dz3

src/main/java/com/batiaev/java2/lesson8/FileHistoryStorage.java

@@ -0,0 +1,61 @@
+package com.batiaev.java2.lesson8;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.util.ArrayList;
+import java.util.List;
+
+public class FileHistoryStorage implements HistoryStorage {
+
+    RandomAccessFile fileHistory;
+    private String HISTORY_FILE_PATH = "history.txt";
+    private List<Long> messagesOffsets = new ArrayList<>();
+
+    public FileHistoryStorage() {
+        try {
+            fileHistory = new RandomAccessFile(new File(HISTORY_FILE_PATH), "rw");
+            fileHistory.seek(0);
+
+            while (fileHistory.getFilePointer() < fileHistory.length()) {
+                messagesOffsets.add(fileHistory.getFilePointer());
+                fileHistory.readLine();
+            }
+
+        } catch (FileNotFoundException e) {
+            e.printStackTrace();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    @Override
+    public void addMessage(String message) {
+        try {
+            fileHistory.seek(fileHistory.getFilePointer());
+            messagesOffsets.add(fileHistory.getFilePointer());
+            fileHistory.writeUTF(message);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+    @Override
+    public String getMessages(int count, int offset) {
+        StringBuilder messages = new StringBuilder();
+        if (count > 0 && offset >= 0 && offset < messagesOffsets.size()) {
+            try {
+                int startOffset = Math.max(0, messagesOffsets.size() - offset - count);
+                fileHistory.seek(messagesOffsets.get(startOffset));
+                for (int i = 0; i < Math.min(count, messagesOffsets.size() - startOffset); i++) {
+                    messages.append(fileHistory.readUTF());
+                }
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+        return messages.toString();
+    }
+}

src/main/java/com/batiaev/java2/lesson8/HistoryStorage.java

@@ -0,0 +1,9 @@
+package com.batiaev.java2.lesson8;
+
+public interface HistoryStorage {
+
+    void addMessage(String message);
+
+    String getMessages(int count, int offset);
+
+}

src/main/java/com/batiaev/java2/lesson8/MyWindow.java

@@ -31,6 +31,8 @@ public class MyWindow extends JFrame {
     private DataOutputStream out;
     private boolean authorized = false;
 
+    HistoryStorage historyStorage = new FileHistoryStorage();
+
     public static void main(String[] args) {
         new MyWindow().setVisible(true);
     }
@@ -111,13 +113,15 @@ private void connect(String login, String password) {
                         if (msg.startsWith(Command.AUTHOK_COMMAND.getText())) {
                             String nick = msg.substring(Command.AUTHOK_COMMAND.getText().length() + 1);
                             setTitle(nick + "'s client");
+                            jta.append(historyStorage.getMessages(100, 0));
                             setAuthorized(true);
                         } else if (msg.startsWith(Command.DISCONNECTED.getText())) {
                             jta.append("Connection closed..=(");
                             setAuthorized(false);
                         } else if (isAuthorized()) {
                             if (msg.equalsIgnoreCase("end session")) break;
                             jta.append(msg + System.lineSeparator());
+                            historyStorage.addMessage(msg + System.lineSeparator());
                         }
                     }
                     setAuthorized(false);