java学习总结（八）：Spring boot

一、SpringBoot简介

传统Spring开发缺点：
1、导入依赖繁琐
2、项目配置繁琐
Spring Boot是全新框架(更像是一个工具， 脚手架)，是Spring提供的一个子项目， 用于快速构建Spring应用程序。
随着Spring 3.0的发布，Spring 团队逐渐开始摆脱XML配置文件，并且在开发过程中大量使用"约定优先配置"（convention over configuration）的思想来摆脱Spring框架中各类繁复纷杂的配置。
SpringBoot的特性：

1. 起步依赖 jar包的管理 starter
2. 自动配置 SpringBoot做了很多默认的配置
3. 内置tomcat

二、创建SpringBoot项目

1、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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-parent</artifactId>
       <version>3.2.5</version>
       <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.situ</groupId>
    <artifactId>springboot</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot</name>
    <description>springboot</description>
    <properties>
       <java.version>17</java.version>
    </properties>
    <dependencies>
       <!--Spring相关依赖-->
       <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter</artifactId>
       </dependency>
       <!--SpringMVC相关依赖-->
       <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-web</artifactId>
       </dependency>
       <!-- mysql驱动 -->
       <dependency>
          <groupId>mysql</groupId>
          <artifactId>mysql-connector-java</artifactId>
          <version>8.0.31</version>
       </dependency>
       <!-- mybatis -->
       <dependency>
          <groupId>org.mybatis.spring.boot</groupId>
          <artifactId>mybatis-spring-boot-starter</artifactId>f
          <version>3.0.3</version>
       </dependency>
       <!--thymeleaf相关依赖-->
       <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-thymeleaf</artifactId>
       </dependency>
       <!--lombok帮助我们生成实体类的构造方法、get、set、toString-->
       <dependency>
          <groupId>org.projectlombok</groupId>
          <artifactId>lombok</artifactId>
          <version>1.18.14</version>
          <scope>provided</scope>
       </dependency>
       <!-- 分页插件 -->
       <dependency>
          <groupId>com.github.pagehelper</groupId>
          <artifactId>pagehelper-spring-boot-starter</artifactId>
          <version>1.4.1</version>
       </dependency>

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

    <build>
       <plugins>
          <plugin>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-maven-plugin</artifactId>
          </plugin>
       </plugins>
    </build>

</project>

2、SpringbootApplication启动类

//SpringBoot项目启动类
@SpringBootApplication
@MapperScan("com.situ.springboot.mapper")
public class SpringbootApplication {

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

@Controller
@RequestMapping("/admin")
public class AdminController {


    @RequestMapping("/selectAll")
    @ResponseBody
    public List<Admin> selectAll() {
        System.out.println("AdminController.selectAll");
        List<Admin> list = new ArrayList<>();
        Admin admin1 = new Admin();
        admin1.setId(1);
        admin1.setName("zhangsan");
        Admin admin2 = new Admin();
        admin2.setId(2);
        admin2.setName("list");
        Admin admin3 = new Admin();
        admin3.setId(3);
        admin3.setName("wangwu");
        list.add(admin1);
        list.add(admin2);
        list.add(admin3);
        return list;
    }
}

3、application.properties

server.port=8080

#DB Configuration
spring.datasource.driverClassName=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/blog?useSSL=false&useUnicode=true&characterEncoding=utf8&serverTimezone=GMT%2b8&zeroDateTimeBehavior=CONVERT_TO_NULL
spring.datasource.username=root
spring.datasource.password=1234

spring.mvc.static-path-pattern=/static/**

#Spring MyBatis
mybatis.type-aliases-package=com.situ.springboot.pojo
mybatis.mapper-locations=classpath:mapper/*Mapper.xml
mybatis.configuration.map-underscore-to-camel-case=true
#log
mybatis.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl

4、AdminMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.situ.springboot.mapper.AdminMapper">
    <select id="selectAll" resultType="Admin">
        SELECT id,name,password,nick_name,role,image FROM admin
    </select>
</mapper>

三、Thymeleaf

<!--thymeleaf相关依赖-->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>

application.properties:

spring.mvc.static-path-pattern=/static/**

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org/">
<head>
    <title>主页 </title>
    <link rel="stylesheet" type="text/css" th:href="@{/static/layui/css/layui.css}"/>
    <script th:src="@{/static/layui/layui.js}" type="text/javascript" charset="utf-8"></script>
</head>

@Controller
@RequestMapping("/page")
public class PageController {

    /**
     * /page/user/add     /page/login
     *
     * @return
     */
    @RequestMapping("/**")
    public String path(HttpServletRequest request) {
        String requestURI = request.getRequestURI();
        System.out.println("requestURI: " + requestURI);
        String[] paths = requestURI.split("/");
        //["","page","user","list"]
        //["","page","login"]
        if (paths.length == 4) {
            return paths[2] + "_" + paths[3];
        } else if (paths.length == 3) {
            return paths[2];
        } else {
            return "index";
        }
    }
}

四、登录拦截器

//拦截器的作用：浏览器访问服务器的请求，都要首先经过拦截器
public class LoginInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //
        
        //1.判断用户有没有登录
        //2.如果登录了，就放行，可以访问后台的资源
        //3.如果没有登录，跳转到登录界面
        HttpSession session = request.getSession();
        Admin admin = (Admin) session.getAttribute("admin");
        if (admin == null) {
            //没有登录，跳转到登录界面
            response.sendRedirect("/page/login");
            return false;
        }

        //已经登录，放行
        return true;
    }
}

拦截器配置

WebMvcConfigurer提供了配置SpringMVC底层的所有组件入口

// @Component    <bean>
// @Controller  @Service @Repository
// 这四个注解的作用是一样的，下面三个不一样主要是为了区分不同层

// @Configuration用于定义配置类，可以替换xml配置文件，
// 加了这个注解的类的内部包含一个或多个被@Bean注解的方法
@Configuration
public class WebConfig implements WebMvcConfigurer {

    /* <bean name="admin" class="com.situ.springboot.pojo.Admin"/>*/
    @Bean
    public Admin createAdmin() {
        return new Admin();
    }


    //配置虚拟路径
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/pic/**")
                .addResourceLocations("file:/D:/mypic/");
        WebMvcConfigurer.super.addResourceHandlers(registry);
    }

    /*<!-- 配置拦截器 -->
   <mvc:interceptors>
      <mvc:interceptor>
         <mvc:mapping path="/**"/>
         <mvc:exclude-mapping path=""/>
         <bean class="com.situ.mvc.interceptor.MyInterceptor1"></bean>
      </mvc:interceptor>
   </mvc:interceptors>*/
    // 这个方法用来注册拦截器，我们写的拦截器需要在这里配置才能生效
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        //把登录的拦截器配置上才能起作用
        // addPathPatterns("/**") 拦截器拦截所有的请求，静态资源也拦截了，需要放行
        // excludePathPatterns 代表哪些请求不需要拦截
        registry.addInterceptor(new LoginInterceptor())
                .addPathPatterns("/**")
                .excludePathPatterns("/page/login", "/admin/login", "/admin/logout", "/static/**");
    }
}