Druid是Java语言中最好的数据库连接池。对于一个简单的数据库应用，由于对于数据库的访问不是很频繁。这时可以简单地在需要访问数据库时，就新创建一个连接，用完后就关闭它，这样做也不会带来什么明显的性能上的开销。但是对于一个复杂的数据库应用，情况就完全不同了。频繁的建立、关闭连接，会极大的减低系统的性能，因为对于连接的使用成了系统性能的瓶颈。这个时候，我们通过建立一个数据库连接池以及一套连接使用管理策略，使得一个数据库连接可以得到高效、安全的复用，避免了数据库连接频繁建立、关闭的开销。

那么，我们在springboot程序当中，如何配置druid数据库连接池呢？

第一步：maven引入相应的jar包。

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.0.5</version>
</dependency>

第二步：application.properties文件，添加数据库的访问配置

# 数据库访问配置
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis?useSSL=false&useUnicode=true&characterEncoding=utf-8&allowMultiQueries=true
spring.datasource.username=root
spring.datasource.password=123456
# 下面为连接池的补充设置，应用到上面所有数据源中
spring.datasource.initialSize=5
spring.datasource.minIdle=5
spring.datasource.maxActive=20
# 配置获取连接等待超时的时间
spring.datasource.maxWait=60000
# 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒
spring.datasource.timeBetweenEvictionRunsMillis=60000
# 配置一个连接在池中最小生存的时间，单位是毫秒
spring.datasource.minEvictableIdleTimeMillis=300000
spring.datasource.validationQuery=SELECT 1 FROM DUAL
spring.datasource.testWhileIdle=true
spring.datasource.testOnBorrow=false
spring.datasource.testOnReturn=false
# 配置监控统计拦截的filters，去掉后监控界面sql无法统计，'wall'用于防火墙
spring.datasource.filters=stat,wall,log4j
spring.datasource.logSlowSql=true

第三步：由于springboot程序的特性，我们在工程的config包下面，创建DruidConfig.java文件，配置数据库连接池。

第一种的配置方式：

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.util.StringUtils;
import org.apache.ibatis.io.VFS;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.annotation.MapperScan;
import org.mybatis.spring.boot.autoconfigure.SpringBootVFS;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.bind.RelaxedPropertyResolver;
import org.springframework.context.ApplicationContextException;
import org.springframework.context.EnvironmentAware;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;
 
import java.sql.SQLException;
import java.util.Arrays;
 
@Configuration
@EnableTransactionManagement
public class DuridConfig implements EnvironmentAware {
    private static final Logger logger = LoggerFactory.getLogger(DuridConfig.class);
 
    private Environment environment;
    private RelaxedPropertyResolver propertyResolver;
 
    @Override
    public void setEnvironment(Environment environment) {
        this.environment = environment;
        this.propertyResolver = new RelaxedPropertyResolver(environment, "spring.datasource.");
    }
 
    //注册dataSource
    @Bean(initMethod = "init", destroyMethod = "close")
    public DruidDataSource dataSource() throws SQLException {
        if (StringUtils.isEmpty(propertyResolver.getProperty("url"))) {
            System.out.println("Your database connectio n pool configuration is incorrect!"
                    + " Please check your Spring profile, current profiles are:"
                    + Arrays.toString(environment.getActiveProfiles()));
            throw new ApplicationContextException(
                    "Database connection pool is not configured correctly");
        }
        DruidDataSource druidDataSource = new DruidDataSource();
        druidDataSource.setDriverClassName(propertyResolver.getProperty("driver-class-name"));
        druidDataSource.setUrl(propertyResolver.getProperty("url"));
        druidDataSource.setUsername(propertyResolver.getProperty("username"));
        druidDataSource.setPassword(propertyResolver.getProperty("password"));
        druidDataSource.setInitialSize(Integer.parseInt(propertyResolver.getProperty("initialSize")));
        druidDataSource.setMinIdle(Integer.parseInt(propertyResolver.getProperty("minIdle")));
        druidDataSource.setMaxActive(Integer.parseInt(propertyResolver.getProperty("maxActive")));
        druidDataSource.setMaxWait(Integer.parseInt(propertyResolver.getProperty("maxWait")));
        druidDataSource.setTimeBetweenEvictionRunsMillis(Long.parseLong(propertyResolver.getProperty("timeBetweenEvictionRunsMillis")));
        druidDataSource.setMinEvictableIdleTimeMillis(Long.parseLong(propertyResolver.getProperty("minEvictableIdleTimeMillis")));
        druidDataSource.setValidationQuery(propertyResolver.getProperty("validationQuery"));
        druidDataSource.setTestWhileIdle(Boolean.parseBoolean(propertyResolver.getProperty("testWhileIdle")));
        druidDataSource.setTestOnBorrow(Boolean.parseBoolean(propertyResolver.getProperty("testOnBorrow")));
        druidDataSource.setTestOnReturn(Boolean.parseBoolean(propertyResolver.getProperty("testOnReturn")));
        druidDataSource.setPoolPreparedStatements(Boolean.parseBoolean(propertyResolver.getProperty("poolPreparedStatements")));
        druidDataSource.setMaxPoolPreparedStatementPerConnectionSize(Integer.parseInt(propertyResolver.getProperty("maxPoolPreparedStatementPerConnectionSize")));
        druidDataSource.setFilters(propertyResolver.getProperty("filters"));
        logger.info("DuridConfig-----数据源完成");
        return druidDataSource;
    }
 
    @Bean
    public SqlSessionFactory sqlSessionFactory() throws Exception {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSource());
//        //mybatis分页
//        PageHelper pageHelper = new PageHelper();
//        Properties props = new Properties();
//        props.setProperty("dialect", "mysql");
//        props.setProperty("reasonable", "true");
//        props.setProperty("supportMethodsArguments", "true");
//        props.setProperty("returnPageInfo", "check");
//        props.setProperty("params", "count=countSql");
//        pageHelper.setProperties(props);
//        //添加插件
//        sqlSessionFactoryBean.setPlugins(new Interceptor[]{pageHelper});
        //添加XML目录
        VFS.addImplClass(SpringBootVFS.class);
        PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        sqlSessionFactoryBean.setMapperLocations(resolver.getResources("classpath:mapper/*.xml"));
        logger.info("dao层扫描包为:mapper/*.xml");
        return sqlSessionFactoryBean.getObject();
    }
 
    @Bean
    public PlatformTransactionManager transactionManager() throws SQLException {
        return new DataSourceTransactionManager(dataSource());
 
    }
 
 
}

第二种的配置方式：

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.support.http.StatViewServlet;
import com.alibaba.druid.support.http.WebStatFilter;
import com.github.pagehelper.PageHelper;
import org.apache.ibatis.io.VFS;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.annotation.MapperScan;
import org.mybatis.spring.boot.autoconfigure.SpringBootVFS;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
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 org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;
 
import javax.sql.DataSource;
import java.sql.SQLException;
import java.util.Properties;
 
/**
 *                             _ooOoo_
 *                            o8888888o
 *                            88" . "88
 *                            (| -_- |)
 *                            O\  =  /O
 *                         ____/`---'\____
 *                       .'  \\|     |//  `.
 *                      /  \\|||  :  |||//  \
 *                     /  _||||| -:- |||||-  \
 *                     |   | \\\  -  /// |   |
 *                     | \_|  ''\---/''  |   |
 *                     \  .-\__  `-`  ___/-. /
 *                   ___`. .'  /--.--\  `. . __
 *                ."" '<  `.___\_<|>_/___.'  >'"".
 *               | | :  `- \`.;`\ _ /`;.`/ - ` : | |
 *               \  \ `-.   \_ __\ /__ _/   .-` /  /
 *          ======`-.____`-.___\_____/___.-`____.-'======
 *                             `=---='
 *          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 *                     佛祖保佑        永无BUG
 *            佛曰:
 *                   写字楼里写字间，写字间里程序员；
 *                   程序人员写程序，又拿程序换酒钱。
 *                   酒醒只在网上坐，酒醉还来网下眠；
 *                   酒醉酒醒日复日，网上网下年复年。
 *                   但愿老死电脑间，不愿鞠躬老板前；
 *                   奔驰宝马贵者趣，公交自行程序员。
 *                   别人笑我忒疯癫，我笑自己命太贱；
 *                   不见满街漂亮妹，哪个归得程序员？
 */
@Configuration
@EnableTransactionManagement
public class DruidConfig {
 
    private Logger logger = LoggerFactory.getLogger(DruidConfig.class);
 
 
    @Value("${spring.datasource.url}")
    private String dbUrl;
 
    @Value("${spring.datasource.username}")
    private String username;
 
    @Value("${spring.datasource.password}")
    private String password;
 
    @Value("${spring.datasource.driver-class-name}")
    private String driverClassName;
 
    @Value("${spring.datasource.initialSize}")
    private int initialSize;
 
    @Value("${spring.datasource.minIdle}")
    private int minIdle;
 
    @Value("${spring.datasource.maxActive}")
    private int maxActive;
 
    @Value("${spring.datasource.maxWait}")
    private int maxWait;
 
    @Value("${spring.datasource.timeBetweenEvictionRunsMillis}")
    private int timeBetweenEvictionRunsMillis;
 
    @Value("${spring.datasource.minEvictableIdleTimeMillis}")
    private int minEvictableIdleTimeMillis;
 
    @Value("${spring.datasource.validationQuery}")
    private String validationQuery;
 
    @Value("${spring.datasource.testWhileIdle}")
    private boolean testWhileIdle;
 
    @Value("${spring.datasource.testOnBorrow}")
    private boolean testOnBorrow;
 
    @Value("${spring.datasource.testOnReturn}")
    private boolean testOnReturn;
 
    @Value("${spring.datasource.filters}")
    private String filters;
 
    @Value("${spring.datasource.logSlowSql}")
    private String logSlowSql;
 
    @Bean
    public ServletRegistrationBean druidServlet() {
        ServletRegistrationBean reg = new ServletRegistrationBean();
        reg.setServlet(new StatViewServlet());
        reg.addUrlMappings("/druid/*");
        reg.addInitParameter("loginUsername", username);
        reg.addInitParameter("loginPassword", password);
        reg.addInitParameter("logSlowSql", logSlowSql);
        return reg;
    }
 
    @Bean
    public FilterRegistrationBean filterRegistrationBean() {
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
        filterRegistrationBean.setFilter(new WebStatFilter());
        filterRegistrationBean.addUrlPatterns("/*");
        filterRegistrationBean.addInitParameter("exclusions", "*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*");
        filterRegistrationBean.addInitParameter("profileEnable", "true");
        return filterRegistrationBean;
    }
 
    @Bean
    public DataSource druidDataSource() {
        DruidDataSource datasource = new DruidDataSource();
        datasource.setUrl(dbUrl);
        datasource.setUsername(username);
        datasource.setPassword(password);
        datasource.setDriverClassName(driverClassName);
        datasource.setInitialSize(initialSize);
        datasource.setMinIdle(minIdle);
        datasource.setMaxActive(maxActive);
        datasource.setMaxWait(maxWait);
        datasource.setTimeBetweenEvictionRunsMillis(timeBetweenEvictionRunsMillis);
        datasource.setMinEvictableIdleTimeMillis(minEvictableIdleTimeMillis);
        datasource.setValidationQuery(validationQuery);
        datasource.setTestWhileIdle(testWhileIdle);
        datasource.setTestOnBorrow(testOnBorrow);
        datasource.setTestOnReturn(testOnReturn);
        try {
            datasource.setFilters(filters);
        } catch (SQLException e) {
            logger.error("druid configuration initialization filter", e);
        }
        return datasource;
    }
 
    @Bean
    public SqlSessionFactory sqlSessionFactory() throws Exception {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(druidDataSource());
        //mybatis分页
        PageHelper pageHelper = new PageHelper();
        Properties props = new Properties();
        props.setProperty("dialect", "mysql");
        props.setProperty("reasonable", "true");
        props.setProperty("supportMethodsArguments", "true");
        props.setProperty("returnPageInfo", "check");
        props.setProperty("params", "count=countSql");
        pageHelper.setProperties(props);
        //添加插件
       sqlSessionFactoryBean.setPlugins(new Interceptor[]{pageHelper});
        //添加XML目录
        VFS.addImplClass(SpringBootVFS.class);
        PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        sqlSessionFactoryBean.setMapperLocations(resolver.getResources("classpath:mapper/*.xml"));
        logger.info("dao层扫描包为:mapper/*.xml");
        return sqlSessionFactoryBean.getObject();
    }
 
    @Bean
    public PlatformTransactionManager transactionManager() throws SQLException {
        return new DataSourceTransactionManager(druidDataSource());
 
    }
 
 
 
 
 
}

现在我们打开http://localhost:8018/druid/login.html,用我们配置的druid监控的账号和密码进行登录，就可以看到监控的信息，发现我们配置的都已经生效了。

https://blog.csdn.net/qq_38455201/article/details/80769354