databaseconn.java

人才招聘网站,该系统是从软件工程的角度的,以人才招聘网站的开发为例,详细介绍一个数据库应用系统的开发过程,介绍的人才系统使用SQL Server2000作为后台的数据管理系统,前端使用JDBC对象和数

package XiaoYuJob.util;

import java.sql.*;

/**
 *负责连接sql server数据库
 */
public class DataBaseConn {
    private static Connection con;
    private Statement stmt;
    private ResultSet rs;
    private static final String drivername =
        "com.microsoft.jdbc.sqlserver.SQLServerDriver";
    private static final String url = "jdbc:microsoft:sqlserver://127.0.0.1:1305;DatabaseName=xiaoyujob;user=sa;password=;";

    /**
     *获得到数据库得一个连接对象
     */
    public static synchronized Connection getCon() throws Exception {
        try {
            Class.forName(drivername);
            con = DriverManager.getConnection(url);
            return con;
        } catch (SQLException e) {
            System.err.println(e.getMessage());
            throw e;
        }
    }

    /**
     *获得一个Statement对象，只读
     */
    public Statement getStmtread() {
        try {
            con = getCon();
            stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
                                       ResultSet.CONCUR_READ_ONLY);
            return stmt;
        } catch (Exception e) {
            System.err.println(e.getMessage());
            e.printStackTrace();
        }
        return null;
    }

    /**
     *获得一个结果集
     */
    public ResultSet getRs(String sql) {
        try {
            stmt = getStmtread();
            rs = stmt.executeQuery(sql);
            return rs;
        } catch (Exception e) {
            System.err.println(e.getMessage());
            e.printStackTrace();
        }
        return null;
    }

    /**
     *获得一个Statement对象，可以更新和insert
     */
    public Statement getStmt() {
        try {
            con = getCon();
            stmt = con.createStatement();
            return stmt;
        } catch (Exception e) {
            System.err.println(e.getMessage());
            e.printStackTrace();
        }
        return null;
    }

    /**
     *释放结果集rs Statement对象 关闭连接
     */
    public synchronized void close() {
        try {
            if (rs != null) {
                rs.close();
                rs = null;
            }
        } catch (Exception e) {
            System.err.println(e.getMessage());
            e.printStackTrace();
        }
        try {
            if (stmt != null) {
                stmt.close();
                stmt = null;
            }
        } catch (Exception e) {
            System.err.println(e.getMessage());
            e.printStackTrace();
        }
        try {
            if (con != null) {
                con.close();
                con = null;
            }
        } catch (Exception e) {
            System.err.println(e.getMessage());
            e.printStackTrace();
        }
    }
}