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方法一：
package C3P0;
import
java.sql.Connection;
import
java.sql.SQLException;
import
java.beans.PropertyVetoException;
import
com.mchange.v2.c3p0.ComboPooledDataSource;
public class DBPool{
private
static DBPool dbPool;
private
ComboPooledDataSource dataSource;
static {
dbPool=new
DBPool();
}
public
DBPool(){
try
{
dataSource=new
ComboPooledDataSource();
dataSource.setUser( "id ");
dataSource.setPassword( "pw ");
dataSource.setJdbcUrl(
"jdbc:mysql://127.0.0.1:3306/test?
autoReconnect=true&useUnicode=true&characterEncoding=GB2312
");
dataSource.setDriverClass( "com.mysql.jdbc.Driver
");
dataSource.setInitialPoolSize(2);
dataSource.setMinPoolSize(1);
dataSource.setMaxPoolSize(10);
dataSource.setMaxStatements(50);
dataSource.setMaxIdleTime(60);
}
catch (PropertyVetoException
e) {
throw new
RuntimeException(e);
}
}
public
final static DBPool
getInstance(){
return
dbPool;
}
public
final Connection
getConnection() {
try
{
return
dataSource.getConnection();
}
catch (SQLException
e) {
throw new
RuntimeException( "無(wú)法從數(shù)據(jù)源獲取連接 ",e);
}
}
public
static void main(String[]
args) throws
SQLException
{
Connection con =
null;
try {
con =
DBPool.getInstance().getConnection();
} catch (Exception
e){
} finally
{
if (con !=
null)
con.close();
}
}
}
方法二：
原來(lái)不知道使用c3p0 是如此的簡(jiǎn)單，我一直使用properties
文件去配置c3p0，但總是連接不上數(shù)據(jù)庫(kù)，后來(lái)調(diào)試才發(fā)現(xiàn)ComboPooledDataSource
這個(gè)對(duì)象的屬性沒(méi)有被設(shè)置成功，我是先獲取了properties文件的內(nèi)容，封裝在一個(gè) Properties對(duì)象里面，然后直接調(diào)用
ComboPooledDataSource 的 setProperties（Properties
p）
方法來(lái)配置c3p0，程序是沒(méi)有報(bào)錯(cuò)，但連不上數(shù)據(jù)庫(kù)，調(diào)試發(fā)現(xiàn)屬性都沒(méi)有設(shè)置成功，只是properties這個(gè)屬性被設(shè)置了而已，結(jié)果我對(duì)每個(gè)屬性調(diào)用set方法后就連接上了。。。
public final class ConnectionManager {
private static ConnectionManager instance;
public ComboPooledDataSource ds;
private static String c3p0Properties =
"c3p0.properties";
private ConnectionManager() throws Exception
{
Properties p = new
Properties();
p.load(this.getClass().getResourceAsStream(c3p0Properties));
ds = new
ComboPooledDataSource();
ds.setUser(p.getProperty("user"));
ds.setPassword(p.getProperty("user"));
ds.setJdbcUrl(p.getProperty("user"));
ds.setDriverClass(p.getProperty("user"));
ds.setInitialPoolSize(Integer.parseInt(p.getProperty("initialPoolSize")));
ds.setMinPoolSize(Integer.parseInt(p.getProperty("minPoolSize")));
ds.setMaxPoolSize(Integer.parseInt(p.getProperty("maxPoolSize")));
ds.setMaxStatements(Integer.parseInt(p.getProperty("maxStatements")));
ds.setMaxIdleTime(Integer.parseInt(p.getProperty("maxIdleTime")));
}
public static final ConnectionManager
getInstance() {
if (instance == null)
{
try
{
instance
= new ConnectionManager();
} catch
(Exception e) {
e.printStackTrace();
}
}
return instance;
}
public synchronized final Connection
getConnection() {
try {
return
ds.getConnection();
} catch (SQLException e)
{
e.printStackTrace();
}
return null;
}
protected void finalize() throws Throwable
{
DataSources.destroy(ds); //
關(guān)閉datasource
super.finalize();
}
}
如此就可以獲取connection來(lái)做jdbc操作了：
Connection
conn=ConnectionManager.getInstance().getConnection();
記得使用完后調(diào)用close方法：
conn.close();
c3p0 的某些參數(shù)的配置以及意義見(jiàn)另外一篇文章http://kangzye.blog.163.com/blog/static/368192232010442162576/
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