数据库连接池Druid的介绍，配置分析对比总结

今天药忘吃喽~ 2022-01-12 03:27 295阅读 0赞

### Druid的简介 ###

Druid首先是一个数据库连接池。Druid是目前最好的数据库连接池，在功能、性能、扩展性方面，都超过其他数据库连接池，包括DBCP、C3P0、BoneCP、Proxool、JBoss DataSource。Druid已经在阿里巴巴部署了超过600个应用，经过一年多生产环境大规模部署的严苛考验。Druid是阿里巴巴开发的号称为监控而生的数据库连接池！

### Druid的功能 ###

1、替换DBCP和C3P0。Druid提供了一个高效、功能强大、可扩展性好的数据库连接池。

2、可以监控数据库访问性能，Druid内置提供了一个功能强大的StatFilter插件，能够详细统计SQL的执行性能，这对于线上分析数据库访问性能有帮助。

3、数据库密码加密。直接把数据库密码写在配置文件中，这是不好的行为，容易导致安全问题。DruidDruiver和DruidDataSource都支持PasswordCallback。

4、SQL执行日志，Druid提供了不同的LogFilter，能够支持Common-Logging、Log4j和JdkLog，你可以按需要选择相应的LogFilter，监控你应用的数据库访问情况。

5、扩展JDBC，如果你要对JDBC层有编程的需求，可以通过Druid提供的Filter机制，很方便编写JDBC层的扩展插件。

所以Druid可以： 1、充当数据库连接池。 2、可以监控数据库访问性能 3、获得SQL执行日志

### 工程配置如下： ###

1、工程引入druid-1.0.15.jar

<dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>${druid-version}</version>
        </dependency>
    复制代码

2、数据源配置

<bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource" destroy-method="close">  
        <property value="${jdbc_url}" name="url"></property>  
        <property value="${jdbc_user}" name="username"></property>  
        <property value="${jdbc_password}" name="password"></property>  
       
        <property value="stat" name="filters"></property>  
       
        <property value="20" name="maxActive"></property>  
        <property value="1" name="initialSize"></property>  
        <property value="60000" name="maxWait"></property>  
        <property value="1" name="minIdle"></property>  
       
        <property value="60000" name="timeBetweenEvictionRunsMillis"></property>  
        <property value="300000" name="minEvictableIdleTimeMillis"></property>  
       
        <property value="SELECT 'x'" name="validationQuery"></property>  
        <property value="true" name="testWhileIdle"></property>  
        <property value="false" name="testOnBorrow"></property>  
        <property value="false" name="testOnReturn"></property>  
        <property value="true" name="poolPreparedStatements"></property>  
        <property value="20" name="maxPoolPreparedStatementPerConnectionSize"></property>  
    </bean> 
    复制代码

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 <tbody style="font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">配置</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">缺省值</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">说明</td> 
  </tr> 
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   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">name</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">&nbsp;</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">配置这个属性的意义在于，如果存在多个数据源，监控的时候<br>可以通过名字来区分开来。如果没有配置，将会生成一个名字，<br>格式是：”DataSource-” + System.identityHashCode(this)</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">jdbcUrl</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">&nbsp;</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">连接数据库的url，不同数据库不一样。例如：<br>mysql : jdbc:mysql://10.20.153.104:3306/druid2&nbsp;<br>oracle : jdbc:oracle:thin:@10.20.149.85:1521:ocnauto</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">username</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">&nbsp;</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">连接数据库的用户名</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">password</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">&nbsp;</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">连接数据库的密码。如果你不希望密码直接写在配置文件中，<br>可以使用ConfigFilter。详细看这里：<br><span style="font-family:inherit;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"><span style="font-family:inherit;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"><a style="color:rgb(118,0,0);border:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;" href="https://link.juejin.im?target=https%3A%2F%2Fgithub.com%2Falibaba%2Fdruid%2Fwiki%2F%25E4%25BD%25BF%25E7%2594%25A8ConfigFilter" rel="nofollow">github.com/alibaba/dru…</a></span></span></td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">driverClassName</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">根据url自动识别</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">这一项可配可不配，如果不配置druid会根据url自动识别dbType，<br>然后选择相应的driverClassName</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">initialSize</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">0</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">初始化时建立物理连接的个数。初始化发生在显示调用init方法，<br>或者第一次getConnection时</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">maxActive</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">8</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">最大连接池数量</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">maxIdle</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">8</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">已经不再使用，配置了也没效果</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">minIdle</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">&nbsp;</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">最小连接池数量</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">maxWait</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">&nbsp;</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">获取连接时最大等待时间，单位毫秒。配置了maxWait之后，<br>缺省启用公平锁，并发效率会有所下降，<br>如果需要可以通过配置useUnfairLock属性为true使用非公平锁。</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">poolPreparedStatements</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">false</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">是否缓存preparedStatement，也就是PSCache。<br>PSCache对支持游标的数据库性能提升巨大，比如说oracle。<br>在mysql5.5以下的版本中没有<span style="font-family:inherit;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;">PSCache功能，建议关闭掉。<br>5.5及以上版本有PSCache，建议开启。</span></td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">maxOpenPreparedStatements</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">-1</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">要启用PSCache，必须配置大于0，当大于0时，<br>poolPreparedStatements自动触发修改为true。<br>在Druid中，不会存在Oracle下PSCache占用内存过多的问题，<br>可以把这个数值配置大一些，比如说100</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">validationQuery</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">&nbsp;</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">用来检测连接是否有效的sql，要求是一个查询语句。<br>如果validationQuery为null，testOnBorrow、testOnReturn、<br>testWhileIdle都不会其作用。</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">testOnBorrow</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">true</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">申请连接时执行validationQuery检测连接是否有效，<br>做了这个配置会降低性能。</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">testOnReturn</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">false</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">归还连接时执行validationQuery检测连接是否有效，<br>做了这个配置会降低性能</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">testWhileIdle</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">false</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">建议配置为true，不影响性能，并且保证安全性。<br>申请连接的时候检测，如果空闲时间大于<br>timeBetweenEvictionRunsMillis，<br>执行validationQuery检测连接是否有效。</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">timeBetweenEvictionRunsMillis</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">&nbsp;</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">有两个含义：<br>1) Destroy线程会检测连接的间隔时间<br>&nbsp;2) testWhileIdle的判断依据，详细看testWhileIdle属性的说明</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">numTestsPerEvictionRun</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">&nbsp;</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">不再使用，一个DruidDataSource只支持一个EvictionRun</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">minEvictableIdleTimeMillis</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">&nbsp;</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">&nbsp;</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">connectionInitSqls</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">&nbsp;</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">物理连接初始化的时候执行的sql</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">exceptionSorter</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">根据dbType自动识别</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">当数据库抛出一些不可恢复的异常时，抛弃连接</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">filters</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">&nbsp;</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">属性类型是字符串，通过别名的方式配置扩展插件，<br>常用的插件有：<br>监控统计用的filter:stat&nbsp;<br>日志用的filter:log4j<br>&nbsp;防御sql注入的filter:wall</td> 
  </tr> 
  <tr style="border-top-width:0px;font-family:inherit;font-style:inherit;font-variant:inherit;font-weight:inherit;line-height:inherit;vertical-align:baseline;"> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">proxyFilters</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">&nbsp;</td> 
   <td style="font-weight:inherit;border:none;color:rgb(51,51,51);font-family:inherit;font-style:inherit;font-variant:inherit;vertical-align:top;">类型是List&lt;com.alibaba.druid.filter.Filter&gt;，<br>如果同时配置了filters和proxyFilters，<br>是组合关系，并非替换关系</td> 
  </tr> 
 </tbody> 
</table>

3、Web.xml配置

<servlet>
          <servlet-name>DruidStatView</servlet-name>
          <servlet-class>com.alibaba.druid.support.http.StatViewServlet</servlet-class>
        </servlet>
        <servlet-mapping>
          <servlet-name>DruidStatView</servlet-name>
          <url-pattern>/druid/*</url-pattern>
        </servlet-mapping>
    复制代码

至此基本配置完成，可以查看内置监控页面了，路径是/druid/index.html， 完整路径是http://127.0.0.1:8080/druid/index.html 如果还需要使用Web应用、URI监控、Session监控、Spring监控等则还需要继续增加配置。

4、Wen应用配置 WebStatFilter用于采集web-jdbc关联监控的数据

在Web.xml中增加配置，就可以使用Web应用、URI监控、Session监控等功能

<filter>
        <filter-name>DruidWebStatFilter</filter-name>
        <filter-class>com.alibaba.druid.support.http.WebStatFilter</filter-class>
        <init-param>
            <param-name>exclusions</param-name>
            <param-value>*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*</param-value>
        </init-param>
        <init-param>
        	<param-name>profileEnable</param-name>
        	<param-value>true</param-value>
    	</init-param>
    	<init-param>
            <param-name>principalCookieName</param-name>
            <param-value>USER_COOKIE</param-value>
        </init-param>
        <init-param>
            <param-name>principalSessionName</param-name>
            <param-value>USER_SESSION</param-value>
        </init-param>
    </filter>
    
    <filter-mapping>
     <filter-name>DruidWebStatFilter</filter-name>
     <url-pattern>/*</url-pattern>
    </filter-mapping>
    复制代码

5、Spring监控配置 在Spring配置文件中增加

<bean id="druid-stat-interceptor" class="com.alibaba.druid.support.spring.stat.DruidStatInterceptor">
        </bean>
    <bean id="druid-stat-pointcut" class="org.springframework.aop.support.JdkRegexpMethodPointcut" scope="prototype">
       <property name="patterns">
           <list>
               <value>com.company.bussines.service.*</value>
               <value>com.company.bussines.dao.*</value>
           </list>
       </property>
    </bean>
    
    <aop:config proxy-target-class="true">
       <aop:advisor advice-ref="druid-stat-interceptor" pointcut-ref="druid-stat-pointcut" />
    </aop:config>
    复制代码

所有配置完成。

--------------------

# 1. Druid是什么？ #

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。

# 2. 在哪里下载druid #

*  正式版本下载：  
    maven中央仓库: [central.maven.org/maven2/com/…][central.maven.org_maven2_com]

# 3. 怎么获取Druid的源码 #

Druid是一个开源项目，源码托管在github上，源代码仓库地址是 [github.com/alibaba/dru…][github.com_alibaba_dru]。同时每次Druid发布正式版本和快照的时候，都会把源码打包，你可以从上面的下载地址中找到相关版本的源码

# 4. 怎么配置maven #

Druid 0.1.18 之后版本都发布到maven中央仓库中，所以你只需要在项目的pom.xml中加上dependency就可以了。例如：

<dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>${druid-version}</version>
        </dependency>
    复制代码

也可以选择 Maven仓库查找公共的仓库地址:[www.mvnrepository.com/artifact/co…][www.mvnrepository.com_artifact_co]

# 5. 怎么打开Druid的监控统计功能 #

Druid的监控统计功能是通过filter-chain扩展实现，如果你要打开监控统计功能，配置StatFilter，具体看这里：[github.com/alibaba/dru…][github.com_alibaba_dru 1]

# 6. 怎样使用Druid的内置监控页面 #

内置监控页面是一个Servlet，具体配置看这里：[github.com/alibaba/dru…][github.com_alibaba_dru 2]

# 7. 内置监控中的Web和Spring关联监控怎么配置？ #

*  Web关联监控配置  
    [github.com/alibaba/dru…][github.com_alibaba_dru 3]
 *  Spring关联监控配置  
    [github.com/alibaba/dru…][github.com_alibaba_dru 4]

# 8. 怎么配置防御SQL注入攻击 #

Druid提供了WallFilter，它是基于SQL语义分析来实现防御SQL注入攻击的。具体配置看这里：[github.com/alibaba/dru…][github.com_alibaba_dru 5]

# 9. Druid有没有参考配置 #

不同的业务场景需求不同，你可以使用我们的参考配置，但建议你仔细阅读相关文档，了解清楚之后做定制配置。[github.com/alibaba/dru…][github.com_alibaba_dru 6]

# 10. 我想日志记录JDBC执行的SQL，如何配置 #

Druid提供了Log4jFilter、CommonsLogFilter和Slf4jFilter，具体配置看这里[github.com/alibaba/dru…][github.com_alibaba_dru 7]

# 11. 我的程序可能产生连接泄漏了，有什么办法？ #

Druid提供了多种监测连接泄漏的手段，具体看这里：[github.com/alibaba/dru…][github.com_alibaba_dru 8]

# 12. 在Druid中使用PSCache会有内存占用过大问题么？ #

连接Oracle数据库，打开PSCache，在其他的数据库连接池都会存在内存占用过多的问题，Druid是唯一解决这个问题的连接池。具体看这里：[github.com/alibaba/dru…][github.com_alibaba_dru 9]

# 13. 有没有和其他数据库连接池的对比？ #

*  各种数据库连接池对比[github.com/alibaba/dru…][github.com_alibaba_dru 10]

# 14. 从其他连接池迁移要注意什么？ #

*  不同连接池的参数参照对比： [code.alibabatech.com/wiki/pages/…][code.alibabatech.com_wiki_pages]
 *  DBCP迁移 [github.com/alibaba/dru…][github.com_alibaba_dru 11]

# 15. Druid中有没有类似Jboss DataSource中的ExceptionSorter #

ExceptionSorter是JBoss DataSource中的优秀特性，Druid也有一样功能的ExceptionSorter，但不用手动配置，自动识别生效的。具体看这里：[github.com/alibaba/dru…][github.com_alibaba_dru 12]

# 16. Druid中的maxIdle为什么是没用的？ #

maxIdle是Druid为了方便DBCP用户迁移而增加的，maxIdle是一个混乱的概念。连接池只应该有maxPoolSize和minPoolSize，druid只保留了maxActive和minIdle，分别相当于maxPoolSize和minPoolSize。

# 17. 我的应用配置的是JNDI数据源，可以用DruidDataSource么？ #

DruidDataSource支持JNDI配置，具体看这里：[github.com/alibaba/dru…][github.com_alibaba_dru 13]  
具体实现的类是这个：com.alibaba.druid.pool.DruidDataSourceFactory，你可以阅读代码加深理解。

# 18. 我的应用已使用DBCP，是代码中写死的，怎样更换为Druid？ #

可以的，Druid提供了一个中完全平滑迁移DBCP的办法。

*  1) 从[repo1.maven.org/maven2/com/…][repo1.maven.org_maven2_com] 下载druid-wrapper-xxx.jar
 *  2) 加入druid-xxx.jar
 *  3) 从你的WEB-INF/lib/中删除dbcp-xxx.jar
 *  4) 按需要加上配置，比如JVM启动参数加上-Ddruid.filters=stat，动态配置druid的filters

这种用法，使得可以在一些非自己开发的应用中使用Druid，例如在sonar中部署druid，sonar是一个使用jruby开发的web应用，写死了DBCP，只能够通过这种方法来更换。

# 19. 我想试用快照版本，怎么获取？ #

直接获取快照版本的地址是：[code.alibabatech.com/mvn/snapsho…][code.alibabatech.com_mvn_snapsho] ，使用快照版本建议加入我们QQ群 92748305，遇到问题直接反馈给我们。

# 20. 有一些SQL执行很慢，我希望日志记录下来，怎么设置？ #

在StatFilter配置中有慢SQL执行日志记录，看这里[github.com/alibaba/dru…][github.com_alibaba_dru 1]

# 21. 我希望加密我的数据库密码怎么办？ #

运维和DBA都不希望把密码明文直接写在配置文件中，Druid提供了数据库秘密加密的功能。具体看这里：[github.com/alibaba/dru…][github.com_alibaba_dru 14]

# 22. 如何参与Druid的开发 #

Druid是一个通过github开源的项目，github的特性，使得你很容易参与其中。这里有详细说明[github.com/alibaba/dru…][github.com_alibaba_dru 15]

# 23. Druid的发布周期是怎样？ #

Druid是一个活跃的项目，长期维护。每个月有一个发布窗口，除非遇到重大bug和非常紧急的需求，否则都是每个月最多发布一次。如果没有足够多的需求，发布窗口就不会被使用。

# 24. 如果DruidDataSource在init的时候失败了，不再使用，是否需要close #

是的，如果DruidDataSource不再使用，必须调用close来释放资源，释放的资源包括关闭Create和Destory线程。

# 25. DruidDataSource支持哪些数据库？ #

理论上说，支持所有有jdbc驱动的数据库。实际测试过的有

<table> 
 <tbody> 
  <tr> 
   <td>数据库</td> 
   <td>支持状态</td> 
  </tr> 
  <tr> 
   <td>mysql</td> 
   <td>支持，大规模使用</td> 
  </tr> 
  <tr> 
   <td>oracle</td> 
   <td>支持，大规模使用</td> 
  </tr> 
  <tr> 
   <td>sqlserver</td> 
   <td>支持</td> 
  </tr> 
  <tr> 
   <td>postgres</td> 
   <td>支持</td> 
  </tr> 
  <tr> 
   <td>db2</td> 
   <td>支持</td> 
  </tr> 
  <tr> 
   <td>h2</td> 
   <td>支持</td> 
  </tr> 
  <tr> 
   <td>derby</td> 
   <td>支持</td> 
  </tr> 
  <tr> 
   <td>sqlite</td> 
   <td>支持</td> 
  </tr> 
  <tr> 
   <td>sybase</td> 
   <td>支持</td> 
  </tr> 
 </tbody> 
</table>

# 26. Oracle下jdbc executeBatch时，更新行数计算不正确 #

使用jdbc的executeBatch 方法，如果数据库为oracle，则无论是否成功更新到数据，返回值都是-2，而不是真正被sql更新到的记录数，这是Oracle JDBC Driver的问题，Druid不作特殊处理。

# 27. Druid如何自动根据URL自动识别DriverClass的 #

Druid是根据url前缀来识别DriverClass的，这样使得配置更方便简洁。

<table> 
 <tbody> 
  <tr> 
   <td>前缀</td> 
   <td>DriverCLass</td> 
   <td>描述信息</td> 
  </tr> 
  <tr> 
   <td>jdbc:odps</td> 
   <td>com.aliyun.odps.jdbc.OdpsDriver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:derby</td> 
   <td>org.apache.derby.jdbc.EmbeddedDriver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:mysql</td> 
   <td>com.mysql.jdbc.Driver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:oracle</td> 
   <td>oracle.jdbc.driver.OracleDriver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:microsoft</td> 
   <td>com.microsoft.jdbc.sqlserver.SQLServerDriver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:sybase:Tds</td> 
   <td>com.sybase.jdbc2.jdbc.SybDriver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:jtds</td> 
   <td>net.sourceforge.jtds.jdbc.Driver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:postgresql</td> 
   <td>org.postgresql.Driver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:fake</td> 
   <td>com.alibaba.druid.mock.MockDriver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:mock</td> 
   <td>com.alibaba.druid.mock.MockDriver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:hsqldb</td> 
   <td>org.hsqldb.jdbcDriver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:db2</td> 
   <td>COM.ibm.db2.jdbc.app.DB2Driver</td> 
   <td>DB2的JDBC Driver十分混乱，这个匹配不一定对</td> 
  </tr> 
  <tr> 
   <td>jdbc:sqlite</td> 
   <td>org.sqlite.JDBC</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:ingres</td> 
   <td>com.ingres.jdbc.IngresDriver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:h2</td> 
   <td>org.h2.Driver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:mckoi</td> 
   <td>com.mckoi.JDBCDriver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:cloudscape</td> 
   <td>COM.cloudscape.core.JDBCDriver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:informix-sqli</td> 
   <td>com.informix.jdbc.IfxDriver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:timesten</td> 
   <td>com.timesten.jdbc.TimesTenDriver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:as400</td> 
   <td>com.ibm.as400.access.AS400JDBCDriver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:sapdb</td> 
   <td>com.sap.dbtech.jdbc.DriverSapDB</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:JSQLConnect</td> 
   <td>com.jnetdirect.jsql.JSQLDriver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:JTurbo</td> 
   <td>com.newatlanta.jturbo.driver.Driver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:firebirdsql</td> 
   <td>org.firebirdsql.jdbc.FBDriver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:interbase</td> 
   <td>interbase.interclient.Driver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:pointbase</td> 
   <td>com.pointbase.jdbc.jdbcUniversalDriver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:edbc</td> 
   <td>ca.edbc.jdbc.EdbcDriver</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>jdbc:mimer:multi1</td> 
   <td>com.mimer.jdbc.Driver</td> 
   <td>&nbsp;</td> 
  </tr> 
 </tbody> 
</table>

# 28. 如何保存监控记录 #

[github.com/alibaba/dru…][github.com_alibaba_dru 16]

# 29. 我想Log输出SQL执行的信息怎么办？ #

[github.com/alibaba/dru…][github.com_alibaba_dru 7]

# 30. 如何配置Druid内置的log实现 #

[github.com/alibaba/dru…][github.com_alibaba_dru 17]

## **附：示例项目：** ##

github.com/windwant/sp…

https://github.com/windwant/spring-boot-service.git

https://github.com/windwant/spring-cloud-service.git

转载于:https://juejin.im/post/5d0b01975188253ebf449234

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