throw ResourceAccessException
catch (IOException )
HttpMessageNotReadableException
response extractData
finallyresponse.close()
ResourceAccessException
读取response流，字符转换
HttpMessageConversionException
NestedRuntimeException
throw IOExceptionHttpMessageNotReadableExceptionRestClientException（没有匹配的HttpMessageConverter）
根据response状态码，处理异常
捕获IOException，转成ResourceAccessException抛出
HttpMessageNotWritableException
HttpStatusCodeException
throw IOExceptionHttpMessageNotWritableExceptionRestClientException（没有匹配的HttpMessageConverter）
RuntimeException
HttpServerErrorException
handleResponse
HttpClientErrorException
execute
doWithRequest
doExecute
try
UnknownHttpStatusCodeException
IOException
createRequest
throw IOExceptionNoHttpResponseException
装载http header，http body 根据配置的HttpMessageConverter做字符对象转换
NoHttpResponseException
RestClientException
1 createHttpUriRequest（根据http method创建request）2 createHttpContext（创建HttpClientContext，填充属性http.request-config）
RestClientResponseException
40x，throw HttpClientErrorException50x，throw HttpServerErrorException其他情况，throw RestClientException(Unknown status code);
throw IOException
request.execute() 拿到response
