dbconnection.java

这是一本关于高级软件工程的书籍

package org.tsinghua.netshop.beans;
import java.sql.*;
import java.util.*;

public class DBConnection {
    Connection cn = null;
    public DBConnection() {
    }

    public DBConnection(String servername, String dbname) {
        this.connect(servername, dbname);
    }

    public void connect(String servername, String dbname) {
        try {
            Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver");
            cn = DriverManager.getConnection("jdbc:microsoft:sqlserver://" +
                                             servername + ":1433;databasename=" +
                                             dbname, "sa", "");
            System.out.println("信息提示：连接" + servername + "服务器" + dbname +
                               "数据库已成功！");
        } catch (Exception e) {
            System.out.println("信息提示：连接" + servername + "服务器" + dbname +
                               "失败！\n" + e);
        }
    }

    public ResultSet select(String sql) {

        if (cn == null) {
            System.out.println(
                    "您还没有连接到数据库，请尝试调用connect(String servername,String dbname)方法！");
        }
        try {
            Statement st = cn.createStatement();
            ResultSet rs = st.executeQuery(sql);
            return rs;
        } catch (Exception e1) {
            System.out.println("数据库查询失败！" + e1);
            return null;
        }

    }


    public boolean update(String sql) {
        if (cn == null) {
            System.out.println(
                    "您还没有连接到数据库，请尝试调用connect(String servername,String dbname)方法！");
        }
        try {
            System.out.println("您要执行的sql语句是:" + sql);
            Statement st = cn.createStatement();
            int i = st.executeUpdate(sql);
            System.out.println("sql语句执行成功！");
            if (i == 0) {
                return false;
            } else {
                return true;
            }
        } catch (Exception e2) {
            System.out.println("数据库操作失败" + e2);
            return false;
        }
    }

    public void connectionClose() {
        try {
            cn.close();
            System.out.println("Connection已关闭");
        } catch (SQLException ex) {
            System.out.println("Connection关闭错误" + ex);
        }
    }
}