Spring 适配模式应用

需求：

完成多通道支付系统，例如支持 微信支付，支付宝支付等，后续会持续集成其他支付通道。

 

条件：

为下游商户提供一个统一的下单接口，根据参数、通道标识码 来调用对就的通道完成下单。

 

思路：

遇到这种情景，首先想到的是使用 适配模式来完成。项目框架是spring 体系，所以要在pring下来做适配模式。解决各种 if  else ，使不同通道代码解耦，并易扩展其他支付通道

 

1.定义一个下单的service接口，每一个支付通道就是一个独立的实现类。因为不同通道中具有相同的业务逻辑，所以上层在抽象一个父类。

 

2.创建一个集中管理和路由的上下文，来管理和路由各个通道实现类。

 

3.因为不同的支付传递的参数也不同，所以可根据接收参数的实体来进行路由。

 

 

代码:

注：按照代码执行顺序列出。

 

package com.zzkx.pay.wechat.controller.test;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.lang3.StringUtils;
import org.json.JSONException;
import org.json.JSONObject;
import org.reflections.Reflections;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.MethodParameter;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;

import com.google.gson.Gson;
import com.zzkx.pay.common.enums.ExpCodeEnum;
import com.zzkx.pay.common.exception.CommonBizException;

/**
 * @author lyy
 */
public class OrderRequestParamResolver implements HandlerMethodArgumentResolver {
	
	private final Logger LOG = LoggerFactory.getLogger(OrderRequestParamResolver.class);
	
	private final Map> map = new HashMap<>();
	
	private final Reflections reflection = new Reflections("com.zzkx");
	
	private final Gson gson = new Gson();
	
	public  OrderRequestParamResolver() {
		
		Set> clazzs = reflection.getTypesAnnotatedWith(PayAnnotation.class);
		for(Class clazz : clazzs) {
			PayAnnotation annotation = AnnotationUtils.getAnnotation(clazz, PayAnnotation.class);
			String code = annotation.value();
			map.put(code, clazz);
		}
	}
	

	@Override
	public boolean supportsParameter(MethodParameter parameter) {
		return parameter.hasMethodAnnotation(PayAnnotation.class);
	}

	@Override
	public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
			NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
		HttpServletRequest httpServletRequest = webRequest.getNativeRequest(HttpServletRequest.class);
		String value = parameter.getMethodAnnotation(PayAnnotation.class).value();
		Object object = requestToBean(httpServletRequest,value);
		return object;
	}
	
	private Object requestToBean(HttpServletRequest request,String name) throws UnsupportedEncodingException, IOException {

		try {
			BufferedReader streamReader = new BufferedReader( new InputStreamReader(request.getInputStream(), "UTF-8"));
			StringBuilder responseStrBuilder = new StringBuilder();
			String inputStr;
			while ((inputStr = streamReader.readLine()) != null)
				responseStrBuilder.append(inputStr);
			
			JSONObject jsonObject = new JSONObject(responseStrBuilder.toString());
			String code = jsonObject.getString(name);
			if(!StringUtils.isNotBlank(code))throw new CommonBizException(ExpCodeEnum.PARAM_INVALID);
			Class clazz = map.get(code);
			if(clazz == null)throw new CommonBizException(ExpCodeEnum.CHANNEL_WITHOUT);
			
			Object object = gson.fromJson(jsonObject.toString(), clazz);
			return object;
		} catch (UnsupportedEncodingException e) {
			LOG.error(e.getMessage(),e);
			new CommonBizException();
		} catch(IOException e) {
			LOG.error(e.getMessage(),e);
			new CommonBizException();
		} catch (JSONException e) {
			throw new CommonBizException(ExpCodeEnum.JSON_INVALID);
		}

		return null;

	}
	

}

package com.zzkx.pay.wechat.controller.test;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * @author lyy
 */
@Target({ElementType.METHOD,ElementType.TYPE})  
@Retention(RetentionPolicy.RUNTIME)  
public @interface PayAnnotation {

	String value();
}

@RestController
public class TestController {
	@Autowired
	private TestService testService;
	
	
	@Autowired
	private PayService