Springboot 入门 | Springboot

1.作用

便捷搭建基于Spring的工程脚手架，尽可能减少一切xml的配置

2.使用步骤

1.创建工程
2.添加启动器依赖
3.创建启动类
4.创建处理器Controller
5.测试

• 创建Maven工程

• 添加启动器依赖

  <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>
  
      <!-- 父工程依赖，统一版本 -->
      <parent>
          <artifactId>spring-boot-starter-parent</artifactId>
          <groupId>org.springframework.boot</groupId>
          <version>2.7.0</version>
      </parent>
  
      <groupId>com.miaokela</groupId>
      <artifactId>springboot</artifactId>
      <version>1.0-SNAPSHOT</version>
      <packaging>jar</packaging>
  
      <!--  设置java版本  -->
      <properties>
          <java.version>1.8</java.version>
      </properties>
  
      <dependencies>
          <dependency>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-starter-web</artifactId>
          </dependency>
      </dependencies>
  </project>
  

• 创建启动类

  package com.miaokela;
  
  import org.springframework.boot.SpringApplication;
  import org.springframework.boot.autoconfigure.SpringBootApplication;
  
  /**
   * SpringBootApplication
   */
  @SpringBootApplication
  public class App {
      public static void main(String[] args) {
          SpringApplication.run(App.class, args);
      }
  }
  

• 创建Controller

  package com.miaokela.controller;
  
  import org.springframework.web.bind.annotation.GetMapping;
  import org.springframework.web.bind.annotation.RestController;
  
  @RestController
  public class HelloController {
  
      @GetMapping("hello")
      public String hello() {
          return "hello world";
      }
  }
  

• 在application.properties中设置端口

  server.port = 8081
  

3.Java代码方式配置

使用@Value获取配置文件配置项 结合@Bean注册组件到Spring

• Java配置相关注解

  @Configuration // 声明一个配置类，代替xml文件
  @Bean // 声明在方法上，将方法返回值加入到Bean容器，代替Bean标签
  @value // 属性注入
  @PropertySource // 指定外部属性文件
  

• Java代码配置数据库连接池，并在Controller中注入使用

  1.添加依赖；
  2.创建数据库；
  3.创建数据库连接参数配置文件 jdbc.properties;
  4.创建配置类
  5.改造Controller注入数据源，并使用
  

  • 添加依赖

    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid</artifactId>
        <version>1.2.4</version>
    </dependency>
    

  • 创建数据库

  • 创建数据库连接参数配置文件

    jdbc.properties

    jdbc.driverClassName=com.mysql.jdbc.Driver
    jdbc.url=jdbc:mysql://127.0.0.1:3306/springboot
    jdbc.username=root
    jdbc.password=123456
    

  • 添加配置类

    package com.miaokela.config;
    
    import com.alibaba.druid.pool.DruidDataSource;
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.context.annotation.PropertySource;
    
    import javax.sql.DataSource;
    
    @Configuration
    @PropertySource("classpath:jdbc.properties")
    public class JdbcConfig {
        @Value("${jdbc.url}")
        String url;
    
        @Value("${jdbc.driverClassName}")
        String driverClassName;
    
        @Value("${jdbc.username}")
        String username;
    
        @Value("${jdbc.password}")
        String password;
    
        @Bean
        public DataSource dataSource() {
            DruidDataSource druidDataSource = new DruidDataSource();
    
            druidDataSource.setDriverClassName(driverClassName);
            druidDataSource.setUrl(url);
            druidDataSource.setUsername(username);
            druidDataSource.setPassword(password);
    
            return druidDataSource;
        }
    }
    

  • 修改Controller

    controller.HelloController

    package com.miaokela.controller;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    import javax.sql.DataSource;
    
    @RestController
    public class HelloController {
    
        @Autowired
        private DataSource dataSource;
    
        @GetMapping("hello")
        public String hello() {
            System.out.println(dataSource);
            return "hello world";
        }
    }
    

• Spring Boot优雅属性注入方式

  将配置文件配置项读取到一个对象中
  注解默认支持.properties与.yml

  • 配置类

    config.JdbcConfig

    package com.miaokela.config;
    
    import com.alibaba.druid.pool.DruidDataSource;
    import org.springframework.boot.context.properties.ConfigurationProperties;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    
    import javax.sql.DataSource;
    
    @Configuration
    public class JdbcConfig {
        @Bean
        @ConfigurationProperties(prefix = "jdbc")
        public DataSource dataSource() {
            return new DruidDataSource();
        }
    }
    

    application.properties

    jdbc.driverClassName=com.mysql.jdbc.Driver
    jdbc.url=jdbc:mysql://127.0.0.1:3306/springboot
    jdbc.username=root
    jdbc.password=123456
    
    server.port=8081
    

• yaml多文件配置

  yaml与properties配置文件除了展示形式不相同以外，其他功能和作用都是一样的，读取方式不变

  jdbc:
      driverClassName: com.mysql.jdbc.Driver
      url: jdbc:mysql://127.0.0.1:3306/springboot
      username: root
      password: 123456
  

  • 多文件配置要求

    1.名称必须为application-***.yml
    2.必须在application.yml中激活
    

4.lombok应用

简化POJO类
插件工具类包，提供@Data,@Getter等注解去简化构造方法，get/set等方法

• 步骤

  1.IDE安装lombok插件
  2.添加依赖坐标
  3.改造实体类
  

  • 导入坐标

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

  • 实体类

    entity.User

    @Data // 在编译阶段会根据注解自动生成对应的方法：get/set/hashCode/equels/toString等方法
    public class User {
        private Long id;
        private String userName;
        private String password;
        private String name;
        private Integer age;
        private Integer sex;
        private Date birthday;
        private String note;
        private Date created;
        private Date updated;
    }
    

5.Spring Boot整合MVC

• 整合Spring MVC端口和静态资源

  • 修改tomcat端口

    properties

    server.port = 8081
    

    yaml

    server:
        port: 8081
    

  • 访问项目中的静态资源

• 整合 Spring-MVC拦截器

  • 步骤

    1.编写拦截器 实现接口HandlerInterceptor
    2.编写配置类 WebMvcConfigurer， 在类中添加各种组件
    3.测试
    

  • 编写拦截器

    interceptor.MyInterceptor 拦截器类

    import lombok.extern.slf4j.Slf4j;
    import org.springframework.web.servlet.HandlerInterceptor;
    import org.springframework.web.servlet.ModelAndView;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    @Slf4j
    public class MyInterceptor implements HandlerInterceptor {
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
            log.debug("preHandle");
            return HandlerInterceptor.super.preHandle(request, response, handler);
        }
    
        @Override
        public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
            log.debug("postHandle");
            HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
        }
    
        @Override
        public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
            log.debug("afterCompletion");
            HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
        }
    }
    

    config.MvcConfig 配置类

    package com.miaokela.config;
    
    import com.miaokela.interceptor.MyInterceptor;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.web.servlet.config.annotation.InterceptorRegistration;
    import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
    import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
    
    @Configuration
    public class MvcConfig implements WebMvcConfigurer {
        // 注册拦截器
        @Bean
        public MyInterceptor myInterceptor() {
            return new MyInterceptor();
        }
        // 添加拦截器到Spring MVC拦截器链
        public void addInterceptors(InterceptorRegistry registry) {
            registry.addInterceptor(myInterceptor()).addPathPatterns("/*");
        }
    }
    

• 整合事务与连接池

  配置Spring Boot自带默认的hikari连接池和使用@Transactional注解

  事务配置：
  1.添加事务相关的启动器依赖，mysql依赖
  2.编写UserService使用事务注解@Transactional
  数据库连接池hikari配置
  

  • 添加依赖坐标

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

  • 编写UserService

    package com.miaokela.service;
    
    import com.miaokela.domain.User;
    
    public class UserService {
        // 根据id查询
        public User queryById(Long id) {
            return new User();
        }
        @Transactional // 添加事务
        public void saveUser(User user) {
            System.out.println("新增用户");
        }
    }
    

  • hikari配置

    spring.datasource.driver-class-name=com.mysql.jdbc.Driver
    spring.datasource.url=jdbc:mysql://127.0.0.1:3306/springboot
    spring.datasource.username=root
    spring.datasource.password=123456
    

6.Spring Boot整合Mybatis

配置整合包，设置mabatis实体类别名，输出执行sql语句配置项

• 步骤

  1.添加启动器依赖 mybatis提供
  2.配置Mybatis：实体类别名，日志，映射文件
  3.配置MapperScan
  

  • 添加启动器依赖

    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>2.2.2</version>
    </dependency>
    

  • 配置Mybatis

    # 配置实体类别名包
    mybatis.type-aliases-package=com.mkl.domain
    mybatis.configuration.log-impl=org.apache.ibatis.logging.stdout.StdoutImpl
    

  • 添加Mapper接口

    UserMapper

    package com.miaokela.mapper;
    
    import org.apache.ibatis.annotations.Mapper;
    
    @Mapper
    public interface UserMapper {
    }
    

  • 主运行文件中添加Mapper扫描

    @SpringBootApplication
    @MapperScan("com.mkl.mapper")
    public class App {
        public static void main( String[] args ) {
            SpringApplication.run(App.class, args);
        }
    }
    

• 使用通用Mapper

  配置通用mapper组件到Spring Boot项目中并使用Mapper接口
  实现自动拼接sql语句，所有Mapper都不需要编写任何方法（生气了语句），提高开发效率

  1.添加启动器依赖
  2.改造UserMapper继承Mapper<User>;
  3.修改App中Mapper扫描注解
  4.修改User实体类添加jpa注解
  5.改造UserService实现业务
  

  • 添加启动器依赖

    通用mapper

    <dependency>
        <groupId>tk.mybatis</groupId>
        <artifactId>mapper-spring-boot-starter</artifactId>
        <version>4.2.1</version>
    </dependency>
    

  • 添加Mapper扫描注解

    package com.miaokela.mapper;
    
    import org.apache.ibatis.annotations.Mapper;
    
    @Mapper
    public interface UserMapper {
    }
    

  • 修改Dao

    domain.User

    package com.miaokela.domain;
    
    import lombok.Data;
    import tk.mybatis.mapper.annotation.KeySql;
    
    import javax.persistence.Column;
    import javax.persistence.Id;
    import javax.persistence.Table;
    
    @Data
    @Table(name="springboot")
    public class User {
        @Id
        @KeySql(useGeneratedKeys=true) // 主键回填
        private Long id;
    
        @Column
        private String name;
        private String sex;
    }