目录

一、JDBC连接数据库

1. 创建项目，导入需要的依赖

2. 配置数据源

3. 测试连接

4. 项目启动成功，能够看出连接信息

二、配置数据库连接池Druid

1. 添加druid的maven配置

2. 添加数据源的配置

3. 重新执行测试代码，发现数据库连接池已经更改

4. 添加Druid其他增强的配置

5. 写配置类加载Druid的配置

6. 引入log4j的依赖

7. 测试一下数据库连接

8. 查看控制台的监控信息

---

Druid是Java语言中最好的数据库连接池。Druid能够提供强大的监控和扩展功能。

Druid 是一个 JDBC 组件库，包含数据库连接池、SQL Parser 等组件, 被大量业务和技术产品使用或集成，经历过最严苛线上业务场景考验，是你值得信赖的技术产品。

一、JDBC连接数据库

1. 创建项目，导入需要的依赖

  <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>

2. 配置数据源

server:
  port: 8085
spring:
  application:
    name: user-service
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/hm49?serverTimezone=UTC&useUnicode=true@characterEncoding=utf-8
    username: root
    password: root

3. 测试连接

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;

@SpringBootTest
class DataApplicationTests {

    @Autowired
    DataSource dataSource;
    
    /**
     * 验证数据库连接
     * @throws Exception
     */
    @Test
    void testConnection() throws Exception {
        System.out.println(dataSource.getClass());
        Connection connection = dataSource.getConnection();
        System.out.println(connection);
        connection.close();
    }

    /**
     * 验证连接池的配置信息，是否生效
     * @throws Exception
     */
    /*@Test
    void contextLoads() throws Exception {
        System.out.println(dataSource.getClass());
        DruidDataSource druidDataSource = (DruidDataSource) dataSource;
        System.out.println("initSize:" + druidDataSource.getInitialSize());
        System.out.println("maxSize:" + druidDataSource.getMaxActive());
        Connection connection = dataSource.getConnection();
        System.out.println(connection);
        connection.close();
    }*/

}

4. 项目启动成功，能够看出连接信息

      默认配置的数据源为class com.zaxxer.hikari.HikariDataSource

二、配置数据库连接池Druid

1. 添加druid的maven配置

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.1.12</version>
</dependency>

2. 添加数据源的配置

server:
  port: 8085
spring:
  application:
    name: user-service
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/hm49?serverTimezone=UTC&useUnicode=true@characterEncoding=utf-8
    username: root
    password: root
    type: com.alibaba.druid.pool.DruidDataSource

3. 重新执行测试代码，发现数据库连接池已经更改

      此时配置的数据源为com.alibaba.druid.pool.DruidDataSource

4. 添加Druid其他增强的配置

官网介绍如下：常见问题 · alibaba/druid Wiki · GitHub

server:
  port: 8085
spring:
  application:
    name: user-service
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/hm49?serverTimezone=UTC&useUnicode=true@characterEncoding=utf-8
    username: root
    password: root
    type: com.alibaba.druid.pool.DruidDataSource
    #Spring Boot 默认是不注入这些属性值的，需要自己绑定
    #druid 数据源专有配置
    initialSize: 5
    minIdle: 5
    maxActive: 20
    maxWait: 60000
    timeBetweenEvictionRunsMillis: 60000
    minEvictableIdleTimeMillis: 300000
    validationQuery: SELECT 1 FROM DUAL
    testWhileIdle: true
    testOnBorrow: false
    testOnReturn: false
    poolPreparedStatements: true

    #配置监控统计拦截的filters，stat:监控统计、log4j：日志记录、wall：防御sql注入
    #如果允许时报错  java.lang.ClassNotFoundException: org.apache.log4j.Priority
    #则导入 log4j 依赖即可，Maven 地址： https://mvnrepository.com/artifact/log4j/log4j
    filters: stat,wall,log4j
    maxPoolPreparedStatementPerConnectionSize: 20
    useGlobalDataSourceStat: true
    connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500

#第一步连接数据库
#第二步配置连接池+type
#第三部测试查询jdbcTemplate.queryForList(sql);
#第四部添加连接池配置

5. 写配置类加载Druid的配置

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.support.http.StatViewServlet;
import com.alibaba.druid.support.http.WebStatFilter;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.servlet.Servlet;
import javax.sql.DataSource;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class DruidConfig {
    @ConfigurationProperties(prefix = "spring.datasource")
    @Bean
    public DataSource druidDataSource(){
        return new DruidDataSource();
    }

    @Bean
    public ServletRegistrationBean druidServletRegistrationBean(){
        ServletRegistrationBean<Servlet> servletRegistrationBean = new ServletRegistrationBean<>(new StatViewServlet(),"/druid/*");
        Map<String,String> initParams = new HashMap<>();
        initParams.put("loginUsername","admin");
        initParams.put("loginPassword","123456");
        //后台允许谁可以访问
        //initParams.put("allow", "localhost")：表示只有本机可以访问
        //initParams.put("allow", "")：为空或者为null时，表示允许所有访问
        initParams.put("allow","");
        //deny：Druid 后台拒绝谁访问
//        initParams.put("msb", "192.168.1.20");//表示禁止此ip访问

        servletRegistrationBean.setInitParameters(initParams);
        return servletRegistrationBean;
    }

    //配置 Druid 监控 之  web 监控的 filter
    //WebStatFilter：用于配置Web和Druid数据源之间的管理关联监控统计
    @Bean
    public FilterRegistrationBean webStatFilter() {
        FilterRegistrationBean bean = new FilterRegistrationBean();
        bean.setFilter(new WebStatFilter());

        //exclusions：设置哪些请求进行过滤排除掉，从而不进行统计
        Map<String, String> initParams = new HashMap<>();
        initParams.put("exclusions", "*.js,*.css,/druid/*");
        bean.setInitParameters(initParams);

        //"/*" 表示过滤所有请求
        bean.setUrlPatterns(Arrays.asList("/*"));
        return bean;
    }
}

6. 引入log4j的依赖

        <!-- https://mvnrepository.com/artifact/log4j/log4j -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>

7. 测试一下数据库连接

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;


@RestController
public class JDBCController {

    @Autowired
    JdbcTemplate jdbcTemplate;

    @RequestMapping("selectAll")
    public List<Map<String,Object>> selectAll(){
        String sql = "select * from tb_user";
        List<Map<String, Object>> maps = jdbcTemplate.queryForList(sql);
        return maps;
    }

   
}

8. 查看控制台的监控信息

http://localhost:8085/druid/login.html

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