dbconn.java

This book code procedure according to the chapter arrangement, the 1st chapter of example under "1"

package com.example.database;
import java.sql.*;
import java.util.*;

/**
 * <p>Title: 数据库连接类</p>
 * <p>Description: 这是一个很简单的完成数据库连接，和Sql语句执行的类。</p>
 * <p>Copyright: Copyright (c) 2005</p>
 * <p>Company: </p>
 * @author 杜江
 * @version 1.0
 */
public class DbConn {
  /**
   * 获取数据库连接
   * @return 连接对象
   */
  public Connection getConn(String driver, String url, String user, String pass) {
    try {
      Class.forName(driver);
      Connection conn = DriverManager.getConnection(url, user, pass);
      return conn;
    }
    catch (ClassNotFoundException s) {
      System.out.println(s);
      return null;
    }
    catch (SQLException e) {
      System.out.println(e);
      return null;
    }
  }

  /**
   * 执行sql语句
   * @param pSql 要执行的Sql语句
   * @return 处理结果集
   * @throws SQLException  如果数据库操作有异常则抛出
   */
  public Object execute(Connection conn, String pSql) throws SQLException {
  	System.out.println("sql="+pSql);
    Statement Stm = conn.createStatement();
    Vector vResult = new Vector();
    if (isSelect(pSql)) {
      ResultSet rs = Stm.executeQuery(pSql);
      int columnCount = rs.getMetaData().getColumnCount();
      while (rs.next()) {
        java.util.Vector vTemp = new Vector();
        for (int i = 0; i < columnCount; i++) {
          String sTemp = rs.getString(i + 1);
          vTemp.addElement(sTemp == null ? "" : sTemp.trim());
        }
        vResult.addElement(vTemp);
      }
      rs.close();
      Stm.close();
      return vResult;
    }
    else {
      Integer iResult = new Integer(Stm.executeUpdate(pSql));
      return iResult;
    }
  }

  /**
   * 判断是否为Select语句
   * @param pSql 运行的sql语句
   * @return 如果是select语句，则返回true。如果不是则返回false。
   */
  private boolean isSelect(String pSql) {
    String sql = pSql.trim().toUpperCase();
    if (sql.indexOf("SELECT") != 0)
      return false;
    return true;
  }

  /**
   * 关闭连接
   * @param conn 打开的连接
   */
  public void close(Connection conn) {
    try {
      conn.close();
    }
    catch (SQLException se) {
    }
  }


}