简介
- RestTemplate是spring支持的一个请求http rest服务的模板对象，性质上有点像jdbcTemplate
- 是Spring用于同步client端的核心类，简化了与http服务的通信，并满足RestFul原则，程序代码可以给它提供URL，并提取结果。默认情况下，RestTemplate默认依赖jdk的HTTP连接工具。当然你也可以 通过setRequestFactory属性切换到不同的HTTP源，比如Apache HttpComponents、Netty和OkHttp。本章讨论的就是设置RestTemplate底层使用的httpclient（org.apache.http.client.HttpClient）发送请求
- HttpClient可以做连接池，而发送消息的工具类可以使用RestTemplate，所以如果你的项目需求http连接池，RestTemplate+httpclient连接池是一种不错的方式，可以节省开发工作，也可以更优雅的使用。
配置
- maven依赖
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.6</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>2. Java配置类
import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;
@Component
@ConfigurationProperties(prefix = "http-pool")
@Data
public class HttpPoolProperties {
private Integer maxTotal;
private Integer defaultMaxPerRoute;
private Integer connectTimeout;
private Integer connectionRequestTimeout;
private Integer socketTimeout;
private Integer validateAfterInactivity;
}
import org.apache.http.client.HttpClient;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.config.Registry;
import org.apache.http.config.RegistryBuilder;
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.impl.client.HttpClientBuilder;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.client.ClientHttpRequestFactory;
import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
import org.springframework.web.client.RestTemplate;
@Configuration
public class RestTemplateConfig {
@Autowired
private HttpPoolProperties httpPoolProperties;
@Bean
public RestTemplate restTemplate() {
return new RestTemplate(httpRequestFactory());
}
@Bean
public ClientHttpRequestFactory httpRequestFactory() {
return new HttpComponentsClientHttpRequestFactory(httpClient());
}
@Bean
public HttpClient httpClient() {
Registry<ConnectionSocketFactory> registry = RegistryBuilder.<ConnectionSocketFactory>create()
.register("http", PlainConnectionSocketFactory.getSocketFactory())
.register("https", SSLConnectionSocketFactory.getSocketFactory())
.build();
PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager(registry);
connectionManager.setMaxTotal(httpPoolProperties.getMaxTotal());
connectionManager.setDefaultMaxPerRoute(httpPoolProperties.getDefaultMaxPerRoute());
connectionManager.setValidateAfterInactivity(httpPoolProperties.getValidateAfterInactivity());
RequestConfig requestConfig = RequestConfig.custom()
.setSocketTimeout(httpPoolProperties.getSocketTimeout()) //服务器返回数据(response)的时间，超过抛出read timeout
.setConnectTimeout(httpPoolProperties.getConnectTimeout()) //连接上服务器(握手成功)的时间，超出抛出connect timeout
.setConnectionRequestTimeout(httpPoolProperties.getConnectionRequestTimeout())//从连接池中获取连接的超时时间，超时间未拿到可用连接，会抛出org.apache.http.conn.ConnectionPoolTimeoutException: Timeout waiting for connection from pool
.build();
return HttpClientBuilder.create()
.setDefaultRequestConfig(requestConfig)
.setConnectionManager(connectionManager)
.build();
}
}3.使用方法
import org.json.JSONException;
import org.json.JSONObject;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;
import java.io.IOException;
@Service
public class TestService {
@Autowired
private RestTemplate restTemplate;
public void startTest() throws JSONException, IOException {
JSONObject jsonObject = new JSONObject();
jsonObject.put("first","jinjian");
jsonObject.put("second","aaaaaaa");
long start = System.currentTimeMillis();
//{1} 表示第一个占位符，也可以填写name,但是这是另一个getForEntity重载方法
//TestResponseEntity 为自定义dto
ResponseEntity<TestResponseEntity> entity = restTemplate.getForEntity("http://39.107.104.221/api/test/{1}", TestResponseEntity.class, 123);
long end = System.currentTimeMillis();
long cost = end - start;
System.out.println("耗时："+cost);
RuiooResponseEntity body = entity.getBody();
body.getData();
body.getStatus();
body.getMessage();
System.out.println("响应体："+ body);
}
}