SpringBoot学习笔记

SpringBoot

一、快速入门

1.1 创建项目

1.左上文件==新建==项目==左侧选择Maven Archetype==输入项目名HelloWorld，位置~\IdeaProjects
2.选择maven-archetype-webapp==点开高级设置==鼠标往下拉==组ID输入com.tys和版本号1.0==点击创建
3.对着src文件==右键新建==目录==全选==回车

1.2 引入依赖

//pom.xml 复制进去，刷新Maven



<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>4.0.0modelVersion>

  <groupId>com.tysgroupId>
  <artifactId>HelloWorldartifactId>
  <version>1.0version>
  <packaging>jarpackaging>

  <properties>
    <project.build.sourceEncoding>UTF-8project.build.sourceEncoding>
    <maven.compiler.source>1.8maven.compiler.source>
    <maven.compiler.target>1.8maven.compiler.target>
  properties>

  <parent>
    <groupId>org.springframework.bootgroupId>
    <artifactId>spring-boot-starter-parentartifactId>
    <version>2.3.4.RELEASEversion>
  parent>

  <dependencies>
    <dependency>
      <groupId>org.springframework.bootgroupId>
      <artifactId>spring-boot-starter-webartifactId>
    dependency>
    <dependency>
      <groupId>org.springframework.bootgroupId>
      <artifactId>spring-boot-configuration-processorartifactId>
      <optional>trueoptional>
    dependency>
  dependencies>

project>

1.3 编写业务

//对着src/main/java==右键新建==软件包==com.tys.boot.controller
//对着com.tys.boot.controller==右键新建==Java类==HelloController

package com.tys.boot.controller;

import org.springframework.stereotype.*;
import org.springframework.web.bind.annotation.*;

@Controller
@ResponseBody
public class HelloController {
   
    @RequestMapping("/hello")
    public String handle01(){
   
        return "Hello, Spring Boot 2!";
    }
}

1.4 创建主程序

//对着src/main/java==右键新建==Java类==com.tys.boot.MainApplication

package com.tys.boot;

import org.springframework.boot.*;
import org.springframework.boot.autoconfigure.*;

@SpringBootApplication
public class MainApplication {
   

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

//点击第7行的小箭头，控制台出现多少秒，打开浏览器
//访问：localhost:8080/hello   看见网页出现 Hello, Spring Boot 2! 代表成功

二、底层注解

2.1 @Configuration

1、配置类里面使用@Bean标注在方法上给容器注册组件，默认也是单实例的
2、配置类本身也是组件
3、proxyBeanMethods：代理bean的方法，有两种
    
Full模式(proxyBeanMethods = true)（默认值，每个@Bean方法被调用多少次返回的组件都是单实例的）
Lite模式(proxyBeanMethods = false)（每个@Bean方法被调用多少次返回的组件都是新创建的）

//告诉SpringBoot这是一个配置类 == 配置文件
@Configuration(proxyBeanMethods = false)    
public class MyConfig {
   
    
    //给容器中添加组件。以方法名作为组件的id。返回类型就是组件类型
    @Bean 
    public User user01(){
   
        User zhangsan = new User("zhangsan", 18);
        zhangsan.setPet(tomcatPet());          //user组件依赖了Pet组件
        return zhangsan;
    }

    @Bean("tom")
    public Pet tomcatPet(){
   
        return new Pet("tomcat");
    }
}

2.2 @Import

//给容器中自动创建出这两个类型的组件，默认组件的名字就是全限定名

@Import({
   User.class, DBHelper.class})
@Configuration(proxyBeanMethods = false) 
public class MyConfig {
   
}

2.3 @Conditional

//@Conditional是条件装配：满足指定的条件，则进行组件注入

//以@ConditionalOnMissingBean进行举例说明
    
@Configuration(proxyBeanMethods = false)
@ConditionalOnMissingBean(name = "tom")//没有tom名字的Bean时，MyConfig类的Bean才能生效。
public class MyConfig {
   

    @Bean
    public User user01(){
   
        User zhangsan = new User("zhangsan", 18);
        zhangsan.setPet(tomcatPet());
        return zhangsan;
    }

    @Bean("tom22")
    public Pet tomcatPet(){
   
        return new Pet("tomcat");
    }
}

2.4 @ImportResource

//beans.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans ...">

    <bean id="haha" class="com.lun.boot.bean.User">
        <property name="name" value="zhangsan"></property>
        <property name="age" value="18"></property>
    </bean>

    <bean id="hehe" class="com.lun.boot.bean.Pet">
        <property name="name" value="tomcat"></property>
    </bean>
</beans>
=======================================================================================   //比如公司使用bean.xml文件生成配置bean，而非注解@bean
//使用@ImportResource导入配置文件

@ImportResource("classpath:beans.xml")
public class MyConfig {
   
...
}                                         

2.5 @ConfigurationProperties

//配置文件application.properties

mycar.brand=BYD
mycar.price=100000
=======================================================================================   //配置绑定 如何使用Java读取到properties文件中的内容，并且把它封装到JavaBean中
//只有在容器中的组件，才会拥有SpringBoot提供的强大功能，所以需要@Component

@Component
@ConfigurationProperties(prefix = "mycar")
public class Car {
   
  Car的实体类
}    

三、web开发

3.1 静态资源

# 对着/src/main/resources==右键新建==目录==static   在这放一张图片01.png

# 对着/src/main/resources==右键新建==文件==application.yaml

# /*表示拦截当前目录，/**表示拦截所有文件包括子文件夹里的
# 前两行表示访问路径是以static开头，localhost:8080/static/xx.png
# 后两行表示告诉spring，静态资源在项目的static文件夹下

spring:
  mvc:
    static-path-pattern: /static/**
  resources:
    static-locations: [classpath:/static/]

# 浏览器访问：localhost:8080/static/01.png
=======================================================================================
# 欢迎页

# 在/src/main/resources/static路径下，新建index.html，也可以在controller层指定

spring:
#  mvc:
#    static-path-pattern: /static/**    有了url前缀，会导致欢迎页功能失效
  resources:
    static-locations: [classpath:/static/]
    
#访问：localhost:8080  会自动打开index.html
=======================================================================================
# Favicon图标

# 在/src/main/resources/static路径下，放入favicon.ico 

spring:
#  mvc:
#    static-path-pattern: /static/**    有了url前缀，会导致小图标功能失效
  resources:
    static-locations: [classpath:/static/]
    
#访问：localhost:8080  

3.2 Restful风格

spring:
  mvc:
    hiddenmethod:
      filter:
        enabled: true   #开启网页表单的Restful功能

<form action="/user" method="get">
    <input value="GET提交" type="submit" />
form>

<form action="/user" method="post">
    <input value="POST提交" type="submit" />
form>

<form action="/user" method="post">
    <input name="_method" type="hidden" value="DELETE"/>
    <input value="DELETE 提交" type="submit"/>
form>

<form action="/user" method="post">
    <input name="_method" type="hidden" value="PUT" />
    <input value="PUT提交"type="submit" />
<form>

//springboot出了新注解，其实两种注解方式功能实现一样的

@GetMapping("/user")
//@RequestMapping(value = "/user",method = RequestMethod.GET)
public String getUser(){
   
    return "GET-张三";
}

@PostMapping("/user")
//@RequestMapping(value = "/user",method = RequestMethod.POST)
public String saveUser(){
   
    return "POST-张三";
}

@PutMapping("/user")
//@RequestMapping(value = "/user",method = RequestMethod.PUT)
public String putUser(){
   
    return "PUT-张三";
}

@DeleteMapping("/user")
//@RequestMapping(value = "/user",method = RequestMethod.DELETE)
public String deleteUser(){
   
    return "DELETE-张三";
}

3.3 获取request域中的值

//此注解@RequestAttribute，获取request域中的值

@Controller
public class RequestController {
   

    @GetMapping("/goto")
    public String goToPage(HttpServletRequest request){
   

        request.setAttribute("msg","成功了...");
        request.setAttribute("code",200);
        return "forward:/success";  //转发到success页面
    }

    @ResponseBody
    @GetMapping("/success")
    public Map success(@RequestAttribute(value = "msg",required = false) String msg,
                       @RequestAttribute(value = "code",required = false) Integer code){
   
        Map<String,Object> map = new HashMap<String,Object>();
        map.put("msg",msg);
        map.put("code",code);
		return map;
    }
}

3.4 自定义类型转换器

//Pet实体类，以前传name="啊猫" age=3  
//现在直接逗号分割，直接传"啊猫,3"

    @Bean
    public WebMvcConfigurer webMvcConfigurer(){
   return new WebMvcConfigurer() {
   
            @Override
            public void addFormatters(FormatterRegistry registry) {
   
                registry.addConverter(new Converter<String, Pet>() {
   
                    @Override
                    public Pet convert(String source) {
   
                        if(!StringUtils.isEmpty(source)){
   
                            Pet pet = new Pet();
                            String[] split = source.split(",");
                            pet.setName(split[0]);
                            pet.setAge(Integer.parseInt(split[1]));
                            return pet;
                        }
                        return null;
                    }
                });
            }
        };
    }

3.5 拦截器

//编写一个拦截器实现登录检查,没有账号登录，直接输入网址，进不了后台管理页面
//对着src/main/java==右键新建==软件包==com.tys.boot.interceptor
//对着com.tys.boot.interceptor==右键新建==Java类==LoginInterceptor

public class LoginInterceptor implements HandlerInterceptor {
   
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
   
        String requestURI = request.getRequestURI();
        HttpSession session = request.getSession();
        Object loginUser = session.getAttribute("loginUser");
        if(loginUser != null){
   
            return true;
        }
        request.setAttribute("msg","请先登录");
        request.getRequestDispatcher("/").forward(request,response);
        return false;
    }
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
   
        log.info("postHandle执行{}",modelAndView);
    }
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
   
        log.info("afterCompletion执行异常{}",ex);
    }
}

//拦截器注册到容器中并且指定拦截规则
//对着src/main/java==右键新建==软件包==com.tys.boot.config
//对着com.tys.boot.config==右键新建==Java类==AdminWebConfig

@Configuration
public class AdminWebConfig implements WebMvcConfigurer{
   
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
   
        registry.addInterceptor(new LoginInterceptor())//拦截器注册到容器中
                .addPathPatterns("/**")  //所有请求都被拦截包括静态资源
                .excludePathPatterns("/","/login","/css/**","/fonts/**","/images/**",
                        "/js/**","/aa/**"); //放行的请求

3.6 文件上传

//页面代码/static/form/form_layouts.html

<form role="form" th:action="@{/upload}" method="post" enctype="multipart/form-data">
    <div class="form-group">
        <label for="exampleInputEmail1">邮箱