moin aleks

public class ServerClientthread extends Thread {
    Socket s;
    Statement stmt;
    OutputStreamWriter out;
    InputStreamReader in;
    int zeichen;
    static Object monitor;

    public ServerClientthread(Socket s) {
        this.s = s;
    }

    public void verbinden() {
        Connection conn;
        try {
            conn = DriverManager.getConnection("jdbc:mysql://localhost/buchladen", "root", "root");
            stmt = conn.createStatement();
            System.out.println("Verbunden !");
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    public void anmeldung() {
        try {
            ResultSet rs = stmt.executeQuery("SELECT * FROM buch ORDER BY titel ASC");
            out.write("L");
            out.flush();
            while (rs.next()) {
                String isbn = rs.getString("isbn");
                String titel = rs.getString("titel");
                String autor = rs.getString("autor");
                String befehl = isbn + " " + titel + " (" + autor + ")";
                out.write(befehl);
                out.flush();
                out.write("§");
                out.flush();
            }
            out.write("$");
            out.flush();

        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

    public void bestellung() {
        try {
            String kundennr = "";
            String isbn = "";
            String stückzahl = "";
            System.out.println("Bestellung");
            while ((zeichen = in.read()) != '$') {
                kundennr += (char) zeichen;
            }
            System.out.println(kundennr);
            while ((zeichen = in.read()) != '§') {
                isbn += (char) zeichen;
            }
            System.out.println(isbn);
            while ((zeichen = in.read()) != '%') {
                stückzahl += (char) zeichen;
            }
            System.out.println(stückzahl);
            synchronized (monitor) {
                try {
                    ResultSet rs = stmt.executeQuery("SELECT bestand FROM buch WHERE isbn ='" + isbn + "'");
                    rs.next();
                    int bestand = rs.getInt("bestand");
                    if (bestand < Integer.parseInt(stückzahl)) {
                        out.write("N" + bestand + "$");
                        out.flush();

                    } else {
                        int neueanzahl = bestand - Integer.parseInt(stückzahl);
                        String sql = "UPDATE buch set bestand =" + neueanzahl + " WHERE isbn ='" + isbn + "'";
                        String sql2 = "INSERT INTO bestellung VALUES (NULL," + kundennr + ",'" + isbn + "'," + stückzahl
                                + ");";
                        System.out.println(sql);
                        System.out.println(sql2);
                        stmt.executeUpdate(sql);
                        stmt.executeUpdate(sql2);
                        out.write("J");
                        out.flush();
                        System.out.println("Bestellt !");
                    }
                } catch (SQLException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

            }
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }

    }

    public void stonierung() {
        String kundennr = "";
        String isbn = "";
        try {
            while ((zeichen = in.read()) != '$') {
                kundennr += (char) zeichen;
            }
            System.out.println(kundennr);
            while ((zeichen = in.read()) != '§') {
                isbn += (char) zeichen;
            }
            synchronized (monitor) {

                String sql = "SELECT anzahl FROM bestellung WHERE isbn ='" + isbn + "' AND kundennr =" + kundennr + "";
                ResultSet rs = stmt.executeQuery(sql);
                int zurückgegeben = 0;
                while (rs.next()) {
                    int anzahl = rs.getInt("anzahl");
                    zurückgegeben += anzahl;
                }
                if (zurückgegeben > 0) {
                    System.out.println("" + zurückgegeben);
                    rs = stmt.executeQuery("SELECT bestand FROM buch WHERE isbn ='" + isbn + "'");
                    rs.next();
                    int bestand = rs.getInt("bestand");
                    System.out.println("" + bestand);
                    bestand += zurückgegeben;
                    stmt.executeUpdate("UPDATE buch set bestand =" + bestand + " WHERE isbn ='" + isbn + "'");
                    stmt.executeUpdate("DELETE FROM bestellung WHERE isbn ='" + isbn + "' AND kundennr =" + kundennr);
                    System.out.println("" + bestand);
                    out.write("S");
                    out.flush();
                } else {
                    out.write("F");
                    out.flush();
                }
            }
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

    public void run() {
        int zeichen;
        monitor = new Object();
        try {
            in = new InputStreamReader(s.getInputStream(), "UTF-8");
            out = new OutputStreamWriter(s.getOutputStream(), "UTF-8");
            verbinden();
            anmeldung();
            while ((zeichen = in.read()) != -1) {
                char c = (char) zeichen;
                switch (c) {
                case 'B':
                    bestellung();
                    break;
                case 'S':
                    stonierung();
                    break;

                }
            }
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

}