Building Web Apps with Spring 5 and Angular 4

    /*
     * This class demonstrates the dependency of higher-level object   
     * (DrawWithoutIOC)
     * onto lower level objects such as Rectangle, Square which are 
     * created within 
     * Shape class based on the value of shapeType which is passed as a 
     * method 
     * parameter to draw method.
     */

    public class DrawWithoutIOC {

      Logger logger = Logger.getLogger(DrawWithoutIOC.class.getName());

      public void draw(String shapeType) {
        Shape shape = new Shape();
        try {
          shape.draw(shapeType);
        } 
        catch (UndefinedShapeException e) {
          logger.log(Level.INFO, e.getMessage(), e);
        }
      }
    /*
     * Note that Shape class creates instances of Rectangle or Square   
       class
     * based on the value of shapeType. Any new value that needs to be   
       supported requires change in the draw method of Shape class.
     */

      private class Shape {
        public void draw(String shapeType) throws 
          UndefinedShapeException 
        {
          if(shapeType.equals("rectangle")) {
            Rectangle rectangle = new Rectangle();
            rectangle.draw();
          } else if(shapeType.equals("square")) {
            Square square = new Square();
            square.draw();
          } else {
            String shapeNotSupportedMessage = "Shape " + shapeType + " 
                   not supported";
            logger.log(Level.INFO, shapeNotSupportedMessage);
            throw new UndefinedShapeException 
              (shapeNotSupportedMessage);
          }
        }
      }

      public static void main(String[] args) {
        DrawWithoutIOC drawWithoutIOC = new DrawWithoutIOC();
        drawWithoutIOC.draw("circle");
      }
    }

    /**
     * In this class, the Shape is passed as parameter to DrawWithIOC   
     * constructor. 
     * draw method on a DrawWithIOC object just invokes the draw method  
     * on Shape object. 
     * It, no longer, manage the creation of Shape object based on 
     * shapeType and there upon, invoke the draw method.
     **/

    public class DrawWithIOC {
      Logger logger = Logger.getLogger(DrawWithIOC.class.getName());

      private Shape shape;

      public DrawWithIOC(Shape shape) {
        this.shape = shape;
      }

      public void draw() { 
        this.shape.draw(); 
      } 

      public static void main(String[] args) {
        Shape shape = new Rectangle();
        DrawWithIOC drawWithIOC = new DrawWithIOC(shape);
        drawWithIOC.draw();
      }
    }

    package com.example;

    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.ResponseBody;

    import com.services.UserService;
    import com.services.domain.User;

    @Controller
    @SpringBootApplication (scanBasePackages={"com.services"})
    public class DemoApplication {

@Autowired
        private UserService userService;

        @RequestMapping("/")
        @ResponseBody
        String home() { 
            User user = null;
            return "Hello " + userService.getUsername(user) + ". How are you?";
        }

        public static void main(String[] args) {
            SpringApplication.run(DemoApplication.class, args);
        }
    }

        import org.springframework.beans.factory.annotation.Autowired;
        import org.springframework.stereotype.Service;

        import com.services.dao.UserDAO;
        import com.services.domain.User;

        @Service ("userService")
        public class UserService {

            @Autowired
            private UserDAO userDAO;

            public String getUsername(User user) {
                return userDAO.getUsername(user);
            }
        }

        import org.springframework.stereotype.Repository;

        import com.services.domain.User;

        @Repository ("userDAO")
        public class UserDAO {

            public String getUsername(User user) {
                return "Albert Einstein";
            }
        }

        @Controller
@SpringBootApplication
        public class HelloWorldApplication {

@RequestMapping("/")
            String home() { 
                return "Hello world. How are you?";
            }

            public static void main(String[] args) {
                SpringApplication.run(HelloWorldApplication.class, args);
            }
        }

            <dependency>
              <groupId>org.apache.tomcat.embed</groupId>
              <artifactId>tomcat-embed-jasper</artifactId>
            </dependency>
            <dependency>
              <groupId>javax.servlet</groupId>
              <artifactId>jstl</artifactId>
            </dependency>

            spring.mvc.view.prefix=/WEB-INF/jsp/
            spring.mvc.view.suffix=.jsp

            @Controller
@SpringBootApplication
            public class HelloWorldApplication {

@RequestMapping("/")
                String home() { 
                    return "index";
                }

                public static void main(String[] args) {
                    SpringApplication.run(HelloWorldApplication.class, args);
                }
            }

    @Controller
    @RequestMapping("/account/*")
    public class UserAccountController {

@GetMapping("/signup")
        public String signup() {
            return "signup";
        } 

@PostMapping("/signup/process")
        public String processSignup(ModelMap model, 
@RequestParam("nickname") String nickname, 
        @RequestParam("emailaddress") String emailAddress, 
        @RequestParam("password") String password) {
            model.addAttribute("login", true);
            model.addAttribute("nickname", nickname);
            return "index";
        }
    }

    @RestController
    public class RestDemoController {

@PostMapping("/hello")
        public HelloMessage getHelloMessage(@RequestBodyUser user) {
            HelloMessage helloMessage = new HelloMessage();
            String name = user.getName();
            helloMessage.setMessage( "Hello " + name + "! How are you doing?");
            helloMessage.setName(name);
            return helloMessage;
        }  
    }

        {"name": "Calvin Hobbes"}

    public class User {
      private String name;

      public String getName() {
        return name;
      } 

      public void setName(String name) {
        this.name = name;
      }
    }

   public class HelloMessage {
     private String message;
     private String name;
     public String getMessage() {
       return message;
     }
     public void setMessage(String message) {
       this.message = message;
     }
     public String getName() {
       return name;
     }
     public void setName(String name) {
       this.name = name;
     }
   }

    {"message": "message text goes here...", "name": "name goes here..."}

    @Controller
    @SpringBootApplication
    public class HealthAppApplication {

      @RequestMapping("/") 
      public String home() {
        return "index";
      }

@GetMapping("/{nickname}")
      public String home(ModelMap model, @PathVariable String nickname) {
        model.addAttribute("name", nickname);
        return "index";
      }

      public static void main(String[] args) {
        SpringApplication.run(HealthAppApplication.class, args);
      }
    }

    @Controller
    @SpringBootApplication
    public class HealthAppApplication {
     //
     // RequestParam is used to retrieve value of parameter, name. 
     //
     @RequestMapping("/") 
     public String usingRequestParam(Model model, 
                   @RequestParam(value="name", required=false) String nickname) {
      model.addAttribute("nickname", nickname);
      return "index";
    }

    @RequestMapping("/{nickname}") 
     public String usingPathVariable(Model model, @PathVariable String nickname) 
     {
       model.addAttribute("nickname", nickname);
       return "index";
     }
   }

    @Controller
    @RequestMapping("/account/*")
    public class UserAccountController {

      @PostMapping("/signup/process")
      public ModelAndView processSignup(ModelMap model, @RequestParam("nickname")       String  nickname, @RequestParam("emailaddress") 
      String emailAddress, @RequestParam("password") String password) {
        model.addAttribute("login", true);
        model.addAttribute("nickname", nickname);
        model.addAttribute("message", "Have a great day ahead.");
return new ModelAndView("index", model);
      }
    }

    // Will result in display of index.jsp page
    return new ModelAndView("index");

    // Will result in display of index.jsp page. 
    //The JSP page could consist of code such as "Hello ${name}" 
    //which will get displayed as "Hello Calvin Hobbes"  

    return new ModelAndView("index", "name", "Calvin Hobbes");

    // Will result in display of index.jsp page. 
    // The JSP page could consist of code such as 
    //"Hello ${model.firstName} ${model.lastName}" 
    //which will get displayed as "Hello Calvin Hobbes"

    UserInfo userInfo = new UserInfo();
    userInfo.setFirstName("Calvin");
    userInfo.setLastName("Hobbes");
    return new ModelAndView("index", "model", userInfo);

    // Will result in display of index.jsp page. 
    // The JSP page could consist of code such as "Hello ${name}" 
    // which will get displayed as "Hello Calvin Hobbes"

    Map<String, Object> map = new HashMap<String, Object>();
    map.put("name", "Calvin Hobbes");
    return new ModelAndView("index", map);

    @Controller
    public class RestDemoController {

      @RequestMapping(value="/hello", method=RequestMethod.POST, produces="application/json")
@ResponseBody
      public HelloMessage getHelloMessage(@RequestBody User user) {
        HelloMessage helloMessage = new HelloMessage();
        String name = user.getName();
        helloMessage.setMessage( "Hello " + name + "! How are you doing?");
        helloMessage.setName(name);
        return helloMessage;
      }
    }