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heibaiyingheibaiying
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设计模式
1 parent 6cd2987 commit 6858a78

17 files changed

Lines changed: 694 additions & 17 deletions

‎code/Java/design-pattern/EnumSingletonFile‎

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‎code/Java/design-pattern/SingletonFile‎

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‎code/Java/design-pattern/src/main/java/com/heibaiying/creational/simple_factory/PhoneFactory.java‎

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Original file line numberDiff line numberDiff line change
@@ -14,15 +14,10 @@ public Phone getPhone(String type) {
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public Phone getPhone(Class<? extends Phone> phoneClass) {
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try {
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return (Phone) Class.forName(phoneClass.getName()).newInstance();
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} catch (InstantiationException e) {
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e.printStackTrace();
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} catch (IllegalAccessException e) {
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e.printStackTrace();
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} catch (ClassNotFoundException e) {
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} catch (InstantiationException | IllegalAccessException | ClassNotFoundException e) {
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e.printStackTrace();
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}
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return null;
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}
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}

‎code/Java/design-pattern/src/main/java/com/heibaiying/creational/singleton/DoubleCheckLazySingletonSafe.java‎

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package com.heibaiying.creational.singleton;
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/**
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* 使用双重检查锁来保证线程安全
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*/
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public class DoubleCheckLazySingletonSafe {
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private static volatile DoubleCheckLazySingletonSafe instance = null;
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private DoubleCheckLazySingletonSafe() {
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}
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public static DoubleCheckLazySingletonSafe getInstance() {
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if (instance == null) {
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synchronized (DoubleCheckLazySingletonSafe.class) {
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if (instance == null) {
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instance = new DoubleCheckLazySingletonSafe();
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}
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}
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}
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return instance;
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}
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}

‎code/Java/design-pattern/src/main/java/com/heibaiying/creational/singleton/EnumInstance.java‎

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package com.heibaiying.creational.singleton;
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/**
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* 利用枚举实现单例
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*/
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public enum EnumInstance {
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INSTANCE;
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private String field;
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public String getField() {
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return field;
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}
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public void setField(String field) {
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this.field = field;
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}
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public static EnumInstance getInstance() {
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return INSTANCE;
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}
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}

‎code/Java/design-pattern/src/main/java/com/heibaiying/creational/singleton/EnumInstanceTest.java‎

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package com.heibaiying.creational.singleton;
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import java.io.*;
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import java.lang.reflect.Constructor;
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public class EnumInstanceTest {
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public static void main(String[] args) throws Exception {
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// 序列化攻击
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EnumInstance instance = EnumInstance.getInstance();
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ObjectOutputStream outputStream = new ObjectOutputStream(new FileOutputStream("EnumSingletonFile"));
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outputStream.writeObject(instance);
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ObjectInputStream inputStream = new ObjectInputStream(new FileInputStream(new File("EnumSingletonFile")));
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EnumInstance newInstance = (EnumInstance) inputStream.readObject();
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System.out.println(instance == newInstance);
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// 反射攻击，Enum类中只有一个两个参数的构造器：Enum(String name, int ordinal)
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Constructor<EnumInstance> constructor = EnumInstance.class.getDeclaredConstructor(String.class, int.class);
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constructor.setAccessible(true);
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EnumInstance enumInstance = constructor.newInstance("name", 0);
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System.out.println(instance == enumInstance);
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}
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}

‎code/Java/design-pattern/src/main/java/com/heibaiying/creational/singleton/HungrySingleton.java‎

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package com.heibaiying.creational.singleton;
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import java.io.Serializable;
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/**
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* 利用静态代码块来实现饿汉式单例
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*/
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public class HungrySingleton implements Serializable {
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private static final HungrySingleton instance;
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static {
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instance = new HungrySingleton();
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}
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private HungrySingleton() {
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if (instance != null) {
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throw new RuntimeException("单例模式禁止反射调用");
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}
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}
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public static HungrySingleton getInstance() {
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return instance;
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}
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private Object readResolve() {
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return instance;
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}
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}

‎code/Java/design-pattern/src/main/java/com/heibaiying/creational/singleton/LazySingletonUnsafe.java‎

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package com.heibaiying.creational.singleton;
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/**
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* 线程不安全的懒汉式单例模式
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*/
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public class LazySingletonUnsafe {
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private static LazySingletonUnsafe instance = null;
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private LazySingletonUnsafe() {
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}
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public static LazySingletonUnsafe getInstance() {
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if (instance == null) {
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instance = new LazySingletonUnsafe();
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}
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return instance;
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}
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}

‎code/Java/design-pattern/src/main/java/com/heibaiying/creational/singleton/ReflectionDamage.java‎

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package com.heibaiying.creational.singleton;
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import java.lang.reflect.Constructor;
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/**
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* 利用反射破坏单例
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*/
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public class ReflectionDamage {
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public static void main(String[] args) throws Exception {
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Constructor<HungrySingleton> constructor = HungrySingleton.class.getDeclaredConstructor();
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constructor.setAccessible(true);
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HungrySingleton hungrySingleton = constructor.newInstance();
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System.out.println(hungrySingleton);
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}
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}

‎code/Java/design-pattern/src/main/java/com/heibaiying/creational/singleton/SerializationDamage.java‎

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package com.heibaiying.creational.singleton;
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import java.io.*;
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/**
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* 利用序列化破坏单例
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*/
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public class SerializationDamage {
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public static void main(String[] args) throws IOException, ClassNotFoundException {
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HungrySingleton instance = HungrySingleton.getInstance();
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ObjectOutputStream outputStream = new ObjectOutputStream(new FileOutputStream("SingletonFile"));
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outputStream.writeObject(instance);
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ObjectInputStream inputStream = new ObjectInputStream(new FileInputStream(new File("SingletonFile")));
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HungrySingleton newInstance = (HungrySingleton) inputStream.readObject();
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System.out.println(instance == newInstance);
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}
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}

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