一、SpringBoot 与 Feign 适配性问题。

1、结论：

1)、在SpringBoot1.x下，引入的feign依赖：
<dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-feign</artifactId>
        <version>1.4.6.RELEASE</version>
</dependency>

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2)、在SpringBoot2.x下，引入的feign依赖：
<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-starter-openfeign</artifactId>
	<version>2.1.0.RELEASE</version>
</dependency>


-----------------------------------------------------------------------------------------

3)、备注：
    在spring boot2.x下，Spring Cloud对Feign的支持由
spring-cloud-netflix-core --> spring-cloud-openfeign-core,

    而Finchley.M9版本下的 spring-cloud-starter-openfeign:2.0.0.M2 的pom依赖文件中导入的是spring-cloud-netflix-core而非spring-cloud-openfeign-core。故上述第二点需注意对版本的控制。

2、参考博客：

https://www.cnblogs.com/sxdcgaq8080/p/9860939.html

二、Feign 内部调用超时。

1、报错信息：

feign.RetryableException: Read timed out executing POST ***** ……

java.net.SocketTimeoutException: Read timed out
	at java.net.SocketInputStream.socketRead0(Native Method) ~[na:1.8.0_25]
	at java.net.SocketInputStream.read(Unknown Source) ~[na:1.8.0_25]
	at java.net.SocketInputStream.read(Unknown Source) ~[na:1.8.0_25]
	at java.io.BufferedInputStream.fill(Unknown Source) ~[na:1.8.0_25]
	at java.io.BufferedInputStream.read1(Unknown Source) ~[na:1.8.0_25]
	at java.io.BufferedInputStream.read(Unknown Source) ~[na:1.8.0_25]
	at sun.net.www.http.HttpClient.parseHTTPHeader(Unknown Source) ~[na:1.8.0_25]
……

2、环境说明：

<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-starter-openfeign</artifactId>
	<version>2.1.0.RELEASE</version>
</dependency>

3、解决方案：

@Configuration
public class FeignConfig {
    public static int connectTimeoutMills = 60000;
    public static int readTimeoutMills = 60000;

    @Bean
    public Request.Options options(){
        return new Request.Options(connectTimeoutMills, readTimeoutMills);
    }

    @Bean
    public Retryer feignRetryer(){
        return new Retryer.Default();
    }
}

4、参考博客：

https://blog.csdn.net/VitaminZH/article/details/80892395

三、Feign传递token

1、原理：设置拦截器，将postman中的请求头，原封不动的封装到feign的调用请求中去。

2、代码如下：

@Configuration
public class FeignInterceptor implements RequestInterceptor{


    @Override
    public void apply(RequestTemplate requestTemplate) {
        HttpServletRequest request = getHttpRequest();

        if(Objects.isNull(request)){
            return;
        }

        Map<String, String> headers = getHeaders(request);
        if(headers.size() > 0){
            for(Map.Entry<String, String> entry : headers.entrySet()){
                requestTemplate.header(entry.getKey(), entry.getValue());
            }
        }
    }


    private HttpServletRequest getHttpRequest(){
        try {
            
            return ((ServletRequestAttributes) (RequestContextHolder.currentRequestAttributes())).getRequest();
        } catch (IllegalStateException e) {
            return null;
        }
    }



    private Map<String, String> getHeaders(HttpServletRequest request){
        Map<String, String> map = new LinkedHashMap<>();

        Enumeration<String> headerNames = request.getHeaderNames();
        while(headerNames.hasMoreElements()){
            String key = headerNames.nextElement();
            map.put(key, request.getHeader(key));
        }

        return map;
    }
}

四、Feign消费端传参List<String>报错

1、报错信息：

feign.FeignException: status 500 reading FeignOrderInterface#****方法名****(List)

	at feign.FeignException.errorStatus(FeignException.java:78)
	at feign.codec.ErrorDecoder$Default.decode(ErrorDecoder.java:93)
	at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:149)
	at feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:78)
	at feign.ReflectiveFeign$FeignInvocationHandler.invoke(ReflectiveFeign.java:103)
	at com.sun.proxy.$Proxy146.findProgramOrderByTechnicianIdList(Unknown Source)
	at com.ywkj.spa.accounts.Demo2.method9(Demo2.java:279)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at 

2、解决方案：

1）方案一：将服务端和消费端，参数List改为数组传递和接收，即可解决。List<String> strList  --> String[] arr。

附上转换代码：

        List<String> techList = new ArrayList<>();
        techList.add("02");
        techList.add("03");
        String[] techArr = techList.toArray(new String[techList.size()]);

2）方案二：服务端改为对象接收，对象中声明属性List<String> tempList。消费端依旧以List<String> tempList形式传输。

五、打包、部署运行报错【no main manifest attribute, in /ms-eureka.jar】

1、现象描述：SpringCloud多模块打包，打包的jar包只有几k，jar包无法运行，运行报错：no main manifest attribute, in /ms-eureka.jar

2、解决方案：子模块pom文件中添加如下如下插件。【父级pom中不需要指定plugin】

<build>
	<plugins>
	    <plugin>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-maven-plugin</artifactId>
		<configuration>
		    <!-- 指定该Main Class为全局的唯一入口 -->
		    <mainClass>com.ywkj.spa.mall.SpaMallApplication</mainClass>
		    <layout>ZIP</layout>
		</configuration>

		<executions>
		    <execution>
		        <goals>
                            <!--可以把依赖的包都打包到生成的Jar包中-->
			    <goal>repackage</goal>
			</goals>
		    </execution>
		</executions>
	    </plugin>
        </plugins>
</build>

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