简单工厂模式

普通做法：

      

package com.zhen.build_template.simple_factory.general;

/**
 * @author zhen
 * @Date 2019/5/28 11:13
 */
public interface Sender {
    public void send();
}

package com.zhen.build_template.simple_factory.general;

/**
 * @author zhen
 * @Date 2019/5/28 11:13
 */
public class MailSender implements Sender{
    @Override
    public void send() {
        System.out.println("this is mailSender");
    }
}

package com.zhen.build_template.simple_factory.general;

/**
 * @author zhen
 * @Date 2019/5/28 11:14
 */
public class SmsSender implements Sender {
    @Override
    public void send() {
        System.out.println("this is SmsSender");
    }
}

package com.zhen.build_template.simple_factory.general;

/**
 * @author zhen
 * @Date 2019/5/28 11:15
 */
public class SendFactory {
    public Sender getSenderInstance(String type){
        if ("mail".equals(type)){
            return new MailSender();
        }else if("sms".equals(type)){
            return new SmsSender();
        }else{
            System.out.println("请输入正确的类型");
            return null;
        }
    }
}

package com.zhen.build_template.simple_factory.general;

/**
 * @author zhen
 * @Date 2019/5/28 11:17
 */
public class FactoryTest {
    public static void main(String[] args) {
        SendFactory factory = new SendFactory();
        Sender sender = factory.getSenderInstance("sms");
        sender.send();
    }
}

普通简单工厂有一个问题：

     如果传入的类型是错误的，则得不到对象

多方法类型做法：

package com.zhen.build_template.simple_factory.many_method;


/**
 * @author zhen
 * @Date 2019/5/28 11:15
 */
public class SendFactory {
    public Sender getSmsSenderInstance(){
            return new SmsSender();
    }

    public Sender getMailSenderInstance(){
        return new MailSender();
    }
}

package com.zhen.build_template.simple_factory.many_method;

/**
 * @author zhen
 * @Date 2019/5/28 11:17
 */
public class FactoryTest {
    public static void main(String[] args) {
        SendFactory factory = new SendFactory();
        Sender sender = factory.getMailSenderInstance();
        sender.send();
    }
}

package com.zhen.build_template.simple_factory.many_method;

/**
 * @author zhen
 * @Date 2019/5/28 11:13
 */
public interface Sender {
    public void send();
}

package com.zhen.build_template.simple_factory.many_method;

/**
 * @author zhen
 * @Date 2019/5/28 11:13
 */
public class MailSender implements Sender {
    @Override
    public void send() {
        System.out.println("this is mailSender");
    }
}

package com.zhen.build_template.simple_factory.many_method;

/**
 * @author zhen
 * @Date 2019/5/28 11:14
 */
public class SmsSender implements Sender {
    @Override
    public void send() {
        System.out.println("this is SmsSender");
    }
}

　使用多个方法解决了传入错误类型得不到对象的情况，但是每次创造对象都依赖工厂实例

多静态方法做法：

package com.zhen.build_template.simple_factory.many_static_method;

/**
 * @author zhen
 * @Date 2019/5/28 11:13
 */
public interface Sender {
    public void send();
}

package com.zhen.build_template.simple_factory.many_static_method;

/**
 * @author zhen
 * @Date 2019/5/28 11:13
 */
public class MailSender implements Sender {
    @Override
    public void send() {
        System.out.println("this is mailSender");
    }
}

package com.zhen.build_template.simple_factory.many_static_method;

/**
 * @author zhen
 * @Date 2019/5/28 11:14
 */
public class SmsSender implements Sender {
    @Override
    public void send() {
        System.out.println("this is SmsSender");
    }
}

package com.zhen.build_template.simple_factory.many_static_method;


/**
 * @author zhen
 * @Date 2019/5/28 11:15
 */
public class SendFactory {
    public static Sender getSmsSenderInstance(){
            return new SmsSender();
    }

    public static Sender getMailSenderInstance(){
        return new MailSender();
    }
}


package com.zhen.build_template.simple_factory.many_static_method;

/**
 * @author zhen
 * @Date 2019/5/28 11:17
 */
public class FactoryTest {
    public static void main(String[] args) {
        Sender sender = SendFactory.getMailSenderInstance();
        sender.send();
    }
}

  使用的静态方法方式解决了依赖工厂实例的问题，一般简单工厂都采用第三种。