JAVA series - database connection pool

Database connection pool class

There are only 2 commonly used in the market at present, and the others do not need to be looked at.

• HikariCP (built-in by default in Spring)
• Druid

HikariCP is the default database connection pool solution in Spring, but Druid is generally used in China

The difference between druid and druid-spring-boot-starter

• druid-spring-boot-starterIt is druidpackaged on the basis of and dedicated to integrating spring-bootprojects without writing configuration files
• druidNeed to manually write a configuration class file

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.2.8</version>
</dependency>

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.2.8</version>
</dependency>

Conclusion: use druid-spring-boot-starter

Using druid-spring-boot-starter

There are 3 steps

1. Import coordinates in pom, 3 coordinates
2. Write the configuration information in the application.yml file, pay attention to the format
3. Write a test class to verify

Note that there is no need to write configuration classes

---

1. Import coordinates in pom, 3 coordinates

<!--   数据库连接   -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.2.8</version>
</dependency>

2. Write configuration information in the application.yml file

Note that in the configuration file: url、username、password、driver four items, the level is below datasource . For other druid configurations, similarly initial-size，min-idle这种的, the hierarchy must be located druidbelow, so that these configurations will be automatically wrapped into DruidDataSourceWrapper by druid

server:
  port: 9110

spring:
  application:
    name: reggie
  datasource:
    # JDBC配置：
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/firstdemo?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&useSSL=false
    username: root
    password: 123456

    # 连接池配置：
    druid:
      initial-size: 10   # 初始化大小
      min-idle: 5     # 最小空闲连接个数
      max-active: 20    # 最大连接个数
      max-wait: 60000   # 配置获取连接等待超时的时间
      pool-prepared-statements: true  # 打开PSCache，并且指定每个连接上PSCache的大小
      max-pool-prepared-statement-per-connection-size: 20
      time-between-eviction-runs-millis: 60000    # 配置间隔多久才进行一次监测，监测需要关闭的空闲连接，单位时毫秒
      min-evictable-idle-time-millis: 60000       # 配置一个连接在池中最小生存的时间

      #validation-query: SELECT 1 FROM DUAL
      test-while-idle: true            # 建议配置为true，不影响性能，并且保证安全性。如果空闲时间大于timeBetweenEvictionRunsMillis，执行validationQuery检测连接是否有效。
      test-on-borrow: false            # 申请连接时执行validationQuery检测连接是否有效，做了这个配置会降低性能
      test-on-return: false            # 归还连接时执行validationQuery检测连接是否有效，做了这个配置会降低性能

      # 启用Druid内置的Filter，会使用默认的配置。可自定义配置，见下方的各个filter节点。
      filters: stat,wall

      # StatViewServlet监控器。开启后，访问http://域名/druid/index.html
      stat-view-servlet:
        enabled: true # 开启 StatViewServlet，即开启监控功能
        login-username: daniel # 访问监控页面时登录的账号
        login-password: 1234 # 密码
        url-pattern: /druid/* # Servlet的映射地址，不填写默认为"/druid/*"。如填写其它地址，访问监控页面时，要使用相应的地址
        reset-enable: false # 是否允许重置数据（在页面的重置按钮）。（停用后，依然会有重置按钮，但重置后不会真的重置数据）
        allow: 127.0.0.1,192.168.2.29,192.168.1.1 # 监控页面访问白名单。默认为127.0.0.1。与黑名单一样，支持子网掩码，如128.242.127.1/24。多个ip用英文逗号分隔
        deny: 22.1.2.3 # 监控页面访问黑名单

      # 配置 WebStatFilter（StatFilter监控器中的Web模板）
      web-stat-filter:
        enabled: true # 开启 WebStatFilter，即开启监控功能中的 Web 监控功能
        url-pattern: /* # 映射地址，即统计指定地址的web请求
        exclusions: '*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*' # 不统计的web请求，如下是不统计静态资源及druid监控页面本身的请求
        session-stat-enable: true # 是否启用session统计
        session-stat-max-count: 1 # session统计的最大个数，默认是1000。当统计超过这个数，只统计最新的
        principal-session-name: userName # 所存用户信息的serssion参数名。Druid会依照此参数名读取相应session对应的用户名记录下来（在监控页面可看到）。如果指定参数不是基础数据类型，将会自动调用相应参数对象的toString方法来取值
        principal-cookie-name: userName # 与上类似，但这是通过Cookie名取到用户信息
        profile-enable: true # 监控单个url调用的sql列表（试了没生效，以后需要用再研究）


      filter:
        stat:
          log-slow-sql: false
          slow-sql-millis: 1000
          merge-sql: false
        wall:
          config:
            multi-statement-allow: true

3. Write a test class to verify

package com.cool.reggie;


import com.alibaba.druid.pool.DruidDataSource;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.jdbc.core.JdbcTemplate;

import javax.annotation.Resource;
import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.List;
import java.util.Map;


/**
 * @Author [email protected]
 * @Date 2022/6/30 9:46
 * @Version 1.0.0
 * @Description
 **/
@SpringBootTest
public class DruidStarterTest {
    
    

    @Autowired
    private JdbcTemplate jdbcTemplate;

    @Resource
    private DataSource dataSource;


    @Test
    public void testDruidConnector() throws SQLException, InstantiationException, IllegalAccessException {
    
    
        DruidDataSource druidDataSource = (DruidDataSource) dataSource;
        // 成功读取连接池配置
        System.out.println(druidDataSource.getUsername());
        System.out.println(druidDataSource.getPassword());
        System.out.println(dataSource.getClass());

        Connection connection = dataSource.getConnection();
        // 成功连接到数据库
        System.out.println(connection);
        connection.close();

        List<Map<String, Object>> maps = jdbcTemplate.queryForList("select * from student");
        // 成功使用数据库连接池执行 SQL 操作
        for (Map<String, Object> map : maps) {
    
    
            System.out.println(map);
        }

    }

}

druid monitoring

Druid is not only a database connection pool , but also can view data sources, sql monitoring, sql firewall, web applications, session monitoring, URI monitoring, spring monitoring, json api and other information.

It can observe the running status of the database connection pool and SQL in real time, helping us to troubleshoot the problems in the system in time.

Access address: http://localhost:9110/druid/index.html

If you copied the above configuration content, then the stat-view-servlet.allow white list needs to be changed to your own local IP address, or this item should not be set.
Otherwise, you will see the page Sorry, you are not permitted to view this page.
tips: To view the ip address of your own machine, enter in the command line ipconfig,

References

Maven warehouse - druid
configuration StatFilter
druid-start automatic assembly principle