介绍

使用一个单独的类去实现创建实例的过程。实现要操作类和实际操作类的解耦，增加程序可扩展性。

使用

public class SimpleFactory {    public static void main(String[] args) {        Operation operation = OperationFactory.createOperation("+");        operation.setNumberA(1);        operation.setNumberB(4);        System.out.println(operation.getResult());    }}/** * 抽象操作类 */abstract class Operation{    private double numberA;    private double numberB;    public double getNumberA() {        return numberA;    }    public void setNumberA(double numberA) {        this.numberA = numberA;    }    public double getNumberB() {        return numberB;    }    public void setNumberB(double numberB) {        this.numberB = numberB;    }    public abstract double getResult();}/** * 加法操作 */class OperationAdd extends Operation{    @Override    public double getResult() {        return getNumberA() + getNumberB();    }}/** * 减法操作 */class OperationSub extends Operation{    @Override    public double getResult() {        return getNumberA() - getNumberB();    }}/** * 乘法操作 */class OperationMul extends Operation{    @Override    public double getResult() {        return getNumberA() * getNumberB();    }}/** * 除法操作 */class OperationDiv extends Operation{    @Override    public double getResult() {        if (getNumberB() == 0){            try {                throw new Exception("除数不能为0");            } catch (Exception e) {                e.printStackTrace();            }        }        return getNumberA() / getNumberB();    }}/** * 操作工厂类 */class OperationFactory{    public static Operation createOperation(String operation){        if (operation.equals("+")){            return new OperationAdd();        } else if (operation.equals("-")){            return new OperationSub();        } else if (operation.equals("*")){            return new OperationMul();        } else {            return new OperationDiv();        }    }}复制代码