searchcontroller.java

一个关于图书馆的服务器的管理程序

import java.util.*;
import java.io.*;
import java.net.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
import library.DBWrapper;
import library.BookTitleSet;
import library.BookTitle;

/**
 * Class <b>SearchController</b> contains 
 * the servlet controller functionality for processing
 * user search requests.
 * 
 *
 * @author CTE
 * @version 1.0
 */
public class SearchController extends Controller {

    /**
     * SearchController doPost method.  This is can be called
     * by <b>Controller</b> superclass' doGet() method.
     * @param req HttpServletRequest servlet request object
     * @param res HttpServletResponse servlet response object
     * @throws ServletException
     * @throws IOException
     */
    public void doPost (HttpServletRequest req, HttpServletResponse res)
	throws ServletException, IOException {
	
	// Get the search parameters.
	String action = req.getParameter("action");
	String pterms = req.getParameter("str");
	
	// Redirect the user back to the index page if no terms are selected
	if (pterms.equals("")) {
	    res.sendRedirect("/library/index.jsp");
	} else {
	    // Get the searchby parameter;
	    String searchby = req.getParameter("searchby");		
	    
	    // Build the sql statement based on what is to be searched on (author or title).
	    String sql = "SELECT * FROM BookTitle WHERE ";
	    
	    if (searchby.equals("author")) {
		sql += "author like '%" + pterms + "%'";
	    } else {
		sql += "name like '%" + pterms + "%'";
	    }
	    
	    // The results of the search are to be stored in a BookTitleSet object.
	    BookTitleSet results = new BookTitleSet();
	    
	    // Execute the search and fill the BookTitleSet with the results.
	    try {
		ResultSet r = null;
		
		// Get an instance of the singleton DBWrapper object.
		DBWrapper db = DBWrapper.Instance();
		
		// Run the query.
		r = db.runQuery( sql );
		
		// Fill the BookTitleSet with BookTitles.
		while (r.next()) {
		    BookTitle tempTitle =  new BookTitle( r.getString( "callNumber" ), r.getString( "name" ),
							  r.getString( "author" ), r.getString( "isbn" ), 
							  r.getString( "edition" ), r.getString( "publisher" ),
							  r.getInt( "year" ));
		    results.addBookTitle( tempTitle );
		    
		}
	    } catch ( Exception e ) {
		// Send this exception to the standard error page.
		sendErrorRedirect(req, res, e);
	    }
	    
	    /**
	     * Redirect to the search.jsp page to display the search results.
	     * The search results are stored in the HttpServletRequest's
	     * session.
	     */
	    try {
		req.getSession().setAttribute("results", results);
		
		// Be sure to tell search.jsp that it should initially show books 0-9, i.e. the first ten books.
		String url = "/library/search.jsp?start=0&searchby=" + searchby +
		    "&str=" + URLEncoder.encode(pterms, "UTF-8");
		res.sendRedirect(url);
	    } catch( Exception e ){
		sendErrorRedirect(req, res, e);
	    }
	    return;
	}
    }
}