I have encountered with the following issue. I would like to create Spring #Component with generic
#Component
public class ResponseDtoValidator<DTO> {
public ResponseEntity<DTO> methodToInvoke(DTO dto) {
return Optional.ofNullable(dto).map(result -> new >ResponseEntity<>
(result, HttpStatus.OK))
.orElse(new ResponseEntity<>(HttpStatus.NOT_FOUND)); }
}
#Controller
public class SomeController {
#Inject
private ResponseDtoValidator<DTO1> responseDtoValidator1;
#Inject
private ResponseDtoValidator<DTO2> responseDtoValidator2;
public void someMethod() {
DTO1 dto1 = new DTO1();
DTO2 dto2 = new DTO2();
responseDtoValidator1.methodToInvoke(dto1);
responseDtoValidator2.methodToInvoke(dto2);
}
}
Can I inject this Component like above? Actually, I have tried and it seems to work properly, can you please confirm that I am correct or not?
Firstly, a spring bean can not be injected in itself.
In regards to your question,yes it is injectable but dont use generic signs when injecting. Just inject it normally. Generic type is send when a method of generic class is utilizing.
For instance;
#Component
public class ResponseDtoValidator<DTO> {
public void getAbc(List<DTO> aList) {}
}
Then;
public class Test {
#Autowired // or #Inject
private ResponseDtoValidator responseDtoValidator;
public void testMethod() {
responseDtoValidator.getAbc(List<EnterATypeInHere> aList);
}
}
Related
I have code as follows
public class A {
#Inject
private Supplier<Set<String>> set;
.
.
}
I am writing test cases for this class, where my Unit test looks like :
#Test(groups = "MyApp.unit")
public class ATest extends someOtherClass {
#Inject
private A a;
& my unit config looks like
#Configuration
#Import({someClass.class})
public class UnitTestConfig {
...
#Bean
public Supplier<Set<String>> set() {
Supplier<Set<String>> items = () -> Sets.newHashSet("100");
return items;
}
#Bean
public A a() {
return new A();
}
}
I am unable to inject Supplier bean into my class A. Had put debug points and tried testing, it enters the bean function but Supplier class doesnt get created. It gives the message "Class has no fields"
All other beans seem fine. Does anyone have any insights on this?
If you're already using the #Configuration to configure the bean, why won't you use constructor injection?
I suggest you to rewrite the A class as follows:
public class A {
private final Supplier<Set<String>> sup;
public A(Supplier<Set<String>> sup) {
this.sup = sup;
}
}
Now you can use one of the following options:
#Configuration
public class SampleConfig {
#Bean
public Supplier<Set<String>> set () {
return () -> Set.of("a","b", "c");
}
#Bean
public A a (Supplier<Set<String>> sup) {
return new A(sup);
}
}
Or another way:
#Configuration
public class SampleConfig {
#Bean
public Supplier<Set<String>> set () {
return () -> Set.of("a","b", "c");
}
#Bean
public A a () {
return new A(set());
}
}
In the second option I call set() as if its a regular method. Spring handles classes annotated with #Configuration, so its a "special" call used for injection.
Since a supplier is a singleton, multiple calls to this set method (say, from different beans) will return the same instance of the Supplier.
The first method is more flexible though, because it allows to keep the definition of the supplier and class A in different configuration files, the second way assumes that they're both defined in the same #Configuration.
Update (based on Op's Comments)
With field injection it will work just the same:
public class A {
#Autowired
private Supplier<Set<String>> sup;
public Set<String> getSet() {
return this.sup.get();
}
}
#Configuration
public class SampleConfig {
#Bean
public Supplier<Set<String>> set () {
return () -> Set.of("a","b", "c");
}
#Bean
public A a () {
return new A();
}
// this is called right before the application gets started (after all the injections are done - this is just for the sake of illustration)
#EventListener(ApplicationReadyEvent.class)
public void onReady(ApplicationReadyEvent evt) {
A a = evt.getApplicationContext().getBean(A.class);
System.out.println(a.getSet()); // this will return your set
}
}
I want to use #Qualifier to dynamically specifying parameters? how to do it ?
#Qualifier("two") 'two' as a parameter ，can be 'one' 'three' or other.
Can i use aop dynamically design 'two'?
means I want to change the name of service with a #Qualifier by parameters.
the parameter from the url 'Token'.
case: url: http://localhost:8080/insert/order, token has a parameter: companyId = one
#RestController
public class ApiWebService {
#Autowired
#Qualifier("two")
//#Qualifier("one")
private BaseService baseService;
#GetMapping("insert/order")
public void test() {
baseService.insertOrder();
}
}
#Service("one")
public class CompanyOneService extends BaseService {
#Override
public void insertOrder() {
System.out.println("conpanyOne");
System.out.println("baseInsertOrder");
}
}
#Service("two")
public class CompanyTwoService extends BaseService {
#Override
public void insertOrder(){
System.out.println("companyTwo");
System.out.println("baseInsertOrder");
}
}
three
four
...
#Service
public class BaseService {
public void insertOrder(){
System.out.println("baseInsertOrder");
}
}
你好 !
No you cannot , mostly because the attribute in Java annotation does not allow to assign with variables.
Actually you want to choose an implementation to use based on some runtime conditions(i.e.companyId in your case). You can achieve it using factory pattern with #Configuration and #Bean which is much more elegant and easier to understand than your ugly AOP solution:
First define a factory:
#Configuration
public class ServiceFactory{
#Bean
public BaseService companyOneService(){
return new CompanyOneService();
}
#Bean
public BaseService companyTwoService(){
return new CompanyTwoService();
}
public BaseService getService(Integer companyId){
if(companyId == 1){
return companyOneService();
}else if(company==2){
return companyTwoService();
}else{
//blablablab
}
}
}
In the controller , inject the ServiceFactory to get the related Service based on the the company Id
#RestController
public class ApiWebService {
#Autowired
private ServiceFactory serviceFactory;
#GetMapping("insert/order")
public void test() {
Integer companyId = getCompanyIdFromToken(httpServletRequest);
BaseService service = serviceFactory.getService(companyId);
service.blablabla();
}
}
Inject (autowire) ApplicationContext into your class and use one of getBeans* method to find the exact bean you need.
aspect
#Aspect
#Component
public class ApiAspect {
#Pointcut("execution(* com.example.demo.control.ApiWebService.*(..))")
public void apiInputWebService() {
}
#Before("apiInputWebService()")
public void apiInputAuth(JoinPoint joinPoint) throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder
.getRequestAttributes())
.getRequest();
String token = request.getHeader("Authorization");
//compangId can be from token
String compangId = "one";
Object target = joinPoint.getTarget();
Method method = target.getClass().getMethod("before", String.class);
method.invoke(target, compangId);
}
}
control
#RestController
public class ApiWebService {
private ApiService baseService;
#Autowired
private ApplicationContext applicationContext;
public void before(String company) {
baseService = (ApiService) applicationContext.getBean(company);
}
#GetMapping("insert/order")
public void test() {
baseService.insertOrder();
}
}
service
#Service
public class ApiService {
public void insertOrder(){
System.out.println("baseInsertOrder");
}
}
#Service("one")
public class CompanyOneService extends ApiService {
#Override
public void insertOrder() {
System.out.println("conpanyOne");
System.out.println("baseInsertOrder");
}
}
#Service("two")
public class CompanyTwoService extends ApiService {
#Override
public void insertOrder(){
System.out.println("companyTwo");
System.out.println("baseInsertOrder");
}
}
I have problem with injecting bean with generic types. Look at the example. I will inject to the service a repository which types takes from App class. Now i have exception:
No qualifying bean of type 'asd.IRepository' available: expected single matching bean but found 2: a,b
asd here is package, just for tests.
What can I do in this situation? Is any way to makes it?
public interface IRepository<T, V> {
void print();
}
#Component
public class A implements IRepository<String,String> {
#Override
public void print() {
System.out.println("A");
}
}
#Component
public class B implements IRepository<Double,String> {
#Override
public void print() {
System.out.println("A");
}
}
#Service
public class ServiceABC<V, T> {
#Autowired
private IRepository<V,T> repo;
public void print(){
repo.print();
}
}
#Controller
public class App {
#Autowired
private ServiceABC<String, String> serviceABC;
public static void main(String[] args) {
ApplicationContext ctx =
new AnnotationConfigApplicationContext("asd");
App app = ctx.getBean(App.class);
app.serviceABC.print();
}
It looks like you don't know in advance which implementation of your IRepository interface you will need. And you will know that at runtime. In this case it is a typical case for Factory pattern where you will have a IRepositoryFactory that will have a method thhat retrieves specific implementation by type (for example IRepositoryFactory.getInstance(String type); So in your ServiceABC you may use the IRepository to get specific bean at runtime. So Factory pattern may be an answer to your question. I also wrote an article that deals with this type of problem and proposes the idea of self-populating Factory (using Open source library that provides such utility). Here is the link to the article: Non-intrusive access to "Orphaned" Beans in Spring framework
You have to name your components and autowire by name:
#Component("A")
public class A implements IRepository<String,String> {...}
#Component("B")
public class B implements IRepository<Double,String> {...}
[...]
#Autowired
#Qualifier("B")
private IRepository repo;
Something like that?
#Controller
public class RepositoryFactory {
#Autowired
private IRepository<String, String> a;
#Autowired
private IRepository<Double, String> b;
public IRepository getRepository(String className) {
if(className.equalsIgnoreCase("a")) {
return a;
} else if(className.equalsIgnoreCase("b")) {
return b;
}
return null;
}
}
#Service
public class ServiceABC {
#Autowired
private RepositoryFactory repositoryFactory;
public void print(String className){
repositoryFactory.getRepository(className).print();
}
}
#Controller
public class App {
#Autowired
private ServiceABC serviceABC;
public static void main(String[] args) {
ApplicationContext ctx =
new AnnotationConfigApplicationContext("asd");
App app = ctx.getBean(App.class);
app.serviceABC.print(A.class.getSimpleName());
}
}s
I have my AbstractBinder and I bind several classes with the same interface. Let's say I bind Fish and Cat which both implement Animal interface.
What is the easiest/proper way of injecting them into a bean which takes Collection<Animal> ?
PS: Spring has equivalent in simply #Autowire List<Animal> and the collection is created and populated by Spring.
HK2 has IterableProvider<T>, as mentioned here in the documentation. You can get the service by name, by qualifier annotation, or just iterate over them, as it's an Iterable. Just for fun, here is a test.
public class IterableProviderTest {
public static interface Service {}
public static class ServiceOne implements Service {}
#QualAnno
public static class ServiceTwo implements Service {}
#Qualifier
#Target(ElementType.TYPE)
#Retention(RetentionPolicy.RUNTIME)
public static #interface QualAnno {
public static class Instance
extends AnnotationLiteral<QualAnno> implements QualAnno {
public static QualAnno get() {
return new Instance();
}
}
}
public class Binder extends AbstractBinder {
#Override
protected void configure() {
bind(ServiceOne.class).to(Service.class).named("one");
bind(ServiceTwo.class).to(Service.class).qualifiedBy(QualAnno.Instance.get());
}
}
#Inject
private IterableProvider<Service> services;
#Test
public void test_IterableProvider() {
ServiceLocator locator = ServiceLocatorUtilities.bind(new Binder());
locator.inject(IterableProviderTest.this);
assertEquals(2, services.getSize());
Service serviceOne = services.named("one").get();
assertTrue(serviceOne instanceof ServiceOne);
Service serviceTwo = services.qualifiedWith(QualAnno.Instance.get()).get();
assertTrue(serviceTwo instanceof ServiceTwo);
}
}
UPDATE
For a List<Service> (to avoid HK2 InterablProvider), the only think I can think of is to use a Factory and inject the IterableProvider into it, and from there return the list. For example
public class Binder extends AbstractBinder {
#Override
protected void configure() {
...
bindFactory(ListServiceFactory.class).to(new TypeLiteral<List<Service>>(){});
}
}
public static class ListServiceFactory implements Factory<List<Service>> {
#Inject
private IterableProvider<Service> services;
#Override
public List<Service> provide() {
return Lists.newArrayList(services);
}
#Override
public void dispose(List<Service> t) {}
}
Yeah it's a little bit of extra work.
In the latest release of hk2 (2.4.0) you can
#Inject Iterable<Foo> foos;
That allows you to keep your pojo's without any hk2 API in them.
For more information see: Iterable Injection
I have the DataPrepareService that prepare data for reports and I have an Enum with report types, and I need to inject ReportService into Enum or have access to ReportService from enum.
my service:
#Service
public class DataPrepareService {
// my service
}
my enum:
public enum ReportType {
REPORT_1("name", "filename"),
REPORT_2("name", "filename"),
REPORT_3("name", "filename")
public abstract Map<String, Object> getSpecificParams();
public Map<String, Object> getCommonParams(){
// some code that requires service
}
}
I tried to use
#Autowired
DataPrepareService dataPrepareService;
, but it didn't work
How can I inject my service into enum?
public enum ReportType {
REPORT_1("name", "filename"),
REPORT_2("name", "filename");
#Component
public static class ReportTypeServiceInjector {
#Autowired
private DataPrepareService dataPrepareService;
#PostConstruct
public void postConstruct() {
for (ReportType rt : EnumSet.allOf(ReportType.class))
rt.setDataPrepareService(dataPrepareService);
}
}
[...]
}
weekens' answer works if you change inner class to static so spring can see it
Maybe something like this:
public enum ReportType {
#Component
public class ReportTypeServiceInjector {
#Autowired
private DataPrepareService dataPrepareService;
#PostConstruct
public void postConstruct() {
for (ReportType rt : EnumSet.allOf(ReportType.class))
rt.setDataPrepareService(dataPrepareService);
}
}
REPORT_1("name", "filename"),
REPORT_2("name", "filename"),
...
}
There is one another approach you may like to explore. However instead of injecting a bean into enum it associates a bean with an enum
Say you have an enum WidgetType and Widget class
public enum WidgetType {
FOO, BAR;
}
public class Widget {
WidgetType widgetType;
String message;
public Widget(WidgetType widgetType, String message) {
this.widgetType = widgetType;
this.message = message;
}
}
And you want to create Widgets of this type using a Factory BarFactory or FooFactory
public interface AbstractWidgetFactory {
Widget createWidget();
WidgetType factoryFor();
}
#Component
public class BarFactory implements AbstractWidgetFactory {
#Override
public Widget createWidget() {
return new Widget(BAR, "A Foo Widget");
}
#Override
public WidgetType factoryFor() {
return BAR;
}
}
#Component
public class FooFactory implements AbstractWidgetFactory {
#Override
public Widget createWidget() {
return new Widget(FOO, "A Foo Widget");
}
#Override
public WidgetType factoryFor() {
return FOO;
}
}
The WidgetService is where most of the work happens. Here I have a simple AutoWired field which keeps tracks of all the registered WidgetFactories. As a postConstruct operation we create a map of the enum and the associated factory.
Now clients could inject the WidgetService class and get the factory for the given enum type
#Service
public class WidgetService {
#Autowired
List<AbstractWidgetFactory> widgetFactories;
Map<WidgetType, AbstractWidgetFactory> factoryMap = new HashMap<>();
#PostConstruct
public void init() {
widgetFactories.forEach(w -> {
factoryMap.put(w.factoryFor(), w);
});
}
public Widget getWidgetOfType(WidgetType widgetType) {
return factoryMap.get(widgetType).createWidget();
}
}
Enums are static, so you have to figure out a way to access to the beans from a static context.
You can create a class named ApplicationContextProvider that implements the ApplicationContextAware interface.
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
public class ApplicationContextProvider implements ApplicationContextAware{
private static ApplicationContext appContext = null;
public static ApplicationContext getApplicationContext() {
return appContext;
}
public void setApplicationContext(ApplicationContext appContext) throws BeansException {
this.appContext = appContext;
}
}
then add this your application context file:
<bean id="applicationContextProvider" class="xxx.xxx.ApplicationContextProvider"></bean>
after that you could access to the application context in a static way like this:
ApplicationContext appContext = ApplicationContextProvider.getApplicationContext();
it will be hard to control that the spring container is already up and running at the time the enum is instantiated (if you had a variable with this type in a test-case, your container will usually not be there, even aspectj autowiring won't help there). i would recommend to just let the dataprepare-service or something give you the specific-params with a lookup-method with the enum-parameter.
I think this what you need
public enum MyEnum {
ONE,TWO,THREE;
}
Autowire the enum as per usual
#Configurable
public class MySpringConfiguredClass {
#Autowired
#Qualifier("mine")
private MyEnum myEnum;
}
Here is the trick, use the factory-method="valueOf" and also make sure
lazy-init="false"
so the container creates the bean upfront
<bean id="mine" class="foo.bar.MyEnum" factory-method="valueOf" lazy-init="false">
<constructor-arg value="ONE" />
</bean>
and you are done!
Just pass it to the method manually
public enum ReportType {
REPORT_1("name", "filename"),
REPORT_2("name", "filename"),
REPORT_3("name", "filename")
public abstract Map<String, Object> getSpecificParams();
public Map<String, Object> getCommonParams(DataPrepareService dataPrepareService){
// some code that requires service
}
}
As long as you call the method only from managed beans, you can inject it in these beans and pass the reference to the enum on each call.
Maybe you can use this solution ;
public enum ChartTypes {
AREA_CHART("Area Chart", XYAreaChart.class),
BAR_CHART("Bar Chart", XYBarChart.class),
private String name;
private String serviceName;
ChartTypes(String name, Class clazz) {
this.name = name;
this.serviceName = clazz.getSimpleName();
}
public String getServiceName() {
return serviceName;
}
#Override
public String toString() {
return name;
}
}
And in another class which you need the bean of the Enum :
ChartTypes plotType = ChartTypes.AreaChart
Object areaChartService = applicationContext.getBean(chartType.getServiceName());