提交策略模式代码

Author: bebee4java

pom.xml

@@ -10,6 +10,7 @@
 
  <modules>
  <module>singleton</module>
+ <module>strategy</module>
  </modules>
 
  <dependencies>

singleton/src/main/java/os/dt/design/patterns/singleton/EnumPresident.java

@@ -2,7 +2,7 @@
 
 /**
  * 枚举式
- * 不仅线程安全，还可以反序列化
+ * 不仅线程安全，还可以反序列化 (原因是枚举类没有构造方法)
  * （有点别扭）
  * Created by songgr on 2019/10/17.
  */

singleton/src/main/java/os/dt/design/patterns/singleton/InitializingOnDemandHolderPresident.java

@@ -13,13 +13,13 @@ private InitializingOnDemandHolderPresident(){
  }
 
  // 可以做到延迟加载
- private static class HelperHolder {
+ private static class SingletonHolder {
  private static final InitializingOnDemandHolderPresident INSTANCE =
  new InitializingOnDemandHolderPresident();
  }
 
  public static InitializingOnDemandHolderPresident getInstance() {
- return HelperHolder.INSTANCE;
+ return SingletonHolder.INSTANCE;
  }
 
 }

singleton/src/test/java/os/dt/design/patterns/singleton/UnitTest.java

@@ -133,7 +133,7 @@ public void enumPresident() throws InterruptedException {
 
  @After
  public void check() {
- assert objs.size() > 1;
+ assert objs.size() == 4;
 
  for (int i=0; i<objs.size()-1; i++){
  for (int j=i+1; j<objs.size(); j++){

strategy/pom.xml

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+ xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+ xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+ <parent>
+ <artifactId>java-design-patterns</artifactId>
+ <groupId>os.dt.design.patterns</groupId>
+ <version>1.0-SNAPSHOT</version>
+ </parent>
+ <modelVersion>4.0.0</modelVersion>
+
+ <artifactId>strategy</artifactId>
+
+
+</project>

strategy/src/main/java/os/dt/design/patterns/strategy/Class.java

@@ -0,0 +1,30 @@
+package os.dt.design.patterns.strategy;
+
+/**
+ * Created by songgr on 2020/05/27.
+ */
+public class Class implements Comparable<Class> {
+ // 班级编号
+ int cid;
+ // 语文平均成绩
+ int chinese;
+ // 数学平成绩
+ int math;
+
+ public Class(int cid, int chinese, int math) {
+ this.cid = cid;
+ this.chinese = chinese;
+ this.math = math;
+ }
+
+ public int compareTo(Class o) {
+ if (this.chinese > o.chinese) return 1;
+ else if (this.chinese < o.chinese) return -1;
+ else return 0;
+ }
+
+ @Override
+ public String toString() {
+ return "{cid:"+cid+",chinese:"+chinese+",math:"+math+"}";
+ }
+}

strategy/src/main/java/os/dt/design/patterns/strategy/SortApp.java

@@ -0,0 +1,66 @@
+package os.dt.design.patterns.strategy;
+
+import java.util.*;
+
+/**
+ * Created by songgr on 2020/05/27.
+ */
+public class SortApp {
+
+ public static void main(String[] args) {
+
+ Student[] arr = {new Student(1, 90, 100),
+ new Student(2, 80, 89),
+ new Student(3, 91, 90)
+ };
+
+// Class[] arr = {new Class(1, 90, 100),
+// new Class(2, 80, 89),
+// new Class(3, 91, 90)
+// };
+
+
+ new Sorters<Student>().sort(arr, StudentStrategyEnum.MATH.strategy());
+ System.out.println(Arrays.toString(arr));
+
+ Sorter sorter = new Sorter();
+ sorter.sort_v1(arr);
+ System.out.println(Arrays.toString(arr));
+
+
+
+
+// new Sorters<Class>().sort(arr, new Comparator<Class>() {
+// public int compare(Class o1, Class o2) {
+// if (o1.chinese > o2.chinese) return 1;
+// else if (o1.chinese < o2.chinese) return -1;
+// else return 0;
+// }
+// });
+//
+// System.out.println(Arrays.toString(arr));
+
+
+// new Sorters<Class>().sort(arr, new Comparator<Class>() {
+// public int compare(Class o1, Class o2) {
+// if (o1.math > o2.math) return 1;
+// else if (o1.math < o2.math) return -1;
+// else return 0;
+// }
+// });
+//
+// System.out.println(Arrays.toString(arr));
+
+
+ List<Integer> list = new ArrayList<Integer>();
+ list.add(3);list.add(1);list.add(2);
+ Collections.sort(list, new Comparator<Integer>() {
+ public int compare(Integer o1, Integer o2) {
+ if (o1 > o2) return 1;
+ else if (o1 < o2) return -1;
+ else return 0;
+ }
+ });
+ System.out.println(list);
+ }
+}

strategy/src/main/java/os/dt/design/patterns/strategy/Sorter.java

@@ -0,0 +1,65 @@
+package os.dt.design.patterns.strategy;
+
+import java.util.Comparator;
+
+/**
+ * 排序者
+ * Created by songgr on 2019/10/22.
+ */
+public class Sorter {
+
+ // 只能对student进行排序
+ public void sort_v1(Student[] arr) {
+ for (int i=0; i<arr.length-1; i++){
+ int minPos = i;
+ for (int j=i+1; j<arr.length; j++){
+ minPos = arr[j].compareTo(arr[minPos]) == -1 ? j : minPos;
+ }
+ swap(arr, i, minPos);
+ }
+ }
+
+ void swap(Student[] arr, int i, int j) {
+ Student temp = arr[i];
+ arr[i] = arr[j];
+ arr[j] = temp;
+ }
+
+ // 能对所有的Comparable对象进行排序, 但是比较方法不能修改
+ public void sort_v2(Comparable[] arr) {
+ for (int i=0; i<arr.length-1; i++){
+ int minPos = i;
+ for (int j=i+1; j<arr.length; j++){
+ minPos = arr[j].compareTo(arr[minPos]) == -1 ? j : minPos;
+ }
+ swap(arr, i, minPos);
+ }
+ }
+
+
+ void swap(Comparable[] arr, int i, int j) {
+ Comparable temp = arr[i];
+ arr[i] = arr[j];
+ arr[j] = temp;
+ }
+
+}
+
+
+class Sorters<T> {
+ public void sort(T[] arr, Comparator<T> comparator) {
+ for (int i=0; i<arr.length-1; i++){
+ int minPos = i;
+ for (int j=i+1; j<arr.length; j++){
+ minPos = comparator.compare(arr[j],arr[minPos]) == -1 ? j : minPos;
+ }
+ swap(arr, i, minPos);
+ }
+ }
+
+ void swap(T[] arr, int i, int j) {
+ T temp = arr[i];
+ arr[i] = arr[j];
+ arr[j] = temp;
+ }
+}

strategy/src/main/java/os/dt/design/patterns/strategy/Student.java

@@ -0,0 +1,64 @@
+package os.dt.design.patterns.strategy;
+
+import java.util.Comparator;
+
+/**
+ * Created by songgr on 2020/05/27.
+ */
+public class Student implements Comparable<Student> {
+
+ // 学号
+ int sid;
+ // 语文成绩
+ int chinese;
+ // 数学成绩
+ int math;
+
+ public Student(int sid, int chinese, int math) {
+ this.sid = sid;
+ this.chinese = chinese;
+ this.math = math;
+ }
+
+ public int compareTo(Student o) {
+ if (this.chinese > o.chinese) return 1;
+ else if (this.chinese < o.chinese) return -1;
+ else return 0;
+ }
+
+ @Override
+ public String toString() {
+ return "{sid:"+sid+",chinese:"+chinese+",math:"+math+"}";
+ }
+}
+
+enum StudentStrategyEnum {
+ CHINESE {
+ @Override
+ public Comparator strategy(){
+ return new Comparator<Student>(){
+ public int compare (Student o1, Student o2){
+ if (o1.chinese > o2.chinese) return 1;
+ else if (o1.chinese < o2.chinese) return -1;
+ else return 0;
+ }
+ };
+ }
+ },
+
+ MATH {
+ @Override
+ public Comparator strategy(){
+ return new Comparator<Student>(){
+ public int compare (Student o1, Student o2){
+ if (o1.math > o2.math) return 1;
+ else if (o1.math < o2.math) return -1;
+ else return 0;
+ }
+ };
+ }
+ };
+
+ public abstract Comparator strategy();
+}
+