springboot中如何使用RestTemplate请求url获取返回信息呢?

RestTemplate简介

RestTemplate是spring支持的一个请求http rest服务的模板对象

RestTemplate底层是使用httpclient(org.apache.http.client.HttpClient)发送请求

SpringBoot使用RestTemplate的方法

1.引入相应的依赖
2.配置相应的属性
3.编写相应的代码，即可实现RestTemplate请求url，返回http信息

maven依赖包引入

<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>

配置信息写入

 
httpConfig.properties：

http.maxTotal=500
http.defaultMaxPerRoute=300
#设置连接超时时间，单位毫秒
http.connectTimeout=10000
#http clilent中从connetcion pool中获得一个connection的超时时间,单位毫秒
http.connectionRequestTimeout=500
#请求获取数据的超时时间，单位毫秒。 如果访问一个接口，多少时间内无法返回数据，就直接放弃此次调用
http.socketTimeout=15000
http.staleConnectionCheckEnabled=true

业务代码

import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.PropertySource;
import org.springframework.stereotype.Component;
 
@Component
@PropertySource(value= {"classpath:properties/httpConfig.properties"})
@ConfigurationProperties(prefix = "http.pool.conn")
@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.http.converter.HttpMessageConverter;
import org.springframework.http.converter.StringHttpMessageConverter;
import org.springframework.web.client.RestTemplate;

import java.nio.charset.StandardCharsets;
import java.util.list;
 
@Configuration
public class RestTemplateConfig {

    @Autowired
    private HttpPoolProperties httpPoolProperties;

    @Bean
    public RestTemplate restTemplate() {
        RestTemplate restTemplate = new RestTemplate(httpRequestFactory());
        List<HttpMessageConverter<?>> converterList = restTemplate.getMessageConverters();

        //重新设置StringHttpMessageConverter字符集为UTF-8，解决中文乱码问题
        HttpMessageConverter<?> converterTarget = null;
        for (HttpMessageConverter<?> item : converterList) {
            if (StringHttpMessageConverter.class == item.getClass()) {
                converterTarget = item;
                break;
            }
        }
        if (null != converterTarget) {
            converterList.remove(converterTarget);
        }
        converterList.add(1, new StringHttpMessageConverter(StandardCharsets.UTF_8));
        return restTemplate;
    }

    @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();
    }

}

测试示例

@Autowired
private ObjectMapper objectMapper;
@Autowired
private RestTemplate restTemplate;
@Override
public WeatherApiPojo getWeather(String requestUrl) {
	WeatherApiPojo weatherApiPojo = new WeatherApiPojo();
	try {
		logger.info("I'm going to send request: " + requestUrl);

		ResponseEntity<String> responseEntity = restTemplate.getForEntity(requestUrl,String.class);
		if (responseEntity!=null && responseEntity.getStatusCodeValue()==200){
			objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
			weatherApiPojo = objectMapper.readValue(responseEntity.getBody(), WeatherApiPojo.class);
		} else {
			weatherApiPojo.setCode("-1");
		}
		return weatherApiPojo;
	} catch (Exception e) {
		logger.error("API接口getWeather error {} ", e);
		weatherApiPojo.setCode("-1");
	}
	return weatherApiPojo;
}