标签：callback 设置 rest stop header sso lte message inter
转自：https://ethendev.github.io/2018/11/06/RestTemplate-error-handler/
一些 API 的报错信息通过 Response 的 body返回。使用 HttpClient 能正常获取到 StatusCode 和 body 中的错误提示。然而使用 RestTemplate ，会直接抛出下面的异常。如果想获取原始的信息并进一步处理会比较麻烦。
org.springframework.web.client.HttpClientErrorException: 404 null at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:94) at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:79) at org.springframework.web.client.ResponseErrorHandler.handleError(ResponseErrorHandler.java:63) at org.springframework.web.client.RestTemplate.handleResponse(RestTemplate.java:777) at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:730) at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:704) at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:621)
下面看一下原因， RestTemplate 中的 getForObject, getForEntity 和 exchange 等常用方法最终都是调用 doExecute 方法。下面是 doExecute 方法源码
public class RestTemplate extends InterceptingHttpAccessor implements RestOperations { private ResponseErrorHandler errorHandler; ...... @Nullable protected <T> T doExecute(URI url, @Nullable HttpMethod method, @Nullable RequestCallback requestCallback, @Nullable ResponseExtractor<T> responseExtractor) throws RestClientException { Assert.notNull(url, "‘url‘ must not be null"); Assert.notNull(method, "‘method‘ must not be null"); ClientHttpResponse response = null; String resource; try { ClientHttpRequest request = this.createRequest(url, method); if (requestCallback != null) { requestCallback.doWithRequest(request); } response = request.execute(); // 处理 Response this.handleResponse(url, method, response); if (responseExtractor != null) { Object var14 = responseExtractor.extractData(response); return var14; } resource = null; } catch (IOException var12) { resource = url.toString();
String query = url.getRawQuery(); resource = query != null ? resource.substring(0, resource.indexOf(63)) : resource; throw new ResourceAccessException("I/O error on " + method.name() + " request for \"" + resource + "\": " + var12.getMessage(), var12); } finally { if (response != null) { response.close(); } } return resource; } protected void handleResponse(URI url, HttpMethod method, ClientHttpResponse response) throws IOException { ResponseErrorHandler errorHandler = this.getErrorHandler(); boolean hasError = errorHandler.hasError(response); if (this.logger.isDebugEnabled()) { try { this.logger.debug(method.name() + " request for \"" + url + "\" resulted in " + response.getRawStatusCode() + " (" + response.getStatusText() + ")" + (hasError ? "; invoking error handler" : "")); } catch (IOException var7) { ; } } // 异常处理 if (hasError) { errorHandler.handleError(url, method, response); } } }
从下面的代码可以看出，DefaultResponseErrorHandler 捕获并抛出了异常。
public class DefaultResponseErrorHandler implements ResponseErrorHandler { ... protected void handleError(ClientHttpResponse response, HttpStatus statusCode) throws IOException { switch(statusCode.series()) { case CLIENT_ERROR: throw new HttpClientErrorException(statusCode, response.getStatusText(), response.getHeaders(), this.getResponseBody(response), this.getCharset(response)); case SERVER_ERROR: throw new HttpServerErrorException(statusCode, response.getStatusText(), response.getHeaders(), this.getResponseBody(response), this.getCharset(response)); default: throw new UnknownHttpStatusCodeException(statusCode.value(), response.getStatusText(), response.getHeaders(), this.getResponseBody(response), this.getCharset(response)); } } }
如果想自己捕获异常信息，自己处理异常的话可以通过实现 ResponseErrorHandler 类来实现。其源码如下：
public interface ResponseErrorHandler { // 标示 Response 是否存在任何错误。实现类通常会检查 Response 的 HttpStatus。 boolean hasError(ClientHttpResponse var1) throws IOException; // 处理 Response 中的错误, 当 HasError 返回 true 时才调用此方法。 void handleError(ClientHttpResponse var1) throws IOException; // handleError 的替代方案，提供访问请求URL和HTTP方法的额外信息。 default void handleError(URI url, HttpMethod method, ClientHttpResponse response) throws IOException { this.handleError(response); } }
如果想像 HttpClient 一样直接从 Response 获取 HttpStatus 和 body 中的报错信息 而不抛出异常，可以通过下面的代码实现：
public class CustomErrorHandler implements ResponseErrorHandler { @Override public boolean hasError(ClientHttpResponse response) throws IOException { return true; } @Override public void handleError(ClientHttpResponse response) throws IOException { } }
设置 RestTemplate 的异常处理类
restTemplate.setErrorHandler(new CustomErrorHandler()); ResponseEntity<String> response = restTemplate.exchange(uri, HttpMethod.GET, null, String.class); System.out.println(response.getBody());
输出结果
{"code":404,"result":null,"message":"Resources not found"}
标签：callback 设置 rest stop header sso lte message inter
原文地址：https://www.cnblogs.com/guanbin-529/p/11489264.html
