RestTemplate配置

什么是RestTemplate？

RestTemplate是Spring提供的用于访问Rest服务的客户端，RestTemplate提供了多种便捷访问远程Http服务的方法，能够大大提高客户端的编写效率。
调用RestTemplate的默认构造函数，RestTemplate对象在底层通过使用java.net包下的实现创建HTTP 请求，可以通过使用ClientHttpRequestFactory指定不同的HTTP请求方式。
ClientHttpRequestFactory接口主要提供了两种实现方式

• 一种是SimpleClientHttpRequestFactory，使用J2SE提供的方式（既java.net包提供的方式）创建底层的Http请求连接。
• 一种方式是使用HttpComponentsClientHttpRequestFactory方式，底层使用HttpClient访问远程的Http服务，使用HttpClient可以配置连接池和证书等信息。

 RestTemplate默认是使用SimpleClientHttpRequestFactory，内部是调用jdk的HttpConnection，默认超时为-1

RestTemplate有两个构造方法，分别是：

/**
 * Create a new instance of the {@link RestTemplate} using default settings.
 */
public RestTemplate() {
    this.messageConverters.add(new ByteArrayHttpMessageConverter());
    this.messageConverters.add(new StringHttpMessageConverter());
    this.messageConverters.add(new ResourceHttpMessageConverter());
    this.messageConverters.add(new SourceHttpMessageConverter());
    this.messageConverters.add(new AllEncompassingFormHttpMessageConverter());
    if (romePresent) {
        this.messageConverters.add(new AtomFeedHttpMessageConverter());
        this.messageConverters.add(new RssChannelHttpMessageConverter());
    }
    if (jaxb2Present) {
        this.messageConverters.add(new Jaxb2RootElementHttpMessageConverter());
    }
    if (jackson2Present) {
        this.messageConverters.add(new MappingJackson2HttpMessageConverter());
    }
    else if (jacksonPresent) {
        this.messageConverters.add(new MappingJacksonHttpMessageConverter());
    }
}

/**
 * Create a new instance of the {@link RestTemplate} based on the given {@link ClientHttpRequestFactory}.
 * @param requestFactory HTTP request factory to use
 * @see org.springframework.http.client.SimpleClientHttpRequestFactory
 * @see org.springframework.http.client.HttpComponentsClientHttpRequestFactory
 */
public RestTemplate(ClientHttpRequestFactory requestFactory) {
    this();
    setRequestFactory(requestFactory);
}

其中，第二个构造方法中可以传入ClientHttpRequestFactory参数，第一个进行默认初始化，因为我们经常需要对请求超时进行设置并能 够对超时进行后续处理，而第一个构造方法，我们无法控制超时时间，第二个构造中的ClientHttpRequestFactory接口的实现类中存在 timeout属性，因此选用第二个构造方法。

基于jdk的spring的RestTemplate

xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans 
　　　　http://www.springframework.org/schema/beans/spring-beans.xsd"
       default-autowire="byName" default-lazy-init="true">
 
    
    <bean id="ky.requestFactory" class="org.springframework.http.client.SimpleClientHttpRequestFactory">
        <property name="readTimeout" value="10000"/>
        <property name="connectTimeout" value="5000"/>
    bean>
 
    <bean id="simpleRestTemplate" class="org.springframework.web.client.RestTemplate">
        <constructor-arg ref="ky.requestFactory"/>
        <property name="messageConverters">
            <list>
                <bean class="org.springframework.http.converter.FormHttpMessageConverter"/>
                <bean class="org.springframework.http.converter.xml.MappingJackson2XmlHttpMessageConverter"/>
                <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"/>
                <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                    <property name="supportedMediaTypes">
                        <list>
                            <value>text/plain;charset=UTF-8value>
                        list>
                    property>
                bean>
            list>
        property>
    bean>
 
beans>

 

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.annotation.Lazy;
import org.springframework.http.client.SimpleClientHttpRequestFactory;
import org.springframework.http.converter.FormHttpMessageConverter;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.StringHttpMessageConverter;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.http.converter.xml.MappingJackson2XmlHttpMessageConverter;
import org.springframework.stereotype.Component;
import org.springframework.web.client.DefaultResponseErrorHandler;
import org.springframework.web.client.RestTemplate;
 
import javax.annotation.PostConstruct;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;
 
@Component
@Lazy(false)
public class SimpleRestClient {
 
    private static final Logger LOGGER = LoggerFactory.getLogger(SimpleRestClient.class);
 
    private static RestTemplate restTemplate;
 
    static {
        SimpleClientHttpRequestFactory requestFactory = new SimpleClientHttpRequestFactory();
        requestFactory.setReadTimeout(5000);
        requestFactory.setConnectTimeout(5000);
 
        // 添加转换器
        List> messageConverters = new ArrayList<>();
        messageConverters.add(new StringHttpMessageConverter(Charset.forName("UTF-8")));
        messageConverters.add(new FormHttpMessageConverter());
        messageConverters.add(new MappingJackson2XmlHttpMessageConverter());
        messageConverters.add(new MappingJackson2HttpMessageConverter());
 
        restTemplate = new RestTemplate(messageConverters);
        restTemplate.setRequestFactory(requestFactory);
        restTemplate.setErrorHandler(new DefaultResponseErrorHandler());
 
        LOGGER.info("SimpleRestClient初始化完成");
    }
 
    private SimpleRestClient() {
 
    }
 
    @PostConstruct
    public static RestTemplate getClient() {
        return restTemplate;
    }
 
}

 

使用Httpclient连接池的方式(推荐)

<bean id="httpClientBuilder" class="org.apache.http.impl.client.HttpClientBuilder" factory-method="create">
    <property name="connectionManager">
        <bean class="org.apache.http.impl.conn.PoolingHttpClientConnectionManager">
            
            <property name="maxTotal" value="50"/>
            
            <property name="defaultMaxPerRoute" value="50"/>
        bean>
    property>
    
    <property name="retryHandler">
        <bean class="org.apache.http.impl.client.DefaultHttpRequestRetryHandler">
            <constructor-arg value="2"/>
            <constructor-arg value="true"/>
        bean>
    property>
    <property name="defaultHeaders">
        <list>
            <bean class="org.apache.http.message.BasicHeader">
                <constructor-arg value="Content-Type"/>
                <constructor-arg value="text/html;charset=UTF-8"/>
            bean>
            <bean class="org.apache.http.message.BasicHeader">
                <constructor-arg value="Accept-Encoding"/>
                <constructor-arg value="gzip,deflate"/>
            bean>
            <bean class="org.apache.http.message.BasicHeader">
                <constructor-arg value="Accept-Language"/>
                <constructor-arg value="zh-CN"/>
            bean>
        list>
    property>
bean>

<bean id="httpClient" factory-bean="httpClientBuilder" factory-method="build"/>

<bean id="restTemplate" class="org.springframework.web.client.RestTemplate">
    <property name="messageConverters">
        <list value-type="org.springframework.http.converter.HttpMessageConverter">
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <property name="supportedMediaTypes">
                    <value>text/html;charset=UTF-8value>
                property>
            bean>
            <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
                <property name="supportedMediaTypes">
                    <value>application/json;charset=UTF-8value>
                property>
            bean>
            <bean class="org.springframework.http.converter.ResourceHttpMessageConverter"/>
            <bean class="org.springframework.http.converter.support.AllEncompassingFormHttpMessageConverter"/>
            <bean class="org.springframework.http.converter.FormHttpMessageConverter"/>
            <bean class="org.springframework.http.converter.xml.MappingJackson2XmlHttpMessageConverter"/>
        list>
    property>
    <property name="requestFactory">
        <bean class="org.springframework.http.client.HttpComponentsClientHttpRequestFactory">
            <constructor-arg ref="httpClient"/>
            
            <property name="connectTimeout" value="20000"/>
            
            <property name="readTimeout" value="20000"/>
        bean>
    property>
bean>

 

import org.apache.http.Header;
import org.apache.http.client.HttpClient;
import org.apache.http.impl.client.DefaultConnectionKeepAliveStrategy;
import org.apache.http.impl.client.DefaultHttpRequestRetryHandler;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.http.message.BasicHeader;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.annotation.Lazy;
import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
import org.springframework.http.converter.FormHttpMessageConverter;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.StringHttpMessageConverter;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.http.converter.xml.MappingJackson2XmlHttpMessageConverter;
import org.springframework.stereotype.Component;
import org.springframework.web.client.DefaultResponseErrorHandler;
import org.springframework.web.client.RestTemplate;
 
import javax.annotation.PostConstruct;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.TimeUnit;
 
@Component
@Lazy(false)
public class RestClient {
 
    private static final Logger LOGGER = LoggerFactory.getLogger(SimpleRestClient.class);
 
    private static RestTemplate restTemplate;
 
    static {
        // 长连接保持30秒
        PoolingHttpClientConnectionManager pollingConnectionManager = new PoolingHttpClientConnectionManager(30, TimeUnit.SECONDS);
        // 总连接数
        pollingConnectionManager.setMaxTotal(1000);
        // 同路由的并发数
        pollingConnectionManager.setDefaultMaxPerRoute(1000);
 
        HttpClientBuilder httpClientBuilder = HttpClients.custom();
        httpClientBuilder.setConnectionManager(pollingConnectionManager);
        // 重试次数，默认是3次，没有开启
        httpClientBuilder.setRetryHandler(new DefaultHttpRequestRetryHandler(2, true));
        // 保持长连接配置，需要在头添加Keep-Alive
        httpClientBuilder.setKeepAliveStrategy(new DefaultConnectionKeepAliveStrategy());
 
//        RequestConfig.Builder builder = RequestConfig.custom();
//        builder.setConnectionRequestTimeout(200);
//        builder.setConnectTimeout(5000);
//        builder.setSocketTimeout(5000);
//
//        RequestConfig requestConfig = builder.build();
//        httpClientBuilder.setDefaultRequestConfig(requestConfig);
 
        List
 headers = new ArrayList<>();
        headers.add(new BasicHeader("User-Agent", "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.16 Safari/537.36"));
        headers.add(new BasicHeader("Accept-Encoding", "gzip,deflate"));
        headers.add(new BasicHeader("Accept-Language", "zh-CN"));
        headers.add(new BasicHeader("Connection", "Keep-Alive"));
 
        httpClientBuilder.setDefaultHeaders(headers);
 
        HttpClient httpClient = httpClientBuilder.build();
 
        // httpClient连接配置，底层是配置RequestConfig
        HttpComponentsClientHttpRequestFactory clientHttpRequestFactory = new HttpComponentsClientHttpRequestFactory(httpClient);
        // 连接超时
        clientHttpRequestFactory.setConnectTimeout(5000);
        // 数据读取超时时间，即SocketTimeout
        clientHttpRequestFactory.setReadTimeout(5000);
        // 连接不够用的等待时间，不宜过长，必须设置，比如连接不够用时，时间过长将是灾难性的
        clientHttpRequestFactory.setConnectionRequestTimeout(200);
        // 缓冲请求数据，默认值是true。通过POST或者PUT大量发送数据时，建议将此属性更改为false，以免耗尽内存。
        // clientHttpRequestFactory.setBufferRequestBody(false);
 
        // 添加内容转换器
        List> messageConverters = new ArrayList<>();
        messageConverters.add(new StringHttpMessageConverter(Charset.forName("UTF-8")));
        messageConverters.add(new FormHttpMessageConverter());
        messageConverters.add(new MappingJackson2XmlHttpMessageConverter());
        messageConverters.add(new MappingJackson2HttpMessageConverter());
 
        restTemplate = new RestTemplate(messageConverters);
        restTemplate.setRequestFactory(clientHttpRequestFactory);
        restTemplate.setErrorHandler(new DefaultResponseErrorHandler());
 
        LOGGER.info("RestClient初始化完成");
    }
 
    private RestClient() {
 
    }
 
    @PostConstruct
    public static RestTemplate getClient() {
        return restTemplate;
    }
 
}

 初体验(POST)

Spring的RestTemplate对post的常用接口：

public  T postForObject(String url, Object request, Class responseType, Object... uriVariables)
            throws RestClientException
public  T postForObject(String url, Object request, Class responseType, Map uriVariables)
            throws RestClientException
public  T postForObject(URI url, Object request, Class responseType) throws RestClientException

常用

HttpHeaders headers = new HttpHeaders();
headers.add("X-Auth-Token", "e348bc22-5efa-4299-9142-529f07a18ac9");

MultiValueMap postParameters = new LinkedMultiValueMap();
postParameters.add("owner", "11");
postParameters.add("subdomain", "aoa");
postParameters.add("comment", "");

HttpEntity> requestEntity  = new HttpEntity>(postParameters, headers);

ParseResultVo exchange = null;
try {
    exchange = restTemplate.postForObject("http://l-dnsutil1.ops.beta.cn6.qunar.com:10085/v1/cnames/tts.piao",  requestEntity, ParseResultVo.class);
    logger.info(exchange.toString());
} catch (RestClientException e) {
    logger.info("。。。。");
}

package com.winner.rest;

import com.alibaba.fastjson.JSON;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

import javax.annotation.Resource;
import java.io.UnsupportedEncodingException;

/**
 * Created by winner_0715 on 2017/1/7.
 */
@Service
public class TestGet {

    @Resource
    private RestTemplate restTemplate;

    /**
     * 要请求的url，一般放在配置文件中
     */
    @Value(value = "@{remote.url}")
    private String remoteUrl;

    public String postRemoteData(ParameterRo ro) throws UnsupportedEncodingException {
        /**
         * 设置请求头
         */
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.parseMediaType("application/json;charset=UTF-8"));
        headers.add("Accept", MediaType.APPLICATION_JSON.toString());

        /**
         * POST请求参数，根据需要进行封装
         */
        String bodyData = new String(Base64Util.encodeData(JSON.toJSONString(ro)).getBytes("UTF-8"), "UTF-8");

        /**
         * 查看HttpEntity的构造方法，包含只有请求头和只有请求体的情况
         */
        HttpEntity httpEntity = new HttpEntity(bodyData, headers);

        /**
         * 执行操作
         */
        String result = restTemplate.postForObject(remoteUrl, httpEntity, String.class);

        return result;
    }

    /**
     * 模拟请求参数
     */
    private class ParameterRo {
        
        private Integer id = 123;

        public Integer getId() {
            return id;
        }

        public void setId(Integer id) {
            this.id = id;
        }
    }
}

初体验(GET)

Spring的RestTemplate提供了许多的支持，这里仅仅列出常用的接口：

public  T getForObject(String url, Class responseType, Object... urlVariables) throws RestClientException 
public  T getForObject(String url, Class responseType, Map urlVariables) throws RestClientException
public  T getForObject(URI url, Class responseType) throws RestClientException

对于GET请求来说，我一般常用的几种形式如下：

String result = restTemplate.getForObject("http://example.com/hotels/{hotel}/bookings/{booking}", String.class,"42", "21");

或者下面这种形式：

Map vars = Collections.singletonMap("hotel", "42");
String result = restTemplate.getForObject("http://example.com/hotels/{hotel}/rooms/{hotel}", String.class, vars);

以及：

String message = restTemplate.getForObject("http://localhost:8080/yongbarservice/appstore/appgoods/restTemplate?name=zhaoshijie&id=80", String.class );

package com.winner.rest;

import com.alibaba.fastjson.JSON;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

import javax.annotation.Resource;
import java.io.UnsupportedEncodingException;

/**
 * Created by winner_0715 on 2017/1/7.
 */
@Service
public class TestGet {

    @Resource
    private RestTemplate restTemplate;

    /**
     * 要请求的url，一般放在配置文件中
     */
    @Value(value = "@{remote.url}")
    private String remoteUrl;

    public String getRemoteData(ParameterRo ro) throws UnsupportedEncodingException {

        //根据需要也可以设置请求头

        /**
         * get请求参数，根据需要进行封装(加密等)
         */
        String getData = new String(Base64Util.encodeData(JSON.toJSONString(ro)).getBytes("UTF-8"), "UTF-8");

        /**
         * 执行操作
         */
        String result = restTemplate.getForObject(remoteUrl + "?" + getData, String.class);

        return result;
    }

    /**
     * 模拟请求参数
     */
    private class ParameterRo {

        private Integer id = 123;

        public Integer getId() {
            return id;
        }

        public void setId(Integer id) {
            this.id = id;
        }
    }
}