使用注解 + 策略模式，减少代码中的if/switch语句，增加代码灵活性
需求描述
现在我们有一个接受供应商订单状态通知的接口，目前支持的功能有退款，改签，后续可能需要接入新功能，比如航变，订单状态改变之类。接口的请求格式一致，接口如下：
基本解决方案：使用switch或if
请求
package com.ahut.contract.flight;
/**
* @desc : 供应商通知请求
* @author : cheng
* @date : 2019-03-04 21:18
*/
public class VendorOrderNotifyRequest {
/**
* 数据
*/
private String data;
/**
* 依据tag判断事件类型
*/
private String tag;
/**
* 创建时间
*/
private long createTime;
/**
* 签名
*/
private String sign;
public String getData() {
return data;
}
public void setData(String data) {
this.data = data;
}
public String getTag() {
return tag;
}
public void setTag(String tag) {
this.tag = tag;
}
public long getCreateTime() {
return createTime;
}
public void setCreateTime(long createTime) {
this.createTime = createTime;
}
public String getSign() {
return sign;
}
public void setSign(String sign) {
this.sign = sign;
}
}
响应
package com.ahut.contract.flight;
/**
* @desc : 供应商通知响应
* @author : cheng
* @date : 2019-03-04 21:21
*/
public class VendorOrderNotifyResponse {
private int code;
private String message;
public int getCode() {
return code;
}
public void setCode(int code) {
this.code = code;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}
请求统一入口接口
package com.ahut.flight.service;
import com.ahut.contract.flight.VendorOrderNotifyRequest;
import com.ahut.contract.flight.VendorOrderNotifyResponse;
/**
* @desc :
* @author : cheng
* @date : 2019-03-04 21:16
*/
public interface VendorOrderNotifyService {
/**
* @desc :
* @author : cheng
* @date : 2019-03-04 21:24
*/
VendorOrderNotifyResponse orderNotify(VendorOrderNotifyRequest request);
}
使用if/switch
package com.ahut.flight.service.impl;
import com.ahut.contract.flight.VendorOrderNotifyRequest;
import com.ahut.contract.flight.VendorOrderNotifyResponse;
import com.ahut.flight.service.OrderNotifyContextService;
import com.ahut.flight.service.OrderNotifyHandleService;
import com.ahut.flight.service.VendorOrderNotifyService;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.Optional;
@Service
public class VendorOrderNotifyServiceImpl implements VendorOrderNotifyService {
/**
* @desc :
* @author : cheng
* @date : 2019-03-04 21:25
*/
@Override
public VendorOrderNotifyResponse orderNotify(VendorOrderNotifyRequest request) {
String tag = Optional.ofNullable(request).map(VendorOrderNotifyRequest::getTag).orElse("");
if (StringUtils.equals(tag, "change")) {
// 改签
} else if (StringUtils.equals(tag, "refund")) {
// 退款
} else {
// 不支持
}
switch (tag) {
case "change":
// 改签
break;
case "refund":
// 退款
break;
default:
// 不支持
}
return null;
}
}
缺点：代码不灵活，下次新增功能时，需要修改现有代码（增加if分支或者switch分支）
优化：使用注解 + 策略模式
定义注解
package com.ahut.common.annotation;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* @desc :
* @author : cheng
* @date : 2019-03-04 21:56
*/
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
public @interface RequestTag {
public String value() default "";
}
定义处理请求data的统一接口
package com.ahut.flight.service;
import com.ahut.contract.flight.VendorOrderNotifyResponse;
/**
* @desc : 处理请求
* @author : cheng
* @date : 2019-03-04 21:29
*/
public interface OrderNotifyHandleService {
/**
* @desc :
* @author : cheng
* @date : 2019-03-04 21:46
*/
VendorOrderNotifyResponse orderNotify(String data);
}
实现统一接口，退款，使用自定义注解
package com.ahut.flight.service.impl;
import com.ahut.common.annotation.RequestTag;
import com.ahut.contract.flight.VendorOrderNotifyResponse;
import com.ahut.flight.service.OrderNotifyHandleService;
import org.springframework.stereotype.Service;
/**
* @desc : 退款
* @author : cheng
* @date : 2019-03-04 21:50
*/
@Service("RefundNotifyHandleServiceImpl")
@RequestTag("refund")
public class RefundNotifyHandleServiceImpl implements OrderNotifyHandleService {
/**
* @desc :
* @author : cheng
* @date : 2019-03-04 22:11
*/
@Override
public VendorOrderNotifyResponse orderNotify(String data) {
VendorOrderNotifyResponse response = new VendorOrderNotifyResponse();
response.setCode(0);
response.setMessage("处理退票通知");
return response;
}
}
实现统一接口，改签，使用自定义注解
package com.ahut.flight.service.impl;
import com.ahut.common.annotation.RequestTag;
import com.ahut.contract.flight.VendorOrderNotifyResponse;
import com.ahut.flight.service.OrderNotifyHandleService;
import org.springframework.stereotype.Service;
/**
* @desc : 改签
* @author : cheng
* @date : 2019-03-04 21:50
*/
@Service("ChangeNotifyHandleServiceImpl")
@RequestTag("change")
public class ChangeNotifyHandleServiceImpl implements OrderNotifyHandleService {
/**
* @desc :
* @author : cheng
* @date : 2019-03-04 22:04
*/
@Override
public VendorOrderNotifyResponse orderNotify(String data) {
VendorOrderNotifyResponse response = new VendorOrderNotifyResponse();
response.setCode(0);
response.setMessage("处理改签通知");
return response;
}
}
实现统一接口，不支持的tag，使用自定义注解
package com.ahut.flight.service.impl;
import com.ahut.common.annotation.RequestTag;
import com.ahut.contract.flight.VendorOrderNotifyResponse;
import com.ahut.flight.service.OrderNotifyHandleService;
import org.springframework.stereotype.Service;
/**
* @desc : 不支持
* @author : cheng
* @date : 2019-03-05 22:11
*/
@Service("NonSupportNotifyHandleServiceImpl")
@RequestTag("nonsupport")
public class NonSupportNotifyHandleServiceImpl implements OrderNotifyHandleService {
/**
* @desc :
* @author : cheng
* @date : 2019-03-05 22:12
*/
@Override
public VendorOrderNotifyResponse orderNotify(String data) {
VendorOrderNotifyResponse response = new VendorOrderNotifyResponse();
response.setCode(0);
response.setMessage("不支持的通知");
return response;
}
}
定义上下文接口，依据tag，返回具体的处理实例
package com.ahut.flight.service;
/**
* @desc : 上下文
* @author : cheng
* @date : 2019-03-04 21:27
*/
public interface OrderNotifyContextService {
/**
* @desc :
* @author : cheng
* @date : 2019-03-04 22:04
*/
OrderNotifyHandleService getContext(String tag);
}
上下文实现
package com.ahut.flight.service.impl;
import com.ahut.common.annotation.RequestTag;
import com.ahut.flight.service.OrderNotifyContextService;
import com.ahut.flight.service.OrderNotifyHandleService;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import javax.annotation.Resource;
import java.util.List;
/**
* @desc : 上下文
* @author : cheng
* @date : 2019-03-04 22:05
*/
@Service
public class OrderNotifyContextServiceImpl implements OrderNotifyContextService {
@Autowired
private List handleServiceList;
@Resource(name = "NonSupportNotifyHandleServiceImpl")
private OrderNotifyHandleService nonsupportService;
@Override
public OrderNotifyHandleService getContext(String tag) {
if (StringUtils.isBlank(tag)) {
return nonsupportService;
}
// 对比注解中的value和tag
OrderNotifyHandleService handleService = handleServiceList.stream()
.filter(f -> StringUtils.equals(tag, f.getClass().getAnnotation(RequestTag.class).value()))
.findFirst()
.orElse(nonsupportService);
return handleService;
}
}
实现请求统一入口
package com.ahut.flight.service.impl;
import com.ahut.contract.flight.VendorOrderNotifyRequest;
import com.ahut.contract.flight.VendorOrderNotifyResponse;
import com.ahut.flight.service.OrderNotifyContextService;
import com.ahut.flight.service.OrderNotifyHandleService;
import com.ahut.flight.service.VendorOrderNotifyService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.Optional;
@Service
public class VendorOrderNotifyServiceImpl implements VendorOrderNotifyService {
/**
* 持有上下文
*/
@Autowired
private OrderNotifyContextService contextService;
/**
* @desc :
* @author : cheng
* @date : 2019-03-04 21:25
*/
@Override
public VendorOrderNotifyResponse orderNotify(VendorOrderNotifyRequest request) {
String tag = Optional.ofNullable(request).map(VendorOrderNotifyRequest::getTag).orElse("");
OrderNotifyHandleService handleService = contextService.getContext(tag);
VendorOrderNotifyResponse response = handleService.orderNotify(request.getData());
return response;
}
}
总结
增加了代码的灵活性
符合开闭原则
新增功能时，不用修改原有的代码，直接实现接口即可
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原文链接：https://blog.csdn.net/qq_28988969/article/details/88209001