本文共 5152 字，大约阅读时间需要 17 分钟。
菜鸟的Java设计模式学习总结
单例模式通过确保一个类只创建一个实例来优化资源使用。饿汉式和饥汉式仅在于实例化时机不同，但核心思想相同。
public class SingleObject { private static SingleObject instance = new SingleObject(); private SingleObject() { } public static SingleObject getInstance() { return instance; } public void showMessage() { System.out.println("hello world!"); }} 通过调用Singleton.getInstance()获取唯一实例。
工厂模式通过引入抽象工厂，统一管理对象创建，避免直接暴露实现细节。
public class ShapeFactory { public Shape getShape(String shapeType) { if (shapeType == null) return null; if (shapeType.equalsIgnoreCase("CIRCLE")) return new Circle(); else if (shapeType.equalsIgnoreCase("RECTANGLE")) return new Rectangle(); else if (shapeType.equalsIgnoreCase("SQUARE")) return new Square(); return null; }} // 获取不同形状的实例Shape circle = shapeFactory.getShape("CIRCLE");Shape rectangle = shapeFactory.getShape("RECTANGLE"); 代理模式允许在不修改目标对象代码的情况下增强功能，分为基于子类和接口动态代理。
public class Producer { public void saleProduct(float money) { System.out.println("您好！这里是生产产家的销售..."); } public void afterService(float money) { System.out.println("您好，这里是生产产家的售后..."); }}class MyProxy { public Producer proxy() { Producer producer = new Producer(); return (Producer) Enhancer.create( producer.getClass(), new MethodInterceptor() { public Object intercept(Object obj, Method method, Object[] args, MethodProxy methodProxy) throws Throwable { System.out.println("\t方法被拦截：" + method); Object invoke = null; if ("saleProduct".equals(method.getName())) { invoke = method.invoke(producer, (float) args[0] * 0.8f); } return invoke; } } ); }} public interface IProducer { void saleProduct(float money); void afterService(float money);}class MyProxy implements InvocationHandler { private IProducer target; public MyProxy(IProducer target) { this.target = target; } public void invoke(IProducer target, Method method, Object[] args) throws Throwable { System.out.println("\t方法被拦截：" + method); Object invoke = null; if ("saleProduct".equals(method.getName())) { invoke = method.invoke(target, (float) args[0] * 0.8f); } return invoke; }}public class Test { public static void main(String[] args) { MemoryCard card = new MemoryCard(); Computer computer = new ComputerImpl(); Adapter02 adapter = new Adapter02(card); computer.getContent(); computer.readContent(); }} 适配者模式通过桥接不兼容的接口，实现系统间互操作。
public class MemoryCard { public String content() { return "学习资料\n\t--日韩\n\t--欧美\n\t--国产\n\t--主播"; }}public interface Computer { String getContent(); void readContent();}public class Adapter01 implements Computer { private MemoryCard memoryCard = new MemoryCard(); public String getContent() { System.out.println("内存卡内容读取中..."); String content = memoryCard.content(); System.out.println("内存卡内容读取完成..."); return content; } public void readContent() { String content = getContent(); System.out.println("电脑正在输出读取到的内存卡信息..."); System.out.println("\n电脑读取到的内容：\n" + content); }} public class Adapter02 extends MemoryCard implements Computer { public String getContent() { System.out.println("内存卡内容读取中..."); String content = super.content(); System.out.println("内存卡内容读取完成..."); return content; } public void readContent() { String content = getContent(); System.out.println("电脑正在输出读取到的内存卡信息..."); System.out.println("\n电脑读取到的内容：\n" + content); }} 建造者模式将对象的构建过程分解为独立的步骤，便于管理复杂对象的创建。
public interface IBuilder { void buildGround(); void buildGroundBeam(); void buildFixture(); void buildCement(); void buildRoof(); House getHouse();}public class DefaultBuilder implements IBuilder { protected House house = new House(); public DefaultBuilder() { this.house = new House(); } @Override public void buildGround() { house.setGround("打地基完成"); } @Override public void buildGroundBeam() { house.setGroundBeam("地梁施工完成"); } @Override public void buildFixture() { house.setFixture("钢筋施工完成"); } @Override public void buildCement() { house.setCement("水泥施工完成"); } @Override public void buildRoof() { house.setRoof("屋顶施工完成"); } @Override public House getHouse() { return house; }}public class Director { public static House create(IBuilder builder) { builder.buildGround(); builder.buildGroundBeam(); builder.buildFixture(); builder.buildCement(); builder.buildRoof(); return builder.getHouse(); }} House house = Director.create(new DefaultBuilder());
这些设计模式在软件开发中发挥着重要作用，了解它们的特点和适用场景有助于有效地解决实际问题。通过不断学习和实践，可以更好地掌握这些模式并灵活运用以优化代码质量。
转载地址：http://xomwk.baihongyu.com/