wms项目学习（二）

一、接口的异常—初见FallbackFactory

今天在做项目时，发现个很有意思的知识点（自我认为），在这里总结下来。

我在做项目时，需要做一个新的需求，该项目是以前说过的多个服务通过远程调用（remote命名，@RequestMapping(value = “/wms-service/in/wmsinreceipt/listSKInfo”)远程服务匹配的机制）。来看接口。

WmsInReceiptRemote.java

@FeignClient(name = "gateway-server", fallbackFactory = WmsInReceiptRemoteFallBackFactory.class)
public interface WmsInReceiptRemote {

	@RequestMapping(value = "/wms-service/in/wmsinreceipt/listScmMat", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
	R listScmMat(@RequestBody Map params);

    @RequestMapping(value = "/wms-service/in/wmsinreceipt/listSKInfo", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
    public R listSKInfo(@RequestBody Map params);

   @RequestMapping(value = "/wms-service/in/wmsinreceipt/listPOMat", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
   public R listPOMat(@RequestBody Map params);

   @RequestMapping(value = "/wms-service/in/wmsinreceipt/listOutMat", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
   public R listOutMat(@RequestBody Map params);

   @RequestMapping(value = "/wms-service/in/wmsinreceipt/listPOCFMat", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
   public R listPOCFMat(@RequestBody Map params);

   @RequestMapping(value = "/wms-service/in/wmsinreceipt/list303Mat", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
   public R list303Mat(@RequestBody Map params);

   @RequestMapping(value = "/wms-service/in/wmsinreceipt/list303AMat", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
   public R  list303AMat(@RequestBody Map params);

   @RequestMapping(value = "/wms-service/in/wmsinreceipt/listPOAMat", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
   public R  listPOAMat(@RequestBody Map params);

   @RequestMapping(value = "/wms-service/in/wmsinreceipt/listOutAMat", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
   public R  listOutAMat(@RequestBody Map params);

   @RequestMapping(value = "/wms-service/in/wmsinreceipt/boundIn", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
   public R boundIn(@RequestBody Map params);

   @RequestMapping(value = "/wms-service/in/wmsinreceipt/getMatInfo", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
   public R getMatInfo(@RequestParam Map params);

   @RequestMapping(value = "/wms-service/in/wmsinreceipt/getCostMatInfo", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
   public R getCostMatInfo(@RequestParam Map params);

   @RequestMapping(value = "/wms-service/in/wmsinreceipt/info/{qty}")
   public R info(@PathVariable("qty") Long qty);

   @RequestMapping(value = "/wms-service/in/wmsinreceipt/listCloudMat", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
	R listCloudMat(@RequestBody Map params);

   @RequestMapping(value = "/wms-service/in/wmsinreceipt/listCloudMatSyn", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
    R listCloudMatSyn(@RequestBody Map params);

   @RequestMapping(value = "/wms-service/in/wmsinreceipt/getSAPMatDetail", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
    R getSAPMatDetail(@RequestParam(value = "params") Map params);

   @RequestMapping(value = "/wms-service/in/wmsinreceipt/exportExcel", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
   R exportExcel(@RequestParam(value = "params") Map params);

	@RequestMapping(value = "/wms-service/in/wmsinreceipt/listStoMat", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
	R listStoMat(@RequestBody Map params);
}

//   @RequestMapping(value = "/test")   松开测试新加方法
//   R newAddMethod(@RequestBody Map params);

该接口里的所有方法不用管，就是一些业务。而此时我新做了个业务，需要在这里面加一个方法，此时有趣的问题就来了。因为采用的是热部署，不过一会儿（其实就是因为java代码更改重新build的过程）错误信息就出来了。

我就很好奇这个问题，于是就访问相关文件。

WmsInReceiptRemoteFallBackFactory.java

import feign.hystrix.FallbackFactory;

@Component
public class WmsInReceiptRemoteFallBackFactory implements FallbackFactory {

	@Override
	public WmsInReceiptRemote create(Throwable cause) {
		return new WmsInReceiptRemote() {

			@Override
			public R listScmMat(Map params) {
//				return R.error(500, "WMS-BUSINESS-SERVICE服务异常！");
				return R.error(500,LocaleLanguageFactory.getValue("J_WMS_BUSINESS_SERVICEFWYC"));
			}

			@Override
			public R listSKInfo(Map params) {
//				return R.error(500, "WMS-BUSINESS-SERVICE服务异常！");
				return R.error(500,LocaleLanguageFactory.getValue("J_WMS_BUSINESS_SERVICEFWYC"));
			}

			@Override
			public R listPOMat(Map params) {
//				return R.error(500, "WMS-BUSINESS-SERVICE服务异常！");
				return R.error(500,LocaleLanguageFactory.getValue("J_WMS_BUSINESS_SERVICEFWYC"));
			}

			@Override
			public R listOutMat(Map params) {
//				return R.error(500, "WMS-BUSINESS-SERVICE服务异常！");
				return R.error(500,LocaleLanguageFactory.getValue("J_WMS_BUSINESS_SERVICEFWYC"));
			}

			@Override
			public R listPOCFMat(Map params) {
//				return R.error(500, "WMS-BUSINESS-SERVICE服务异常！");
				return R.error(500,LocaleLanguageFactory.getValue("J_WMS_BUSINESS_SERVICEFWYC"));
			}

			@Override
			public R list303Mat(Map params) {
//				return R.error(500, "WMS-BUSINESS-SERVICE服务异常！");
				return R.error(500,LocaleLanguageFactory.getValue("J_WMS_BUSINESS_SERVICEFWYC"));
			}

			@Override
			public R list303AMat(Map params) {
//				return R.error(500, "WMS-BUSINESS-SERVICE服务异常！");
				return R.error(500,LocaleLanguageFactory.getValue("J_WMS_BUSINESS_SERVICEFWYC"));
			}

			@Override
			public R listPOAMat(Map params) {
//				return R.error(500, "WMS-BUSINESS-SERVICE服务异常！");
				return R.error(500,LocaleLanguageFactory.getValue("J_WMS_BUSINESS_SERVICEFWYC"));
			}

			@Override
			public R listOutAMat(Map params) {
//				return R.error(500, "WMS-BUSINESS-SERVICE服务异常！");
				return R.error(500,LocaleLanguageFactory.getValue("J_WMS_BUSINESS_SERVICEFWYC"));
			}

			@Override
			public R boundIn(Map params) {
//				return R.error(500, "WMS-BUSINESS-SERVICE服务异常！");
				return R.error(500,LocaleLanguageFactory.getValue("J_WMS_BUSINESS_SERVICEFWYC"));
			}

			@Override
			public R getMatInfo(Map params) {
//				return R.error(500, "WMS-BUSINESS-SERVICE服务异常！");
				return R.error(500,LocaleLanguageFactory.getValue("J_WMS_BUSINESS_SERVICEFWYC"));
			}

			@Override
			public R getCostMatInfo(Map params) {
//				return R.error(500, "WMS-BUSINESS-SERVICE服务异常！");
				return R.error(500,LocaleLanguageFactory.getValue("J_WMS_BUSINESS_SERVICEFWYC"));
			}

			@Override
			public R info(Long qty) {
//				return R.error(500, "WMS-BUSINESS-SERVICE服务异常！");
				return R.error(500,LocaleLanguageFactory.getValue("J_WMS_BUSINESS_SERVICEFWYC"));
			}

			@Override
			public R listCloudMat(Map params) {
//				return R.error(500, "WMS-BUSINESS-SERVICE服务异常！");
				return R.error(500,LocaleLanguageFactory.getValue("J_WMS_BUSINESS_SERVICEFWYC"));
			}

			@Override
			public R listCloudMatSyn(Map params) {
//				return R.error(500, "WMS-BUSINESS-SERVICE服务异常！");
				return R.error(500,LocaleLanguageFactory.getValue("J_WMS_BUSINESS_SERVICEFWYC"));
			}


			@Override
			public R getSAPMatDetail(Map params) {
//				return R.error(500, "WMS-BUSINESS-SERVICE服务异常！");
				return R.error(500,LocaleLanguageFactory.getValue("J_WMS_BUSINESS_SERVICEFWYC"));
			}

			@Override
			public R exportExcel(Map params) {
//				return R.error(500, "WMS-BUSINESS-SERVICE服务异常！");
				return R.error(500,LocaleLanguageFactory.getValue("J_WMS_BUSINESS_SERVICEFWYC"));
			}

			@Override
			public R listStoMat(Map params) {
//				return R.error(500, "WMS-BUSINESS-SERVICE服务异常！");
				return R.error(500,LocaleLanguageFactory.getValue("J_WMS_BUSINESS_SERVICEFWYC"));
			}
		};
	}

}

报错的原因原来是这里使用了匿名内部类new接口，因为不是abstract的，所以需要完成接口的所有方法。

问题很容易解决，再将没实现的方法实现一下就行了。

不过，吸引我的是为什么会有WmsInReceiptRemoteFallBackFactory这个类？它是干什么的？

看回WmsInReceiptRemoteFallBackFactory的java源码文件，发现其就是再做一件事抛异常，这个类就是只专注做一件事抛异常，于是我就有了大胆的猜测。

1.1、猜测小结

以前学习接口的时候，会发现接口可以带抛出异常，但是我们知道接口是抽象的，而接口的实现类是定性的，同一接口的不同实现类处理方法实现业务可能有自己不同的异常，不同实现类可以自己万紫千红地自己表达自己的异常，如何把这些异常统一起来表达，这就是FallbackFactory在做的。

接口可能有不同的实现类，不同实现类做的同一业务（或者说执行的同一方法）可能有自己不同的异常信息，为了保护这些异常信息不对外，或者为了将这些异常信息总结为同一个信息。也就是说任意实现类执行这个方法出错了（也就是只要这个接口方法执行出错），你在所有实现类写的任意错误信息都不会表达出来，而会同一表达成定义在FallbackFactory的错误信息。这也就是接口的统一异常。

随后，我在网上搜索了FallbackFactory的相关知识。得到了这个结论。Hystrix的功能，当网络不通时返回默认的配置数据。在FeignClient中，可以通过制定fallback，实现在服务不可用时自动调用fallback指定定的处理方法。

关于如何使用（绑定）。

xx接口类，绑定xxFallbackFactory类。也就是加注解@FeignClient(name = “…”, fallbackFactory = xxxFallBackFactory.class)。
xxFallbackFactory类更新create代码。

FallbackFactory的作用理解了，底层怎么实现的不知道，需要后续学习。

上述类R也不用在意，其就是模仿浏览器的状态码，看R源码。

R.java

public class R extends HashMap {
	private static final long serialVersionUID = 1L;
	
	public R() {
		put("code", 0);
		put("msg", "success");
	}
	
	public static R error() {
//		return error(500, "未知异常，请联系管理员");
		return error(500, LocaleLanguageFactory.getValue("J_UK_EXCEP_CONT_ADMIN"));
	}
	
	public static R error(String msg) {
		return error(500, msg);
	}
	
	public static R error(int code, String msg) {
		R r = new R();
		r.put("code", code);
		r.put("msg", msg);
		return r;
	}

	public static R ok(String msg) {
		R r = new R();
		r.put("msg", msg);
		return r;
	}
	
	public static R ok(Map map) {
		R r = new R();
		r.putAll(map);
		return r;
	}
	
	public static R ok() {
		return new R();
	}

	@Override
	public R put(String key, Object value) {
		super.put(key, value);
		return this;
	}

	public Boolean isOk(){
		return (Integer)this.get("code") == 0;
	}
}

wms项目学习（二）

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