conndb.java

来自「一个功能强大的图书馆管理系统」· Java 代码 · 共 100 行

package com.core;

import java.sql.*;

public class ConnDB {
    public Connection conn=null;
    public ResultSet rs=null;
    public Statement stmt=null;
    /*private String proxool = "org.logicalcobwebs.proxool.ProxoolDriver";
    private String poolname = "proxool.library";*/
   
    //说明：此处需要配置web.xml文件
    public ConnDB() {   //构造方法
    }
    public Connection getConnection() {
    	try {
			Class.forName("com.mysql.jdbc.Driver");
			System.out.println("OK1");//连接数据库 如果成功并提示OK1
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		try {
			conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/db_library","root","111");
			System.out.println("OK2");//初始化con 如果成功并提示OK2
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}//异常处理
		return conn;//按发法要求返回个Connection对象
    }
    /*
 *功能：执行查询语句
 */
public ResultSet executeQuery(String sql) {
  try {
    conn = getConnection();
    stmt = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
                                ResultSet.CONCUR_READ_ONLY);
    rs = stmt.executeQuery(sql);
  }
  catch (SQLException ex) {
    System.err.println(ex.getMessage());
  }
  return rs;
}

/*
 *功能:执行更新操作
 */
public int executeUpdate(String sql) {
  int result = 0;
  try {
    conn = getConnection();
    stmt = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
                                ResultSet.CONCUR_READ_ONLY);
    result = stmt.executeUpdate(sql);
  }
  catch (SQLException ex) {
    result = 0;
  }
  try {
    stmt.close();
  }
  catch (SQLException ex1) {
  }
  return result;
}

    /*
     *功能:关闭数据库的连接
     */
    public void close() {
      try {
        if (rs != null) {
          rs.close();
        }
      }
      catch (Exception e) {
        e.printStackTrace(System.err);
      }
      try {
        if (stmt != null) {
          stmt.close();
        }
      }
      catch (Exception e) {
        e.printStackTrace(System.err);
      }
      try {
        if (conn != null) {
          conn.close();
        }
      }
      catch (Exception e) {
        e.printStackTrace(System.err);
      }
  }
}