For the first time, I am writing an app that manually creates a new thread. I am creating and using the thread like so:
#Service
public class MyAppService
{
myThread = new Thread(runnableThreadImpl);
myThread.start();
}
runnableThreadImpl is an instance of:
public class RunnableThreadImpl implements Runnable
{
public void run()
{
myProcessor.start()
}
}
myProcessor is an instance of:
#Component
#Transactional
public class MyProcessor
{
...
}
My boss would like me to combine RunnableThreadImpl and MyProcessor into one class that would look something like:
#Component
#Transactional
public class MyProcessor implements Runnable
{
public void run()
{
...
}
}
My question is: Are there any problems with having a Spring Bean implement Runnable?
Thx!
Related
Is there a way to annotate just the class and have all the methods in the class create new spans? Basically, I am trying to get sleuth/spring to create new spans for all calls in a given repository class.
spring-boot version: '2.7.0'
Something like -
import org.springframework.cloud.sleuth.annotation.NewSpan;
#Newspan
public class ContactOperations{
public void doSomething(){
}
public void doSomethingElse(){
}
.....
}
Instead of
public class ContactOperations{
#Newspan
public void doSomething(){
}
#Newspan
public void doSomethingElse(){
}
.....
}
No this is not possible. The annotation NewSpan is only allowed on methods as you can see in the source code:
#Retention(value=RUNTIME)
#Inherited
#Target(value=METHOD)
public #interface NewSpan
I have a Service class that has a generic type and a setController method that is based on the same generic type. the generic type of the servic object is only known at the time of declaration.
The problem is now when i define a ControllerImpl where the generic type is defined the #Autowired method of setController does not use that component.
Has somebody an idea how to fix it and keep the ServiceImpl generic. (it would work when i define the typ in ServiceImpl as well).
The following example show the problem i'm facing with:
#SpringBootTest
#ActiveProfiles("local")
public class AccessTest {
#Autowired
private ServiceA<BeanA> service;
#Test
void test(){
Assertions.assertNotNull(service.controller);
}
interface ValueGetter{
}
static class BeanA implements ValueGetter{
}
static class AbstractService<B extends ValueGetter>{
Controller<B> controller;
#Autowired
void setController(#Nullable Controller<B> controller){
this.controller = controller;
}
}
interface Controller<B extends ValueGetter>{
void doSomething(B value);
}
//not inner class
#Service
public class ServiceA<B extends AccessTest.ValueGetter> extends AccessTest.AbstractService<B> {
}
//not inner class
#Component
public class ControllerImpl implements AccessTest.Controller<AccessTest.BeanA> {
#Override
public void doSomething(final AccessTest.BeanA value) {
}
}
}
I'm trying to figure out how to build a Spring Boot standalone app. Of course to have things autowired requires some initial context starting point. If I just try to Autowire a class to run a job it is null even if I make it static.
Is there a way to use Spring #Services in a standalone non-web app?
#SpringBootApplication
public class MyApplication {
#Autowired
private static JobRunnerService job;
public static void main(String[] args) {
SpringApplication.run(MyApplication.class, args);
job.send(); //job is null !
}
}
So first wired in a static JobRunnerService to the main running MyApplication the JobRunner(Service) Class has a non-static SshSessionService wired into it.
the SshSession(Service) finally just has a no-arg constructor.
#Service("jobRunnerService")
public final class JobRunner implements JobRunnerService{
#Autowired
private SshSessionService ssh;
#Autowired
public JobRunner(SshSessionService ssh){
this.ssh = ssh;
}
public void sendToAgent() { ....
}
#Service("sshSessionService")
public class SshSession implements SshSessionService {
public SshSession() {
}
}
It starts off being null at the JobRunnerService job reference.
Several different solutions comes to mind:
If you take a look at the SpringApplication.run() method you will notice that it returns a ApplicationContext. From that, you can fetch the JobRunnerService, e.g.
#SpringBootApplication
public class MyApplication {
public static void main(String[] args) {
ApplicationContext ctx = SpringApplication.run(MyApplication.class, args);
JobRunnerService job = ctx.getBean(JobRunnerService.class);
job.send();
}
}
Another solution is to use #PostConstruct annotation for the send() method:
#Service("jobRunnerService")
public class JobRunner implements JobRunnerService {
#PostConstruct
public void send() { ... }
}
However in your case, I would implement the ApplicationRunner interface, either as a separate bean which autowires the JobRunnerService and then calls its send() method
#Component
public class SendRunner implements ApplicationRunner {
#Autowired
private JobRunnerService job;
#Override
public void run(ApplicationArguments args) {
job.send();
}
}
or let the JobRunner implement the ApplicationRunner interface directly:
#Service("jobRunnerService")
public class JobRunner implements JobRunnerService, ApplicationRunner {
#Override
public void send() { ... }
#Override
public void run(ApplicationArguments args) {
send();
}
}
You haven't provided the code for JobRunnerService but I am assuming it has a default constructor and that it is annotated by #Component for Spring to figure it out as a bean before you can actually autowire it. your job is null probably because it's not able to find an autowired bean for JobRunnerService and that's probably because you don't have an identifier for Spring to scan and create bean of type JobRunnerService
You can use #Servicesor #Component to the JobRunnerService class then add annotation #ComponentScan("package of JobRunnerService") below #SpringBootApplication, see this link:
How to scan multiple paths using the #ComponentScan annotation?
You need a few steps to get your standalone app working:
A class with main() method.
A #SpringBootApplication annotation to your main class.
And a call to the SpringApplication.run() method.
package com.example.myproject;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
#SpringBootApplication // same as #Configuration #EnableAutoConfiguration #ComponentScan
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
As noted, the #SpringBootApplication is a composite annotation which consist of #Configuration #EnableAutoConfiguration and #ComponentScan. In other words, it can be replaced by the three latter annotations. Alternatively, you can use the alias scanBasePackage or scanBasePackageClasses to customize which directories that should be used for component scanning.
The example is copied from the #SpringBootApplication paragraph in the Spring Boot reference docs (see link above). If you would like to quick start your project, complete with build scripts (Maven or Gradle), dependencies, etc, you can generate a project skeleton using the Spring Initializr
I'm trying to run as Thread/runnable now as mentioned in the Spring document 3. Task Execution and Scheduling..
import org.springframework.core.task.TaskExecutor;
public class TaskExecutorExample {
private class MessagePrinterTask implements Runnable {
private String message;
public MessagePrinterTask(String message) {
this.message = message;
}
public void run() {
System.out.println(message);
}
}
private TaskExecutor taskExecutor;
public TaskExecutorExample(TaskExecutor taskExecutor) {
this.taskExecutor = taskExecutor;
}
public void printMessages() {
for(int i = 0; i < 25; i++) {
taskExecutor.execute(new MessagePrinterTask("Message" + i));
}
}
}
So in my case I'm trying...
#Service("jobRunnerService")
#Component
public class JobRunner implements JobRunnerService, ApplicationRunner{
#Autowired
public TaskExecutor taskExecutor;
#Autowired
private SshSessionService ssh;
private class JobTask implements Runnable{
public void run(){
Boolean success = connectToAgent();
if(success){
log.debug("CONNECTED!!!");
}
}
}
/**
* Construct JobRunner with TaskExecutor
* #param taskExecutor
*/
#Autowired
public JobRunner(TaskExecutor taskExecutor, SshSessionService ssh) {
this.taskExecutor = taskExecutor;
this.ssh = ssh;
}
private Map<String, String> sessionParams;
private final Logger log = LoggerFactory.getLogger(this.getClass());
#Override
public void run(ApplicationArguments args) {
/**
* Starting point of application
*
*/
taskExecutor.execute(new JobTask());
}
just getting org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.core.task.TaskExecutor] found for dependency
How can i get the imported lib to be accepted as a TaskExecutor Bean ??
I am using spring-boot for implementing a REST server. Inside a function for request mapping, I have to create an object which is heavyweight, so for every REST call I have do it and it is slowing things down. Is it possible to create the object in main and access from the function?
#SpringBootApplication
public class MyClass{
public static void main(String[] args) {
/* I want to initialize the object here */
SpringApplication.run(MyClass.class, args);
}
}
#RestController
public class MyController {
#RequestMapping("/go/to/user/summary")
public Users[] getUsers(#RequestParam(value="length", defaultValue="10") int length) {
/* I want to use the object here */
}
You can create a bean in MyClass and then consume that bean in MyController. Spring will only create a single instance of the bean so you'll avoid the cost of creating it multiple times. Something like this:
#SpringBootApplication
public class MyClass {
public static void main(String[] args) {
SpringApplication.run(MyClass.class, args);
}
#Bean
public Heavyweight heavyweight() {
// Initialize and return heavyweight object here
}
}
#RestController
public class MyController {
private final Heavyweight heavyweight;
#Autowired
public MyController(Heavyweight heavyweight) {
this.heavyweight = heavyweight;
}
#RequestMapping("/go/to/user/summary")
public Users[] getUsers(#RequestParam(value="length", defaultValue="10") int length) {
// Use heavyweight here
this.heavyweight.foo();
// ...
return users;
}
}
I think You can use #Service for this approach. Service class is Singleton so if You create object inside it on startup application then You can use it requests in Your controllers class.
Example service:
#Service
public class MyService{
private MyLargeObject largeObject;
public MyLargeObject set(MyLargeObject largeObject){
this.largeObject = largeObject;
}
public MyLargeObject get(){
return largeObject;
}
}
Example controller:
#RestController
public class MyController{
#Inject
private MyService myService;
#RequestMapping("/go/to/user/summary")
public Users[] getUsers(#RequestParam(value="length", defaultValue="10") int length) {
MyLargeObject o = myService.get();
}
}
EDIT1:
If You want init Your largeObject directly in service You can use #PostConstruct annotation. For example:
#PostConstruct
public void init() {
// initialization Your object here
}
I'm having a Spring boot application in which based on a variable, I need to call corresponding implementation classes of an interface. This is what I have right now:
public interface Parent{
public void call();
}
public class ABC implements Parent{
public void call(){
System.out.println("Called ABC");
}
}
public class XYZ implements Parent{
public void call(){
System.out.println("Called XYZ");
}
}
#Service("caller")
public class Caller{
#Autowired
protected OrderInfoRepository orderInfoRepository;
AnnotationConfigApplicationContext context;
public Caller(){
context = new AnnotationConfigApplicationContext(Config.class);
}
public void callMethod(String param){
Parent p = (Parent) context.getBean(param+"_Caller");
p.call();
}
}
#Configuration
public class Config{
#Bean(name="ABC_Caller")
public Parent getABC(){
return new ABC();
}
#Bean(name="XYZ_Caller")
public Parent getXYZ(){
return new XYZ();
}
}
#Repository
public interface MyRepo extends Repository<MyDAO, Long> {
// ....
}
Basically what I want to do is, based on the param passed to Caller.callMethod(), I want to add "_Caller" to the param, and call the corresponding implementation class. So, I'm defining a #Configuration class, where I define which implementation class to return. And then using the AnnotationConfigApplicationContext, I get the corresponding bean. This works fine.
The problem I'm having is, when I try to Autowire anything in the implementation classes, I get a NoSuchBeanDefinitionException. For instance, when I autowire in the implementation class ABC
public class ABC implements Parent{
#Autowired
MyRepo myRepo;
public void call(){
System.out.println("Called ABC");
}
}
I get Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.persistence.repositories.MyRepo] when I try to start the application. However, when I do the Autowiring in the Caller class instead, it works fine. I had asked a similar question a while back, but was not able to resolve it. Any ideas?