寒假学习24篇

### 3.3 静态资源处理

> 在WEB开发中我们需要引入一些静态资源 , 例如 : HTML , CSS , JS , 图片等 , 如果是普通的项目静态资源可以放在项目的webapp目录下。现在使用Spring Boot做开发 , 项目中没有webapp目录 , 我们的项目是一个jar工程，那么就没有webapp，我们的静态资源该放哪里呢？

1. 默认路径

在springboot中就定义了静态资源的默认查找路径：

```Java
package org.springframework.boot.autoconfigure.web;
//..................
public static class Resources {
private static final String[] CLASSPATH_RESOURCE_LOCATIONS = new String[]{"classpath:/META-INF/resources/", "classpath:/resources/", "classpath:/static/", "classpath:/public/"};
private String[] staticLocations;
private boolean addMappings;
private boolean customized;
private final Chain chain;
private final Cache cache;

public Resources() {
this.staticLocations = CLASSPATH_RESOURCE_LOCATIONS;
this.addMappings = true;
this.customized = false;
this.chain = new Chain();
this.cache = new Cache();
}
//...........
```

**默认的静态资源路径为：**

**· classpath:/META-INF/resources/**

**· classpath:/resources/**

**· classpath:/static/**

**· classpath:/public/**

我们只要静态资源放在这些目录中任何一个，SpringMVC都会帮我们处理。 我们习惯会把静态资源放在classpath:/static/ 目录下。在resources目录下创建index.html文件


打开浏览器输入 : [http://localhost:8080/index.html](http://localhost:8080/index.html)
2. 覆盖路径

```YAML
# web相关的配置
# https://docs.spring.io/spring-boot/docs/current/reference/html/application-properties.html#appendix.application-properties.server
server:
# 端口号设置
port: 80
# 项目根路径
servlet:
context-path: /boot
spring:
web:
resources:
# 配置静态资源地址,如果设置,会覆盖默认值
static-locations: classpath:/webapp
```


访问地址：[http://localhost/boot/login.html](http://localhost/boot/login.html)

### 3.4 自定义拦截器(SpringMVC配置)
1. 拦截器声明

```Java
package com.atguigu.interceptor;

import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

@Component
public class MyInterceptor implements HandlerInterceptor {
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
System.out.println("MyInterceptor拦截器的preHandle方法执行....");
return true;
}

@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
System.out.println("MyInterceptor拦截器的postHandle方法执行....");
}

@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
System.out.println("MyInterceptor拦截器的afterCompletion方法执行....");
}
}
```
2. 拦截器配置

正常使用配置类，只要保证，**配置类要在启动类的同包或者子包方可生效！**

```Java
package com.atguigu.config;

import com.atguigu.interceptor.MyInterceptor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class MvcConfig implements WebMvcConfigurer {

@Autowired
private MyInterceptor myInterceptor ;

/**
* /** 拦截当前目录及子目录下的所有路径 /user/** /user/findAll /user/order/findAll
* /* 拦截当前目录下的以及子路径 /user/* /user/findAll
* @param registry
*/
@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(myInterceptor).addPathPatterns("/**");
}
}
```
3. 拦截器效果测试

1. 创建程序
2. 引入依赖

```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>

<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>3.0.5</version>
</parent>
<groupId>com.atguigu</groupId>
<artifactId>springboot-starter-druid-04</artifactId>
<version>1.0-SNAPSHOT</version>

<properties>
<maven.compiler.source>17</maven.compiler.source>
<maven.compiler.target>17</maven.compiler.target>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>

<dependencies>
<!-- web开发的场景启动器 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>

<!-- 数据库相关配置启动器 jdbctemplate 事务相关-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>

<!-- druid启动器的依赖 -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid-spring-boot-3-starter</artifactId>
<version>1.2.18</version>
</dependency>

<!-- 驱动类-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.28</version>
</dependency>

<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.28</version>
</dependency>

</dependencies>

<!-- SpringBoot应用打包插件-->
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>

</project>
```
3. 启动类

```Java
@SpringBootApplication
public class MainApplication {

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

```
4. 配置文件编写

> 添加druid连接池的基本配置

```YAML
spring:
datasource:
# 连接池类型
type: com.alibaba.druid.pool.DruidDataSource

# Druid的其他属性配置 springboot3整合情况下,数据库连接信息必须在Druid属性下!
druid:
url: jdbc:mysql://localhost:3306/day01
username: root
password: root
driver-class-name: com.mysql.cj.jdbc.Driver
# 初始化时建立物理连接的个数
initial-size: 5
# 连接池的最小空闲数量
min-idle: 5
# 连接池最大连接数量
max-active: 20
# 获取连接时最大等待时间，单位毫秒
max-wait: 60000
# 申请连接的时候检测，如果空闲时间大于timeBetweenEvictionRunsMillis，执行validationQuery检测连接是否有效。
test-while-idle: true
# 既作为检测的间隔时间又作为testWhileIdel执行的依据
time-between-eviction-runs-millis: 60000
# 销毁线程时检测当前连接的最后活动时间和当前时间差大于该值时，关闭当前连接(配置连接在池中的最小生存时间)
min-evictable-idle-time-millis: 30000
# 用来检测数据库连接是否有效的sql 必须是一个查询语句(oracle中为 select 1 from dual)
validation-query: select 1
# 申请连接时会执行validationQuery检测连接是否有效,开启会降低性能,默认为true
test-on-borrow: false
# 归还连接时会执行validationQuery检测连接是否有效,开启会降低性能,默认为true
test-on-return: false
# 是否缓存preparedStatement, 也就是PSCache,PSCache对支持游标的数据库性能提升巨大，比如说oracle,在mysql下建议关闭。
pool-prepared-statements: false
# 要启用PSCache，必须配置大于0，当大于0时，poolPreparedStatements自动触发修改为true。在Druid中，不会存在Oracle下PSCache占用内存过多的问题，可以把这个数值配置大一些，比如说100
max-pool-prepared-statement-per-connection-size: -1
# 合并多个DruidDataSource的监控数据
use-global-data-source-stat: true

logging:
level:
root: debug
```
5. 编写Controller

```Java
@Slf4j
@Controller
@RequestMapping("/user")
public class UserController {

@Autowired
private JdbcTemplate jdbcTemplate;

@GetMapping("/getUser")
@ResponseBody
public User getUser(){
String sql = "select * from users where id = ? ; ";
User user = jdbcTemplate.queryForObject(sql, new BeanPropertyRowMapper<>(User.class), 1);
log.info("查询的user数据为:{}",user.toString());
return user;
}

}
```
6. 启动测试
7. 问题解决

通过源码分析，druid-spring-boot-3-starter目前最新版本是1.2.18，虽然适配了SpringBoot3，但缺少自动装配的配置文件，需要手动在resources目录下创建META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports，文件内容如下!

```Java
com.alibaba.druid.spring.boot3.autoconfigure.DruidDataSourceAutoConfigure
```