2.开发web应用 - spring实战第五版

1.展示信息

Taco Cloud是一个可以订taco的应用，所以需要展示各种taco。
我们需要三个组件：

• 一个domain class来定义taco；
• 一个controller来处理和推送数据给view；
• 一个view template渲染页面给流浪器。

1.1 建立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
	}

}

利用Lombok，可以简化代码。
添加依赖：

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

在Eclipse中添加Lombok的插件方法：Eclipse当中安装Lombok插件。

1.2 创建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 定义view

学习Thymeleaf。

3. 验证输入数据

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

• 在类的成员变量声明校验规则；
• 在controller层的方法中声明校验；
• 在view层显示校验信息。

1. 在类的成员变量声明校验规则

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. 在controller层的方法中声明校验
   添加注解@Valid，告诉springMVC，在提交表单信息后， 调用方法之前做校验，如果有错误信息由Errors捕获。

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

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

3. 展示校验信息

 	  <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

有些controller很简单，不处理数据，仅仅返回需要访问的页面，可以如以下实现：

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");
	}

}