springCloud系列四（feign负载均衡）

 Feign是一个声明式的Web服务客户端，使得编写Web服务客户端变得非常容易， 只需要创建一个接口，然后在上面添加注解即可。

Feign是spring cloud中服务消费端的调用框架,通常与ribbon,hystrix等组合使用。

但是在某些项目中，由于遗留原因，整个系统并不是spring cloud项目，甚至不是spring项目，而使用者关注的重点仅仅是简化http调用代码的编写。

如果采用httpclient或者okhttp这样相对较重的框架，对初学者来说编码量与学习曲线都会是一个挑战，而使用spring中RestTemplate，又没有配置化的解决方案，由此想到是否可以脱离spring cloud，独立使用Feign。

在http://47.101.47.253:8082/reed/  中提供如下两个接口。

@RequestMapping(value = "/hello",method = RequestMethod.GET) public String say(){ return "reed"; } @RequestMapping(value = "/hello1/{price}",method = RequestMethod.GET) public Integer price(@PathVariable("price") Integer price){ return price; }

在demo工程中新建如下两个接口，

import feign.Param; import feign.RequestLine; public interface RemoteService { @RequestLine("GET /reed/hello") String getUserName(); @RequestLine("GET /reed/hello1/{price}") String getPrice(@Param(value = "price") Integer price); }

在main方法中可进行接口调用

public static void main(String[] args) { RemoteService service = Feign.builder() .options(new Request.Options(1000, 3500)) .retryer(new Retryer.Default(5000, 5000, 3)) .target(RemoteService.class, "http://47.101.47.253:8082"); String result = service.getUserName(); System.out.println(result); String price = service.getPrice(100); System.out.println(price); }

运行结果如下

如果需要调用的是Https的地址，在访问前需要加上如下操作，跳过ssl安全验证

// 跳过SSL验证 ，在获取connection之前调用这个方法 trustAllHttpsCertificates private static void trustAllHttpsCertificates() throws Exception { javax.net.ssl.TrustManager[] trustAllCerts = new javax.net.ssl.TrustManager[1]; javax.net.ssl.TrustManager tm = new miTM(); trustAllCerts[0] = tm; javax.net.ssl.SSLContext sc = javax.net.ssl.SSLContext .getInstance("SSL"); sc.init(null, trustAllCerts, null); javax.net.ssl.HttpsURLConnection.setDefaultSSLSocketFactory(sc .getSocketFactory()); } static class miTM implements javax.net.ssl.TrustManager, javax.net.ssl.X509TrustManager { public java.security.cert.X509Certificate[] getAcceptedIssuers() { return null; } public boolean isServerTrusted( java.security.cert.X509Certificate[] certs) { return true; } public boolean isClientTrusted( java.security.cert.X509Certificate[] certs) { return true; } public void checkServerTrusted( java.security.cert.X509Certificate[] certs, String authType) throws java.security.cert.CertificateException { return; } public void checkClientTrusted( java.security.cert.X509Certificate[] certs, String authType) throws java.security.cert.CertificateException { return; }

feign调用非resful形式api

http://47.101.47.253:8080/find_music_entry_by_keywords?keyWords=qinghuaci

要想调用上面的接口

可以用如下形式

import com.cisco.reed.httpClient.MusicEntryVo; import feign.Param; import feign.RequestLine; import java.net.URI; public interface MusicFeignTest { @RequestLine("GET /find_music_entry_by_keywords?keyWords={keyWords}") MusicEntryVo findMusicEntry( URI uri, @Param(value = "keyWords") String keyWords); }

Client代码如下

public static void main(String[] args) { String urlString = "http://47.101.47.253:8080"; URI uri = URI.create(urlString); MusicFeignTest musicFeignTest = Feign.builder().options(new Request.Options(1000, 3500)) .retryer(new Retryer.Default(5000, 5000, 3)) .decoder(new JacksonDecoder()).encoder(new JacksonEncoder()).target(Target.EmptyTarget.create(MusicFeignTest.class)); MusicEntryVo musicEntryVo = musicFeignTest.findMusicEntry(uri,"qinghuaci"); System.out.println(musicEntryVo.toString()); }

运行结果如下

MusicEntryVo(viewCounts=1, id=1, entryKeywords=qinghuaci, officialExplain=officialExplain, oralExplain=oralExplain, createUser=苏日乐格, createTime=Sat Aug 09 11:20:46 CST 2008, updateTime=Sat Aug 09 11:20:46 CST 2008)

或者采用如下的形式：

@RequestLine("GET /find_music_entry_by_keywords?keyWords={keyWords}") MusicEntryVo findMusicEntry(@Param(value = "keyWords") String keyWords);

客户端代码

FeignTest feignTest = Feign.builder() .options(new Request.Options(1000, 3500)) .retryer(new Retryer.Default(5000, 5000, 3)) .decoder(new JacksonDecoder()) .encoder(new JacksonEncoder()) .target(FeignTest.class, "http://47.101.47.253:8080"); MusicEntryVo musicEntryVo = feignTest.findMusicEntry("qinghuaci");

Post发送form表单形式的数据

@RequestLine("POST /token") @Headers({"Content-Type: application/x-www-form-urlencoded","Accept: application/json"}) AuthPojo getAuth( URI uri, String str );

调用 ，注意encoder的格式，然后将body以key value的形式拼接出来

public static void main(String[] args) throws Exception{ String uriString = "https://login.microsoftonline.com"; trustAllHttpsCertificates(); URI uri = URI.create(uriString); AuthService authorizationService = Feign.builder(). options(new Request.Options(1000, 3500)) .retryer(new Retryer.Default(5000, 5000, 3)) .decoder(new JacksonDecoder()) //特别要注意，此处的encoder格式 .encoder(new SpringFormEncoder()).target(Target.EmptyTarget.create(AuthService.class)); String str = "grant_type=client_credentials&client_id=f6b81139-923f-41a7-816f-ddd02a199ed6&scope=https://graph.microsoft.com/.default"; AuthPojo authPojo = authorizationService.getAuth(uri,str ); System.out.println(authPojo.toString()); }