searchcontroller.java

图书馆检索系统

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

public class SearchController extends Controller {
  public void doPost (HttpServletRequest req, HttpServletResponse res)
          throws ServletException, IOException {
    String pterms = req.getParameter("str");

    // Redirect back to the index page if no terms are selected
    if (pterms.equals("")) {
      res.sendRedirect("/library/index.jsp");
    } else {
      String action = req.getParameter("action");
      String searchby = req.getParameter("searchby");
      
      // Make sure to replace any characters that
      // could mess up the SQL statement.
      String terms = StringReplace.replace(pterms, "\'", "\'\'"); // Apostrophe

      // 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 '%" + terms + "%'";
      } else {
        sql += "name like '%" + terms + "%'";
      }

      Vector results = new Vector();

      // Execute the search and fill a vector with search results.
      try {
        BookTitle searchResults = new BookTitle(sql);

        while (searchResults.getNext()) {
          SearchResult sr = searchResults.getSearchResult();
          results.add(sr);
        }
      } catch (SQLException e) {
        System.err.println(e.toString());
        sendErrorRedirect(req, res, e);
      }

      // Redirect to the search.jsp page to
      // display the search results.
      req.getSession().setAttribute("results", results);
      String url = "/library/search.jsp?start=0&searchby=" + searchby +
              "&str=" + URLEncoder.encode(pterms, "UTF-8");

      res.sendRedirect(url);

      return;
    }
  }
}