策略模式与模板方法模式

当前位置:

首页 > 编程开发 > Java教程 >

策略模式与模板方法模式

1. 策略模式

策略模式是一种行为设计模式，它能让你定义一系列算法，并将每种算法分别放入独立的类中，以使算法的对象能够相互替换。

当你有许多仅在执行某些行为时略有不同的相似类时，可使用策略模式。使用该模式能将类的业务逻辑与其算法实现细节隔离开来。

说白了，其实还是解耦

策略模式的结构如上图所示，主要包含三个角色：

抽象角色：通常是一个接口
具体角色：接口的具体实现
环境角色：调用接口的上下文环境，通常是一段业务逻辑方法

举个常见的例子：支付

先定义一个接口 PayStrategy.java

package com.example.service;

import com.example.domain.dto.PayDTO;
import com.example.domain.dto.PayDetailDTO;

/**
 * @author ChengJianSheng
 * @date 2021/1/11
 */
public interface PayStrategy {

    /**
     * 下单
     */
    PayDTO prepay();

    /**
     * 查询
     */
    PayDetailDTO query();

    /**
     * 撤销
     */
    void cancel();

    /**
     * 退款
     */
    void refund();

}

然后是具体实现

AlipayStrategy.java

package com.example.service.impl;

import com.alipay.api.AlipayClient;
import com.alipay.api.request.AlipayTradePrecreateRequest;
import com.alipay.api.response.AlipayTradeCancelResponse;
import com.example.domain.dto.PayDTO;
import com.example.domain.dto.PayDetailDTO;
import com.example.service.PayStrategy;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

/**
 * https://opendocs.alipay.com/open/common/abilitymap
 * https://opendocs.alipay.com/open/194/106078
 * 扫码支付
 */
@Component
public class AlipayStrategy implements PayStrategy {

    @Autowired
    private AlipayClient alipayClient;

    @Override
    public PayDTO prepay() {
        AlipayTradePrecreateRequest request = new AlipayTradePrecreateRequest();
        AlipayTradeCancelResponse response = alipayClient.execute(request);
        return null;
    }

    @Override
    public PayDetailDTO query() {
        return null;
    }

    @Override
    public void cancel() {

    }

    @Override
    public void refund() {

    }

    public void payNotify(String data) {

    }

    public void refundNotify() {

    }
}

WeixinPayStrategy.java

package com.example.service.impl;

import com.example.domain.dto.PayDTO;
import com.example.domain.dto.PayDetailDTO;
import com.example.service.PayStrategy;
import com.github.binarywang.wxpay.bean.notify.WxPayOrderNotifyResult;
import com.github.binarywang.wxpay.bean.request.WxPayOrderQueryRequest;
import com.github.binarywang.wxpay.bean.request.WxPayUnifiedOrderRequest;
import com.github.binarywang.wxpay.service.WxPayService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

/**
 * https://pay.weixin.qq.com/wiki/doc/apiv3/wxpay/pages/index.shtml
 * https://github.com/Wechat-Group/WxJava/wiki/%E5%BE%AE%E4%BF%A1%E6%94%AF%E4%BB%98
 * @author ChengJianSheng
 * @date 2021/1/11
 */
@Component
public class WeixinPayStrategy implements PayStrategy {

    @Autowired
    private WxPayService wxPayService;

    @Override
    public PayDTO prepay() {
        WxPayUnifiedOrderRequest request = new WxPayUnifiedOrderRequest();
        wxPayService.createOrder(request);
        return null;
    }

    @Override
    public PayDetailDTO query() {
        WxPayOrderQueryRequest request = new WxPayOrderQueryRequest();
        wxPayService.queryOrder(request);
        return null;
    }

    @Override
    public void cancel() {

    }

    @Override
    public void refund() {

    }

    public void payNotify(String data) {
        WxPayOrderNotifyResult result = wxPayService.parseOrderNotifyResult(data);
    }

    public void refundNotify(String data) {
        WxPayOrderNotifyResult result = wxPayService.parseRefundNotifyResult(data);
    }
}

上下文

package com.example.service.impl;

import com.example.domain.dto.PayDTO;
import com.example.service.PayService;
import com.example.service.PayStrategy;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

/**
 * @author ChengJianSheng
 * @date 2021/1/11
 */
@Service
public class PayServiceImpl implements PayService {
    @Autowired
    private AlipayStrategy alipayStrategy;
    @Autowired
    private WeixinPayStrategy weixinPayStrategy;

    @Override
    public void prePay(PayDTO payDTO) {
        //  创建支付订单
        //  组装参数
        PayStrategy payStrategy = null;
        if (payDTO.getChannel() == 1) {
            payStrategy = alipayStrategy;
        } else {
            payStrategy = weixinPayStrategy;
        }

        payStrategy.prepay();

    }
}

这样就将算法的细节与业务逻辑隔离开，开发始终要遵循的原则是：高内聚，低耦合

其余部分代码补充如下：

pom.xml

<dependency>
    <groupId>com.alipay.sdk</groupId>
    <artifactId>alipay-sdk-java</artifactId>
    <version>4.11.8.ALL</version>
</dependency>
<dependency>
    <groupId>com.github.binarywang</groupId>
    <artifactId>weixin-java-pay</artifactId>
    <version>4.0.0</version>
</dependency>

AlipayConfig.java

package com.example.config;

import com.alipay.api.AlipayClient;
import com.alipay.api.DefaultAlipayClient;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * 扫码支付
 * https://opendocs.alipay.com/open/194/106078
 * https://opendocs.alipay.com/open/common/abilitymap
 *
 * @author ChengJianSheng
 * @date 2021/1/11
 */
@Configuration
public class AlipayConfig {
    @Value("${alipay.appId}")
    private String appId;
    @Value("${alipay.privateKey}")
    private String privateKey;
    @Value("${alipay.publicKey}")
    private String publicKey;

    @Bean
    public AlipayClient alipayClient() {
        AlipayClient alipayClient = new DefaultAlipayClient("https://openapi.alipay.com/gateway.do", appId, privateKey, "json", "UTF-8", publicKey, "RSA2");
        return alipayClient;
    }
}

WeixinPayConfig.java

package com.example.config;

import com.github.binarywang.wxpay.config.WxPayConfig;
import com.github.binarywang.wxpay.service.WxPayService;
import com.github.binarywang.wxpay.service.impl.WxPayServiceImpl;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * https://pay.weixin.qq.com/wiki/doc/apiv3/index.shtml
 * https://github.com/Wechat-Group/WxJava/wiki/%E5%BE%AE%E4%BF%A1%E6%94%AF%E4%BB%98
 * @author ChengJianSheng
 * @date 2021/1/11
 */
@Configuration
public class WeixinPayConfig {
    /**
     * 公众号appid
     */
    @Value("${weixin.pay.appId}")
    private String appId;
    /**
     * 商户号.
     */
    @Value("${weixin.pay.mchId}")
    private String mchId;
    /**
     * 商户密钥.
     */
    @Value("${weixin.pay.mchKey}")
    private String mchKey;

    @Value("${weixin.pay.notifyUrl}")
    private String notifyUrl;

    @Bean
    public WxPayService wxPayService() {
        WxPayConfig payConfig = new WxPayConfig();
        payConfig.setAppId(appId);
        payConfig.setMchId(mchId);
        payConfig.setMchKey(mchKey);
        payConfig.setNotifyUrl(notifyUrl);

        WxPayService wxPayService = new WxPayServiceImpl();
        wxPayService.setConfig(payConfig);
        return wxPayService;
    }
}