dbframe.java

源码为科学出版社出版的英文<java设计模式>(影印版)所用的所有例子程序

import java.net.URL;
import java.sql.*;
import java.util.*;
import java.awt.*;
import java.awt.event.*;

public class dbFrame extends Frame
implements ActionListener, ItemListener {
    Database db;
    java.awt.List Tables, Columns, Data;
    TextArea query;
    Button Search, Quit;
    public dbFrame() {
        super("Database demonstration");
        setGUI();

        db = new Database("sun.jdbc.odbc.JdbcOdbcDriver");
        db.Open("jdbc:odbc:Grocery prices", null);

        String tnames[] = db.getTableNames();
        loadList(Tables, tnames);

        String queryText ="SELECT DISTINCTROW FoodName, StoreName, Price "+
                          "FROM (Food INNER JOIN FoodPrice ON Food.FoodKey = FoodPrice.FoodKey) " +
                          "INNER JOIN Stores ON FoodPrice.StoreKey = Stores.StoreKey "+
                          "WHERE (((Food.FoodName)=\'Oranges\')) ORDER BY FoodPrice.Price;";

        query.setText(queryText);
    }
    //------------------------------------
    private void setGUI() {
        setBackground(Color.lightGray);
        setLayout(new BorderLayout());
        Panel pn = new Panel();
        add("North", pn);
        pn.setLayout(new GridLayout(1,3));
        pn.add(new Label("Tables"));
        pn.add(new Label("Columns"));
        pn.add(new Label("Data"));
        Panel pc = new Panel();
        add("Center", pc);
        pc.setLayout(new GridLayout(1,3));
        pc.add(Tables = new java.awt.List(15));
        pc.add(Columns = new java.awt.List(15));
        pc.add(Data = new java.awt.List(15));
        Tables.addItemListener(this);
        Columns.addItemListener(this);

        Panel ps = new Panel();
        add("South", ps);
        ps.add(query = new TextArea("", 3,40));
        addPanel(ps, Search = new Button("Run Query"));
        addPanel(ps, Quit = new Button("Quit"));
        Search.addActionListener(this);
        Quit.addActionListener(this);
        setBounds(100, 100, 500, 300);
        setVisible(true);
    }
    //------------------------------------
    private void addPanel(Panel ps, Component c) {
        Panel p = new Panel();
        ps.add(p);
        p.add(c);
    }
    //------------------------------------
    private void loadList(java.awt.List list, String[] s) {
        list.removeAll();
        for (int i=0; i< s.length; i++)
            list.add(s[i]);
    }
    //------------------------------------
    public void actionPerformed(ActionEvent e) {
        Object obj = e.getSource();
        if (obj == Quit)
            System.exit(0);
        if (obj == Search)
            clickedSearch();
    }
    //------------------------------------
    public void itemStateChanged(ItemEvent e) {
        Object obj = e.getSource();
        if (obj == Tables)
            showColumns();
        if (obj == Columns)
            showData();
    }
    //------------------------------------
    private void showColumns() {
        String cnames[] = db.getColumnNames(Tables.getSelectedItem());
        loadList(Columns, cnames);
    }
    //------------------------------------
    private void showData() {
        String colname = Columns.getSelectedItem();
        String colval = db.getColumnValue(Tables.getSelectedItem(), colname);
        Data.setVisible(false);
        Data.removeAll();
        Data.setVisible(true);

        colval = db.getNextValue(Columns.getSelectedItem());

        while (colval.length()>0) {
            Data.add(colval);
            colval = db.getNextValue(Columns.getSelectedItem());
        }
    }
    //------------------------------------
    private void clickedSearch() {
        Results rs = db.Execute(query.getText());
        String cnames[] = rs.getMetaData();
        Columns.removeAll();
        queryDialog q = new queryDialog(this, rs);
        q.show();
    }
    //------------------------------------
    static public void main(String argv[]) {
        new dbFrame();
    }
}