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What are the notes that must be mastered in Spring Boot? aiming at this problem, this article introduces the corresponding analysis and solution in detail, hoping to help more partners who want to solve this problem to find a more simple and feasible way.

1.SpringBoot/spring

@ SpringBootApplication:

Including @ Configuration, @ EnableAutoConfiguration, @ ComponentScan is usually used on the main class

@ Repository:

Used to annotate data access components, that is, DAO components

@ Service:

Used to annotate business layer components

@ RestController:

Used to label control layer components (such as action in struts), including @ Controller and @ ResponseBody

@ Controller:

Used for tagging is a control layer component, please use @ Controller instead of @ RestController when you need to return to the page

@ Component:

Generally refers to components, when components are not easy to classify, we can use this annotation for annotation

@ ResponseBody:

The returned result of this method is directly written to HTTP response body, which is generally used when getting data asynchronously. After using @ RequestMapping, the return value is usually resolved to the jump path.

After @ responsebody is added, the returned result will not be parsed as a jump path, but will be directly written to HTTP responsebody. For example, if json data is obtained asynchronously, and @ responsebody is added, json data will be returned directly.

@ RequestBody:

After adding this comment before the parameter, it is considered that the parameter is required. It means to accept the conversion of json string to object List, etc.

@ ComponentScan:

Component scan. Personal understanding is equivalent to registering classes as bean* if @ Component @ Controller @ Service and other annotated classes are scanned

@ Configuration:

It is pointed out that this class is the information source of Bean configuration, which is equivalent to that in XML and is generally added to the main class.

@ Bean:

As in XML, put it on top of the method, not the class, which means to generate a bean and give it to spring to manage.

@ EnableAutoConfiguration:

Let Spring Boot automatically configure the Spring framework according to the dependencies declared by the application, which is generally added to the main class

@ AutoWired:

ByType mode. Use the configured Bean to complete the assembly of properties and methods. It can mark class member variables, methods and constructors and complete the work of automatic assembly.

When (required=false) is added, an error is not reported even if the bean is not found.

@ Qualifier:

When there are multiple Bean of the same type, you can specify it with @ Qualifier ("name"). Used with @ Autowired

@ Resource (name= "name", type= "type"):

If there is no content in parentheses, the default is byName. Do something similar to @ Autowired

@ RequestMapping:

RequestMapping is an annotation that handles request address mapping and can be used on classes or methods. Used on a class, the method that represents all response requests in the class has this address as the parent path

The annotation has six attributes:

Params: specifies that some parameter values must be included in the request to be handled by this method.

Headers: specifies that some specified header value must be included in the request for this method to process the request.

Value: specify the actual address of the request, which can be in URI Template mode

Method: specify the method type of the request, such as GET, POST, PUT, DELETE, etc.

Consumes: specifies the type of submitted content (Content-Type) to process the request, such as application/json,text/html

Produces: specifies the content type to be returned, only if the (Accept) type in the request request header contains the specified type.

@ GetMapping, @ PostMapping, etc.:

Equivalent to @ RequestMapping (value= "/", method=RequestMethod.Get\ Post\ Put\ Delete, etc.). It's a combinatorial annotation.

@ RequestParam:

Used in front of the parameters of the method. Equivalent to request.getParameter ()

@ PathVariable:

Path variable. For example, RequestMapping ("user/get/mac/ {macAddress}")

Public String getByMacAddress (

@ PathVariable ("macAddress") String macAddress) {

/ / do something

}

If the parameter is the same as the name in the curly braces, the parentheses can be left unfilled after the comment.

2.Jpa

@ Entity:

@ Table (name= ""):

Indicates that this is an entity class. Generally used for jpa, these two annotations are usually used together, but @ Table can be omitted if the table name and entity class name are the same

@ MappedSuperClass:

Used to determine the entity that is the parent class. The attribute subclass of the parent class can inherit

@ NoRepositoryBean:

A repository that is generally used as a parent class. With this note, spring will not instantiate the repository

@ Column:

If the field name is the same as the column name, you can omit

@ Id:

Indicates that the property is the primary key

GeneratedValue (strategy=GenerationType.SEQUENCE,generator = "repair_seq"):

Indicates that the primary key generation strategy is sequence (can be Auto, IDENTITY, native, etc., Auto means it can be switched between multiple databases), and the name of sequence is specified as repair_seq.

@ SequenceGeneretor (name = "repair_seq", sequenceName = "seq_repair", allocationSize = 1):

Name is the name of sequence for ease of use, sequenceName is the sequence name of the database, and the two names can be the same.

@ Transient:

Indicates that the property is not a mapping to a field of a database table and will be ignored by the ORM framework.

If a property is not a field mapping of a database table, be sure to mark it as @ Transient, otherwise, the ORM framework defaults to its annotation @ Basic

@ Basic (fetch=FetchType.LAZY):

Tags can specify how entity attributes are loaded

@ JsonIgnore:

The function is to ignore some attributes in java bean when json serialization, and both serialization and deserialization are affected.

JoinColumn (name= "loginId"):

One-to-one: a foreign key in this table that points to another table.

One-to-many: another table points to the foreign key of this table.

@ OneToOne

@ OneToMany

@ ManyToOne:

Corresponds to one-to-one, one-to-many, many-to-one in the Hibernate configuration file.

3. Global exception handling

@ ControllerAdvice:

Contains @ Component. Can be scanned. Unified handling of exceptions

@ ExceptionHandler (Exception.class):

Used on the method to indicate that the following method is executed when this exception is encountered.

4.springcloud

@ EnableEurekaServer:

Used on the springboot startup class to indicate that this is an eureka service registry

@ EnableDiscoveryClient:

Used on the springboot startup class to indicate that this is a service that can be found by the registry

@ LoadBalanced:

Enable load balancing capability

@ EnableCircuitBreaker:

Used in the startup class to turn on the circuit breaker function

HystrixCommand (fallbackMethod= "backMethod"):

Used in methods, fallbackMethod specifies the open callback method

@ EnableConfigServer:

Used on the startup class to indicate that this is a configuration center and enable Config Server

@ EnableZuulProxy:

Enable zuul routing, which is used on startup classes

@ SpringCloudApplication:

Include

@ SpringBootApplication

@ EnableDiscovertyClient

@ EnableCircuitBreaker

They are SpringBoot notes, registry service center Eureka notes and circuit breaker notes. For SpringCloud, these are the three annotations that every microservice must have, which is why the @ SpringCloudApplication annotation collection has been introduced.

This is the answer to the question about what the notes must be mastered in Spring Boot. I hope the above content can be of some help to you. If you still have a lot of doubts to be solved, you can follow the industry information channel to learn more about it.

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