2. Develop web application-Spring Practical Fifth Edition

1. Display information

Taco Cloud is an application that can order taco, so you need to show various taco.
We need three components:

• A domain class to define taco;
• A controller to process and push data to the view;
• A view template renders the page to the vagrant.

1.1 Create domain

package tacos;

import lombok.Data;
import lombok.RequiredArgsConstructor;

@Data
@RequiredArgsConstructor
public class Ingredient {

	private String id;
	private String name;
	private Type type;

	public static enum Type {
		WRAP, PROTEIN, VEGGIES, CHEESE, SAUCE
	}

}

With Lombok, you can simplify the code.
Add dependencies:

	<dependency>
		<groupId>org.projectlombok</groupId>
		<artifactId>lombok</artifactId>
		<optional>true</optional>
	</dependency>

Add Lombok plug-in method in Eclipse: Install Lombok plug- in in Eclipse .

1.2 Create controller

package tacos.web;

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

import javax.validation.Valid;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.Errors;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;

import lombok.extern.slf4j.Slf4j;
import tacos.Ingredient;
import tacos.Ingredient.Type;
import tacos.Taco;

@Slf4j
@Controller
@RequestMapping("/design")
public class DesignTacoController {

	@ModelAttribute
	public void addIngredientsToModel(Model model) {
		List<Ingredient> ingredients = Arrays.asList(new Ingredient("FLTO", "Flour Tortilla", Type.WRAP),
				new Ingredient("COTO", "Corn Tortilla", Type.WRAP), new Ingredient("GRBF", "Ground Beef", Type.PROTEIN),
				new Ingredient("CARN", "Carnitas", Type.PROTEIN),
				new Ingredient("TMTO", "Diced Tomatoes", Type.VEGGIES), new Ingredient("LETC", "Lettuce", Type.VEGGIES),
				new Ingredient("CHED", "Cheddar", Type.CHEESE), new Ingredient("JACK", "Monterrey Jack", Type.CHEESE),
				new Ingredient("SLSA", "Salsa", Type.SAUCE), new Ingredient("SRCR", "Sour Cream", Type.SAUCE));

		Type[] types = Ingredient.Type.values();
		for (Type type : types) {
			model.addAttribute(type.toString().toLowerCase(), filterByType(ingredients, type));
		}
	}

	@GetMapping
	public String showDesignForm(Model model) {
		model.addAttribute("design", new Taco());
		return "design";
	}

	@PostMapping
	public String processDesign(@Valid @ModelAttribute("design") Taco design, Errors errors, Model model) {
		if (errors.hasErrors()) {
			return "design";
		}

		// Save the taco design...
		// We'll do this in chapter 3
		log.info("Processing design: " + design);

		return "redirect:/orders/current";
	}

	private List<Ingredient> filterByType(List<Ingredient> ingredients, Type type) {
		return ingredients.stream().filter(x -> x.getType().equals(type)).collect(Collectors.toList());
	}

}

1.3 Define the view

Learn Thymeleaf.

3. Verify the input data

spring 支持 Java's Bean Validation API (JSR-303).

• Declaring validation rules in class member variables;
• Declare verification in the method of the controller layer;
• Display verification information in the view layer.

1. Declare validation rules in class member variables

package tacos;

import javax.validation.constraints.Digits;
import javax.validation.constraints.NotBlank;
import javax.validation.constraints.Pattern;

import org.hibernate.validator.constraints.CreditCardNumber;

import lombok.Data;

@Data
public class Order {

	@NotBlank(message = "Name is required")
	private String name;

	@NotBlank(message = "Street is required")
	private String street;

	@NotBlank(message = "City is required")
	private String city;

	@NotBlank(message = "State is required")
	private String state;

	@NotBlank(message = "Zip code is required")
	private String zip;

	@CreditCardNumber(message = "Not a valid credit card number")
	private String ccNumber;

	@Pattern(regexp = "^(0[1-9]|1[0-2])([\\/])([1-9][0-9])$", message = "Must be formatted MM/YY")
	private String ccExpiration;

	@Digits(integer = 3, fraction = 0, message = "Invalid CVV")
	private String ccCVV;

}

2. Declaring validation in the method of the controller layer
   Add a comment @Valid to tell springMVC that after submitting the form information, do the validation before calling the method, if there is any error information is captured by Errors.

	@PostMapping
	public String processOrder(@Valid Order order, Errors errors) {
		if (errors.hasErrors()) {
			return "orderForm";
		}

		log.info("Order submitted: " + order);
		return "redirect:/";
	}

3. Display verification information

 	  <h3>Here's how I'll pay...</h3>
      <label for="ccNumber">Credit Card #: </label>
      <input type="text" th:field="*{ccNumber}"/>
      <span class="validationError"
            th:if="${#fields.hasErrors('ccNumber')}"
            th:errors="*{ccNumber}">CC Num Error</span>

4. view controller

Some controllers are very simple, do not process data, and only return the page that needs to be accessed, which can be implemented as follows:

package tacos.web;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class WebConfig implements WebMvcConfigurer {

	@Override
	public void addViewControllers(ViewControllerRegistry registry) {
		registry.addViewController("/").setViewName("home");
	}

}