Java-编写一个jdbc操作类

1.通过读取文件配置

package 数据库操作类;  

    /* * Db.java
    Created on 2007年8月20日, 上午 8:37
    */
    import java.io.*;
    import java.sql.*;
    import java.util.Properties;
    public class DB {
        private String driver;
        private String url;
        private String user;
        private String password;
        private Connection conn;
        private Statement stm;
        private ResultSet rs;
        public DB(){
            this("DBConf.properties");
        }
        public DB(String conf) {
            loadProperties(conf);
            setConn();
        }
        public Connection getConn(){
            return this.conn;
        }
      //handle the properties file to get the informations for connection
        private void loadProperties(String conf){
            Properties props = new Properties();
            try {
                props.load(new FileInputStream(conf));
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            this.driver = props.getProperty("driver");
            this.url = props.getProperty("url");
            this.user = props.getProperty("user");
            this.password = props.getProperty("password");
        }
        //implement the Connection
        private void setConn(){
            try {
                Class.forName(driver);
                this.conn = DriverManager.getConnection(url,user,password);
            } catch(ClassNotFoundException classnotfoundexception) {
                  classnotfoundexception.printStackTrace();
                System.err.println("db: " + classnotfoundexception.getMessage());
            } catch(SQLException sqlexception) {
                System.err.println("db.getconn(): " + sqlexception.getMessage());
            }
        }
           public void doInsert(String sql) {
            try {
                Statement statement = conn.createStatement();
                int i = stm.executeUpdate(sql);
            } catch(SQLException sqlexception) {
                System.err.println("db.executeInset:" + sqlexception.getMessage());
            }
        }
        public void doDelete(String sql) {
            try {
                stm = conn.createStatement();
                int i = stm.executeUpdate(sql);
            } catch(SQLException sqlexception) {
                System.err.println("db.executeDelete:" + sqlexception.getMessage());
            }
        }
        public void doUpdate(String sql) {
            try {
                stm = conn.createStatement();
                int i = stm.executeUpdate(sql);
            } catch(SQLException sqlexception) {
                System.err.println("db.executeUpdate:" + sqlexception.getMessage());
            }
        }  

        public ResultSet doSelect(String sql) {
            try {
                stm = conn.createStatement(java.sql.ResultSet.TYPE_SCROLL_INSENSITIVE,java.sql.ResultSet.CONCUR_READ_ONLY);
                rs = stm.executeQuery(sql);
            } catch(SQLException sqlexception) {
                System.err.println("db.executeQuery: " + sqlexception.getMessage());
            }
            return rs;
        }
        public static void main(String[] args){
            try{
                DB db = new DB();
                Connection conn = db.getConn();
                if(conn != null && !conn.isClosed()) {
                    System.out.println("連結成功");
                    ResultSet rs = db.doSelect("select * from content");
                    while(rs.next()){
                        System.out.println(rs.getString(1)+":"+rs.getString(2)+":"+rs.getString(3));
                      }
                    rs.close();
                    conn.close();
                }
            }catch(SQLException e) {
                e.printStackTrace();
            }
        }
    }