直接使用 tomcat 的连接池包 或直接使用另外的一个连接池包dhcp

package demo;

import java.sql.Connection;
import java.sql.PreparedStatement;
import org.apache.tomcat.dbcp.dbcp.BasicDataSource;

public class Main 
{
    public static void main(String[] args) throws Exception
    {
        BasicDataSource ds = new BasicDataSource();
        ds.setDriverClassName("com.mysql.jdbc.Driver");
        ds.setUrl("jdbc:mysql://localhost:3306/BBS?characterEncoding=gbk");
        ds.setUsername("root");
        ds.setPassword("suicide");
        ds.setInitialSize(5);
        ds.setMinIdle(2);
        ds.setMaxIdle(5);
        ds.setMaxWait(5000);
        ds.setMaxActive(4);
        Connection conn = ds.getConnection();
        PreparedStatement stmt = conn.prepareStatement("update topic set reply_count=3 where topic_id=1");
        System.out.print(stmt.executeUpdate());
        stmt.close();
        conn.close();
    }
}

dhcp

package exp;

import com.mchange.v2.c3p0.ComboPooledDataSource;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.sql.DataSource;
import com.mchange.v2.c3p0.DataSources;
import java.sql.Connection;
import java.sql.PreparedStatement;


public class Index extends HttpServlet 
{
    
    private static ComboPooledDataSource pooledDataSource;
    
    static
    {
        try
        {
            pooledDataSource = new ComboPooledDataSource();
            pooledDataSource.setDriverClass("com.mysql.jdbc.Driver");
            pooledDataSource.setJdbcUrl("jdbc:mysql://localhost:3306/BBS?characterEncoding=gbk");                  
            pooledDataSource.setUser("root");          
            pooledDataSource.setPassword("suicide");
            pooledDataSource.setMaxPoolSize(10);
            pooledDataSource.setMinPoolSize(5);
        }
        catch(Exception e)
        {
            
        }
    }
    
    
    protected final void service(HttpServletRequest request,HttpServletResponse response) throws IOException, ServletException
    {
        PrintWriter out = response.getWriter();
        try
        {
             Connection conn = pooledDataSource.getConnection();
             PreparedStatement stmt = conn.prepareStatement("update topic set reply_count=3 where topic_id=1");
             out.print(stmt.executeUpdate());
             stmt.close();
             conn.close();
        }
        catch(Exception e)
        {
            out.print(e.getMessage());
        }
        
       
        
        out.close();
    }
}