operation.java

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package dsp.database;

/**
 * <p>Title: DSP实验室</p>
 * <p>Description: DSP教学网
 *                 数据库的相关操作：如连接、查询、添加、删除、修改、分页显示
 * </p>
 * <p>Copyright: Copyright (c) 2004</p>
 * <p>Company: </p>
 * @author 李艳生
 * @version 1.0
 */

import java.sql.*;
import java.io.*;
import java.util.*;

public class Operation {
    //数据库驱动程序
	private String strDriver = "";
	//数据库连接字符串
	private String strURL = "";
	//数据库用户名
	private String username = "";
	//数据库密码
	private String password = "";

	private Connection conn = null;
	private Statement stmt = null;
	ResultSet rs = null;

	/** 读到数据库配置信息
		 */
	private void loadProp(){
		InputStream is = getClass().getResourceAsStream("/setup.txt");
		Properties props = new Properties();

		try{
			props.load(is);
		}catch(Exception e){
			System.err.println("不能读取配置文件. 请确保setup.txt在classes指定的路径中");
		}

		Enumeration propNames = props.propertyNames();
		while (propNames.hasMoreElements()) {
			String name = (String) propNames.nextElement();
			if (name.endsWith(".driver")) {
				String poolName = name.substring(0, name.lastIndexOf("."));
				strDriver = props.getProperty(poolName + ".driver");
				strURL = props.getProperty(poolName + ".url");
				username = props.getProperty(poolName + ".user");
				password = props.getProperty(poolName + ".password");
			}
		}
	}

	/** 在创建Operation对象时连接数据库
	 */
	public Operation() {
		//读到数据库配置信息
		loadProp();

		try{
			Class.forName(strDriver);
		}catch(java.lang.ClassNotFoundException e) {
			System.err.println("数据库连接错误：" + e.getMessage());
		}

		try{
			conn=DriverManager.getConnection(strURL,username,password);
		}catch(SQLException ex) {
			System.err.println("数据库连接错误：" + ex.getMessage());
		}
	}

	/** 数据库查询
	 *  sql:SQL查询语句
	 */
	public ResultSet query(String sql) {
		try{
			stmt=conn.createStatement();
			rs=stmt.executeQuery(sql);
		}catch(SQLException ex) {
			System.err.println("数据库查询错误：" + ex.getMessage());
		}
		return rs;
	}

	/** 数据库添加、修改、删除
	 *  sql:SQL语句
	 */
	public void update(String sql) {
		try{
			stmt=conn.createStatement();
			stmt.executeUpdate(sql);
		}catch(SQLException ex) {
			System.err.println("数据库更新错误："+ex.getMessage());
		}
	}

	/** 得到查询结果的总记录数
	 *  rs:查询结果集
	 */
	public int totalRecord(ResultSet rs) throws Exception{
		int total=0;
		//指针移到最后一条记录上
		rs.last();
		total = rs.getRow();
		rs.first();

		return total;
	}

	/** 分页显示
	 *  currPage: 当前页数
	 *  pageSize: 页大小
	 *  pageCount: 总页数
	 *  filename: 使用分页的文件名(文件名的要加?)
	 *  返回字符串： <a href="filename?page=当前页数">
	 */
	public String showPages(int currPage, int pageSize, int pageCount, String filename){
		String addr;

		addr = "<form method=Post name=form1>当前第<strong><font color=red>" + currPage + "</font></strong>页 " +
			"共<strong><font color=red>" + pageCount + "</font></strong>页 ";

		if(currPage > pageCount){
			currPage = pageCount;
		}
		if(currPage < 1){
			currPage = 1;
		}

		if(currPage < 2){
			addr += "首 页 上一页 ";
		}
		else{
			addr += "<a href=" + filename + "page=1>首 页</a> ";
			addr += "<a href=" + filename + "page=" + (currPage - 1) + ">上一页</a> ";
		}

		if(currPage >= pageCount){
			addr += "下一页 尾 页 ";
		}
		else{
			addr += "<a href=" + filename + "page=" + (currPage + 1) + ">下一页</a> ";
			addr += "<a href=" + filename + "page=" + pageCount + ">尾 页</a> ";
		}

		addr += "转到：<select name='page' size='1' style='font-size: 9pt' onChange='javascript:submit()'> ";
		for(int i = 1; i <= pageCount; i ++){
			addr += "<option value="+i+">第"+i+"页</option> ";
		}
		addr += "</select></form>";

		return addr;
	}

	/** 关闭数据集
	 */
	public void closestmt() {
		try{
			stmt.close();
		}catch(SQLException ex) {
			System.err.println("数据集关闭错误："+ex.getMessage());
		}
	}

	/** 关闭数据库连接
	 */
	public void closeconn() {
		try{
			conn.close();
		}catch(SQLException ex) {
			System.err.println("数据库连接关闭错误："+ex.getMessage());
		}
	}
}