springMvc使用client实现服务之间的调用

在做项目的时候，发现别人编写服务框架的时候创建了client来实现服务之间的相互调用，这样就不用导入其他项目的jar包。分析了下其实底层还是使用的restTemplate，不过人家封装的比较好，放到这里分析下。

调用其他服务

public abstract class ApiHandler<T> {
    private String api; //要调用的uri的api地址
    private String requestUrl;  //请求地址：serverUrl+api
    private TypeReference<BaseResponse<T>> responseType; //返回的响应类型

    //构造函数为api和responseType赋值
    public ApiHandler(String api, TypeReference<BaseResponse<T>> responseType) {
        Assert.notNull(responseType);
        if (StringUtils.isEmpty(api)) {
            throw new IllegalArgumentException("api不能为空");
        } else {
            this.api = api;
            this.responseType = responseType;
        }
    }

    public void setServerUrl(String serverUrl) {
        if (StringUtils.isEmpty(serverUrl)) {
            throw new IllegalArgumentException("serverUrl不能为空");
        } else {
            this.requestUrl = serverUrl + this.api;
        }
    }

    //CheckableParameter为所有request都需要实现的接口，其内部只有一个check()方法，所有的request类都需要实现check()方法用来判断request
    //请求是否合理,如果合理则发送post请求
    protected String postForStringResult(CheckableParameter request) throws ClientException {
        request.check();
        return (String)RestTemplateUtil.post(this.requestUrl, request, String.class);
    }

    //使用Jackson对返回的相应转换为想要的responseType类型，外层用BaseResponse包一层
    protected BaseResponse<T> postForBaseResponse(CheckableParameter request) throws ClientException {
        String strResponse = this.postForStringResult(request);

        try {
            return (BaseResponse)JacksonUtil.fromJson(strResponse, this.responseType);
        } catch (CommonException var4) {
            throw new ClientException("解析返回值发生错误", var4);
        }
    }

   //使用Jackson对返回的相应转换为想要的responseType类型,外层没有用BaseResponse包装
    protected T post(CheckableParameter request) throws ClientException {
        BaseResponse<T> response = this.postForBaseResponse(request);
        if (!response.isSuccessful()) {
            throw new ClientException("接口返回结果为失败，信息：" + response.getMessage());
        } else {
            return response.getBody();
        }
    }
}

 

具体的使用类：

public class ImagesDownloadPiccHandler extends ApiHandler<ImagesDownloadPiccResponse> {
    private static final String API = "/v345/piccdata/piccimagesdownload";

    public ImagesDownloadPiccHandler() {
        super(API, new TypeReference<BaseResponse<ImagesDownloadPiccResponse>>() {
        });
    }

    public ImagesDownloadPiccResponse handle(ImagesDownloadPiccRequst imagesDownloadPiccRequst) throws ClientException {
        CheckableParameter request = getRequest(imagesDownloadPiccRequst);
        return post(request);
    }

    //将request对象转换为接口类型，以方便ApiHandler中进行多态的使用
    private CheckableParameter getRequest(ImagesDownloadPiccRequst imagesDownloadPiccRequst) {
        return imagesDownloadPiccRequst;
    }
}

 

自己提供Client供其他服务调用：主要就是自己提供一个Handler接口，使得其他服务可以通过此接口调用ApiHandler的post方法向自己发送请求。

public class BusinessClient {
    private Map<Class, ApiHandler> map = new HashMap();
    private String serverUrl;

    public BusinessClient() {
    }

    public void setServerUrl(String serverUrl) {
        this.serverUrl = serverUrl;
    }

    protected <T extends ApiHandler> T getHandler(Class<T> handlerClass) throws ClientException {
        Assert.notNull(this.serverUrl);

        try {
            T handler = (ApiHandler)this.map.get(handlerClass);
            if (handler == null) {
                handler = (ApiHandler)handlerClass.newInstance();//如果map中没有存储Handler实例就使用反射实例化一个Handler
                handler.setServerUrl(this.serverUrl);
                this.map.put(handlerClass, handler);
            }

            return handler;
        } catch (Exception var3) {
            throw new ClientException("找不到消息处理器", var3);
        }
    }
}

public class PiccDataTempClient extends BusinessClient {

    public ImagesDownloadAliyunResponse downloadImagesFromAliyun(ImagesDownloadAliyunRequest imagesDownloadAliyunRequest) throws ClientException {
        return getHandler(ImagesDownloadAliyunHandler.class).handle(imagesDownloadAliyunRequest);
    }

}