Springboot2--lombok，yaml，web开发介绍

最佳实践-Lombok简化开发

Lombok用标签方式代替构造器、getter/setter、toString()等鸡肋代码。spring boot已经管理Lombok。引入依赖：

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

IDEA中File->Settings->Plugins，搜索安装Lombok插件。

@NoArgsConstructor
//@AllArgsConstructor
@Data
@ToString
@EqualsAndHashCode
public class User {

    private String name;
    private Integer age;

    private Pet pet;

    public User(String name,Integer age){
        this.name = name;
        this.age = age;
    }
}

最佳实践-dev-tools

Spring Boot includes an additional set of tools that can make the
application development experience a little more pleasant. The
spring-boot-devtools module can be included in any project to
provide additional development-time
features.——link

Applications that use spring-boot-devtools automatically restart
whenever files on the classpath change. This can be a useful feature
when working in an IDE, as it gives a very fast feedback loop for code
changes. By default, any entry on the classpath that points to a
directory is monitored for changes. Note that certain resources, such
as static assets and view templates, do not need to restart the
application.——link

Triggering a restart

As DevTools monitors classpath resources, the only way to trigger a
restart is to update the classpath. The way in which you cause the
classpath to be updated depends on the IDE that you are using:

• In Eclipse, saving a modified file causes the classpath to be updated and triggers a restart.
• In IntelliJ IDEA, building the project (Build -> Build Project)(shortcut: Ctrl+F9) has the same effect.

添加依赖：

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <optional>true</optional>
    </dependency>
</dependencies>

在IDEA中，项目或者页面修改以后：Ctrl+F9。

最佳实践-Spring Initailizr

Spring Initailizr是创建Spring Boot工程向导。

在IDEA中，菜单栏New -> Project -> Spring Initailizr。

配置文件-yaml的用法

同以前的properties用法

YAML 是 “YAML Ain’t Markup Language”（YAML 不是一种标记语言）的递归缩写。在开发的这种语言时，YAML 的意思其实是：“Yet Another Markup Language”（仍是一种标记语言）。

非常适合用来做以数据为中心的配置文件。

基本语法

• key: value；kv之间有空格
• 大小写敏感
• 使用缩进表示层级关系
• 缩进不允许使用tab，只允许空格
• 缩进的空格数不重要，只要相同层级的元素左对齐即可
• '#'表示注释
• 字符串无需加引号，如果要加，单引号’'、双引号""表示字符串内容会被 转义、不转义

数据类型

字面量：单个的、不可再分的值。date、boolean、string、number、null

k: v

对象：键值对的集合。map、hash、set、object

#行内写法：  
k: {k1:v1,k2:v2,k3:v3}

或

k: 
  k1: v1
  k2: v2
  k3: v3

数组：一组按次序排列的值。array、list、queue

#行内写法：  
k: [v1,v2,v3]

或

k:
 - v1
 - v2
 - v3

实例

@Data
public class Person {
    private String userName;
    private Boolean boss;
    private Date birth;
    private Integer age;
    private Pet pet;
    private String[] interests;
    private List<String> animal;
    private Map<String, Object> score;
    private Set<Double> salarys;
    private Map<String, List<Pet>> allPets;
}

@Data
public class Pet {
    private String name;
    private Double weight;
}

用yaml表示以上对象

person:
  userName: zhangsan
  boss: false
  birth: 2019/12/12 20:12:33
  age: 18
  pet: 
    name: tomcat
    weight: 23.4
  interests: [篮球,游泳]
  animal: 
    - jerry
    - mario
  score:
    english: 
      first: 30
      second: 40
      third: 50
    math: [131,140,148]
    chinese: {first: 128,second: 136}
  salarys: [3999,4999.98,5999.99]
  allPets:
    sick:
      - {name: tom}
      - {name: jerry,weight: 47}
    health: [{name: mario,weight: 47}]

配置文件-自定义类绑定的配置提示

You can easily generate your own configuration metadata file from items annotated with @ConfigurationProperties by using the spring-boot-configuration-processor jar. The jar includes a Java annotation processor which is invoked as your project is compiled.——link

自定义的类和配置文件绑定一般没有提示。若要提示，添加如下依赖：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-configuration-processor</artifactId>
    <optional>true</optional>
</dependency>

<!-- 下面插件作用是工程打包时，不将spring-boot-configuration-processor打进包内，让其只在编码的时候有用 -->
<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <configuration>
                <excludes>
                    <exclude>
                        <groupId>org.springframework.boot</groupId>
                        <artifactId>spring-boot-configuration-processor</artifactId>
                    </exclude>
                </excludes>
            </configuration>
        </plugin>
    </plugins>
</build>

web场景-web开发简介

Spring Boot provides auto-configuration for Spring MVC that works well with most applications.(大多场景我们都无需自定义配置)

The auto-configuration adds the following features on top of Spring’s defaults:

• Inclusion of ContentNegotiatingViewResolver and BeanNameViewResolver beans.

  • 内容协商视图解析器和BeanName视图解析器

• Support for serving static resources, including support for WebJars (covered later in this document)).

  • 静态资源（包括webjars）

• Automatic registration of Converter, GenericConverter, and Formatter beans.

  • 自动注册 Converter，GenericConverter，Formatter

• Support for HttpMessageConverters (covered later in this document).

  • 支持 HttpMessageConverters （后来我们配合内容协商理解原理）

• Automatic registration of MessageCodesResolver (covered later in this document).

  • 自动注册 MessageCodesResolver （国际化用）

• Static index.html support.

  • 静态index.html 页支持

• Custom Favicon support (covered later in this document).

  • 自定义 Favicon

• Automatic use of a ConfigurableWebBindingInitializer bean (covered later in this document).

  • 自动使用 ConfigurableWebBindingInitializer ，（DataBinder负责将请求数据绑定到JavaBean上）

If you want to keep those Spring Boot MVC customizations and make more
MVCcustomizations(interceptors, formatters, view controllers, and other features), you
can add your own @Configuration class of type WebMvcConfigurer but
without @EnableWebMvc. 不用@EnableWebMvc注解。使用 @Configuration + WebMvcConfigurer 自定义规则 If you want to provide custom instances of RequestMappingHandlerMapping, RequestMappingHandlerAdapter, or ExceptionHandlerExceptionResolver, and still keep the Spring Boot MVC customizations, you can declare a bean of type WebMvcRegistrations and use it to provide custom instances of those components. 声明 WebMvcRegistrations 改变默认底层组件 If you want to take complete control of Spring MVC, you can add your own @Configuration annotated with @EnableWebMvc, or alternatively add your own @Configuration-annotated DelegatingWebMvcConfiguration as described in the Javadoc of @EnableWebMvc.使@EnableWebMvc+@Configuration+DelegatingWebMvcConfiguration 全面接管SpringMVC**

web场景-静态资源规则与定制化

静态资源目录

只要静态资源放在类路径下： called /static (or /public or /resources or /META-INF/resources

访问 ： 当前项目根路径/ + 静态资源名

原理： 静态映射/**。

请求进来，先去找Controller看能不能处理。不能处理的所有请求又都交给静态资源处理器。静态资源也找不到则响应404页面。也可以改变默认的静态资源路径，/static，/public,/resources, /META-INF/resources失效。

resources:
  static-locations: [classpath:/haha/]

静态资源访问前缀

spring:
  mvc:
    static-path-pattern: /res/**

当前项目 + static-path-pattern + 静态资源名 = 静态资源文件夹下找

webjar

可用jar方式添加css，js等资源文件，

https://www.webjars.org/

例如，添加jquery

<dependency>
    <groupId>org.webjarsgroupId>
    <artifactId>jqueryartifactId>
    <version>3.5.1version>
dependency>

访问地址：http://localhost:8080/webjars/jquery/3.5.1/jquery.js 后面地址要按照依赖里面的包路径。

web场景-welcome与favicon功能

官方文档
欢迎页支持

• 静态资源路径下 index.html。
  • 可以配置静态资源路径
  • 但是不可以配置静态资源的访问前缀。否则导致 index.html不能被默认访问

spring:
#  mvc:
#    static-path-pattern: /res/**   这个会导致welcome page功能失效
  resources:
    static-locations: [classpath:/haha/]

controller能处理/index。

自定义Favicon
指网页标签上的小图标。
favicon.ico 放在静态资源目录下即可。

spring:
#  mvc:
#    static-path-pattern: /res/**   这个会导致 Favicon 功能失效

参考

https://www.bilibili.com/video/BV19K4y1L7MT?p=24&t=616.0