dubbo暴露出HTTP服务

   点关注不迷路，欢迎再访！		

前言

通常来说一个dubbo服务都是对内给内部调用的，但也有可能一个服务就是需要提供给外部使用，并且还不能有使用语言的局限性。本章讲到的没有那么复杂，就只是把一个不需要各种权限检验的dubbo服务对外提供为HTTP服务。

准备工作

以下是本文所涉及到的一些知识点：

Spring相关知识
Java反射相关知识
SpringMVC相关知识

其实思路很简单，利用SpringMVC提供一个HTTP接口。在该接口中通过入参进行反射找到具体的dubbo服务实现进行调用。

HttpProviderConf配置类

首先需要定义一个HttpProviderConf类用于保存声明需要对外提供服务的包名，毕竟我们反射时需要用到一个类的全限定名：

public class HttpProviderConf {/*** 提供http访问的包*/private List<String> usePackage ;public List<String> getUsePackage() {return usePackage;}public void setUsePackage(List<String> usePackage) {this.usePackage = usePackage;}}

请求响应入参、出参

HttpRequest入参

public class HttpRequest {private String param ;//入参private String service ;//请求serviceprivate String method ;//请求方法public String getParam() {return param;}public void setParam(String param) {this.param = param;}public String getService() {return service;}public void setService(String service) {this.service = service;}public String getMethod() {return method;}public void setMethod(String method) {this.method = method;}
}

其中param是用于存放真正调用dubbo服务时的入参，传入json在调用的时候解析成具体的参数对象。
service存放dubbo服务声明的interface API的包名。
method则是真正调用的方法名称。

HttpResponse 响应

public class HttpResponse implements Serializable{private static final long serialVersionUID = -6296842759601736401L;	private boolean success;// 成功标志private String code;// 信息码private String description;// 描述public boolean isSuccess() {return success;}public void setSuccess(boolean success) {this.success = success;}public String getCode() {return code;}public void setCode(String code) {this.code = code;}public String getDescription() {return description;}public void setDescription(String description) {this.description = description;}
}

这里只是封装了常用的HTTP服务的响应数据。

暴露服务controller

@Controller
@RequestMapping("/dubboAPI")
public class DubboController implements ApplicationContextAware {private final static Logger logger = LoggerFactory.getLogger(DubboController.class);@Autowiredprivate HttpProviderConf httpProviderConf;// 缓存作用的mapprivate final Map<String, Class<?>> cacheMap = new HashMap<String, Class<?>>();protected ApplicationContext applicationContext;@ResponseBody@RequestMapping(value = "/{service}/{method}", method = RequestMethod.GET)public String api(HttpRequest httpRequest, HttpServletRequest request, @PathVariable String service,@PathVariable String method) {logger.info("ip:{}-httpRequest:{}");String invoke = invoke(httpRequest, service, method);logger.debug("callback :" + invoke);return invoke;}private String invoke(HttpRequest httpRequest, String service, String method) {httpRequest.setService(service);httpRequest.setMethod(method);HttpResponse response = new HttpResponse();logger.debug("input param:" + JSON.toJSONString(httpRequest));if (!CollectionUtils.isEmpty(httpProviderConf.getUsePackage())) {boolean isPac = false;for (String pac : httpProviderConf.getUsePackage()) {if (service.startsWith(pac)) {isPac = true;break;}}if (!isPac) {// 调用的是未经配置的包logger.error("service is not correct,service=" + service);response.setCode("2");response.setSuccess(false);response.setDescription("service is not correct,service=" + service);}}try {Class<?> serviceCla = cacheMap.get(service);if (serviceCla == null) {serviceCla = Class.forName(service);logger.debug("serviceCla:" + JSON.toJSONString(serviceCla));// 设置缓存cacheMap.put(service, serviceCla);}Method[] methods = serviceCla.getMethods();Method targetMethod = null;for (Method m : methods) {if (m.getName().equals(method)) {targetMethod = m;break;}}if (method == null) {logger.error("method is not correct,method=" + method);response.setCode("2");response.setSuccess(false);response.setDescription("method is not correct,method=" + method);}Object bean = this.applicationContext.getBean(serviceCla);Object result = null;Class<?>[] parameterTypes = targetMethod.getParameterTypes();if (parameterTypes.length == 0) {// 没有参数result = targetMethod.invoke(bean);} else if (parameterTypes.length == 1) {Object json = JSON.parseObject(httpRequest.getParam(), parameterTypes[0]);result = targetMethod.invoke(bean, json);} else {logger.error("Can only have one parameter");response.setSuccess(false);response.setCode("2");response.setDescription("Can only have one parameter");}return JSON.toJSONString(result);} catch (ClassNotFoundException e) {logger.error("class not found", e);response.setSuccess(false);response.setCode("2");response.setDescription("class not found");} catch (InvocationTargetException e) {logger.error("InvocationTargetException", e);response.setSuccess(false);response.setCode("2");response.setDescription("InvocationTargetException");} catch (IllegalAccessException e) {logger.error("IllegalAccessException", e);response.setSuccess(false);response.setCode("2");response.setDescription("IllegalAccessException");}return JSON.toJSONString(response);}/*** 获取IP* * @param request* @return*/private String getIP(HttpServletRequest request) {if (request == null)return null;String s = request.getHeader("X-Forwarded-For");if (s == null || s.length() == 0 || "unknown".equalsIgnoreCase(s)) {s = request.getHeader("Proxy-Client-IP");}if (s == null || s.length() == 0 || "unknown".equalsIgnoreCase(s)) {s = request.getHeader("WL-Proxy-Client-IP");}if (s == null || s.length() == 0 || "unknown".equalsIgnoreCase(s)) {s = request.getHeader("HTTP_CLIENT_IP");}if (s == null || s.length() == 0 || "unknown".equalsIgnoreCase(s)) {s = request.getHeader("HTTP_X_FORWARDED_FOR");}if (s == null || s.length() == 0 || "unknown".equalsIgnoreCase(s)) {s = request.getRemoteAddr();}if ("127.0.0.1".equals(s) || "0:0:0:0:0:0:0:1".equals(s))try {s = InetAddress.getLocalHost().getHostAddress();} catch (UnknownHostException unknownhostexception) {return "";}return s;}@Overridepublic void setApplicationContext(ApplicationContext applicationContext) throws BeansException {this.applicationContext = applicationContext;}
}

• 首先是定义了一个DubboController,并使用了SpringMVC的注解对外暴露HTTP服务。

• 实现了org.springframework.context.ApplicationContextAware类， 实现了setApplicationContext()方法用于初始化Spring上下文对象，在之后可以获取到容器里的相应对象。

• 核心的invoke()方法。

• 调用时：http://127.0.0.1:8080/dubbo-provider/dubboAPI/com.dubbo.service.IDubboService/getUser。

• 具体如上文的调用实例。先将com.dubbo.service.IDubboService、getUser赋值到httpRequest入参中。

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsdhttp://code.alibabatech.com/schema/dubbohttp://code.alibabatech.com/schema/dubbo/dubbo.xsd"><!-- 定义了提供方应用信息，用于计算依赖关系。在dubbo-admin 或 dubbo-monitor 会显示这个名字，方便识别 --><dubbo:application name="admin-provider" owner="admin" organization="dubbox"/><!-- 使用zookeeper 注册中心暴露服务，注意要先开启 zookeeper --><dubbo:registry address="zookeeper://127.0.0.1:2181"/><!-- 用dubbo协议在20880端口暴露服务 --><dubbo:protocol name="dubbo" port="20880"/><!-- 用dubbo 协议实现定义好的 api 接口 --><dubbo:service interface="com.dubbo.service.IDubboService" ref="dubboService" protocol="dubbo"/><dubbo:service interface="com.dubbo.service.IUserService" ref="userService" protocol="dubbo"/><!--dubbo服务暴露为http服务--><bean class="com.crossoverJie.dubbo.http.conf.HttpProviderConf"><property name="usePackage"><list><!--需要暴露服务的接口包名，可多个--><value>com.dubbo.service</value></list></property></bean>
</beans>

其中的com.dubbo.service就是自己需要暴露的包名，可以多个。

• 接着在缓存map中取出反射获取到的接口类类型，如果获取不到则通过反射获取，并将值设置到缓存map中，这样不用每次都反射获取，可以节省系统开销(反射很耗系统资源)。
• 接着也是判断该接口中是否有传入的getUser方法。
• 取出该方法的参数列表，如果没有参数则直接调用。
• 如果有参数，判断个数。这里最多只运行一个参数。也就是说在真正的dubbo调用的时候只能传递一个BO类型，具体的参数列表可以写到BO中。因为如果有多个在进行json解析的时候是无法赋值到两个参数对象中去的。
• 之后进行调用，将调用返回的数据进行返回即可。