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1
2
3 package com.db4odoc.f1.clientserver;
4
5 import java.io.File  ;
6
7 import com.db4o.Db4o;
8 import com.db4o.ObjectContainer;
9 import com.db4o.ObjectServer;
10 import com.db4o.ObjectSet;
11 import com.db4o.ext.ExtClient;
12 import com.db4odoc.f1.Util;
13
14
15 public class ExtClientExample {
16
17 public final static String EXTFILENAME="formula1e.yap";
18
19 public static void main(String [] args) {
20 switchExtClients();
21 }
22
24 public static void switchExtClients() {
25 new File (Util.YAPFILENAME).delete();
26 new File (EXTFILENAME).delete();
27 ObjectServer server=Db4o.openServer(Util.YAPFILENAME,0);
28 try {
29 ObjectContainer client=server.openClient();
30 deleteAll(client); Car car = new Car("BMW");
32 client.set(car);
33 System.out.println("Objects in the main database file:");
34 retrieveAll(client);
35
36 System.out.println("Switching to additional database:");
37 ExtClient clientExt = (ExtClient)client;
38 clientExt.switchToFile(EXTFILENAME);
39 car = new Car("Ferrari");
40 clientExt.set(car);
41 retrieveAll(clientExt);
42 System.out.println("Main database file again: ");
43 clientExt.switchToMainFile();
44 retrieveAll(clientExt);
45 clientExt.close();
46 }
47 finally {
48 server.close();
49 }
50 }
51
53 public static void retrieveAll(ObjectContainer db){
54 ObjectSet result=db.get(new Object ());
55 listResult(result);
56 }
57
59 public static void deleteAll(ObjectContainer db) {
60 ObjectSet result=db.get(new Object ());
61 while(result.hasNext()) {
62 db.delete(result.next());
63 }
64 }
65
67 public static void listResult(ObjectSet result) {
68 System.out.println(result.size());
69 while(result.hasNext()) {
70 System.out.println(result.next());
71 }
72 }
73 }
75 |
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Java API By Example, From Geeks To Geeks.