Spring Cloud Edgware对Hystrix回退的逻辑进行了一些改进。本文将信息探讨新旧版本的回退操作,并分析的原因及改进后的优势。
Dalston及更低版本
对于Dalston及更低版本,要想为Zuul提供回退,只需编写代码如下:
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| @Component public class MyFallbackProvider implements ZuulFallbackProvider { @Override public String getRoute() { return "*"; }
@Override public ClientHttpResponse fallbackResponse() { return new ClientHttpResponse() { @Override public HttpStatus getStatusCode() throws IOException { return HttpStatus.OK; }
@Override public int getRawStatusCode() throws IOException { return this.getStatusCode().value(); }
@Override public String getStatusText() throws IOException { return this.getStatusCode().getReasonPhrase(); }
@Override public void close() { }
@Override public InputStream getBody() throws IOException { return new ByteArrayInputStream("用户微服务不可用,请稍后再试。".getBytes()); }
@Override public HttpHeaders getHeaders() { HttpHeaders headers = new HttpHeaders(); MediaType mt = new MediaType("application", "json", Charset.forName("UTF-8")); headers.setContentType(mt);
return headers; } }; } }
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Edgware及更高版本
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| @Component public class MyFallbackProvider implements FallbackProvider { @Override public String getRoute() { return "*"; }
@Override public ClientHttpResponse fallbackResponse(Throwable cause) { if (cause instanceof HystrixTimeoutException) { return response(HttpStatus.GATEWAY_TIMEOUT); } else { return this.fallbackResponse(); } }
@Override public ClientHttpResponse fallbackResponse() { return this.response(HttpStatus.INTERNAL_SERVER_ERROR); }
private ClientHttpResponse response(final HttpStatus status) { return new ClientHttpResponse() { @Override public HttpStatus getStatusCode() throws IOException { return status; }
@Override public int getRawStatusCode() throws IOException { return status.value(); }
@Override public String getStatusText() throws IOException { return status.getReasonPhrase(); }
@Override public void close() { }
@Override public InputStream getBody() throws IOException { return new ByteArrayInputStream("服务不可用,请稍后再试。".getBytes()); }
@Override public HttpHeaders getHeaders() { HttpHeaders headers = new HttpHeaders(); MediaType mt = new MediaType("application", "json", Charset.forName("UTF-8")); headers.setContentType(mt); return headers; } }; } }
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分析
由代码可知:
- Dalston及更低版本通过实现
ZuulFallbackProvider
接口,从而实现回退;
- Edgware及更高版本通过实现
FallbackProvider
接口,从而实现回退。
- 在Edgware中:
- FallbackProvider是ZuulFallbackProvider的子接口。
- ZuulFallbackProvider已经被标注
Deprecated
,很可能在未来的版本中被删除。
- FallbackProvider接口比ZuulFallbackProvider多了一个
ClientHttpResponse fallbackResponse(Throwable cause);
方法,使用该方法,可获得造成回退的原因。
- 笔者将在下一篇文章详细总结在Spring Cloud中如何获得造成回退原因的各种姿势。
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