Java Spring C3P0心得

1.定义配置文件，放在src目录下：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="
 http://www.springframework.org/schema/beans
 http://www.springframework.org/schema/beans/spring-beans.xsd">

 <bean id="greetingServiceImp" class="Sample.GreetingServiceImp">
  <property name="message">
   <value>jerry</value>
  </property>
 </bean>

 <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"
  destroy-method="close">
  <property name="driverClass">
   <value>com.microsoft.sqlserver.jdbc.SQLServerDriver</value>
  </property>
  <property name="jdbcUrl">
   <value>jdbc:sqlserver://127.0.0.1:1433;databaseName=Test
   </value>
  </property>
  <property name="user">
   <value>aa</value>
  </property>
  <property name="password">
   <value>bb</value>
  </property>    <!--连接池中保留的最小连接数。 -->
  <property name="minPoolSize">
   <value>1</value>
  </property>    <!--连接池中保留的最大连接数。Default: 15 -->
  <property name="maxPoolSize">
   <value>20</value>
  </property>    <!--初始化时获取的连接数，取值应在minPoolSize与maxPoolSize之间。Default: 3 -->
  <property name="initialPoolSize">
   <value>1</value>
  </property>    <!--最大空闲时间,60秒内未使用则连接被丢弃。若为0则永不丢弃。Default: 0 -->
  <property name="maxIdleTime">
   <value>60</value>
  </property>    <!--当连接池中的连接耗尽的时候c3p0一次同时获取的连接数。Default: 3 -->
  <property name="acquireIncrement">
   <value>5</value>
  </property>    <!--JDBC的标准参数，用以控制数据源内加载的PreparedStatements数量。但由于预缓存的statements 属于单个connection而不是整个连接池。所以设置这个参数需要考虑到多方面的因素。
   如果maxStatements与maxStatementsPerConnection均为0，则缓存被关闭。Default: 0 -->
  <property name="maxStatements">
   <value>0</value>
  </property>    <!--每60秒检查所有连接池中的空闲连接。Default: 0 -->
  <property name="idleConnectionTestPeriod">
   <value>60</value>
  </property>    <!--定义在从数据库获取新连接失败后重复尝试的次数。Default: 30 -->
  <property name="acquireRetryAttempts">
   <value>30</value>
  </property>    <!--获取连接失败将会引起所有等待连接池来获取连接的线程抛出异常。但是数据源仍有效 保留，并在下次调用getConnection()的时候继续尝试获取连接。如果设为true，那么在尝试
   获取连接失败后该数据源将申明已断开并永久关闭。Default: false -->
  <property name="breakAfterAcquireFailure">
   <value>true</value>
  </property>    <!--因性能消耗大请只在需要的时候使用它。如果设为true那么在每个connection提交的 时候都将校验其有效性。建议使用idleConnectionTestPeriod或automaticTestTable
   等方法来提升连接测试的性能。Default: false -->
  <property name="testConnectionOnCheckout">
   <value>false</value>
  </property>
 </bean>

</beans>

 

2.定义bean：

package Sample;

public interface GreetingService {
 public void sayHello();
}

public class GreetingServiceImp implements GreetingService {
 private String message;
 
 public String getMessage() {
  return message;
 }

 public void setMessage(String message) {
  this.message = message;
 }

 public void sayHello(){
  System.out.println("Greet:" + this.message);
 }
 
}

3.测试：

package Sample;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestBean {
 public static void main(String[] args) {
  System.out.println("test");

  BeanFactory beanFactory = new ClassPathXmlApplicationContext("applicationContext.xml");

  GreetingService greetingService = (GreetingService) beanFactory.getBean("greetingServiceImp");

  greetingService.sayHello();

  GreetingService greetingService2 = (GreetingService) beanFactory.getBean(GreetingServiceImp.class);
  greetingService2.sayHello();

  com.mchange.v2.c3p0.ComboPooledDataSource dataSource = (com.mchange.v2.c3p0.ComboPooledDataSource) beanFactory
    .getBean(com.mchange.v2.c3p0.ComboPooledDataSource.class);

  try {

//可以在配置中将maxPoolSize设为1或2，然后测试连接池
   {
    Connection conn = dataSource.getConnection();
    Statement stmt = conn.createStatement();
    ResultSet rs = stmt.executeQuery("select * from Employee where Id=1");
    if (rs.next()){
     System.out.println( "conn1:" + rs.getInt(1)+ "," + rs.getString(2));
    }
    conn.close(); // 一定要关闭连接
   }

   {
    Connection conn2 = dataSource.getConnection();
    Statement stmt = conn2.createStatement();
    ResultSet rs = stmt.executeQuery("select * from Employee where Id=2");
    if (rs.next()){
     System.out.println( "conn2:" + rs.getInt(1)+ "," + rs.getString(2));
    }
    conn2.close(); // 一定要关闭连接
   }

   {
    Connection conn3 = dataSource.getConnection();
    Statement stmt = conn3.createStatement();
    ResultSet rs = stmt.executeQuery("select * from Employee where Id=3");
    if (rs.next()){
     System.out.println( "conn3:" + rs.getInt(1)+ "," + rs.getString(2));
    }
    conn3.close(); // 一定要关闭连接
   }
  } catch (SQLException sqlEx) {
   sqlEx.printStackTrace();
  }
 }

}

 

添加：comons-logging,spring-beans,spring-context,spring-core,spring-expression

sqljdbc4.jar,c3p0-0.9.1.jar

 

或者代码中定义：

com.mchange.v2.c3p0.ComboPooledDataSource tempDataSource = new com.mchange.v2.c3p0.ComboPooledDataSource();
try {
 tempDataSource.setDriverClass("com.microsoft.sqlserver.jdbc.SQLServerDriver");
} catch (PropertyVetoException e) {
 e.printStackTrace();
}
tempDataSource.setJdbcUrl(dbURL);
tempDataSource.setUser(userName);
tempDataSource.setPassword(userPwd);
tempDataSource.setMinPoolSize(1);
tempDataSource.setMaxPoolSize(2);

Connection conn = dataSource.getConnection();