107-*策略模式在Thread和Runnable中的应用分析

Runnable接口与多线程中的哪种设计模式比较接近？

• 策略模式

举例：税收计算器。需多看代码示例，深入理解策略模式。

1. 税收计算器接口。策略模式

   @FunctionalInterface
   public interface CalculatorStrategy {
       /**
        * 计算税率
        *
        * @param salary 薪水
        * @param bonus 奖金
        * @return 税收
        */
       double calculate(double salary, double bonus);
   }

2. 税收计算器实现类

   public class SimpleCalculatorStrategy implements CalculatorStrategy {
       private final static double SALARY_RATE = 0.1;
       private final static double BONUS_RATE = 0.15;
   
       // 计算税率：工资*0.1 + 奖金*0.15
       @Override
       public double calculate(double salary, double bonus) {
           return salary * SALARY_RATE + bonus * BONUS_RATE;
       }
   }

3. 税务计算器。Runnable与多线程设计模式

   @Data
   public class TaxCalculator {
       // 薪水
       private final double salary;
       // 奖金
       private final double bonus;
       private CalculatorStrategy calculatorStrategy;
   
       public TaxCalculator(double salary, double bonus) {
           this.salary = salary;
           this.bonus = bonus;
       }
       public TaxCalculator(double salary, double bonus, CalculatorStrategy calculatorStrategy) {
           this.salary = salary;
           this.bonus = bonus;
           this.calculatorStrategy = calculatorStrategy;
       }
   
       // 计算税率
       protected double calcTax() {
           return calculatorStrategy.calculate(salary, bonus);
       }
   
       // 计算
       public double calculate() {
           return this.calcTax();
       }
   }

4. 税务计算器测试类

   public class TaxCalculatorMain {
       // 1. 模版方法
       @Test
       public void test1() {
           TaxCalculator calculator = new TaxCalculator(10000d, 2000d) {
               @Override
               protected double calcTax() {
                   return getSalary() * 0.1 + getBonus() * 0.15;
               }
           };
           System.out.println(calculator.calculate());
       }
       // 2.1 策略模式
       @Test
       public void test2() {
           TaxCalculator calculator = new TaxCalculator(10000d, 2000d);
           CalculatorStrategy strategy = new SimpleCalculatorStrategy();
           calculator.setCalculatorStrategy(strategy);
           System.out.println(calculator.calculate());
       }
       // 2.2 策略模式-Java8Lambda-1
       @Test
       public void test3() {
           TaxCalculator calculator = new TaxCalculator(10000d, 2000d);
           calculator.setCalculatorStrategy((s, b) -> s * 0.1 + b * 0.15);
           System.out.println(calculator.calculate());
       }
       // 2.2 策略模式-Java8Lambda-2
       @Test
       public void test4() {
           TaxCalculator calculator = new TaxCalculator(10000d, 2000d, (s, b) -> s * 0.1 + b * 0.15);
           System.out.println(calculator.calculate());
       }
   }

通过策略模式的思想改造BankRunnable.java

• 银行大厅

  public class BankRunnable {
      private final static int MAX = 50;
      private int index = 1;
  
      public static void main(String[] args) {
          // 1. 一个runnable实例被多个线程共享
          /*TicketWindowRunnable ticketWindow = new TicketWindowRunnable();*/
          // 2. 策略模式思想改造runnable实例线程
          Runnable ticketWindow = new BankRunnable().getTicketWindow();
  
          Thread windowThread1 = new Thread(ticketWindow, "一号窗口");
          Thread windowThread2 = new Thread(ticketWindow, "二号窗口");
          Thread windowThread3 = new Thread(ticketWindow, "三号窗口");
          windowThread1.start();
          windowThread2.start();
          windowThread3.start();
      }
  
      private Runnable getTicketWindow() {
          return () -> {
              while (index <= MAX) {
                  System.out.println(Thread.currentThread() + " 的号码是:" + (index++));
                  Thread.sleep(100);
              }
          };
      }
  }