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jsp+beans实现读取数据库的例子

发布时间:2008-5-30 9:18:00 浏览次数: 218

JSP+beans实现读取数据库的例子

  jsp+beans实现读取数据库的例子
  Select.jsp

  <html>
  <head>
  <title>Select everything from a database</title>
  </head>
  <body>

  <jsp:useBean id="select" class="DataBaseSelect" scope="request">
  </bean>

  <% out.print(select.connect()); %>
  <br>
  <% out.print(select.select()); %>

  <p>Format results

  <br>
  <%@ page import="Java.util.Vector" %>
  <% Vector aResult = select.getResult(); %>

  <table>
  <% for (int i=0; i < aResult.size(); i++) { %>
  <tr>
  <td>
  <% out.print(aResult.elementAt(i)); %>
  </td>
  </tr>
  <% } %>
  </table>

  </body>
  </html>

  DataBaseSelect.java
  import java.sql.*;
  import java.util.Vector;

  /**
  * DataBaseSelect.java
  * Written by Morgan Catlin
  * August 19, 1999
  *
  * Variables:
  * Vector result = where I put the results of a select query
  *
  * Methods:
  * Vector getResult() = returns result
  * void setResult() = sets result
  * String connect() = connects to a database
  * String select() = selects information from a database
  */

  public class DataBaseSelect {

  private Vector result;

  public DataBaseSelect() {
  result = new Vector();
  } // constructor DataBaseSelect

  public String connect() {
  try {
  Class.forName("a JDBC driver").newInstance();
  return "Driver Loaded!";
  } catch (Exception E) {
  return "Unable to load driver.";
  }
  }

  public String select() {
  try {
  Connection C = DriverManager.getConnection("database connection string");

  Statement Stmt = C.createStatement();

  ResultSet myResult = Stmt.executeQuery("SELECT acolumn from atable");

  while (myResult.next()) {
  result.addElement(myResult.getString(1));
  }

  // Clean up
  myResult.close();
  Stmt.close();
  C.close();
  return "Connection Success!";
  } catch (SQLException E) {
  return "SQLException: " + E.getMessage();
  }
  }

  /**
  * Accessor for result
  **/
  public Vector getResult() {
  return result;
  }

  /**
  * Mutator for result
  **/
  public void setResult(Vector avector) {
  result = avector;
  }

  } // class DataBaseSelect


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