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This article introduces you to use @ Autowired annotation to introduce the server service layer method Times error solution, the content is very detailed, interested friends can refer to, hope to be helpful to you.

@ Autowired annotations introduce server service layer method Times error

ContentTypeService in com.example.demo001.controller.ContentTypeController required a bean of type 'com.example.demo001.service.ContentTypeService' that could not be found

The method of searching on the Internet: it's okay.

Method 1: @ Autowried (required = false) sets the required attribute value to false, and the error disappears

Method 2: replace @ Resource annotation with @ Autowried annotation, the error disappears

JavaBean is a special Java class, written in the Java language, and conforms to the JavaBean API specification. The unique features of JavaBean compared to other Java classes are:

1. Provide a default no-parameter constructor.

2. Need to serialize and implement the Serializable interface

3. There may be a series of readability attributes

4. There may be a series of getter or setter methods.

JavaBean attribute

The property of a JavaBean object should be accessible, which can be any legal Java data type, including a custom Java class.

The properties of a JavaBean object can be read-write, read-only, or write-only. The properties of the JavaBean object are accessed through two methods provided in the JavaBean implementation class

Method

GetPropertyName (): for example, if the name of the property is myName, then the name of the method is written as getMyName () to read the property. This method is also called an accessor.

SetPropertyName (): for example, if the name of the property is myName, then the name of the method is written as setMyName () to write the property. This method is also known as a writer.

A read-only property provides only the getPropertyName () method, and a write-only property provides only the setPropertyName () method.

What is the purpose of @ Autowried?

@ Autowried is an annotation that annotates class member variables, methods, and constructors, allowing spring to automate the assembly of bean.

@ Autowried matches by class by default, and assembles bean by name with @ Qualifier.

The real reason for the error is that it is not imported in serveImpl

When the problem is solved, attach the web address to solve the problem online. which of the above two methods can be used? it is not clear what is going on.

It's just a guide.

The above is the original xml file, if this is equivalent to @ Component of the annotation and @ Service is a @ Component derivative, and autowire is an attribute of bean in xml, so it is valid only if @ Component exists @ Autowire

About the error occurred in the @ Autowired annotation

1. Field injetion is not recommended

2. Consider defining a bean of type 'xxx' in your configuration problem occurs in spring boot automatic injection.

1. Solve

Original code

@ Autowired private final AccountDao accountDao

Error report: Field injetion is not recommended

Change to

/ / final unnecessary private final AccountDao accountDao; @ Autowired public AccountController (AccountDao accountDao) {this.accountDao = accountDao;}

The error disappears

Note: if it is still a warning, directly changing the @ Autowired annotation to @ Resource annotation can eliminate the warning (does not affect injection)

two。 Solve

Originally, account, that is, entity and dao, were put in the upper directory of controller.

Error report: Consider defining a bean of type 'xxx' in your configuration

Put entity and dao in the controler sibling directory or I put them in the account package where the sibling directory is located.

As shown in the following figure

Restart, error disappears ~

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