數(shù)據(jù)庫連接JDBC連接池組件C3P0的使用方法

博雅書屋lhs 2014-08-24

展開全文

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：

原來不知道使用c3p0 是如此的簡單，我一直使用properties 文件去配置c3p0，但總是連接不上數(shù)據(jù)庫，后來調(diào)試才發(fā)現(xiàn)ComboPooledDataSource 這個對象的屬性沒有被設置成功，我是先獲取了properties文件的內(nèi)容，封裝在一個 Properties對象里面，然后直接調(diào)用 ComboPooledDataSource 的 setProperties（Properties p）方法來配置c3p0，程序是沒有報錯，但連不上數(shù)據(jù)庫，調(diào)試發(fā)現(xiàn)屬性都沒有設置成功，只是properties這個屬性被設置了而已，結(jié)果我對每個屬性調(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); // 關閉datasource
super.finalize();
}
}

如此就可以獲取connection來做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)的配置以及意義見另外一篇文章http://kangzye.blog.163.com/blog/static/368192232010442162576/