4
非常簡單的設置：春RestTemplate＆AsyncRestTemplate與Netty4掛起永遠
的pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.example</groupId>
<artifactId>demo-rest-client</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>demo-rest-client</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.4.1.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
<version>4.1.5.Final</version>
</dependency>
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-buffer</artifactId>
<version>4.1.5.Final</version>
</dependency>
<dependency>
<groupId>com.squareup.okhttp3</groupId>
<artifactId>okhttp</artifactId>
<version>3.4.1</version>
</dependency>
<dependency>
<groupId>io.github.openfeign</groupId>
<artifactId>feign-core</artifactId>
<version>9.3.1</version>
</dependency>
<dependency>
<groupId>io.github.openfeign</groupId>
<artifactId>feign-hystrix</artifactId>
<version>9.3.1</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
和測試案例來證明AsyncRestTemplate的不同用途：
SampleTests.java
package com.example;
import com.netflix.hystrix.HystrixCommand;
import com.netflix.hystrix.HystrixCommandProperties;
import feign.RequestLine;
import feign.hystrix.HystrixFeign;
import feign.hystrix.SetterFactory;
import org.junit.Test;
import org.springframework.http.ResponseEntity;
import org.springframework.http.client.Netty4ClientHttpRequestFactory;
import org.springframework.http.client.OkHttp3ClientHttpRequestFactory;
import org.springframework.util.concurrent.ListenableFuture;
import org.springframework.web.client.AsyncRestTemplate;
import org.springframework.web.client.RestTemplate;
public class SampleTests {
private static final String URL = "https://api.github.com/users/octocat";
private static final int DEFAULT_SLEEP_MILLIS = 20;
private static final int DEFAULT_TIMEOUT = 10000;
@Test(timeout = DEFAULT_TIMEOUT)
public void syncRestNetty() throws Exception {
RestTemplate restTemplate = new RestTemplate(new Netty4ClientHttpRequestFactory());
ResponseEntity<String> response = restTemplate.getForEntity(URL, String.class);
System.out.println("response = " + response);
}
@Test(timeout = DEFAULT_TIMEOUT)
public void asyncRestNetty() throws Exception {
AsyncRestTemplate restTemplate = new AsyncRestTemplate(new Netty4ClientHttpRequestFactory());
ListenableFuture<ResponseEntity<String>> listenableFuture = restTemplate.getForEntity(URL, String.class);
listenableFuture.addCallback(result -> System.out.println("result = " + result), Throwable::printStackTrace);
while (!listenableFuture.isDone()) {
Thread.sleep(DEFAULT_SLEEP_MILLIS);
}
System.out.println("the end");
}
@Test
public void asyncRestOkHttp() throws Exception {
AsyncRestTemplate restTemplate = new AsyncRestTemplate(new OkHttp3ClientHttpRequestFactory());
ListenableFuture<ResponseEntity<String>> listenableFuture = restTemplate.getForEntity(URL, String.class);
listenableFuture.addCallback(result -> System.out.println("result = " + result), Throwable::printStackTrace);
while (!listenableFuture.isDone()) {
Thread.sleep(DEFAULT_SLEEP_MILLIS);
}
System.out.println("the end");
}
@Test
public void asyncRestHystrixFeign() throws Exception {
GitHub gitHub = HystrixFeign.builder()
.setterFactory((target, method) -> new SetterFactory.Default().create(target, method).andCommandPropertiesDefaults(HystrixCommandProperties.defaultSetter().withExecutionTimeoutInMilliseconds(10000)))
.target(GitHub.class, "https://api.github.com");
HystrixCommand<String> command = gitHub.octocatAsync();
command.toObservable().subscribe(result -> System.out.println("result = " + result), Throwable::printStackTrace);
while (!command.isExecutionComplete()) {
Thread.sleep(DEFAULT_SLEEP_MILLIS);
}
System.out.println("command.getExecutionTimeInMilliseconds() = " + command.getExecutionTimeInMilliseconds());
System.out.println("the end");
}
interface GitHub {
@RequestLine("GET /users/octocat")
HystrixCommand<String> octocatAsync();
}
}
當試圖運行使用Netty的測試時，它們會永遠掛起。 （爲了看到這個，請刪除JUnit超時限制）。但是，如果我運行與其他客戶端完全相同的代碼，一切都按預期工作。
我嘗試過不同版本的Spring Boot和Netty，但沒有成功。從日誌中看，一切都很好。
我在這裏錯過了什麼？
編輯： 開了票https://jira.spring.io/browse/SPR-14744春的Gitter的建議
EDIT 2：從布賴恩Clozel 回答幫我找到了這是關係到了Netty沒有意識到服務器發送一個空響應的問題（一個特定的Github API和純http的情況下），所以我將其標記爲已接受。