SpringBoot(三)

最佳实践

1.SpringBoot 应用如何编写

引入场景依赖
- 官方文档
查看自动配置了哪些（选做）
- 自己分析，引入场景对应的自动配置一般都生效了
- 配置文件中 debug=true 开启自动配置报告。
  - Negative（不生效）
  - Positive（生效）
是否需要修改
- 参照文档修改配置项
  - 官方文档
  - 自己分析。xxxxProperties 绑定了配置文件的哪些。
- 自定义加入或者替换组件
  - @Bean、@Component…
- 自定义器 XXXXXCustomizer；

2.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;
    }
}

简化日志开发

@Slf4j
@RestController
public class HelloController {
    @RequestMapping("/hello")
    public String handle01(@RequestParam("name") String name){
        log.info("请求进来了....");
        return "Hello, Spring Boot 2!"+"你好："+name;
    }
}

3.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。

4.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

yarm 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。

1.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

2.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]

#或者

k:
 - v1
 - v2
 - v3

3.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 }]

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>

模板

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
         http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <!--项目maven坐标-->
    <groupId>com.nianxi</groupId>
    <artifactId>springboot-mybatis-demo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <!--    继承spring-boot-starter-parent-->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.1.2</version>
    </parent>

    <!--属性设置-->
    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <mysql.version>8.0.33</mysql.version>
        <mybatis-plus.version>3.5.3.1</mybatis-plus.version>
        <lombok.version>1.18.24</lombok.version>
        <devtools.version>3.2.4</devtools.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
        </dependency>

        <!--devtools-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <version>${devtools.version}</version>
        </dependency>


        <!-- mysql -->
        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <version>${mysql.version}</version>
        </dependency>

        <!-- mybatis-plus -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>${mybatis-plus.version}</version>
        </dependency>

        <!-- lombok -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>${lombok.version}</version>
        </dependency>

        <!--字符串的处理-->
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
        </dependency>
    </dependencies>

    <!--添加maven插件，项目的打包工具，打成jar包，否则在打包运行时报错   -->
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

application.yml

server:
  port: 8080

spring:
  profiles:
    # 设置当前环境,用来区分不同环境的配置
    active: dev
  main:
    # 设置banner模式,用来关闭启动时的图标
    allow-circular-references: true
  # 配置Spring boot数据源
  datasource:
    driver-class-name: ${star.datasource.driver-class-name}
    url: ${star.datasource.url}
    username: ${star.datasource.username}
    password: ${star.datasource.password}

# 配置mybatis-plus
mybatis-plus:
  configuration:
    # 配置驼峰命名(实体类属性与数据库字段名称的下划线规则)
    map-underscore-to-camel-case: true
    # 日志
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  # 实体类别名
  type-aliases-package: com.nianxi.entity
  # 全局配置
  global-config:
    db-config:
      # 主键类型
      id-type: auto
  # 映射文件位置
  mapper-locations: classpath:mapper/*Mapper.xml

# 日志配置
logging:
  level: # 日志级别
    com:
      nianxi:
        mapper: debug # mapper包下的日志级别为debug
        service: info
        controller: info

application-dev.yml

star:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/springbootDemo?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=Asia/Shanghai
    username: root
    password: 123456

common.Result.java

package com.nianxi.common;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Result<T> {
    // 状态码 0为成功，1为失败
    private Integer code;
    // 返回信息
    private String msg;
    // 返回前端的数据
    private T data;

    public static <T> Result<T> success() {
        Result<T> result = new Result<T>();
        result.code = 1;
        return result;
    }

    public static <T> Result<T> success(T object) {
        Result<T> result = new Result<T>();
        result.data = object;
        result.code = 1;
        return result;
    }

    public static <T> Result<T> error(String msg) {
        Result<T> result = new Result<T>();
        result.msg = msg;
        result.code = 0;
        return result;
    }
}

config.MyBatisPlusConfig.java

package com.nianxi.config;

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;

@Configuration
public class MyBatisPlusConfig {

    //分页插件
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
        //设置数据库类型
        mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
        return mybatisPlusInterceptor;
    }

    //RestTemplate
    @Bean
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }
}