Spring Annotations

CREATING SIMPLE SPRING PROJECT[JAVA CONFIGURATION]

STEP1 : ADD DEPENDENCIES

groupId :org.springframework spring-core ${spring.version} spring-webmvc <!-- cglib required for @configuration annotation --> cglib:cglib\

STEP 2  : CREATE BEAN CLASS

PROPERTY + CONSTRUTOR + GETTER /SETTERS  

STEP 3  : CREATE CONFIGURTAION CLASS

@Configuration

public class ApplicationConfiguration {

@Bean(name="countryObj")

public Country getCountry()

{

  return new Country("India");

}  

STEP 4  : CREATE MAIN CLASS

public class SpringJavaConfigMain {

public static void main(String[] args) {

ApplicationContext appContext = new AnnotationConfigApplicationContext(ApplicationConfiguration.class);

  Country countryObj = (Country) appContext.getBean("countryObj");

  String countryName=countryObj.getCountryName();

  

  System.out.println("Country name: "+ countryName);

}

SCOPES
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public static void main(String[] args) {

  

ApplicationContext appContext = new ClassPathXmlApplicationContext("ApplicationContext.xml");

  Country countryObj1 = (Country) appContext.getBean("country");

  countryObj1.setCountryName("India");

  System.out.println("Country Name:"+countryObj1.getCountryName());

  

  //getBean called second time

  Country countryObj2 = (Country) appContext.getBean("country");

  System.out.println("Country Name:"+countryObj2.getCountryName());

}

APPLICATIONCONTEXTAWARE

public static void main(String[] args) {

  ApplicationContext appContext = new ClassPathXmlApplicationContext("ApplicationContext.xml");

  Country countryObj = (Country) appContext.getBean("country");

  System.out.println("Capital Name:"+countryObj.getCapitalName("capital"));

SPRING MVC : JAVA BASED
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Step 1 :Add Dependencies
spring-core |spring-webmvc

javax.servlet-api

jstl junit

Step 2 :Add Plugins
Maven plugins
maven-compiler-plugin

maven-war-plugin

Step 3 :Create Configuration 

@EnableWebMvc

@ComponentScan(basePackages = "com.example")

public class SpringConfig extends WebMvcConfigurerAdapter{

    @Bean

    public ViewResolver viewResolver() {@Configuration

        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();

        viewResolver.setViewClass(JstlView.class);

        viewResolver.setPrefix("/WEB-INF/pages/");

        viewResolver.setSuffix(".jsp");

        return viewResolver;

    }

    @Override

    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {

        configurer.enable();

    }

}

Step 4 :Create Configuration for replacing web.xml

public class WebServletConfiguration implements WebApplicationInitializer{

    public void onStartup(ServletContext ctx) throws ServletException {

        AnnotationConfigWebApplicationContext webCtx = new AnnotationConfigWebApplicationContext();

        webCtx.register(SpringConfig.class);

        webCtx.setServletContext(ctx);

        ServletRegistration.Dynamic servlet = ctx.addServlet("dispatcher", new DispatcherServlet(webCtx));

        servlet.setLoadOnStartup(1);

        servlet.addMapping("/");

    }

}

Step 5 :Create Controller


7) Create a package named “org.arpit.java2blog.springmvc.controller”

@Controller

public class GreetController {

    @RequestMapping(path= "/greet/{name}",method=RequestMethod.GET)    

    public String greet(@PathVariable String name, ModelMap model){

        String greet =" Hello !!!" + name + " How are You?";

        model.addAttribute("greet", greet);

        System.out.println(greet);

        return "greet";

    }

}

Step 6 :Create jsp to show message

Step 7: Hit the URL 

http://localhost:8080/SpringWebExample/greet/shamik

References

https://dzone.com/articles/spring-mvc-and-java-based-configuration-1
http://websystique.com/springmvc/spring-4-mvc-helloworld-tutorial-annotation-javaconfig-full-example/

MVC Annotations & concepts _______________________________________________________________________
http://localhost:8080/ProjectName/countries

@RequestMapping - Annotations

@RestController

@RequestMapping(value = "/countries")

public class CountryController {

@RequestMapping(method = RequestMethod.POST, headers = "Accept=application/json")

public Country addCountry(@RequestBody Country country) {

  return countryService.addCountry(country);

}

@RequestMapping(method = RequestMethod.PUT, headers = "Accept=application/json")

public Country updateCountry(@RequestBody Country country) {

  return countryService.updateCountry(country);

}

}

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ModelMap object is used to pass multiple values from Spring MVC controller to JSP .

Some basics about Spring MVC ModelMap class:

• ModelMap class subclasses LinkedHashMap. It add some methods for convenience.
• It provides addAttribute method to put key value pair. This method return ModelMap objects that can be used for chaining.
• ModelMap uses as generics.
• ModelMap checks for null values.

@RequestMapping("/helloworld")

public String hello(ModelMap map) {

  String helloWorldMessage = "Hello world from java2blog!";

  String welcomeMessage = "Welcome to  java2blog!";

  map.addAttribute("helloMessage", helloWorldMessage);

  map.addAttribute("welcomeMessage", welcomeMessage);

  

  return "hello";

}

<body>

${helloMessage}

<br/>

${welcomeMessage}

</body>

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MULTIACTION CONTROLLER

This the expected method struture

public (ModelAndView | Map | String | void) actionName(HttpServletRequest request, HttpServletResponse response, [,HttpSession] [,AnyObject]);
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@Controller

public class PayeeController {

private static final Logger logger = Logger.getLogger(HelloWorldController.class);

@RequestMapping("/payee/add.htm")

public ModelAndView add(HttpServletRequest request,

  HttpServletResponse response) throws Exception {

logger.info("This is info message");

logger.error("This is error message");

  return new ModelAndView("payee", "message", "Payee Added");

}

@RequestMapping("/payee/delete.htm")

public ModelAndView delete(HttpServletRequest request,

  HttpServletResponse response) throws Exception {

  return new ModelAndView("payee", "message", "Payee Deleted");

}

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@MODELATTRIBUTE ANNOTATION'

@ModelAttribute is used to bind request parameters with model object.  Lets say you have 10 request parameters , you can wrap them to model object and pass it in the to handler method.

 

@Controller

public class CountryController {

 

@ModelAttribute

public Country getCountry(@RequestParam String countryName, @RequestParam  long population)

{

  Country country=new Country();

  country.setCountryName(countryName);

  country.setPopulation(population);

  return country;

}

@RequestMapping(value = "/addCountry", method = RequestMethod.POST)

public String addCountry(@ModelAttribute Country country,ModelMap model) {

  model.addAttribute("countryName", country.getCountryName());

  model.addAttribute("population", country.getPopulation());

  return "countryDetails";

}

}

<h3>Country Name: ${countryName}</h3>

<h3>Population : ${population}</h3>

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SPRING ANNOTATIONS
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DEPEDNDENCIES
spring-webmvc

@RequestMapping("/helloworld")

return new ModelAndView("hello", "message", helloWorldMessage);

This means populate the ${message} property in help.jsp with value of helloWorldMessage

<body>

${message}

</body>

@Component

public class Country {

 //this syntax is used to read a String from the property file

@Value("${countryName}")

private String countryName;

https://java2blog.com/spring-boot-hello-world-standalone-application/

.

@SpringBootApplication = @Configuration+ @EnableAutoConfiguration +@EnableWebMVC+@ComponentScan

Normally you would add @EnableWebMvc for a Spring MVC application, but Spring Boot adds it automatically when it sees spring-webmvc on the classpath.

@ComponentScan: scans

components, configurations, and services in the default package, .

@Autowired

@Qualifier("country")

Country countryBean;

public static void main(String[] args)

{

SpringApplication.run(SpringBootHelloWorldStandaloneApplication.class, args);  

}

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Create Restful web services using Spring Boot

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Create Restful web services using Spring Boot

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Spring Security

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@EnableWebSecurity annotation is used to enable spring security for this webapp.

authroizeRequest().addMatchers() method is used 

to configure pattern for request.

For example: If http request url has pattern /hello*(hello.jsp,helloworld.html), it will be accessed to ROLE_ADMIN only.

We have hardcoded username(java2blog) and password(java123)   using inMemoryAuthentication(), so if user provides correct credential for admin then only he will be able to access helloworld.html.

@Configuration

@EnableWebSecurity

public class WebSecurityConfiguaration extends WebSecurityConfigurerAdapter {

    @Override

    protected void configure(HttpSecurity http) throws Exception {

    

     http.authorizeRequests()

.antMatchers("/hello*").access("hasRole('ROLE_ADMIN')").and().formLogin();;

    }

    @Autowired

    public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {

     auth.inMemoryAuthentication().withUser("java2blog").password("java123").roles("ADMIN");

    }

}