undo command

boolean-dev · boolean-dev · commit f4bdf79ddb91 · 2018-11-16T17:38:56.000+08:00
diff --git a/.idea/workspace.xml b/.idea/workspace.xml
diff --git a/ch6-command/src/main/java/com/tao/patterns/ch6command/undo/AddCommand.java b/ch6-command/src/main/java/com/tao/patterns/ch6command/undo/AddCommand.java
@@ -0,0 +1,21 @@
+package com.tao.patterns.ch6command.undo;
+
+public class AddCommand extends Command {
+
+    private Adder adder = new Adder();
+
+
+    @Override
+    int execute(int value) {
+        result =  adder.add(result, value);
+        super.num = value;
+        System.out.println("+" + value + "=" + result);
+        return result;
+    }
+
+    @Override
+    int undo() {
+        result =  adder.add(result, -num);
+        return result;
+    }
+}
diff --git a/ch6-command/src/main/java/com/tao/patterns/ch6command/undo/Adder.java b/ch6-command/src/main/java/com/tao/patterns/ch6command/undo/Adder.java
@@ -0,0 +1,9 @@
+package com.tao.patterns.ch6command.undo;
+
+public class Adder {
+
+    public int add(int num1, int num2) {
+        return num1 + num2;
+    }
+}
+
diff --git a/ch6-command/src/main/java/com/tao/patterns/ch6command/undo/CalculatorForm.java b/ch6-command/src/main/java/com/tao/patterns/ch6command/undo/CalculatorForm.java
@@ -0,0 +1,24 @@
+package com.tao.patterns.ch6command.undo;
+
+public class CalculatorForm {
+
+    private Command command;
+
+    public CalculatorForm(Command command) {
+        this.command = command;
+    }
+
+    public void setCommand(Command command) {
+        this.command = command;
+    }
+
+    public void computer(int num) {
+        int result = command.execute(num);
+        System.out.println("计算结果为:" + result);
+    }
+
+    public void undo() {
+        int result  = command.undo();
+        System.out.println("后退的结果为：" + result);
+    }
+}
diff --git a/ch6-command/src/main/java/com/tao/patterns/ch6command/undo/Command.java b/ch6-command/src/main/java/com/tao/patterns/ch6command/undo/Command.java
@@ -0,0 +1,9 @@
+package com.tao.patterns.ch6command.undo;
+
+public abstract class Command {
+    protected static int result = 0;
+    protected int num = 0;
+
+    abstract int execute(int num);
+    abstract int undo();
+}
diff --git a/ch6-command/src/main/java/com/tao/patterns/ch6command/undo/Main.java b/ch6-command/src/main/java/com/tao/patterns/ch6command/undo/Main.java
@@ -0,0 +1,36 @@
+package com.tao.patterns.ch6command.undo;
+
+/**
+ * 命令模式的undo
+ *
+ * 一个加减法计算器
+ * 可连续进行加减，但是undo只能进行一次，否则数据会出现错误
+ */
+public class Main {
+
+    public static void main(String[] args) {
+        Main main = new Main();
+        main.fun1();
+
+    }
+
+    private void fun1() {
+        Command command = new AddCommand();
+
+
+        CalculatorForm calculatorForm = new CalculatorForm(command);
+        calculatorForm.computer(10);
+        calculatorForm.computer(5);
+        calculatorForm.undo();
+
+        command = new SubCommand();
+        calculatorForm.setCommand(command);
+        calculatorForm.computer(3);
+        calculatorForm.computer(4);
+        calculatorForm.undo();
+        //undo只能后退一步
+//        calculatorForm.undo();
+
+
+    }
+}
diff --git a/ch6-command/src/main/java/com/tao/patterns/ch6command/undo/SubCommand.java b/ch6-command/src/main/java/com/tao/patterns/ch6command/undo/SubCommand.java
@@ -0,0 +1,20 @@
+package com.tao.patterns.ch6command.undo;
+
+public class SubCommand extends Command{
+
+    private Suber suber = new Suber();
+
+    @Override
+    int execute(int value) {
+        super.num = value;
+        result = suber.subtraction(result, value);
+        System.out.println("-" + value + "=" + result);
+        return result;
+    }
+
+    @Override
+    int undo() {
+        result =  suber.subtraction(result, -num);
+        return result;
+    }
+}
diff --git a/ch6-command/src/main/java/com/tao/patterns/ch6command/undo/Suber.java b/ch6-command/src/main/java/com/tao/patterns/ch6command/undo/Suber.java
@@ -0,0 +1,8 @@
+package com.tao.patterns.ch6command.undo;
+
+public class Suber {
+
+    public int subtraction(int num1, int num2){
+        return num1 - num2;
+    }
+}
