新增Command操作工具类

app/src/main/java/com/rdc/lichaojian/note/utils/CommandUtils.java

@@ -0,0 +1,68 @@
+package com.rdc.lichaojian.note.utils;
+
+import com.rdc.lichaojian.note.command.Command;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Created by lichaojian on 16-8-28.
+ */
+public class CommandUtils {
+    private static final String TAG = "CommandUtils";
+    private static CommandUtils mCommandUtils = null;
+    private List<Command> mUndoCommandList = null;
+    private List<Command> mRedoCommandList = null;
+
+    private CommandUtils() {
+        mUndoCommandList = new ArrayList<>();
+        mRedoCommandList = new ArrayList<>();
+    }
+
+    public static CommandUtils getInstance() {
+        if (mCommandUtils == null) {
+            mCommandUtils = new CommandUtils();
+        }
+        return mCommandUtils;
+    }
+
+    public List<Command> getUndoCommandList() {
+        return mUndoCommandList;
+    }
+
+    public List<Command> getRedoCommandList() {
+        return mRedoCommandList;
+    }
+
+    /**
+     * 撤销
+     *
+     * @return 返回需要撤销的指令
+     */
+    public Command undo() {
+        Command command = null;
+        int size = mUndoCommandList.size();
+        if (mUndoCommandList != null && size > 0) {
+            command = mUndoCommandList.get(size - 1);
+            mRedoCommandList.add(command);
+            mUndoCommandList.remove(size - 1);
+        }
+        return command;
+    }
+
+    /**
+     * 恢复操作
+     *
+     * @return 返回恢复的指令
+     */
+    public Command redo() {
+        Command command = null;
+        int size = mRedoCommandList.size();
+        if (mRedoCommandList != null && size > 0) {
+            command = mRedoCommandList.get(size - 1);
+            mUndoCommandList.add(command);
+            mRedoCommandList.remove(size - 1);
+        }
+        return command;
+    }
+}