testsqlwarning.java

非常好的java事例以及带源码事例的java2教程

import java.sql.*;

public class TestSQLWarning
{
  public static void main(String[] args)
  {
    TestSQLWarning theApp = new TestSQLWarning();
    try
    {
      theApp.doQuery();               // Call the method that deals with the DB
    }
    catch(SQLException sqle)          // Catch the exception thrown by the method
    {
      do                              // loop through each exception
      {
        // do something with each exception
        System.err.println("Exception occurred:\nMessage: " + sqle.getMessage());
        System.err.println("SQL state: " + sqle.getSQLState());
        System.err.println("Vendor code: " + sqle.getErrorCode() +
                           "\n----------------");
      }while((sqle = sqle.getNextException()) != null);
    }
  }

  // Method to add an exception to a chain of SQLExceptions
  public void doQuery() throws SQLException
  {
    String url = "jdbc:odbc:technical_library";
    String driver = "sun.jdbc.odbc.JdbcOdbcDriver";
    String user = "guest";
    String password = "guest";
    String theStatement = "SELECT title, price FROM books WHERE price <> NULL";

    try
    {
      Class.forName(driver);
      Connection connection = DriverManager.getConnection(url, user, password);
      Statement queryBooks = connection.createStatement();
      ResultSet results = queryBooks.executeQuery(theStatement);
      int price;
      String title;
      while(results.next());
      {
        title = results.getString("title");
        checkForWarning(results.getWarnings());

        price = results.getInt("price");
        checkForWarning(results.getWarnings());

        System.out.println(title + " " + price);
      }
      queryBooks.close();
    }
    catch(ClassNotFoundException cnfe)
    {
      System.out.println(cnfe);
    }
    catch(SQLException sqle)
    {
      SQLException generatedException = new SQLException(        // New exception
                                      "SQL operation cancelled", // Message
                                      "S1008",                   // SQL state
                                      0);                        // Vendor code
      generatedException.setNextException(sqle);        // Append the old exception
      throw generatedException;    
    }                    // and throw the chain
  }


  boolean checkForWarning(SQLWarning w)
  {
    if(w == null)
      return false;
    do
    {
      System.err.println("Warning:\nMessage: " + w.getMessage());
        System.err.println("SQL state: " + w.getSQLState());
        System.err.println("Vendor code: " + w.getErrorCode() +
                           "\n----------------");
    }while((w = w.getNextWarning())!=null);
      return true;
  }


}