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：

起步依赖 jar包的管理 starter

自动配置 SpringBoot做了很多默认的配置

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/**");
}
}

一、SpringBoot简介