Spring Boot Sample 009之spring-boot-web-thymeleaf

一、环境

• Idea 2020.1
• JDK 1.8
• maven

二、目的

spring boot 整合thymeleaf模板开发web项目。

gitHub地址：https://github.com/ouyushan/ouyushan-spring-boot-samples

三、步骤

3.1、点击File -> New Project -> Spring Initializer，点击next

 3.2、在对应地方修改自己的项目信息

 3.3、选择Web依赖，选中Spring Web。可以选择Spring Boot版本，本次默认为2.2.6，点击Next

 3.4、项目结构

 四、添加配置文件

添加配置文件logback.xml 通过springProfile属性识别不同环境配置

<?xml version="1.0" encoding="UTF-8"?>
<configuration>

    <include resource="org/springframework/boot/logging/logback/base.xml"/>

    <!-- logger name="org.springframework" level="DEBUG"/-->

</configuration>

配置默认application.properties

# Allow Thymeleaf templates to be reloaded at dev time
spring.thymeleaf.cache: false
server.tomcat.access_log_enabled: true
server.tomcat.basedir: target/tomcat

配置message.properties

form.message=Message
form.messages=Messages
form.submit=Submit
form.summary=Summary
form.title=Messages : Create

list.create=Create Message
list.table.created=Created
list.table.empty=No messages
list.table.id=Id
list.table.summary=Summary
list.title=Messages : View all

navbar.messages=Messages
navbar.thymeleaf=Thymeleaf

view.delete=delete
view.messages=Messages
view.modify=modify
view.success=Successfully created a new message
view.title=Messages : View

添加css样式文件

/static/css/bootstrap.min.css

添加页面文件

templates/fragments.html

templates/messages/form.html

templates/messages/list.html

templates/messages/view.html

添加实体类

package org.ouyushan.springboot.web.thymeleaf.entity;

import javax.validation.constraints.NotEmpty;
import java.util.Calendar;

/**
 * @Description:
 * @Author: ouyushan
 * @Email: ouyushan@hotmail.com
 * @Date: 2020/4/29 14:33
 */
public class Message {

    private Long id;

    @NotEmpty(message = "Text is required.")
    private String text;

    @NotEmpty(message = "Summary is required.")
    private String summary;

    private Calendar created = Calendar.getInstance();

    public Long getId() {
        return this.id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public Calendar getCreated() {
        return this.created;
    }

    public void setCreated(Calendar created) {
        this.created = created;
    }

    public String getText() {
        return this.text;
    }

    public void setText(String text) {
        this.text = text;
    }

    public String getSummary() {
        return this.summary;
    }

    public void setSummary(String summary) {
        this.summary = summary;
    }

}

添加repository接口

package org.ouyushan.springboot.web.thymeleaf.repository;

import org.ouyushan.springboot.web.thymeleaf.entity.Message;

/**
 * @Description:
 * @Author: ouyushan
 * @Email: ouyushan@hotmail.com
 * @Date: 2020/4/29 14:35
 */
public interface MessageRepository {

    Iterable<Message> findAll();

    Message save(Message message);

    Message findMessage(Long id);

    void deleteMessage(Long id);

}

添加repository实体类

package org.ouyushan.springboot.web.thymeleaf.repository;

import org.ouyushan.springboot.web.thymeleaf.entity.Message;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicLong;

/**
 * @Description:
 * @Author: ouyushan
 * @Email: ouyushan@hotmail.com
 * @Date: 2020/4/29 14:38
 */
public class InMemoryMessageRepository implements MessageRepository{
    private static AtomicLong counter = new AtomicLong();

    private final ConcurrentMap<Long, Message> messages = new ConcurrentHashMap<>();

    @Override
    public Iterable<Message> findAll() {
        return this.messages.values();
    }

    @Override
    public Message save(Message message) {
        Long id = message.getId();
        if (id == null) {
            id = counter.incrementAndGet();
            message.setId(id);
        }
        this.messages.put(id, message);
        return message;
    }

    @Override
    public Message findMessage(Long id) {
        return this.messages.get(id);
    }

    @Override
    public void deleteMessage(Long id) {
        this.messages.remove(id);
    }
}

添加controller类

package org.ouyushan.springboot.web.thymeleaf.controller;

import org.ouyushan.springboot.web.thymeleaf.entity.Message;
import org.ouyushan.springboot.web.thymeleaf.repository.MessageRepository;
import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;

import javax.validation.Valid;

/**
 * @Description:
 * @Author: ouyushan
 * @Email: ouyushan@hotmail.com
 * @Date: 2020/4/29 14:42
 */
@Controller
@RequestMapping("/")
public class MessageController {

    private final MessageRepository messageRepository;

    public MessageController(MessageRepository messageRepository) {
        this.messageRepository = messageRepository;
    }

    @GetMapping
    public ModelAndView list() {
        Iterable<Message> messages = this.messageRepository.findAll();
        return new ModelAndView("messages/list", "messages", messages);
    }

    @GetMapping("{id}")
    public ModelAndView view(@PathVariable("id") Message message) {
        return new ModelAndView("messages/view", "message", message);
    }

    @GetMapping(params = "form")
    public String createForm(@ModelAttribute Message message) {
        return "messages/form";
    }

    @PostMapping
    public ModelAndView create(@Valid Message message, BindingResult result, RedirectAttributes redirect) {
        if (result.hasErrors()) {
            return new ModelAndView("messages/form", "formErrors", result.getAllErrors());
        }
        message = this.messageRepository.save(message);
        redirect.addFlashAttribute("globalMessage", "view.success");
        return new ModelAndView("redirect:/{message.id}", "message.id", message.getId());
    }

    @RequestMapping("foo")
    public String foo() {
        throw new RuntimeException("Expected exception in controller");
    }

    @GetMapping("delete/{id}")
    public ModelAndView delete(@PathVariable("id") Long id) {
        this.messageRepository.deleteMessage(id);
        Iterable<Message> messages = this.messageRepository.findAll();
        return new ModelAndView("messages/list", "messages", messages);
    }

    @GetMapping("modify/{id}")
    public ModelAndView modifyForm(@PathVariable("id") Message message) {
        return new ModelAndView("messages/form", "message", message);
    }

}

启动程序类

package org.ouyushan.springboot.web.thymeleaf;


import org.ouyushan.springboot.web.thymeleaf.entity.Message;
import org.ouyushan.springboot.web.thymeleaf.repository.InMemoryMessageRepository;
import org.ouyushan.springboot.web.thymeleaf.repository.MessageRepository;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.core.convert.converter.Converter;

@SpringBootApplication
public class SpringBootWebThymeleafApplication {

    @Bean
    public MessageRepository messageRepository() {
        return new InMemoryMessageRepository();
    }

    @Bean
    public Converter<String, Message> messageConverter() {
        return new Converter<String, Message>() {
            @Override
            public Message convert(String id) {
                return messageRepository().findMessage(Long.valueOf(id));
            }
        };
    }

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

}

五、接口测试

访问：
http://localhost:8080/?form
### Controller
* 使用了@PathVariable 从路径中获取参数,注入参数中必须有一属性名称与PathVariable变量名称相同
* 使用params处理路径中请求参数
* 使用@Valid校验参数，BindingResult 存储校验错误，RedirectAttributes 缓存上级页面参数

### repository

* 利用ConcurrentHashMap模拟线程安全数据库
    private static AtomicLong counter = new AtomicLong();
    private final ConcurrentMap<Long,Message> messages = new ConcurrentHashMap<>();

### application启动配置类
* 定义了messageRepository bean以及messageConverter bean
* @SpringBootApplication same as @Configuration @EnableAutoConfiguration @ComponentScan


post方式 create
localhost:8080?id=1&text=text&summary=summary

get查询id=1
http://localhost:8080/1

@GetMapping(params = "form")
localhost:8080?form=&id=1

localhost:8080?form=&id=1&text=text&summary=summary

```
${}  变量表达式（美元表达式，哈哈），用于访问容器上下文环境中的变量，功能同jstl中${}。
*{}  选择表达式（星号表达式）。选择表达式与变量表达式有一个重要的区别：选择表达式计算的是选定的对象，而不是整个环境变量映射
#{}  消息表达式（井号表达式，properties资源表达式）。通常与th:text属性一起使用，指明声明了th:text的标签的文本是#{}中的key所对应的value，而标签内的文本将不会显示
@{}  超链接url表达式
#maps 工具对象表达式。常用于日期、集合、数组对象的访问
#dates
#calendars
#numbers 
#strings
#objects
#bools
#arrays
#lists
#sets

```