Java Spring C3P0心得
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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();
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