首先，最基本的连接方式：

	private String url = "jdbc:odbc:Driver={SQL Server};Server=DELL-PC;Database=MedicalData";
	private String user = "sa";
	private String password = "netlab";
	private Connection conn;

Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newInstance();
conn = DriverManager.getConnection(url, user, password);

			PreparedStatement partnames=conn.prepareStatement(sql);
	        rs=partnames.executeQuery();
	    

Statement partnames=conn.createStatement();
	        partnames.executeUpdate(sql);

遇到问题：

[Microsoft][ODBC SQL Server Driver]连接占线导致另一个 hstmt

查了很多文章以后，感觉应该是由于短时间大量访问，导致没有释放资源，如rs，statement，conn等

这是查到了连接池 ，数据库连接池：查到了链接  http://bbs.csdn.net/topics/340245414      这篇帖子的四楼方法，如下：

在util包中新建两个文件，一个是DataSourceFactory.java,另一个是databaseresource.properties配置文件，还有几个jar包，commons-dbcp-1.2.1.jar，commons-pool-1.3.jar，msbase.jar，mssqlserver.jar，msutil.jar，这5个jar包自己去网上下载下来

DataSourceFactory.java的内容如下

package util;

import org.apache.commons.dbcp.*;
import java.sql.*;
import java.util.*;

public class DataSourceFactory {
	private static String PROPERTIES_FILE = "/util/databaseresource.properties";
	private static DataSourceFactory instance = null;
	private BasicDataSource ds1;

	private DataSourceFactory() {
		Properties prop = new Properties();
		try {
			prop.load(this.getClass().getResourceAsStream(PROPERTIES_FILE));
			ds1 = (BasicDataSource)BasicDataSourceFactory.createDataSource(prop);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public static DataSourceFactory getInstance() {
		if(instance == null) {
			instance = new DataSourceFactory();
		}
		return instance;
	}

	public Connection getConnection() {
		Connection conn = null;
		try {
			conn = ds1.getConnection();
		} catch (Exception e) {
			e.printStackTrace();
			return null;
		}
		return conn;
	}
}

databaseresource.properties中的内容如下：（去除//之后的注释）

driverClassName=com.microsoft.jdbc.sqlserver.SQLServerDriver

url=jdbc:microsoft:sqlserver://127.0.0.1:1433;DatabaseName=friend  //friend为数据库名

username=sa     //数据库连接用户名

password=null   //数据库连接密码

defaultAutoCommit=true  //是否自动提交事务

maxActive=10    //连接池最大连接数

弄好后在程序中用

Connection conn = DataSourceFactory.getInstance().getConnection();

就可以等到数据库连接了

于是有了我的代码：

如下：

package com.k.sqlsever;

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

import util.DataSourceFactory;

public class SQLSeverLink {

	private String url = "jdbc:odbc:Driver={SQL Server};Server=DELL-PC;Database=MedicalData";
	private String user = "sa";
	private String password = "netlab";
	private Connection conn;

	public void link()
	{
		try {

//			Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newInstance();
//		    conn = DriverManager.getConnection(url, user, password);
			conn = DataSourceFactory.getInstance().getConnection();

		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		}
	}

	public void closeLink()
	{
		if(conn!=null)
			try {
				conn.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
	}

	public ResultSet select(String sql)
	{
		ResultSet rs= null;

		try {
			PreparedStatement partnames=conn.prepareStatement(sql);
	        rs=partnames.executeQuery();

		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		}

		return rs;
	}

	public void update(String sql)
	{
		try {
			Statement partnames=conn.createStatement();
	        partnames.executeUpdate(sql);
	        System.out.println("update success!");

		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		}
	}

  /**
    * @param args
    */
  public static void main(String[] args) {
    // TODO Auto-generated method stub
    try {

       Connection conn = DataSourceFactory.getInstance().getConnection();
        PreparedStatement    partnames=conn.prepareStatement("SELECT * FROM dbo.MS_CHK_ALL WHERE id=1");
        ResultSet rs=partnames.executeQuery();
        while(rs.next())
        {
                String  Data=rs.getString("chk_code");
                System.out.println(Data);
        }

    } catch ( Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();

    }
  }

}

这次又出现了新的问题，运行一小会以后，

[Microsoft][SQLServer 2000 Driver for JDBC]Error establishing socket.

我估计还是老问题，资源未释放

忍无可忍，笨方法： 每处理100条以后，断开连接，重连数据库。sleep 100ms 再继续进行

if(i%100==0)
		{
			serverLink.closeLink();
			serverLink.link();
			try {
				Thread.sleep(100);
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}