Druid它好在哪：
它可以提供数据源、sql防火墙，web应用，URI监控、Session监控，spring监控等。
方便进行针对性改造和优化，提高项目性能。
如下是实现的具体操作：
一、引入依赖
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.0.28</version>
</dependency>
二、配置文件（spring.datasource 下的配置）
#配置druid监控参数
type: com.alibaba.druid.pool.DruidDataSource
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
maxPoolPreparedStatementPerConnectionSize: 20
filters: stat,wall,log4j
三、三个关键类（没有试是否可以省略）
(1)DruidConfig
import java.sql.SQLException;
import javax.sql.DataSource;
import org.apache.log4j.Logger;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import com.alibaba.druid.pool.DruidDataSource;
@Configuration
public class DruidConfig {
private Logger logger = Logger.getLogger(this.getClass());
@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("${spring.datasource.poolPreparedStatements}")
private boolean poolPreparedStatements;
@Value("${spring.datasource.maxPoolPreparedStatementPerConnectionSize}")
private int maxPoolPreparedStatementPerConnectionSize;
@Value("${spring.datasource.filters}")
private String filters;
@Value("{spring.datasource.connectionProperties}")
private String connectionProperties;
@Bean
@Primary //主数据源
public DataSource dataSource(){
DruidDataSource datasource = new DruidDataSource();
datasource.setUrl(this.dbUrl);
datasource.setUsername(username);
datasource.setPassword(password);
datasource.setDriverClassName(driverClassName);
//configuration
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);
datasource.setPoolPreparedStatements(poolPreparedStatements);
datasource.setMaxPoolPreparedStatementPerConnectionSize(maxPoolPreparedStatementPerConnectionSize);
try {
datasource.setFilters(filters);
} catch (SQLException e) {
logger.error("druid configuration Exception", e);
}
datasource.setConnectionProperties(connectionProperties);
return datasource;
}
}
(2)DruidFilter
import javax.servlet.annotation.WebFilter;
import javax.servlet.annotation.WebInitParam;
import com.alibaba.druid.support.http.WebStatFilter;
@WebFilter(filterName="druidWebStatFilter",urlPatterns="/*",
initParams={
@WebInitParam(name="exclusions",value="*.js,*.gif,*.jpg,*.bmp,*.png,*.css,*.ico,/druid/*")//忽略资源
}
)
public class DruidFilter extends WebStatFilter {
}
(3)DruidServlet
import javax.servlet.annotation.WebInitParam;
import javax.servlet.annotation.WebServlet;
import com.alibaba.druid.support.http.StatViewServlet;
@WebServlet(urlPatterns="/druid/*",
initParams={
@WebInitParam(name="allow",value=""),// IP白名单(没有配置或者为空，则允许所有访问)
@WebInitParam(name="deny",value=""),// IP黑名单 (deny优先于allow)
@WebInitParam(name="loginUsername",value="admin"),// 登录druid管理页面用户名
@WebInitParam(name="loginPassword",value="admin")// 登录druid管理页面密码
})
public class DruidServlet extends StatViewServlet {
}
四、最后别忘了在启动类上加入注解@ServletComponentScan，让项目扫描到servlet。（一般都会加过了）
五、看看效果
访问页面http://127.0.0.1:8080/{projectName}/druid/index.html就可以访问监控页面了，druid已经将数据友好的显示到页面上了，包括每条sql执行的次数，执行的时间，最慢时间等等很多详细信息，供我们参考，找到哪些执行效率低的耗时长的语句进行优化。同时提供数据源、sql防火墙，web应用，URI监控、Session监控，spring监控等。
如图：可以看到第一个sql执行的慢并且被调用的次数多，
可以针对地优化一下了。
image.png
