關於spring resttemplate超時設置

• Spring org.springframework.web.client.RestTemplate 使用 org.springframework.http.client.SimpleClientHttpRequestFactory建立 java.net.HttpURLConnection
• 后者采用 HttpURLConnection 的默認超時配置

HttpURLConnection 超時屬性

ConnectTimeout(ms)

• a specified timeout value, in milliseconds, to be used when opening a communications link to the resource referenced by this URLConnection.
• If the timeout expires before the connection can be established, a java.net.SocketTimeoutException is raised. A timeout of zero is interpreted as an infinite timeout.

ReadTimeout(ms)

• a specified timeout, in milliseconds.
• A non-zero value specifies the timeout when reading from Input stream when a connection is established to a resource.
• If the timeout expires before there is data available for read, a java.net.SocketTimeoutException is raised.
• A timeout of zero is interpreted as an infinite timeout

RestTemplate 超時設置

Command Line Args (不修改代碼,啟動時配置)

覆蓋 HttpURLConnection 默認設置.

-Dsun.net.client.defaultConnectTimeout=<TimeoutInMiliSec>
-Dsun.net.client.defaultReadTimeout=<TimeoutInMiliSec>

使用 SimpleClientHttpRequestFactory 建立 HttpURLConnection

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.client.SimpleClientHttpRequestFactory;
import org.springframework.web.client.RestTemplate;

import java.security.KeyManagementException;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;

@Configuration
public class RestTemplateConfiguration {
    @Bean
    public RestTemplate restTemplate() throws KeyStoreException, NoSuchAlgorithmException, KeyManagementException {

        SimpleClientHttpRequestFactory clientHttpRequestFactory
                = new SimpleClientHttpRequestFactory();
        clientHttpRequestFactory.setConnectTimeout(10 * 1000);
        clientHttpRequestFactory.setReadTimeout(10 * 1000);
        return new RestTemplate(clientHttpRequestFactory);
    }
}

使用 HttpComponentsClientHttpRequestFactory 建立 HttpURLConnection(推薦)

• org.springframework.http.client.HttpComponentsClientHttpRequestFactory
• HttpComponentsClientHttpRequestFactory 的構造器和 setter 方法支持自定義配置的 org.apache.http.client.HttpClient
• 推薦原因
  * 通過 HttpClient 的構建類 org.apache.http.impl.client.HttpClientBuilder.setConnectionManager(pollingConnectionManager)方法設置連接池
  * HttpClientBuilder.setDefaultRequestConfig 設置超時
  * HttpClientBuilder.setDefaultHeaders(headers) 設置默認 headers

Java Config 實現

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
import org.springframework.web.client.RestTemplate;

import java.security.KeyManagementException;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;

@Configuration
public class RestTemplateConfiguration {
    @Bean
    public RestTemplate restTemplate() throws KeyStoreException, NoSuchAlgorithmException, KeyManagementException {
        HttpComponentsClientHttpRequestFactory httpRequestFactory = new HttpComponentsClientHttpRequestFactory();
        httpRequestFactory.setConnectionRequestTimeout(30 * 1000);
        httpRequestFactory.setConnectTimeout(2 * 60 * 1000);
        httpRequestFactory.setReadTimeout(10 * 60 * 1000);
        return new RestTemplate(httpRequestFactory);
    }
}

Java Config with custom config properties

• 避免超時配置與代碼耦合, 獨立設置
• 同時也可使用配置中心, 動態設置超時時間

rest.template.conn.connect-timeout=3000
rest.template.conn.read-timeout=3000

@Configuration
public class RestTemplateConfig{
    @Bean
    @ConfigurationProperties(prefix = "rest.template.conn")
    public HttpComponentsClientHttpRequestFactory customHttpRequestFactory() {
        return new HttpComponentsClientHttpRequestFactory();
    }

    @Bean
    public RestTemplate customRestTemplate(){
        return new RestTemplate(customHttpRequestFactory());
    }
}