unable to inject bean in simple spring mvc application - spring

Question

I am trying a simple application in the spring mvc using annotations only. In my service class, I am unable to inject DAO class even though I have used relevant annotations.Please let me know what mistake I am doing. Below are my class definitions.
public class AppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
#Override
protected Class<?>[] getRootConfigClasses() {
return new Class[] { SpringRootConfig.class };
//return null;
}
#Override
protected Class<?>[] getServletConfigClasses() {
return new Class[] { SpringWebConfiguration.class };
}
#Override
protected String[] getServletMappings() {
return new String[] { "/" };
}
}
#Configuration
#EnableWebMvc
#ComponentScan(basePackages="com.emp.controller")
public class SpringWebConfiguration extends WebMvcConfigurerAdapter{
#Bean
public InternalResourceViewResolver jspViewResolver() {
InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
viewResolver.setPrefix("/WEB-INF/view/");
viewResolver.setSuffix(".jsp");
return viewResolver;
}
}
#Configuration
#EnableWebMvc
#ComponentScan(basePackages="com.emp.svc,com.emp.dao")
public class SpringRootConfig {
}
package com.emp.svc;
import org.springframework.beans.factory.annotation.Autowired;
import com.emp.dao.LoginDAO;
public class LoginSvc {
#Autowired
private LoginDAO dao;
public boolean validateLogin(){
System.out.println("In the svc method");
return dao.validateLogin();
}
}
package com.emp.dao;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Repository;
#Repository
public class LoginDAO {
public boolean validateLogin(){
System.out.println("In the DAO method");
return true;
}
}
package com.emp.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.ModelAndView;
import com.emp.forms.LoginForm;
import com.emp.svc.LoginSvc;
#Controller
public class LoginController {
#RequestMapping(value = {"/login"},method = RequestMethod.GET)
public ModelAndView launchLoginPage(){
ModelAndView model = new ModelAndView();
model.setViewName("login");
return model;
}
#RequestMapping(value = {"/welcome"},method = RequestMethod.GET)
public ModelAndView validateLogin(#ModelAttribute LoginForm form){
ModelAndView model = new ModelAndView();
LoginSvc svc = new LoginSvc();
if(svc.validateLogin()){
model.setViewName("welcome");
}
else
{
model.setViewName("login");
}
return model;
}
LoginSvc is called from controller. I am expecting that in LoginSvc, LoginDAO will be injected and hence the call to dao dao.validateLogin() will be successful. But what I am getting is Null pointer at dao.validateLogin(), indicating LoginDAO is not injected.
If you can let me know what I am missing, it will be great help.

Answer 1

Add #Service annotation in your LoginSvc class.
package com.emp.svc;
import org.springframework.beans.factory.annotation.Autowired;
import com.emp.dao.LoginDAO;
#Service
public class LoginSvc {
#Autowired
private LoginDAO dao;
public boolean validateLogin(){
System.out.println("In the svc method");
return dao.validateLogin();
}
}
And autowire LoginSvc inside your controller. As you are creating the object yourself invoking constructor of LoginSvc, spring will not provide you autowire candidate.
#Controller
public class LoginController {
#Autowired
private LoginSvc svc;
#RequestMapping(value = {"/login"},method = RequestMethod.GET)
public ModelAndView launchLoginPage(){
ModelAndView model = new ModelAndView();
model.setViewName("login");
return model;
}
#RequestMapping(value = {"/welcome"},method = RequestMethod.GET)
public ModelAndView validateLogin(#ModelAttribute LoginForm form){
ModelAndView model = new ModelAndView();
if(svc.validateLogin()) {
model.setViewName("welcome");
} else {
model.setViewName("login");
}
return model;
}
}