I am new to spring boot. So I am working on a simple application where I have 2 services EnglishLanguageService and SpanishLanguageService. In the end, I would like to print Hello and Hola when the app runs but I am getting the error
Parameter 0 of constructor in controller.ConstructorInjectedController required a single bean, but 2 were found:
- profileEnglishLanguageService: defined in file [/Users/user/Downloads/depdency-injection-example/target/classes/services/EnglishLanguageService.class]
- profileSpanishLanguageService: defined in file [/Users/user/Downloads/depdency-injection-example/target/classes/services/SpanishLanguageService.class]
Action:
Consider marking one of the beans as #Primary, updating the consumer to accept multiple beans, or using #Qualifier to identify the bean that should be consumed
I am not sure where I am going wrong. I will paste my code down below.
MainApplication
#SpringBootApplication
#ComponentScan(basePackages= {"controller" , "services"})
public class DepdencyInjectionExampleApplication {
public static void main(String[] args) {
// returns application context
ApplicationContext ctx = SpringApplication.run(DepdencyInjectionExampleApplication.class, args);
System.out.println(ctx.getBean(PropertyInjectedController.class).getGreeting());
System.out.println(ctx.getBean(ConstructorInjectedController.class).getGreetings());
}
ConstructorInjectedController class
#Component
public class ConstructorInjectedController {
private final GreetingService greetingService;
public ConstructorInjectedController(GreetingService greetingService) {
this.greetingService = greetingService;
}
public String getGreetings() {
return greetingService.sayGreetings();
}
PropertyInjectedControllerClass
#Controller
public class PropertyInjectedController {
public GreetingService greetingService;
public String getGreeting() {
return greetingService.sayGreetings();
}
}
GreetingService interface
public interface GreetingService {
String sayGreetings();
}
EnglishLanguageService class
#Service
public class EnglishLanguageService implements GreetingService {
private GreetingService greetingService;
public EnglishLanguageService(#Qualifier("english")
GreetingService greetingService){
this.greetingService = greetingService;
}
#Override
public String sayGreetings() {
return greetingService.sayGreetings();
}
EnglishServiceImpl
#Profile("english")
public class EnglishServiceImpl implements GreetingService {
#Override
public String sayGreetings() {
return "Hello";
}
SpanishLanguageService
#Service
public class SpanishLanguageService implements GreetingService {
private GreetingService greetingService;
public SpanishLanguageService(#Qualifier("spanish")
GreetingService greetingService){
this.greetingService = greetingService;
}
#Override
public String sayGreetings() {
return greetingService.sayGreetings();
}
SpanishLanguageServiceImpl
#Profile("spanish")
public class SpanishServiceImpl implements GreetingService {
#Override
public String sayGreetings() {
return "Hola";
}
}
You are using the annotations wrong. #Profile is used for something completely other than you think so it should be removed.
You are basically saying to spring "please inject a specific greeting service in class X please".
Right now spring doesn't know which bean you want since you have two different ones implementing the same interface. So we use the #Qualifier annotation to tag a bean, and also to target it during injection.
Fist your implementation should have either a #Service or a #Component so that spring finds it during the component scan, and instantiates it as a spring managed bean. This combined with a #Qualifier so that we tag it, so we later can pick this tag during injection:
#Component
#Qualifier("english")
public class EnglishServiceImpl implements GreetingService {
#Override
public String sayGreetings() {
return "Hello";
}
}
Here we inject the greeting service and use our qualifier to tell spring which bean we want to inject of the available ones.
#Service
public class EnglishLanguageService implements GreetingService {
private GreetingService greetingService;
public SpanishLanguageService(#Qualifier("english") GreetingService greetingService){
this.greetingService = greetingService;
}
#Override
public String sayGreetings() {
return greetingService.sayGreetings();
}
}
Related
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 am using next dozer custom converter
public class MyCustomDozerConverter extends DozerConverter<MyObject, String> {
#Autowired
private AppConfig appConfig;
public MyCustomDozerConverter() {
super(MyObject.class, String.class);
}
#Override
public String convertTo(MyObject source, String destination) {
String myProperty = appConfig.getWhatever();
// business logic
return destination;
}
#Override
public MyObject convertFrom(String source, MyObject destination) {
// business logic
return null;
}
}
My problem is when it goes through convertTo method inside the converter, I always got appConfig instance with null value which of course cause a null pointer exception
Note: my spring boot class have these annotations above:
#SpringBootApplication
#EnableAutoConfiguration
#ComponentScan({"com.xxx"})
#EntityScan("com.xxx")
#EnableJpaRepositories("com.xxx")
I solved this by next trick:
1- Using static with appConfig property.
2- instantiate it by spring so when dozer use default empty constructor it will find appConfig have
a value already (which assigned before to it by spring)
And here are the code i used for this:
#Component //import org.springframework.stereotype.Component;
public class MyCustomDozerConverter extends DozerConverter<MyObject, String> {
private static AppConfig appConfig;
// dozer needs this constructor to create an instance of converter (so it's a mandatory constructor)
public MyCustomDozerConverter() {
super(MyObject.class, String.class);
}
#Autowired // Spring will pass appConfig to constructor
public MyCustomDozerConverter(AppConfig appConfig) {
this();
this.appConfig = appConfig;
}
#Override
public String convertTo(MyObject source, String destination) {
String myProperty = appConfig.getWhatever();
// business logic
return destination;
}
#Override
public MyObject convertFrom(String source, MyObject destination) {
// business logic
return null;
}
}
UPDATE: Another solution
Another trick is using Spring ApplicationContextAware to get a singleton object from getBean method:
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;
#Component
public class ApplicationContextHolder implements ApplicationContextAware {
private static ApplicationContext context;
#Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
context = applicationContext;
}
public static ApplicationContext getContext() {
return context;
}
}
Then create a static method inside AppConfig class and return an instance of the single bean matching the required type:
import org.springframework.context.annotation.Configuration;
import com.tripbru.ms.experiences.ApplicationContextHolder;
#Configuration
public class AppConfig {
// Static method used to return an instatnce
public static AppConfig getInstance() {
return ApplicationContextHolder.getContext().getBean(AppConfig.class);
}
// Properties
}
Then calling it direct inside the dozer converter by AppConfig.getInstance();
public class MyCustomDozerConverter extends DozerConverter<MyObject, String> {
private static AppConfig appConfig;
public MyCustomDozerConverter() {
super(MyObject.class, String.class);
appConfig = AppConfig.getInstance(); // Here are we intializing it by calling the static method we created.
}
#Override
public String convertTo(MyObject source, String destination) {
String myProperty = appConfig.getWhatever();
// business logic
return destination;
}
#Override
public MyObject convertFrom(String source, MyObject destination) {
// business logic
return null;
}
}
Try constructor dependency injection
private AppConfig appConfig;
#Autowired
MyCustomerDozerConverter(AppConfig appConfig)
{
this.appConfig = appConfig;
}
You can put following line in the CustomConverter so that Spring will autowire it.
public class MyCustomDozerConverter extends DozerConverter<MyObject, String> {
#Autowired
private AppConfig appConfig;
public MyCustomDozerConverter() {
super(MyObject.class, String.class);
SpringBeanAutowiringSupport.processInjectionBasedOnCurrentContext(this);
}
...
}
I have a controller like this
#Path("/")
#Produces(MediaType.APPLICATION_JSON)
#Consumes(MediaType.APPLICATION_JSON)
public class AccountController implements CRUDController<Long, Account> {
private AccountDao accountDao;
private AccountService accountService;
#Inject
public AccountController(AccountDao accountDao, AccountService accountService) {
this.accountDao = accountDao;
this.accountService = accountService;
}
...
I'm injecting AccountDao and AccountService using
ResourceConfig config = new ResourceConfig()
.packages("controller", "exception")
.register(new MyDIBinder());
Where MyDIBinder is contains all the bindings (e.g
AccountDaoImpl accountDaoImpl = new AccountDaoImpl();
bind(accountDaoImpl).to(AccountDao.class);
)
Now I want to write a unit test for this controller, is it possible to inject the whole AccountController instance with all of it's transitive dependencies into the test?
Something like
#Inject
AccountController accountController;
You can use the main IoC container, and just explicitly inject the test class. Jersey uses HK2 as its DI framework, and its IoC container is the ServiceLocator, which has a method inject(anyObject) that can inject any objects with dependencies that are in its registry.
For example you could do something like
public class InjectionTest {
#Inject
private TestController controller;
#Before
public void setUp() {
final Binder b = new AbstractBinder() {
#Override
public void configure() {
bindAsContract(TestController.class);
}
};
final ServiceLocator locator = ServiceLocatorUtilities.bind(new TestBinder(), b);
locator.inject(this);
}
#Test
public void doTest() {
assertNotNull(controller);
String response = controller.get();
assertEquals("Hello Tests", response);
}
}
The ServiceLocatorUtilities class is a helper class that allows us to easily create the ServiceLocator, and then we just call inject(this) to inject the InjectionTest.
If it seems repetitive to do this for all your controller tests, you may want to create an abstract base test class. Maybe something like
public abstract class AbstractControllerTest {
protected ServiceLocator locator;
private final Class<?> controllerClass;
protected AbstractControllerTest(Class<?> controllerClass) {
this.controllerClass = controllerClass;
}
#Before
public void setUp() {
final AbstractBinder binder = new AbstractBinder() {
#Override
public void configure() {
bindAsContract(controllerClass);
}
};
locator = ServiceLocatorUtilities.bind(new TestBinder(), binder);
locator.inject(this);
}
#After
public void tearDown() {
if (locator != null) {
locator.shutdown();
}
}
}
Then in your concrete class
public class TestControllerTest extends AbstractControllerTest {
public TestControllerTest() {
super(TestController.class);
}
#Inject
private TestController controller;
#Test
public void doTest() {
assertNotNull(controller);
assertEquals("Hello Tests", controller.get());
}
}
If you spent some more time, I'm sure you could come up with a better abstract test class design. It was the first thing that came to mind for me.
Note: For anything request scoped, you mayb need to just mock it. When running the unit tests, there is no request context, so the test will fail.
See Also:
Using Jersey's Dependency Injection in a Standalone application
HK2 documentation
import org.glassfish.hk2.api.ServiceLocator;
import org.glassfish.hk2.utilities.ServiceLocatorUtilities;
import org.glassfish.hk2.utilities.binding.AbstractBinder;
#BeforeClass
public static void doTest() {
ServiceLocator serviceLocator = ServiceLocatorUtilities.bind(new AbstractBinder() {
#Override
protected void configure() {
bindAsContract(YourClass1.class);
bindAsContract(YourClass2.class);
bindAsContract(YourClass3.class);
}
});
YourClass1 yourClass1 = serviceLocator.getService(YourClass1.class);
...
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());