【WEB系列】RestTemplate之非200状态码信息捕获

文章目录
  1. I. 项目环境
    1. 1. 鉴权端点
  2. II. 异常捕获
    1. 1. 未捕获场景
    2. 2. 异常捕获
  3. II. 其他
    1. 0. 项目&系列博文
    2. 1. 一灰灰Blog

前面介绍的RestTemplate的使用,都是接口正常返回200的状态码case,当返回非200状态码时,会直接抛异常,如果我希望能捕获异常,并针对正常获取返回的message,可以如何处理呢?

I. 项目环境

博文测试项目完全基于【WEB系列】RestTemplate基础用法小结的项目环境,建议配合查看

基本环境:IDEA + maven + SpringBoot 2.2.1.RELEASE

测试的REST服务借助前一篇的鉴权,如果鉴权失败,则返回401状态码,具体实现如下

1. 鉴权端点

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private String getHeaders(HttpServletRequest request) {
Enumeration<String> headerNames = request.getHeaderNames();
String name;

JSONObject headers = new JSONObject();
while (headerNames.hasMoreElements()) {
name = headerNames.nextElement();
headers.put(name, request.getHeader(name));
}
return headers.toJSONString();
}

private String getParams(HttpServletRequest request) {
return JSONObject.toJSONString(request.getParameterMap());
}

private String getCookies(HttpServletRequest request) {
Cookie[] cookies = request.getCookies();
if (cookies == null || cookies.length == 0) {
return "";
}

JSONObject ck = new JSONObject();
for (Cookie cookie : cookies) {
ck.put(cookie.getName(), cookie.getValue());
}
return ck.toJSONString();
}

private String buildResult(HttpServletRequest request) {
return buildResult(request, null);
}

private String buildResult(HttpServletRequest request, Object obj) {
String params = getParams(request);
String headers = getHeaders(request);
String cookies = getCookies(request);

if (obj != null) {
params += " | " + obj;
}

return "params: " + params + "\nheaders: " + headers + "\ncookies: " + cookies;
}

/**
* 标准的http auth验证
*
* @param request
* @param response
* @return
* @throws IOException
*/
@GetMapping(path = "auth")
public String auth(HttpServletRequest request, HttpServletResponse response) throws IOException {
String auth = request.getHeader("Authorization");
if (StringUtils.isEmpty(auth)) {
response.setStatus(401);
response.setHeader("WWW-Authenticate", "Basic realm=\"input username and password\"");
return buildResult(request) + "\n>>>no auth header";
}

String[] userAndPass = new String(new BASE64Decoder().decodeBuffer(auth.split(" ")[1])).split(":");
if (userAndPass.length < 2) {
response.setStatus(401);
response.setHeader("WWW-Authenticate", "Basic realm=\"input username and password\"");
return buildResult(request) + "\n>>>illegal auth: " + auth;
}

if ("user".equalsIgnoreCase(userAndPass[0]) && "pwd".equalsIgnoreCase(userAndPass[1])) {
return buildResult(request) + "\n>>>auth: success!";
}

response.setStatus(401);
response.setHeader("WWW-Authenticate", "Basic realm=\"input username and password\"");
return buildResult(request) + "\n>>>illegal user or pwd!";
}

一个简单的鉴权逻辑如上,从请求头中拿到Authorization对应的value,并解析用户名密码,如果满足则正确返回;如果不存在or不满足,则返回http状态码为401,并携带对应的提示信息

II. 异常捕获

1. 未捕获场景

当我们直接像之前一样使用RestTemplate时,看一下效果如何

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try {
// 如果返回状态码不是200,则直接抛异常,无法拿到responseBody
RestTemplate restTemplate = new RestTemplate();
HttpEntity<String> ans =
restTemplate.getForEntity("http://127.0.0.1:8080/auth?name=一灰灰&age=20", String.class);
log.info("exception with no auth res: {}", ans);
} catch (Exception e) {
log.info("exception with no auth error: {}", e);
}

输出如下,走入了catch逻辑,从异常堆栈中,也只能看到401 Unauthorized,拿不到返回的Response body

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(exception with no auth error: {}

org.springframework.web.client.HttpClientErrorException$Unauthorized: 401 Unauthorized
trueat org.springframework.web.client.HttpClientErrorException.create(HttpClientErrorException.java:81)
trueat org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:123)
trueat org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:102)
trueat org.springframework.web.client.ResponseErrorHandler.handleError(ResponseErrorHandler.java:63)
trueat org.springframework.web.client.RestTemplate.handleResponse(RestTemplate.java:785)
trueat org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:743)
trueat org.springframework.web.client.RestTemplate.execute(RestTemplate.java:677)
trueat org.springframework.web.client.RestTemplate.getForEntity(RestTemplate.java:345)
trueat com.git.hui.boot.resttemplate.rest.RestTemplateDemo.exception(RestTemplateDemo.java:354)
true...

2. 异常捕获

更详细原理定位请参考:【WEB系列】RestTemplate 4xx/5xx 异常信息捕获

为了处理上面的问题,我们可以设置自定义的ResponseErrorHandler来处理

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RestTemplate restTemplate = new RestTemplate();
restTemplate.setErrorHandler(new ResponseErrorHandler() {
@Override
public boolean hasError(ClientHttpResponse clientHttpResponse) throws IOException {
return false;
}

@Override
public void handleError(ClientHttpResponse clientHttpResponse) throws IOException {
log.info("some error!");
}
});
HttpEntity<String> ans = restTemplate.getForEntity("http://127.0.0.1:8080/auth?name=一灰灰&age=20", String.class);
log.info("exception with no auth after errorHandler res: {}", ans);

输出如下, 401为返回的状态码,其中也包含了ResponseBody,然后再业务中根据状态码和返回结果进行处理即可

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(exception with no auth after errorHandler res: <401,params: {"name":["一灰灰"],"age":["20"]}
headers: {"host":"127.0.0.1:8080","connection":"keep-alive","accept":"text/plain, application/json, application/*+json, */*","user-agent":"Java/1.8.0_171"}
cookies:
>>>no auth header,[WWW-Authenticate:"Basic realm="input username and password"", Content-Type:"text/plain;charset=UTF-8", Content-Length:"227", Date:"Mon, 29 Jun 2020 09:57:06 GMT"]>

II. 其他

0. 项目&系列博文

博文

源码

1. 一灰灰Blog

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