连接池 commons-dbcp2-2.1.1使用

原理就不说了 百度一坨坨

配置文件：

driverClassName=dm.jdbc.driver.DmDriverurl=jdbc\:dm\://192.168.0.1\:5240?autoReconnect\=trueusername=aaaapassword=qqqqqq#最小空闲连接minIdle=5#最大空闲连接mzxIdle=20maxActive=400#初始化连接数initialSize=30#连接遗漏时是否打印logAbandoned=true#是否自动回收超时连接removeAbandoned=true#等待超时最大时间maxWait=5000

编写测试代码

package createTmrData;import java.io.InputStream;import java.sql.Connection;import java.sql.ResultSet;import java.sql.Statement;import java.util.Properties;import org.apache.commons.dbcp2.BasicDataSource;import org.apache.commons.dbcp2.BasicDataSourceFactory;public class JDBCTest {    public static void main(String[] args) {        BasicDataSource bs = null;        Properties p = new Properties();        InputStream inStream = JDBCTest.class.getResourceAsStream("/conf/jdbc.properties");        try {            p.load(inStream);            bs = BasicDataSourceFactory.createDataSource(p);                Connection conn = bs.getConnection();            Statement stm = conn.createStatement();            ResultSet set  = stm.executeQuery("select count(*) from RDP_MD_CUSTOMERTABLE");            while(set.next()){                System.out.println("表总数为："+set.getString(1));;            }            conn.close();                       } catch (Exception e) {        }            }}

添加包commons-dbcp2-2.1.1.jar

下载地址：http://commons.apache.org/proper/commons-dbcp/download_dbcp.cgi

执行报如下错误

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactoryat org.apache.commons.dbcp2.BasicDataSourceFactory.<clinit>(BasicDataSourceFactory.java:64)at createTmrData.JDBCTest.main(JDBCTest.java:20)Caused by: java.lang.ClassNotFoundException: org.apache.commons.logging.LogFactoryat java.net.URLClassLoader$1.run(Unknown Source)at java.net.URLClassLoader$1.run(Unknown Source)at java.security.AccessController.doPrivileged(Native Method)at java.net.URLClassLoader.findClass(Unknown Source)at java.lang.ClassLoader.loadClass(Unknown Source)at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)at java.lang.ClassLoader.loadClass(Unknown Source)... 2 more

解决办法：

添加commons-logging-4.0.6.jar

执行结果：

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/pool2/PooledObjectFactoryat org.apache.commons.dbcp2.BasicDataSourceFactory.createDataSource(BasicDataSourceFactory.java:338)at createTmrData.JDBCTest.main(JDBCTest.java:20)Caused by: java.lang.ClassNotFoundException: org.apache.commons.pool2.PooledObjectFactoryat java.net.URLClassLoader$1.run(Unknown Source)at java.net.URLClassLoader$1.run(Unknown Source)at java.security.AccessController.doPrivileged(Native Method)at java.net.URLClassLoader.findClass(Unknown Source)at java.lang.ClassLoader.loadClass(Unknown Source)at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)at java.lang.ClassLoader.loadClass(Unknown Source)... 2 more

解决办法：添加commons-pool2-2.4.2.jar

下载地址：http://commons.apache.org/proper/commons-pool/download_pool.cgi

再执行：

表总数为：5625838

执行成功了

下来看一下基本的参数配置，我们打开BasicDataSourceFactory.createDataSource(p）的源代码：

 public static BasicDataSource createDataSource(Properties properties) throws Exception {        BasicDataSource dataSource = new BasicDataSource();        String value = null;        value = properties.getProperty(PROP_DEFAULTAUTOCOMMIT);        if (value != null) {            dataSource.setDefaultAutoCommit(Boolean.valueOf(value));        }        value = properties.getProperty(PROP_DEFAULTREADONLY);        if (value != null) {            dataSource.setDefaultReadOnly(Boolean.valueOf(value));        }         ..........        // Return the configured DataSource instance        return dataSource;    }

这个方法返回了一个DataSource的实例，这里用了一大堆代码读取我们配置的参数赋值给了BasicDataSource的对象

我们再看一下有有哪些重要配置

在这个的最上面定义了一大堆final 静态的配置，final是为了不让人恶意更改：

下面我列出一些常用的配置：

  private static final String PROP_DEFAULTAUTOCOMMIT = "defaultAutoCommit";//是否自动提交    private static final String PROP_DEFAULTREADONLY = "defaultReadOnly";//是否只读    private static final String PROP_DEFAULTTRANSACTIONISOLATION = "defaultTransactionIsolation";//<code class="language-yaml"><span class="com">指定由连接池所创建的连接的事务隔离级别</span></code>    private static final String PROP_MAXIDLE = "maxIdle";//<code class="language-yaml"><span class="com">最大的空闲连接数量</span></code>    private static final String PROP_MINIDLE = "minIdle";//<code class="language-yaml"><span class="com">最小的空闲链接数量</span></code>    private static final String PROP_INITIALSIZE = "initialSize";//<code class="language-yaml"><span class="com">初始化时连接池中connection数量</span></code>    private static final String PROP_MAXWAITMILLIS = "maxWaitMillis";//<code class="language-yaml"><span class="com">最大的等待时间，单位是毫秒</span></code>     private static final String PROP_PASSWORD = "password";    private static final String PROP_URL = "url";    private static final String PROP_USERNAME = "username";    private static final String PROP_CONNECTIONPROPERTIES = "connectionProperties";//<code class="language-yaml">建立连接时的附加参数，如果指定的编码不一致数据库中会出现乱码</code>    private static final String NUPROP_MAXACTIVE = "maxActive";//<code class="language-yaml"><span class="com">最大连接数量</span></code>