My Config class:
@Configuration
public class TimeOutConfig {
@Value("${value1}")
private int value1;
@Value("${value2}")
private int value2;
@Bean()
User boTimeOut() {
System.out.println("In BOTimeOutConfig");
BeanTest b1 = new BeanTest(value1, value2);
User u1 = new User(b1);
return u1;
}
@Value("${value3}")
private int value3;
@Value("${value4}")
private int value4;
@Bean(name = "BSETimeout")
User getBSEUser() {
System.out.println("In BSETimeOutConfig");
User u2 = new User( new BeanTest(value3, value4));
return u2;
}
}
BeanTest Class:
@Component
public class BeanTest {
private int v1;
private int v2;
BeanWebClient b1;
public BeanTest(){}
public BeanTest(int v1, int v2){
this.v1=v1;
this.v2=v2;
beanWebClient();
}
public BeanWebClient beanWebClient() {
//System.out.println("In BeanTest class beanWebClient() method execution v1 and v2: " v1 v2);
b1 = new BeanWebClient(v1,v2);
System.out.println("In BeanTest class beanWebClient() method execution v1 and v2: " b1.getV1() " " b1.getV2());
return b1;
}
public void message()
{
b1.webClientMessage();
//System.out.println("V1= " v1 " V2= " v2);
}
}
BeanWebClient Class:
@Component
public class BeanWebClient {
private int v1;
private int v2;
public BeanWebClient(int v1, int v2){
this.v1=v1;
this.v2=v2;
System.out.println("Received from BeanTest " v1 " " v2);
}
public BeanWebClient(){
}
public int getV1() {
return v1;
}
public int getV2() {
return v2;
}
public void webClientMessage(){
System.out.println("In BeanWebClient class, printing from autowired dependency " v1 " " v2);
}
}
My User class:
@Component
public class User {
@Autowired
private BeanTest beanTest;
public User(BeanTest beanTest){
this.beanTest=beanTest;
}
public void message()
{
beanTest.message();
}
public User() {
//System.out.println("user create... hashCode :" this.hashCode());
}
}
Finally, My Service class:
@Service
public class BeanService {
@Autowired
@Qualifier("boTimeOut")
private User boUser;
@Autowired
@Qualifier("BSETimeout")
private User bseUser;
public void printBO()
{
boUser.message();
}
public void printBSE()
{
bseUser.message();
}
}
I was trying to understand how components and autowiring dependencies work in spring boot. In my User class, the autowired BeanTest class is initialized, during configuration- all the necessary print statements are executed. But when I call the functions of the Service class, The autowired User dependency has null for beanTest and its members. As opposed to this, when I just create the BeanTest object in my User class everything works as expected. This is what I mean:
@Component
public class User {
BeanTest beanTest;
public User(BeanTest beanTest){
this.beanTest=beanTest;
}
public void message()
{
beanTest.message();
}
public User() {
//System.out.println("user create... hashCode :" this.hashCode());
}
}
I sort of understand that The bean autowired in User class is taken from the container is null. Since Im Autowiring specific User dependency in my service class, I don't understand why it's not working. Can someone please explain If and How I can autowire the BeanTest class into User class correctly. Sorry for so many code files.
Outputs This is the Output I get When I create the BeanTest object manually without @Autowire
In BOTimeOutConfig
Received from BeanTest 10 20
In BeanTest class beanWebClient() method execution v1 and v2: 10 20
In BSETimeOutConfig
Received from BeanTest 30 40
In BeanTest class beanWebClient() method execution v1 and v2: 30 40
2021-11-13 14:37:58.161 WARN 404383 --- [ main] JpaBaseConfiguration$JpaWebConfiguration : spring.jpa.open-in-view is enabled by default. Therefore, database queries may be performed during view rendering. Explicitly configure spring.jpa.open-in-view to disable this warning
2021-11-13 14:37:58.613 INFO 404383 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''
2021-11-13 14:37:58.622 INFO 404383 --- [ main] c.paytmmoney.errordb.ErrordbApplication : Started ErrordbApplication in 4.04 seconds (JVM running for 4.379)
2021-11-13 14:38:07.768 INFO 404383 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring DispatcherServlet 'dispatcherServlet'
2021-11-13 14:38:07.768 INFO 404383 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : Initializing Servlet 'dispatcherServlet'
2021-11-13 14:38:07.769 INFO 404383 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : Completed initialization in 1 ms
In /test method
In BeanWebClient class, printing from autowired dependency 10 20
In /test method
In BeanWebClient class, printing from autowired dependency 30 40
When I autowire BeanTest Class this is the Output:
In BOTimeOutConfig
Received from BeanTest 10 20
In BeanTest class beanWebClient() method execution v1 and v2: 10 20
In BSETimeOutConfig
Received from BeanTest 30 40
In BeanTest class beanWebClient() method execution v1 and v2: 30 40
2021-11-13 14:40:36.072 WARN 404724 --- [ main] JpaBaseConfiguration$JpaWebConfiguration : spring.jpa.open-in-view is enabled by default. Therefore, database queries may be performed during view rendering. Explicitly configure spring.jpa.open-in-view to disable this warning
2021-11-13 14:40:36.585 INFO 404724 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''
2021-11-13 14:40:36.596 INFO 404724 --- [ main] c.paytmmoney.errordb.ErrordbApplication : Started ErrordbApplication in 4.353 seconds (JVM running for 4.75)
2021-11-13 14:40:45.081 INFO 404724 --- [nio-8080-exec-2] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring DispatcherServlet 'dispatcherServlet'
2021-11-13 14:40:45.081 INFO 404724 --- [nio-8080-exec-2] o.s.web.servlet.DispatcherServlet : Initializing Servlet 'dispatcherServlet'
2021-11-13 14:40:45.082 INFO 404724 --- [nio-8080-exec-2] o.s.web.servlet.DispatcherServlet : Completed initialization in 1 ms
In /test method
2021-11-13 14:40:45.204 ERROR 404724 --- [nio-8080-exec-2] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause
java.lang.NullPointerException: null
at com.paytmmoney.errordb.repository.BeanTest.message(BeanTest.java:42) ~[main/:na]
at com.paytmmoney.errordb.repository.User.message(User.java:22) ~[main/:na]
at com.paytmmoney.errordb.service.BeanService.printBO(BeanService.java:21) ~[main/:na]
I'm using a rest controller to call functions in the Service class.
THANK YOU!!!
CodePudding user response：
Given that you are creating BeanTest and User instances on your own in TimeOutConfig, please remove all @Component and @Autowired annotations from BeanTest, BeanWebClient and User as follows:
public class BeanTest {
private int v1;
private int v2;
BeanWebClient b1;
public BeanTest(){}
public BeanTest(int v1, int v2){
this.v1=v1;
this.v2=v2;
beanWebClient();
}
public BeanWebClient beanWebClient() {
//System.out.println("In BeanTest class beanWebClient() method execution v1 and v2: " v1 v2);
b1 = new BeanWebClient(v1,v2);
System.out.println("In BeanTest class beanWebClient() method execution v1 and v2: " b1.getV1() " " b1.getV2());
return b1;
}
public void message() {
b1.webClientMessage();
//System.out.println("V1= " v1 " V2= " v2);
}
}
public class BeanWebClient {
private int v1;
private int v2;
public BeanWebClient(int v1, int v2) {}
this.v1=v1;
this.v2=v2;
System.out.println("Received from BeanTest " v1 " " v2);
}
public BeanWebClient(){ }
public int getV1() {
return v1;
}
public int getV2() {
return v2;
}
public void webClientMessage(){
System.out.println("In BeanWebClient class, printing from autowired dependency " v1 " " v2);
}
}
public class User {
private BeanTest beanTest;
public User(BeanTest beanTest) {
this.beanTest=beanTest;
}
public User() {
//System.out.println("user create... hashCode :" this.hashCode());
}
public void message() {
beanTest.message();
}
}