里氏替换原则原则

.idea/uiDesigner.xml

@@ -0,0 +1,124 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="Palette2">
+    <group name="Swing">
+      <item class="com.intellij.uiDesigner.HSpacer" tooltip-text="Horizontal Spacer" icon="/com/intellij/uiDesigner/icons/hspacer.png" removable="false" auto-create-binding="false" can-attach-label="false">
+        <default-constraints vsize-policy="1" hsize-policy="6" anchor="0" fill="1" />
+      </item>
+      <item class="com.intellij.uiDesigner.VSpacer" tooltip-text="Vertical Spacer" icon="/com/intellij/uiDesigner/icons/vspacer.png" removable="false" auto-create-binding="false" can-attach-label="false">
+        <default-constraints vsize-policy="6" hsize-policy="1" anchor="0" fill="2" />
+      </item>
+      <item class="javax.swing.JPanel" icon="/com/intellij/uiDesigner/icons/panel.png" removable="false" auto-create-binding="false" can-attach-label="false">
+        <default-constraints vsize-policy="3" hsize-policy="3" anchor="0" fill="3" />
+      </item>
+      <item class="javax.swing.JScrollPane" icon="/com/intellij/uiDesigner/icons/scrollPane.png" removable="false" auto-create-binding="false" can-attach-label="true">
+        <default-constraints vsize-policy="7" hsize-policy="7" anchor="0" fill="3" />
+      </item>
+      <item class="javax.swing.JButton" icon="/com/intellij/uiDesigner/icons/button.png" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="3" anchor="0" fill="1" />
+        <initial-values>
+          <property name="text" value="Button" />
+        </initial-values>
+      </item>
+      <item class="javax.swing.JRadioButton" icon="/com/intellij/uiDesigner/icons/radioButton.png" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="3" anchor="8" fill="0" />
+        <initial-values>
+          <property name="text" value="RadioButton" />
+        </initial-values>
+      </item>
+      <item class="javax.swing.JCheckBox" icon="/com/intellij/uiDesigner/icons/checkBox.png" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="3" anchor="8" fill="0" />
+        <initial-values>
+          <property name="text" value="CheckBox" />
+        </initial-values>
+      </item>
+      <item class="javax.swing.JLabel" icon="/com/intellij/uiDesigner/icons/label.png" removable="false" auto-create-binding="false" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="0" anchor="8" fill="0" />
+        <initial-values>
+          <property name="text" value="Label" />
+        </initial-values>
+      </item>
+      <item class="javax.swing.JTextField" icon="/com/intellij/uiDesigner/icons/textField.png" removable="false" auto-create-binding="true" can-attach-label="true">
+        <default-constraints vsize-policy="0" hsize-policy="6" anchor="8" fill="1">
+          <preferred-size width="150" height="-1" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JPasswordField" icon="/com/intellij/uiDesigner/icons/passwordField.png" removable="false" auto-create-binding="true" can-attach-label="true">
+        <default-constraints vsize-policy="0" hsize-policy="6" anchor="8" fill="1">
+          <preferred-size width="150" height="-1" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JFormattedTextField" icon="/com/intellij/uiDesigner/icons/formattedTextField.png" removable="false" auto-create-binding="true" can-attach-label="true">
+        <default-constraints vsize-policy="0" hsize-policy="6" anchor="8" fill="1">
+          <preferred-size width="150" height="-1" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JTextArea" icon="/com/intellij/uiDesigner/icons/textArea.png" removable="false" auto-create-binding="true" can-attach-label="true">
+        <default-constraints vsize-policy="6" hsize-policy="6" anchor="0" fill="3">
+          <preferred-size width="150" height="50" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JTextPane" icon="/com/intellij/uiDesigner/icons/textPane.png" removable="false" auto-create-binding="true" can-attach-label="true">
+        <default-constraints vsize-policy="6" hsize-policy="6" anchor="0" fill="3">
+          <preferred-size width="150" height="50" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JEditorPane" icon="/com/intellij/uiDesigner/icons/editorPane.png" removable="false" auto-create-binding="true" can-attach-label="true">
+        <default-constraints vsize-policy="6" hsize-policy="6" anchor="0" fill="3">
+          <preferred-size width="150" height="50" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JComboBox" icon="/com/intellij/uiDesigner/icons/comboBox.png" removable="false" auto-create-binding="true" can-attach-label="true">
+        <default-constraints vsize-policy="0" hsize-policy="2" anchor="8" fill="1" />
+      </item>
+      <item class="javax.swing.JTable" icon="/com/intellij/uiDesigner/icons/table.png" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="6" hsize-policy="6" anchor="0" fill="3">
+          <preferred-size width="150" height="50" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JList" icon="/com/intellij/uiDesigner/icons/list.png" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="6" hsize-policy="2" anchor="0" fill="3">
+          <preferred-size width="150" height="50" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JTree" icon="/com/intellij/uiDesigner/icons/tree.png" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="6" hsize-policy="6" anchor="0" fill="3">
+          <preferred-size width="150" height="50" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JTabbedPane" icon="/com/intellij/uiDesigner/icons/tabbedPane.png" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="3" hsize-policy="3" anchor="0" fill="3">
+          <preferred-size width="200" height="200" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JSplitPane" icon="/com/intellij/uiDesigner/icons/splitPane.png" removable="false" auto-create-binding="false" can-attach-label="false">
+        <default-constraints vsize-policy="3" hsize-policy="3" anchor="0" fill="3">
+          <preferred-size width="200" height="200" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JSpinner" icon="/com/intellij/uiDesigner/icons/spinner.png" removable="false" auto-create-binding="true" can-attach-label="true">
+        <default-constraints vsize-policy="0" hsize-policy="6" anchor="8" fill="1" />
+      </item>
+      <item class="javax.swing.JSlider" icon="/com/intellij/uiDesigner/icons/slider.png" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="6" anchor="8" fill="1" />
+      </item>
+      <item class="javax.swing.JSeparator" icon="/com/intellij/uiDesigner/icons/separator.png" removable="false" auto-create-binding="false" can-attach-label="false">
+        <default-constraints vsize-policy="6" hsize-policy="6" anchor="0" fill="3" />
+      </item>
+      <item class="javax.swing.JProgressBar" icon="/com/intellij/uiDesigner/icons/progressbar.png" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="6" anchor="0" fill="1" />
+      </item>
+      <item class="javax.swing.JToolBar" icon="/com/intellij/uiDesigner/icons/toolbar.png" removable="false" auto-create-binding="false" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="6" anchor="0" fill="1">
+          <preferred-size width="-1" height="20" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JToolBar$Separator" icon="/com/intellij/uiDesigner/icons/toolbarSeparator.png" removable="false" auto-create-binding="false" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="0" anchor="0" fill="1" />
+      </item>
+      <item class="javax.swing.JScrollBar" icon="/com/intellij/uiDesigner/icons/scrollbar.png" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="6" hsize-policy="0" anchor="0" fill="2" />
+      </item>
+    </group>
+  </component>
+</project>

src/main/java/top/fjy8018/designpattern/principle/liskovsubstitution/classdemo/after/ARectangle.java

@@ -0,0 +1,32 @@
+package top.fjy8018.designpattern.principle.liskovsubstitution.classdemo.after;
+
+/**
+ * 里氏替换原则：如果对每一个类型为S的对象o1，都有类型为T的对象o2，使得以T定义的所有程序P在所有的对象o1都代换为o2，程序P的行为没有发生变化，那么类型S是类型T的子类型
+ * 即：所有使用父类对象的地方替换成子类对象依然正常运行
+ *
+ * @author F嘉阳
+ * @date 2018-09-22 20:01
+ */
+public class ARectangle implements Quadrangle {
+    private long length;
+
+    private long width;
+
+    @Override
+    public long getWidth() {
+        return width;
+    }
+
+    public void setWidth(long width) {
+        this.width = width;
+    }
+
+    @Override
+    public long getLength() {
+        return length;
+    }
+
+    public void setLength(long length) {
+        this.length = length;
+    }
+}

src/main/java/top/fjy8018/designpattern/principle/liskovsubstitution/classdemo/after/ASquare.java

@@ -0,0 +1,23 @@
+package top.fjy8018.designpattern.principle.liskovsubstitution.classdemo.after;
+
+/**
+ * @author F嘉阳
+ * @date 2018-09-22 20:03
+ */
+public class ASquare implements Quadrangle {
+    private long sideLength;
+
+    @Override
+    public long getWidth() {
+        return sideLength;
+    }
+
+    @Override
+    public long getLength() {
+        return sideLength;
+    }
+
+    public void setLength(long sideLength) {
+        this.sideLength = sideLength;
+    }
+}

src/main/java/top/fjy8018/designpattern/principle/liskovsubstitution/classdemo/after/Quadrangle.java

@@ -0,0 +1,13 @@
+package top.fjy8018.designpattern.principle.liskovsubstitution.classdemo.after;
+
+/**
+ * 通过四边形接口连接，防止继承泛滥
+ *
+ * @author F嘉阳
+ * @date 2018-09-22 20:11
+ */
+public interface Quadrangle {
+    long getWidth();
+
+    long getLength();
+}

src/main/java/top/fjy8018/designpattern/principle/liskovsubstitution/classdemo/before/Rectangle.java

@@ -0,0 +1,29 @@
+package top.fjy8018.designpattern.principle.liskovsubstitution.classdemo.before;
+
+/**
+ * 里氏替换原则：如果对每一个类型为S的对象o1，都有类型为T的对象o2，使得以T定义的所有程序P在所有的对象o1都代换为o2，程序P的行为没有发生变化，那么类型S是类型T的子类型
+ * 即：所有使用父类对象的地方替换成子类对象依然正常运行
+ *
+ * @author F嘉阳
+ * @date 2018-09-22 20:01
+ */
+public class Rectangle {
+    private long length;
+    private long width;
+
+    public long getLength() {
+        return length;
+    }
+
+    public void setLength(long length) {
+        this.length = length;
+    }
+
+    public long getWidth() {
+        return width;
+    }
+
+    public void setWidth(long width) {
+        this.width = width;
+    }
+}

src/main/java/top/fjy8018/designpattern/principle/liskovsubstitution/classdemo/before/Square.java

@@ -0,0 +1,34 @@
+package top.fjy8018.designpattern.principle.liskovsubstitution.classdemo.before;
+
+/**
+ * @author F嘉阳
+ * @date 2018-09-22 20:03
+ */
+public class Square extends Rectangle {
+    private long sideLength;
+
+    @Override
+    public long getLength() {
+        return sideLength;
+    }
+
+    /**
+     * 覆盖了父类的实现，不满足里氏替换原则
+     *
+     * @param length
+     */
+    @Override
+    public void setLength(long length) {
+        this.sideLength = length;
+    }
+
+    @Override
+    public long getWidth() {
+        return sideLength;
+    }
+
+    @Override
+    public void setWidth(long width) {
+        this.sideLength = width;
+    }
+}

src/main/java/top/fjy8018/designpattern/principle/liskovsubstitution/method/input/after/Base.java

@@ -0,0 +1,17 @@
+package top.fjy8018.designpattern.principle.liskovsubstitution.method.input.after;
+
+import lombok.extern.slf4j.Slf4j;
+
+import java.util.HashMap;
+
+/**
+ * @author F嘉阳
+ * @date 2018-09-23 11:29
+ */
+@Slf4j
+class Base {
+
+    public void method(HashMap map) {
+        log.info("父类被执行");
+    }
+}

src/main/java/top/fjy8018/designpattern/principle/liskovsubstitution/method/input/after/Child.java

@@ -0,0 +1,38 @@
+package top.fjy8018.designpattern.principle.liskovsubstitution.method.input.after;
+
+import lombok.extern.slf4j.Slf4j;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * 李氏转换原则要求方法入参必须比父类范围更宽，返回值必须比父类更窄
+ *
+ * @author F嘉阳
+ * @date 2018-09-23 11:30
+ */
+@Slf4j
+class Child extends Base {
+
+    /**
+     * 方法重写，入参必须等于父类或者比父类范围更宽
+     * 而返回值比父类更窄已经交由IDE判断，若不符合，则编译不通过
+     *
+     * @param map
+     */
+    @Override
+    public void method(HashMap map) {
+        log.info("子类HashMap入参方法被执行");
+    }
+
+    /**
+     * 方法重写，是子类额外的方法
+     *
+     * @param map
+     */
+    public void method(Map map) {
+        log.info("子类Map入参方法被执行");
+    }
+
+
+}

src/main/java/top/fjy8018/designpattern/principle/liskovsubstitution/method/input/before/Base.java

@@ -0,0 +1,18 @@
+package top.fjy8018.designpattern.principle.liskovsubstitution.method.input.before;
+
+import lombok.extern.slf4j.Slf4j;
+
+import java.util.Map;
+
+
+/**
+ * @author F嘉阳
+ * @date 2018-09-23 11:29
+ */
+@Slf4j
+class Base {
+
+    public void method(Map map) {
+        log.info("父类被执行");
+    }
+}

src/main/java/top/fjy8018/designpattern/principle/liskovsubstitution/method/input/before/Child.java

@@ -0,0 +1,18 @@
+package top.fjy8018.designpattern.principle.liskovsubstitution.method.input.before;
+
+import lombok.extern.slf4j.Slf4j;
+
+import java.util.HashMap;
+
+/**
+ * @author F嘉阳
+ * @date 2018-09-23 11:30
+ */
+@Slf4j
+class Child extends Base {
+
+    public void method(HashMap map) {
+        log.info("子类HashMap入参方法被执行");
+    }
+
+}

src/main/java/top/fjy8018/designpattern/principle/openclose/JavaDiscountCourse.java

@@ -27,23 +27,25 @@ public class JavaDiscountCourse extends JavaCourse {
     }
 
     /**
-     * 获取原价
+     * 实现打折价格逻辑
      *
      * @return
      */
-    public BigDecimal getOriginPrice() {
+    public BigDecimal getDistcountPrice() {
-        return super.getPrice();
+        // BigDecimal推荐使用String构造器，防止精度转换问题
+        return super.getPrice().multiply(new BigDecimal("0.8"));
     }
 
     /**
-     * 实现打折价格逻辑
+     * 根据里氏替换原则：父类实现的方法不应该覆盖
+     * 获取原价
      *
      * @return
      */
     @Override
     public BigDecimal getPrice() {
-        // BigDecimal推荐使用String构造器，防止精度转换问题
+
-        return super.getPrice().multiply(new BigDecimal("0.8"));
+        return super.getPrice();
     }
 
     @Override

src/test/java/top/fjy8018/designpattern/principle/liskovsubstitution/classdemo/before/SquareTest.java

@@ -0,0 +1,61 @@
+package top.fjy8018.designpattern.principle.liskovsubstitution.classdemo.before;
+
+import lombok.extern.slf4j.Slf4j;
+import org.junit.jupiter.api.Test;
+import top.fjy8018.designpattern.principle.liskovsubstitution.classdemo.after.ARectangle;
+import top.fjy8018.designpattern.principle.liskovsubstitution.classdemo.after.Quadrangle;
+
+@Slf4j
+class SquareTest {
+
+    /**
+     * resize要求传入父类对象，对长宽进行设置
+     *
+     * @param rectangle
+     */
+    public static void resize(Rectangle rectangle) {
+        while (rectangle.getWidth() <= rectangle.getLength()) {
+            rectangle.setWidth(rectangle.getWidth() + 1);
+            log.info("width:{} length:{}", rectangle.getWidth(), rectangle.getLength());
+            if (rectangle.getWidth() > 50 || rectangle.getLength() > 50) {
+                log.error("方法溢出");
+                break;
+            }
+        }
+        log.info("resize方法结束 width:{} length:{}", rectangle.getWidth(), rectangle.getLength());
+    }
+
+    public static void resize(Quadrangle quadrangle) {
+        while (quadrangle.getWidth() <= quadrangle.getLength()) {
+//            quadrangle.setWidth(quadrangle.getWidth()+1);报错，原有方法已经不能正确运行，说明原有方法设计存在问题
+            log.info("width:{} length:{}", quadrangle.getWidth(), quadrangle.getLength());
+            if (quadrangle.getWidth() > 50 || quadrangle.getLength() > 50) {
+                log.error("方法溢出");
+                break;
+            }
+        }
+        log.info("resize方法结束 width:{} length:{}", quadrangle.getWidth(), quadrangle.getLength());
+    }
+
+    @Test
+    void before() {
+        // 是长方形时业务正常运行
+        Rectangle rectangle = new Rectangle();
+        rectangle.setWidth(10);
+        rectangle.setLength(20);
+        resize(rectangle);
+        // 使用之类替换父类对象，业务无法运行，方法溢出
+        Square square = new Square();
+        square.setLength(40);
+        resize(square);
+    }
+
+    @Test
+    void after() {
+        // 通过里氏替换原则改造后
+        ARectangle aRectangle = new ARectangle();
+        aRectangle.setLength(20);
+        aRectangle.setWidth(10);
+
+    }
+}

src/test/java/top/fjy8018/designpattern/principle/liskovsubstitution/method/input/after/ChildTest.java

@@ -0,0 +1,20 @@
+package top.fjy8018.designpattern.principle.liskovsubstitution.method.input.after;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.HashMap;
+
+class ChildTest {
+
+    @Test
+    void before() {
+
+    }
+
+    @Test
+    void after() {
+        Child child = new Child();
+        // 此时希望调用子类重写的方法，若子类没重写，则应执行父类的方法
+        child.method(new HashMap());
+    }
+}

src/test/java/top/fjy8018/designpattern/principle/openclose/JavaCourseTest.java

@@ -32,8 +32,8 @@ class JavaCourseTest {
         Course course = new JavaDiscountCourse(1, "Java课程", new BigDecimal("99"));
         JavaDiscountCourse javaCourse = (JavaDiscountCourse) course;
         log.info("课程Id：{},课程名称：{},原价：{},折后价格：{}",
-                javaCourse.getId(), javaCourse.getName(), javaCourse.getOriginPrice(),
+                javaCourse.getId(), javaCourse.getName(), javaCourse.getPrice(),
-                javaCourse.getPrice().setScale(2, BigDecimal.ROUND_HALF_UP));
+                javaCourse.getDistcountPrice().setScale(2, BigDecimal.ROUND_HALF_UP));
     }
 
 }