the specified exception and return the specified HTTP status code, saving each controller method from going to try catch itself. Generally, you can define an exception base class for each application, and then define business exceptions, so that business exceptions can be captured uniformly.

ExceptionHandler (BizException.class) @ ResponseStatus (HttpStatus.BAD_REQUEST) public @ ResponseBody ReturnMessage bizExceptionHandler (Exception ex) {logger.error (ex.getMessage (), ex); return new ReturnMessage (HttpStatus.BAD_REQUEST.value (), ex.getMessage ());}

It is worth noting, however, that this method is limited to exceptions generated by controller's method call chain, and this annotation will not intercept if timing tasks are also used in spring.

@ ControllerAdvice

Method used with @ ExceptionHandler to intercept controller.

@ ControllerAdvice public class ErrorController {private static final Logger logger = LoggerFactory.getLogger (ErrorController.class); @ ExceptionHandler (BizException.class) @ ResponseStatus (HttpStatus.BAD_REQUEST) public @ ResponseBody ReturnMessage bizExceptionHandler (Exception ex) {logger.error (ex.getMessage (), ex); return new ReturnMessage (HttpStatus.BAD_REQUEST.value (), ex.getMessage ()) } @ ExceptionHandler (Exception.class) @ ResponseStatus (HttpStatus.INTERNAL_SERVER_ERROR) public @ ResponseBody ReturnMessage serverExceptionHandler (Exception ex) {logger.error (ex.getMessage (), ex); return new ReturnMessage (HttpStatus.INTERNAL_SERVER_ERROR.value (), ex.getMessage ()) }} the above is what Java Spring's JavaConfig notes look like, and the editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

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