在dropwizard中使用feign,使用hystrix



i18n

前言

用惯了spring全家桶之后,试试dropwizard的Hello World也别有一帆风味。为了增强对外访问API的能力,需要引入open feign。这里简单在dropwizard中使用feign。

1. 什么Dropwizard

Dropwizard is a Java framework for developing ops-friendly, high-performance, RESTful web services.

Dropwizard使成熟、稳定的java生态系统更加简单、轻量(light-weight), 让你更专注于业务逻辑。

Dropwizard 为配置(configuration)、统计(application metrics)、日志(logging)、operational tools提供了开箱即用的能力。让您和您的团队能够在最短的时间内开发出具有生产环境的质量的Web服务。

下面的简介来自REST微服务架构之Dropwizard

DropWizard是由Yammer开发团队贡献的一个后台服务开发框架,其集成了Java生态系统中各个问题域中最优秀的组件,帮助开发者快速的打造一个Rest风格的后台服务。

对开发者来说,使用DropWizard有如下好处:
1、和Maven集成良好,也就是说和Gradle集成也很良好;
2、开发迅速,部署简单;
3、代码结构好,可读性高;
4、自动为服务提供OM框架;
5、让开发者自然的把一个应用拆分为一个个的小服务

DropWizard结构的Web服务组成
1、Configuration:用于设置该服务的配置,比方说在服务开放在哪个端口,数据库配置是怎样的等等。
2、Application(即Service):该服务的主入口,定义该服务使用哪个配置文件,开放哪些Resource,该服务需要哪些HealthCheck等等。
3、Resource:定义一个资源,包括如何获取该资源,对该资源做Get/Post/Delete/Query时,对应的各种业务逻辑。
4、Representation:定义了一个服务返回值对象,当服务返回该对象时,会自动的把该对象按属性值生成一个Json格式的字符串返回给服务调用者。
5、HealthCheck:在DropWizard为每个服务提供的OM框架中用到,通过它可以随时检测当前服务是否可用。

Dropwizard内置了Jetty

Web应用程序不能没有HTTP,所以Dropwizard使用Jetty HTTP库将一个令人难以置信的HTTP服务器直接嵌入到您的项目中。 Dropwizard项目不需要将应用程序交给一个复杂的应用程序服务器,而是一个main方法,它会自动连接一个HTTP服务器。将应用程序作为一个简单的过程运行,消除了Java在生产中的一些不好的东西(没有PermGen问题,没有应用程序服务器配置和维护,没有复杂的部署工具,没有类加载器(class loader)故障,没有隐藏的应用程序日志,没有尝试调整一个垃圾收集器来处理多个应用程序工作负载),并允许您使用所有现有的Unix进程管理工具。

Dropwizard 使用Jersey提供Rest能力

Dropwizard 使用Jackson来处理json

Dropwizard 提供了Metrics类库

2. Hello World For Dropwizard

吹完牛逼,开始干活。
照例,首先本次测试(https://github.com/Ryan-Miao/l4dropwizard)的完整结构图如下:

.
├── dependency-reduced-pom.xml
├── l4dropwizard.iml
├── pom.xml
├── readme.md
└── src
    └── main
        ├── java
        │   └── com
        │       └── test
        │           ├── HelloWorldApplication.java
        │           ├── configuration
        │           │   ├── HelloWorldConfiguration.java
        │           │   └── modules
        │           │       ├── ConnectAndReadConfig.java
        │           │       └── GithubApiConfig.java
        │           └── domain
        │               ├── connect
        │               │   ├── GithubClient.java
        │               │   └── GithubConnector.java
        │               ├── entiry
        │               │   ├── GithubUser.java
        │               │   └── Saying.java
        │               ├── health
        │               │   └── TemplateHealthCheck.java
        │               └── resource
        │                   ├── GithubResource.java
        │                   └── HelloWorldResource.java
        └── resources
            └── config
                └── dev.yml

14 directories, 16 files

2.1 添加依赖

依旧是maven项目,pom中添加dropwizard

<properties>
        <dropwizard.version>1.0.6</dropwizard.version>
        <java.version>1.8</java.version>
        <mainClass>com.test.HelloWorldApplication</mainClass>
    
</properties>
<dependencies>
        <dependency>
            <groupId>io.dropwizard</groupId>
            <artifactId>dropwizard-core</artifactId>
            <version>${dropwizard.version}</version>
        </dependency>
</dependencies>

2.2 添加配置中心

dropwizard采用yaml作为配置文件,同时需要有个配置类对应yaml中的属性。
创建config/dev.yml

template: Hello, %s!
defaultName: Stranger


server:
#  softNofileLimit: 1000
#  hardNofileLimit: 1000
  applicationConnectors:
    - type: http
      port: 8080

    #this requires the alpn-boot library on the JVM's boot classpath
    #- type: h2
    #  port: 8445
    #  keyStorePath: example.keystore
    #  keyStorePassword: example
  adminConnectors:
    - type: http
      port: 8082

然后,新建对应的配置类com.test.configuration.HelloWorldConfiguration

package com.test.configuration;

import com.fasterxml.jackson.annotation.JsonProperty;
import io.dropwizard.Configuration;
import org.hibernate.validator.constraints.NotEmpty;

/**
 * Created by rmiao on 3/14/2017.
 */
public class HelloWorldConfiguration extends Configuration {

    @NotEmpty
    private String template;

    @NotEmpty
    private String defaultName = "Stranger";

    @JsonProperty
    public String getTemplate() {
        return template;
    }

    @JsonProperty
    public void setTemplate(String template) {
        this.template = template;
    }

    @JsonProperty
    public String getDefaultName() {
        return defaultName;
    }

    @JsonProperty
    public void setDefaultName(String name) {
        this.defaultName = name;
    }
}

下一步就是启动类:com.test.application.HelloWorldApplication

package com.test;

import com.test.domain.health.TemplateHealthCheck;
import com.test.domain.resource.HelloWorldResource;
import com.test.configuration.HelloWorldConfiguration;
import io.dropwizard.Application;
import io.dropwizard.setup.Bootstrap;
import io.dropwizard.setup.Environment;

import java.util.Map;

/**
 * Created by Ryan Miao on 3/14/2017.
 */
public class HelloWorldApplication extends Application<HelloWorldConfiguration> {

    public static void main(String[] args) throws Exception {
        new HelloWorldApplication().run(args);
    }

    @Override
    public String getName() {
        return "hello-world";
    }

    @Override
    public void initialize(Bootstrap<HelloWorldConfiguration> bootstrap) {
        // nothing to do yet
    }

    @Override
    public void run(HelloWorldConfiguration configuration, Environment environment) throws Exception {
        final HelloWorldResource resource = new HelloWorldResource(
                configuration.getTemplate(),
                configuration.getDefaultName()
        );
        final TemplateHealthCheck healthCheck =
                new TemplateHealthCheck(configuration.getTemplate());
        environment.healthChecks().register("template", healthCheck);
        environment.jersey().register(resource);
        environment.jersey().register(healthCheck);

    }
}

到此,配置基本完成,只需要添加接口resource就好。

2.3 创建第一个API

对应于springmvc中conroller, dropwizard采用jersey,使用resourc作为接口类:com.test.com.test.resource.HelloWorldResource

package com.test.domain.resource;

import com.codahale.metrics.annotation.Timed;
import com.test.domain.entiry.Saying;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.MediaType;
import java.util.Optional;
import java.util.concurrent.atomic.AtomicLong;

/**
 * Created by rmiao on 3/14/2017.
 */
@Path("/hello-world")
@Produces(MediaType.APPLICATION_JSON)
public class HelloWorldResource {
    private final String template;
    private final String defaultName;
    private final AtomicLong counter;

    public HelloWorldResource(String template, String defaultName) {
        this.template = template;
        this.defaultName = defaultName;
        this.counter = new AtomicLong();
    }

    @GET
    @Timed
    public Saying sayHello(@QueryParam("name") Optional<String> name) {
        final String value = String.format(template, name.orElse(defaultName));
        return new Saying(counter.incrementAndGet(), value);
    }


}

这里的template没啥意思,官网用在这里就是为了彰显下读取配置文件的能力: 通过configuration类来操作配置属性。

另外,需要注意的是,resource并不能像Spring一样自动扫描,需要手动去environment.jersey().register(resource);

2.4 启动

启动前还需要配置fat jar,同Spring-boot一样,fat jar首选. 在pom配置:

<build>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.5.1</version>
                <configuration>
                    <source>${java.version}</source>
                    <target>${java.version}</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <version>3.0.2</version>
                <configuration>
                    <archive>
                        <manifest>
                            <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>2.3</version>
                <configuration>
                    <createDependencyReducedPom>true</createDependencyReducedPom>
                    <filters>
                        <filter>
                            <artifact>*:*</artifact>
                            <excludes>
                                <exclude>META-INF/*.SF</exclude>
                                <exclude>META-INF/*.DSA</exclude>
                                <exclude>META-INF/*.RSA</exclude>
                            </excludes>
                        </filter>
                    </filters>
                </configuration>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                        <configuration>
                            <transformers>
                                <transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
                                <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                    <mainClass>${mainClass}</mainClass>
                                </transformer>
                            </transformers>
                        </configuration>
                    </execution>
                </executions>
            </plugin>

            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>exec-maven-plugin</artifactId>
                <version>1.6.0</version>
                <configuration>
                    <mainClass>${mainClass}</mainClass>
                    <arguments>
                        <argument>server</argument>
                        <argument>target/classes/config/dev.yml</argument>
                    </arguments>
                    <systemProperties>
                        <systemProperty>
                            <key>application.name</key>
                            <value>HelloWorld</value>
                        </systemProperty>
                        <systemProperty>
                            <key>application.home</key>
                            <value>.</value>
                        </systemProperty>
                        <systemProperty>
                            <key>application.environment</key>
                            <value>dev</value>
                        </systemProperty>
                    </systemProperties>
                </configuration>
            </plugin>
        </plugins>
    </build>

接下来,打包:

mvn package 

然后,run jar:

java -jar target\l4dropwizard-1.0-SNAPSHOT.jar server target/classes/config/dev.yml

浏览器访问http://localhost:8080/hello-world?name=Ryan
将得到:

{
    "id": 1,
    "content": "Hello, Ryan!"
}

至此,hello world完成。

什么是Feign

Feign是一个网络请求客户端,简化了网络请求代码,使得我们可以采用更加友好的方式发送请求,并且管理请求。Feign采用注解驱动模板,所以目前只支持text-based apis.

Dropwizard with Feign

依赖

首先,添加依赖:

<dependency>
    <groupId>io.github.openfeign</groupId>
    <artifactId>feign-core</artifactId>
    <version>${feign.version}</version>
</dependency>
<dependency>
    <groupId>io.github.openfeign</groupId>
    <artifactId>feign-hystrix</artifactId>
    <version>${feign.version}</version>
</dependency>
<dependency>
    <groupId>io.github.openfeign</groupId>
    <artifactId>feign-slf4j</artifactId>
    <version>${feign.version}</version>
</dependency>
<dependency>
    <groupId>io.github.openfeign</groupId>
    <artifactId>feign-jackson</artifactId>
    <version>${feign.version}</version>
</dependency>
<dependency>
    <groupId>io.github.openfeign</groupId>
    <artifactId>feign-gson</artifactId>
    <version>${feign.version}</version>
</dependency>
<dependency>
    <groupId>io.reactivex</groupId>
    <artifactId>rxjava</artifactId>
    <version>1.2.1</version>
    <scope>compile</scope>
</dependency>

配置

Feign的配置主要有三个,一个是isolation.thread线程存活时间。一个是connectTimeoutMillis连接超时,一个是readTimeoutMillis

本次测试将采用github的公共API,获取用户信息。首先配置线程存活时间。在dev.yml中添加:

hystrixConfig:
  hystrix.command.GithubConnector#getUserProfile(String).execution.isolation.thread.timeoutInMilliseconds: 7000

然后是两个超时配置:

githubApiConfig:
  baseUrl: "https://api.github.com"
  getUserProfile:
    connectTimeoutMillis: 2000
    readTimeoutMillis: 5000

Dropwizard通过配置类和配置文件绑定的方式获取配置内容。因此,需要对应的在配置类中创建对应的字段。
com.test.configuration.modules.ConnectAndReadConfig

package com.test.configuration.modules;

/**
 * Created by Ryan Miao on 9/14/17.
 */
public class ConnectAndReadConfig {
    private int connectTimeoutMillis;
    private int readTimeoutMillis;

    public int getConnectTimeoutMillis() {
        return connectTimeoutMillis;
    }

    public int getReadTimeoutMillis() {
        return readTimeoutMillis;
    }
}

com.test.configuration.modules.GithubApiConfig

package com.test.configuration.modules;

/**
 * Created by Ryan Miao on 9/14/17.
 */
public class GithubApiConfig {
    private String baseUrl;
    private ConnectAndReadConfig getUserProfile;

    public String getBaseUrl() {
        return baseUrl;
    }

    public ConnectAndReadConfig getGetUserProfile() {
        return getUserProfile;
    }
}

在com.test.configuration.HelloWorldConfiguration中添加:

@NotEmpty
private Map<String, Object> hystrixConfig;

@NotNull
private GithubApiConfig githubApiConfig;

然后在application中配置好hystrix的配置:
在HelloWorldApplication#run方法中

//init hystrix config
Map<String, Object> hystrixConfig = configuration.getHystrixConfig();
for (final Map.Entry<String, Object> config : hystrixConfig.entrySet()) {
    ConfigurationManager.getConfigInstance().setProperty(config.getKey(), config.getValue());
}

创建Feign的connector接口

创建接口com.test.domain.connect.GithubConnector:

package com.test.domain.connect;

import com.test.domain.entiry.GithubUser;
import feign.Headers;
import feign.Param;
import feign.RequestLine;
import rx.Observable;

/**
 * Created by ryan on 9/14/17.
 */
public interface GithubConnector {
    /**
     * @param username
     * @return
     */
    @RequestLine("GET /users/{username}")
    @Headers({"Accept: application/vnd.github.v3+json"})
    Observable<GithubUser> getUserProfile(@Param("username") String username);
}

创建调用客户端

创建客户端com.test.domain.connect.GithubClient

package com.test.domain.connect;

import com.test.configuration.modules.ConnectAndReadConfig;
import com.test.configuration.modules.GithubApiConfig;
import com.test.domain.entiry.GithubUser;
import feign.Request;
import feign.Response;
import feign.gson.GsonDecoder;
import feign.gson.GsonEncoder;
import feign.hystrix.HystrixFeign;
import feign.slf4j.Slf4jLogger;
import org.apache.commons.io.IOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import rx.Observable;

import java.io.IOException;
import java.util.UUID;

/**
 * Created by Ryan Miao on 9/14/17.
 */
public class GithubClient {
    public static final Logger LOGGER = LoggerFactory.getLogger(GithubClient.class);

    private GithubApiConfig githubApiConfig;

    public GithubClient(GithubApiConfig githubApiConfig) {
        this.githubApiConfig = githubApiConfig;
    }


    public Observable<GithubUser> getUserProfile(String username) {
        String baseUrl = githubApiConfig.getBaseUrl();
        ConnectAndReadConfig getUserProfile = githubApiConfig.getGetUserProfile();
        GithubConnector connector = HystrixFeign.builder()
                .decoder(new GsonDecoder())
                .encoder(new GsonEncoder())
                .logger(new Slf4jLogger())
                .options(new Request.Options(getUserProfile.getConnectTimeoutMillis(), getUserProfile.getReadTimeoutMillis()))
                .errorDecoder((methodKey, response) -> {
                    StringBuilder msg = new StringBuilder("status=").append(response.status())
                            .append(";request_headers=").append(response.request().headers())
                            .append(";response_headers=").append(response.headers())
                            .append(";body=");
                    Response.Body body = response.body();
                    if (body != null && body.length() > 0) {
                        try {
                            msg.append(IOUtils.toString(body.asReader()));
                        } catch (IOException e) {
                            msg.append("can not read body,"+e.getMessage());
                        }
                    }

                    return new RuntimeException(msg.toString());
                })
                .requestInterceptor(template -> template.header("requestId", UUID.randomUUID().toString()))
                .target(GithubConnector.class, baseUrl);

        return connector.getUserProfile(username).onErrorReturn(error -> {
            LOGGER.error("Get github user profile failed. ", error);
            return null;
        });
    }
}

创建一个接口测试

最后,创建一个接口来测试下:
com.test.domain.resource.GithubResource

package com.test.domain.resource;

import com.codahale.metrics.annotation.Timed;
import com.test.configuration.modules.GithubApiConfig;
import com.test.domain.connect.GithubClient;
import com.test.domain.entiry.GithubUser;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

/**
 * Created by Ryan Miao on 9/14/17.
 */
@Path("/github")
@Produces(MediaType.APPLICATION_JSON)
public class GithubResource {

    private GithubApiConfig githubApiConfig;

    public GithubResource(GithubApiConfig githubApiConfig) {
        this.githubApiConfig = githubApiConfig;
    }

    @GET
    @Timed
    @Path("/users/{username}")
    public GithubUser getUserProfile(@PathParam("username") final String username){
        GithubClient client = new GithubClient(githubApiConfig);
        return client.getUserProfile(username).toBlocking().first();
    }

}

run main方法启动。访问localhost:8080/github/users/Ryan-Miao就可以得到我的github信息了:

{
    "login": "Ryan-Miao",
    "id": 11866078,
    "avatar_url": "https://avatars3.githubusercontent.com/u/11866078?v=4",
    "url": "https://api.github.com/users/Ryan-Miao",
    "name": "Ryan Miao",
    "email": null,
    "location": "中国深圳",
    "blog": "https://ryan-miao.github.io/"
}

至此,feign的简单集成就搞定了。

一些注意事项

feign采用hystrix的配置的时候,grop key是baseUrl.上栗中,grop Key为https://api.github.com, commandKey为接口+方法和参数,上栗中为GithubConnector#getUserProfile(String)。因此,配置线程超时用了commandKey如上。如果要配置coreSize之类的,必须使用url做为group key了。

source

https://github.com/Ryan-Miao/l4dropwizard

参考

posted @ 2017-09-19 12:10  Ryan.Miao  阅读(1718)  评论(0编辑  收藏  举报