Why the field is not inject by @Inject

[peter tong]

when enter url http://localhost:8080/MySpringMvc/home/test1, I expect apple1 will be injected but not, its value is null, why?

@Configuration
public class MvcConfiguration  implements WebMvcConfigurer{	
	@Bean public Apple apple() throws Exception {return new Apple();}
        //.......

@RestController
@RequestMapping("/home")
public class TestController{
	
	@Inject Apple apple1;
	
	public TestController() {
		System.out.println("TestController constructor");
	}
	
	@RequestMapping(value="/test1")
	public ModelAndView test(HttpServletResponse response) throws IOException{		
		System.out.println(apple1==null?"null":apple1.getA());  // return "null"  <--
		return new ModelAndView("test1");
	}
}

public class Apple {
	String a = "see apple?";

	public String getA() {
		return a;
	}

	public void setA(String a) {
		this.a = a;
	}
}

[Himai Minh]

First of all, in Spring, we use @Autowired instead of @Inject.
Secondly, is your @SpringBootApplication class in the root directory of your project?

[peter tong]

I have no used @SpringBootApplication annotation, in fact I am new in spring, I expect Spring container will create and manage the TestController class as it has @Controller annotation and will instantiate, inject its member field.
I have checked my application pom, it has not use spring boot. the pom is as follow:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>MySpringMvc</groupId>
	<artifactId>MySpringMvc</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>war</packaging>

	<name>MySpringMvc</name>
	<url>http://maven.apache.org</url>

	<properties>
		<java.version>1.8</java.version>
		<spring.version>5.2.3.RELEASE</spring.version>
		
	</properties>

	<dependencies>
		<!-- Spring core & mvc -->
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-context</artifactId>
			<version>${spring.version}</version>
		</dependency>

		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-webmvc</artifactId>
			<version>${spring.version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-orm</artifactId>
			<version>${spring.version}</version>
			<type>jar</type>
			<scope>compile</scope>
		</dependency>

		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-test</artifactId>
			<version>${spring.version}</version>
			<type>jar</type>
			<scope>test</scope>
		</dependency>

		


		<!-- Servlet Spec -->
		<dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
		<dependency>
			<groupId>javax.servlet.jsp</groupId>
			<artifactId>jsp-api</artifactId>
			<version>2.1</version>
			<scope>provided</scope>
		</dependency>
	</dependencies>

	<repositories>
		<repository>
			<id>springsource-milestones</id>
			<name>SpringSource Milestones Proxy</name>
			<url>https://oss.sonatype.org/content/repositories/springsource-milestones</url>
		</repository>
	</repositories>

	<build>
		<finalName>MySpringMvc</finalName>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>2.0.2</version>
				<configuration>
					<source>${java.version}</source>
					<target>${java.version}</target>
				</configuration>
			</plugin>
		</plugins>
	</build>
</project>

Is this related?

[Himai Minh]

First of all, have you tried @Autowired instead of @Inject?
Secondly, do you have @ComponentScan (basePackages = "....") //where basePackage is the name of the base package such as "com.example" ?

[peter tong]

Himai Minh wrote:First of all, have you tried @Autowired instead of @Inject?
Secondly, do you have @ComponentScan (basePackages = "....") //where basePackage is the name of the base package such as "com.example" ?

Oh, yes, after change to @Autowired, apple1 can be injected

But why @Inject cannot?
My classpath has javaee-web-api-8.0-sources.jar.

[Tim Holloway]

peter tong wrote:

Himai Minh wrote:First of all, have you tried @Autowired instead of @Inject?
Secondly, do you have @ComponentScan (basePackages = "....") //where basePackage is the name of the base package such as "com.example" ?

Oh, yes, after change to @Autowired, apple1 can be injected

But why @Inject cannot?
My classpath has javaee-web-api-8.0-sources.jar.

Because @Inject is a CDI annotation, not a Spring annotation.

@Autowired tells Spring to consult its BeanFactory, construct the bean to be injected (if it's not already existing) and set the property value to reference that bean. @Inject references the CDI container, not Spring.

[peter tong]

Tim Holloway wrote:

peter tong wrote:

Himai Minh wrote:First of all, have you tried @Autowired instead of @Inject?
Secondly, do you have @ComponentScan (basePackages = "....") //where basePackage is the name of the base package such as "com.example" ?

Oh, yes, after change to @Autowired, apple1 can be injected

But why @Inject cannot?
My classpath has javaee-web-api-8.0-sources.jar.

Because @Inject is a CDI annotation, not a Spring annotation.

@Autowired tells Spring to consult its BeanFactory, construct the bean to be injected (if it's not already existing) and set the property value to reference that bean. @Inject references the CDI container, not Spring.

"@Inject references the CDI container, not Spring.", yes, I try to use @Inject and test in wildfly server, then even @Inject can do what I want.