使用责任链模式简化if-else代码示例

使用责任链模式简化if-else代码示例：

package com.siasun.java8.function.responsibility;

import java.math.BigDecimal;

/**
 * 使用责任链模式简化if-else代码
 * @author : wanggang
 * @create 2025/7/15 9:01
 */
public class ChainofResponsibilityDemo {

  //定义责任链
  public static Handler handler = new Handler1();

  static {
    Handler handler2 = new Handler2();

    Handler handler3 = new Handler3();
    handler.setNextHandler(handler2);

    handler2.setNextHandler(handler3);
  }

  public static void main(String[] args) {
    BigDecimal yearIncome1 = new BigDecimal(28000);

    BigDecimal tax1 = handler.handleRequest(yearIncome1);

    System.out.println("个人所得税为：" + tax1);

    BigDecimal yearIncome2 = new BigDecimal(124000);

    BigDecimal tax2 = handler.handleRequest(yearIncome2);

    System.out.println("个人所得税为：" + tax2);

    BigDecimal yearIncome3 = new BigDecimal(180000);

    BigDecimal tax3 = handler.handleRequest(yearIncome3);

    System.out.println("个人所得税为：" + tax3);
  }

  public abstract static class Handler {

    protected Handler nextHandler;

    public void setNextHandler(Handler nextHandler) {
      this.nextHandler = nextHandler;
    }

    public abstract BigDecimal handleRequest(BigDecimal yearIncome);

    public abstract boolean canHandle(BigDecimal yearIncome);
  }

  public static class Handler1 extends Handler {

    @Override
    public BigDecimal handleRequest(BigDecimal yearIncome) {
      if (canHandle(yearIncome)) {
        return yearIncome.multiply(BigDecimal.valueOf(0.1));
      } else {
        if (null != nextHandler) {
          return nextHandler.handleRequest(yearIncome);
        } else {
          return BigDecimal.ZERO;
        }
      }
    }

    @Override
    public boolean canHandle(BigDecimal yearIncome) { // 处理36000以下的
      return yearIncome.compareTo(BigDecimal.valueOf(36000)) < 0;
    }
  }

  public static class Handler2 extends Handler {

    @Override
    public BigDecimal handleRequest(BigDecimal yearIncome) {
      if (canHandle(yearIncome)) {
        return yearIncome.multiply(BigDecimal.valueOf(0.2));
      } else {
        if (null != nextHandler) {
          return nextHandler.handleRequest(yearIncome);
        } else {
          return BigDecimal.ZERO;
        }
      }
    }

    @Override
    public boolean canHandle(BigDecimal yearIncome) { // 36000(含)-144000(不含)
      return (
        yearIncome.compareTo(BigDecimal.valueOf(36000)) >= 0 &&
        yearIncome.compareTo(BigDecimal.valueOf(144000)) < 0
      );
    }
  }

  public static class Handler3 extends Handler {

    @Override
    public BigDecimal handleRequest(BigDecimal yearIncome) {
      if (canHandle(yearIncome)) {
        return yearIncome.multiply(BigDecimal.valueOf(0.3));
      } else {
        if (null != nextHandler) {
          return nextHandler.handleRequest(yearIncome);
        } else {
          return BigDecimal.ZERO;
        }
      }
    }

    @Override
    public boolean canHandle(BigDecimal yearIncome) { // 大于等于144000
      return yearIncome.compareTo(BigDecimal.valueOf(144000)) >= 0;
    }
  }
}

 

使用Function Interface简化if-else代码示例