RestTemplate 配置与使用示例
RestTemplate 配置与使用示例
RestTemplate 是 Spring 提供的用于访问 Rest 服务的客户端库。它提供了一套接口，然后分别用三种 Java 最常用 Http 连接的库来分别实现这套接口：
- JDK 自带的 HttpURLConnection
- Apache 的 HttpClient
- OKHttp3
本文使用
HttpClient作为Http连接库进行 RestTemplate 的配置
配置RestTemplate
引入
想要在SpringBoot项目中使用RestTemplate，需要在pom.xml文件中引入spring-boot-starter-web；
pom.xml:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
其次，由于使用HttpClient作为连接库，需要同时引入HttpClient。
pom.xml:
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.12</version>
</dependency>
配置
HttpClient配置
- PoolingHttpClientConnectionManager : 连接池管理，负责设置诸如最大连接数、超时时间等配置；
- ConnectionKeepAliveStrategy : 长连接设置，负责设置连接有效时间；
- idleConnectionMonitor : 连接监控器，负责检查所以连接状态。
HttpClientConfig.java
package com.huawei.gab.AutoTestFrameWork.common.config;
import org.apache.http.HeaderElement;
import org.apache.http.HeaderElementIterator;
import org.apache.http.HttpResponse;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.config.Registry;
import org.apache.http.config.RegistryBuilder;
import org.apache.http.conn.ConnectionKeepAliveStrategy;
import org.apache.http.conn.socket.ConnectionSocketFactory;
import org.apache.http.conn.socket.PlainConnectionSocketFactory;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.conn.ssl.TrustSelfSignedStrategy;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.http.message.BasicHeaderElementIterator;
import org.apache.http.protocol.HTTP;
import org.apache.http.protocol.HttpContext;
import org.apache.http.ssl.SSLContextBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.scheduling.annotation.Scheduled;
import java.security.KeyManagementException;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.util.concurrent.TimeUnit;
@Configuration
@EnableScheduling
public class HttpClientConfig {
private static final Logger LOGGER = LoggerFactory.getLogger(HttpClientConfig.class);
// Determines the timeout in milliseconds until a connection is established.
private static final int CONNECT_TIMEOUT = 30000;
// The timeout when requesting a connection from the connection manager.
private static final int REQUEST_TIMEOUT = 30000;
// The timeout for waiting for data
private static final int SOCKET_TIMEOUT = 60000;
private static final int MAX_TOTAL_CONNECTIONS = 50;
private static final int DEFAULT_KEEP_ALIVE_TIME_MILLIS = 20 * 1000;
private static final int CLOSE_IDLE_CONNECTION_WAIT_TIME_SECS = 30;
@Bean
public PoolingHttpClientConnectionManager poolingConnectionManager() {
SSLContextBuilder builder = new SSLContextBuilder();
try {
builder.loadTrustMaterial(null, new TrustSelfSignedStrategy());
} catch (NoSuchAlgorithmException | KeyStoreException e) {
LOGGER.error("Pooling Connection Manager Initialisation failure because of " + e.getMessage(), e);
}
SSLConnectionSocketFactory sslsf = null;
try {
sslsf = new SSLConnectionSocketFactory(builder.build());
} catch (KeyManagementException | NoSuchAlgorithmException e) {
LOGGER.error("Pooling Connection Manager Initialisation failure because of " + e.getMessage(), e);
}
Registry<ConnectionSocketFactory> socketFactoryRegistry = RegistryBuilder
.<ConnectionSocketFactory>create().register("https", sslsf)
.register("http", new PlainConnectionSocketFactory())
.build();
PoolingHttpClientConnectionManager poolingConnectionManager = new PoolingHttpClientConnectionManager(socketFactoryRegistry);
poolingConnectionManager.setMaxTotal(MAX_TOTAL_CONNECTIONS);
return poolingConnectionManager;
}
@Bean
public ConnectionKeepAliveStrategy connectionKeepAliveStrategy() {
return new ConnectionKeepAliveStrategy() {
@Override
public long getKeepAliveDuration(HttpResponse response, HttpContext context) {
HeaderElementIterator it = new BasicHeaderElementIterator
(response.headerIterator(HTTP.CONN_KEEP_ALIVE));
while (it.hasNext()) {
HeaderElement he = it.nextElement();
String param = he.getName();
String value = he.getValue();
if (value != null && param.equalsIgnoreCase("timeout")) {
return Long.parseLong(value) * 1000;
}
}
return DEFAULT_KEEP_ALIVE_TIME_MILLIS;
}
};
}
@Bean
public CloseableHttpClient httpClient() {
RequestConfig requestConfig = RequestConfig.custom()
.setConnectionRequestTimeout(REQUEST_TIMEOUT)
.setConnectTimeout(CONNECT_TIMEOUT)
.setSocketTimeout(SOCKET_TIMEOUT).build();
return HttpClients.custom()
.setDefaultRequestConfig(requestConfig)
.setConnectionManager(poolingConnectionManager())
.setKeepAliveStrategy(connectionKeepAliveStrategy())
.build();
}
@Bean
public Runnable idleConnectionMonitor(final PoolingHttpClientConnectionManager connectionManager) {
return new Runnable() {
@Override
@Scheduled(fixedDelay = 10000)
public void run() {
try {
if (connectionManager != null) {
LOGGER.trace("run IdleConnectionMonitor - Closing expired and idle connections...");
connectionManager.closeExpiredConnections();
connectionManager.closeIdleConnections(CLOSE_IDLE_CONNECTION_WAIT_TIME_SECS, TimeUnit.SECONDS);
} else {
LOGGER.trace("run IdleConnectionMonitor - Http Client Connection manager is not initialised");
}
} catch (Exception e) {
LOGGER.error("run IdleConnectionMonitor - Exception occurred. msg={}, e={}", e.getMessage(), e);
}
}
};
}
}
RestTemplate配置
- HttpComponentsClientHttpRequestFactory : 这就是基于 HttpClient 的
ClientHttpRequestFactory实现，用来创建 request； - @Scheduled 注释 : 连接上 HttpClientConfig 的配置。
RestTemplateConfig.java:
package com.huawei.gab.AutoTestFrameWork.common.config;
import com.huawei.gab.AutoTestFrameWork.common.utils.HttpClientUtils;
import org.apache.http.impl.client.CloseableHttpClient;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
import org.springframework.scheduling.TaskScheduler;
import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;
import org.springframework.web.client.RestTemplate;
import java.security.KeyManagementException;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
@Configuration
public class RestTemplateConfig {
@Bean
public RestTemplate restTemplate() throws KeyStoreException, NoSuchAlgorithmException, KeyManagementException {
RestTemplate restTemplate = new RestTemplate(clientHttpRequestFactory());
return restTemplate;
}
@Bean
public HttpComponentsClientHttpRequestFactory clientHttpRequestFactory() throws KeyStoreException, NoSuchAlgorithmException, KeyManagementException {
CloseableHttpClient httpClient = HttpClientUtils.acceptsUntrustedCertsHttpClient();
HttpComponentsClientHttpRequestFactory clientHttpRequestFactory = new HttpComponentsClientHttpRequestFactory(httpClient);
return clientHttpRequestFactory;
}
@Bean
public TaskScheduler taskScheduler() {
ThreadPoolTaskScheduler scheduler = new ThreadPoolTaskScheduler();
scheduler.setThreadNamePrefix("poolScheduler");
scheduler.setPoolSize(50);
return scheduler;
}
}
使用RestTemplate
测试
一下是一个简单的RestTemplate测试文件：
TestApplication.java
package com.howtodoinjava;
import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.web.client.RestTemplate;
import com.howtodoinjava.config.HttpClientConfig;
import com.howtodoinjava.config.RestTemplateConfig;
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = { RestTemplateConfig.class, HttpClientConfig.class })
public class TestApplication {
@Autowired
RestTemplate restTemplate;
@Test
public void getEmployees() {
final String uri = "http://localhost:8080/hello";
String result = restTemplate.getForObject(uri, String.class);
Assert.assertEquals(true, result != null);
}
}
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