基于springboot的RestTemplate、okhttp和HttpClient对比分析

1、HttpClient：代码复杂，还得操心资源回收等。代码很复杂，冗余代码多，不建议直接使用。

2、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。

引入jar包：

 <dependency>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter-web</artifactId>
       </dependency>

添加初始化配置（也可以不配，有默认的）--注意RestTemplate只有初始化配置，没有什么连接池

package com.itunion.config;

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

@Configuration
public class ApiConfig {
   @Bean
   public RestTemplate restTemplate(ClientHttpRequestFactory factory) {
       return new RestTemplate(factory);
   }

@Bean
   public ClientHttpRequestFactory simpleClientHttpRequestFactory() {
       SimpleClientHttpRequestFactory factory = new SimpleClientHttpRequestFactory();//默认的是JDK提供http连接，需要的话可以//通过setRequestFactory方法替换为例如Apache HttpComponents、Netty或//OkHttp等其它HTTP library。
       factory.setReadTimeout(5000);//单位为ms
       factory.setConnectTimeout(5000);//单位为ms
       return factory;
   }
}

1）get请求（不带参的即把参数取消即可）

// 1-getForObject()
User user1 = this.restTemplate.getForObject(uri, User.class);

// 2-getForEntity()
ResponseEntity<User> responseEntity1 = this.restTemplate.getForEntity(uri, User.class);
HttpStatus statusCode = responseEntity1.getStatusCode();
HttpHeaders header = responseEntity1.getHeaders();
User user2 = responseEntity1.getBody();

// 3-exchange()
RequestEntity requestEntity = RequestEntity.get(new URI(uri)).build();
ResponseEntity<User> responseEntity2 = this.restTemplate.exchange(requestEntity, User.class);
User user3 = responseEntity2.getBody();

方式一：

Notice notice = restTemplate.getForObject("http://fantj.top/notice/list/{1}/{2}"
               , Notice.class,1,5);

方式二：

Map<String,String> map = new HashMap();
       map.put("start","1");
       map.put("page","5");
       Notice notice = restTemplate.getForObject("http://fantj.top/notice/list/"
               , Notice.class,map);

2）post请求：

// 1-postForObject()
User user1 = this.restTemplate.postForObject(uri, user, User.class);

// 2-postForEntity()
ResponseEntity<User> responseEntity1 = this.restTemplate.postForEntity(uri, user, User.class);

// 3-exchange()
RequestEntity<User> requestEntity = RequestEntity.post(new URI(uri)).body(user);
ResponseEntity<User> responseEntity2 = this.restTemplate.exchange(requestEntity, User.class);

方式一：

String url = "http://demo/api/book/";
       HttpHeaders headers = new HttpHeaders();
       MediaType type = MediaType.parseMediaType("application/json; charset=UTF-8");
       headers.setContentType(type);
       String requestJson = "{...}";
       HttpEntity<String> entity = new HttpEntity<String>(requestJson,headers);
       String result = restTemplate.postForObject(url, entity, String.class);
       System.out.println(result);

方式二：

@Test
public void rtPostObject(){
   RestTemplate restTemplate = new RestTemplate();
   String url = "http://47.xxx.xxx.96/register/checkEmail";
   HttpHeaders headers = new HttpHeaders();
   headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
   MultiValueMap<String, String> map= new LinkedMultiValueMap<>();
   map.add("email", "844072586@qq.com");

HttpEntity<MultiValueMap<String, String>> request = new HttpEntity<>(map, headers);
   ResponseEntity<String> response = restTemplate.postForEntity( url, request , String.class );
   System.out.println(response.getBody());
}

其它：还支持上传和下载功能；

3、okhttp：OkHttp是一个高效的HTTP客户端，允许所有同一个主机地址的请求共享同一个socket连接；连接池减少请求延时；透明的GZIP压缩减少响应数据的大小；缓存响应内容，避免一些完全重复的请求

当网络出现问题的时候OkHttp依然坚守自己的职责，它会自动恢复一般的连接问题，如果你的服务有多个IP地址，当第一个IP请求失败时，OkHttp会交替尝试你配置的其他IP，OkHttp使用现代TLS技术(SNI, ALPN)初始化新的连接，当握手失败时会回退到TLS 1.0。

1）使用：它的请求/响应 API 使用构造器模式builders来设计，它支持阻塞式的同步请求和带回调的异步请求。

引入jar包：

<dependency>
   <groupId>com.squareup.okhttp3</groupId>
   <artifactId>okhttp</artifactId>
   <version>3.10.0</version>
</dependency>

2）配置文件：

import okhttp3.ConnectionPool;
import okhttp3.OkHttpClient;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;
import java.security.KeyManagementException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.concurrent.TimeUnit;

@Configuration
public class OkHttpConfiguration {

@Bean
   public OkHttpClient okHttpClient() {
       return new OkHttpClient.Builder()
               //.sslSocketFactory(sslSocketFactory(), x509TrustManager())
               .retryOnConnectionFailure(false)
               .connectionPool(pool())
               .connectTimeout(30, TimeUnit.SECONDS)
               .readTimeout(30, TimeUnit.SECONDS)
               .writeTimeout(30,TimeUnit.SECONDS)
               .build();
   }

@Bean
   public X509TrustManager x509TrustManager() {
       return new X509TrustManager() {
           @Override
           public void checkClientTrusted(X509Certificate[] x509Certificates, String s) throws CertificateException {
           }
           @Override
           public void checkServerTrusted(X509Certificate[] x509Certificates, String s) throws CertificateException {
           }
           @Override
           public X509Certificate[] getAcceptedIssuers() {
               return new X509Certificate[0];
           }
       };
   }

@Bean
   public SSLSocketFactory sslSocketFactory() {
       try {
           //信任任何链接
           SSLContext sslContext = SSLContext.getInstance("TLS");
           sslContext.init(null, new TrustManager[]{x509TrustManager()}, new SecureRandom());
           return sslContext.getSocketFactory();
       } catch (NoSuchAlgorithmException e) {
           e.printStackTrace();
       } catch (KeyManagementException e) {
           e.printStackTrace();
       }
       return null;
   }

/**
    * Create a new connection pool with tuning parameters appropriate for a single-user application.
    * The tuning parameters in this pool are subject to change in future OkHttp releases. Currently
    */
   @Bean
   public ConnectionPool pool() {
       return new ConnectionPool(200, 5, TimeUnit.MINUTES);
   }
}

3）util工具：

import okhttp3.*;
import org.apache.commons.lang3.exception.ExceptionUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.util.Iterator;
import java.util.Map;

public class OkHttpUtil{
   private static final Logger logger = LoggerFactory.getLogger(OkHttpUtil.class);

private static OkHttpClient  okHttpClient;

@Autowired
   public OkHttpUtil(OkHttpClient  okHttpClient) {
       OkHttpUtil.okHttpClient= okHttpClient;
   }

/**
    * get
    * @param url     请求的url
    * @param queries 请求的参数，在浏览器？后面的数据，没有可以传null
    * @return
    */
   public static  String get(String url, Map<String, String> queries) {
       String responseBody = "";
       StringBuffer sb = new StringBuffer(url);
       if (queries != null && queries.keySet().size() > 0) {
           boolean firstFlag = true;
           Iterator iterator = queries.entrySet().iterator();
           while (iterator.hasNext()) {
               Map.Entry entry = (Map.Entry<String, String>) iterator.next();
               if (firstFlag) {
                   sb.append("?" + entry.getKey() + "=" + entry.getValue());
                   firstFlag = false;
               } else {
                   sb.append("&" + entry.getKey() + "=" + entry.getValue());
               }
           }
       }
       Request request = new Request.Builder()
               .url(sb.toString())
               .build();
       Response response = null;
       try {
           response = okHttpClient.newCall(request).execute();
           int status = response.code();
           if (response.isSuccessful()) {
               return response.body().string();
           }
       } catch (Exception e) {
           logger.error("okhttp3 put error >> ex = {}", ExceptionUtils.getStackTrace(e));
       } finally {
           if (response != null) {
               response.close();
           }
       }
       return responseBody;
   }

/**
    * post
    *
    * @param url    请求的url
    * @param params post form 提交的参数
    * @return
    */
   public static String post(String url, Map<String, String> params) {
       String responseBody = "";
       FormBody.Builder builder = new FormBody.Builder();
       //添加参数
       if (params != null && params.keySet().size() > 0) {
           for (String key : params.keySet()) {
               builder.add(key, params.get(key));
           }
       }
       Request request = new Request.Builder()
               .url(url)
               .post(builder.build())
               .build();
       Response response = null;
       try {
           response = okHttpClient.newCall(request).execute();
           int status = response.code();
           if (response.isSuccessful()) {
               return response.body().string();
           }
       } catch (Exception e) {
           logger.error("okhttp3 post error >> ex = {}", ExceptionUtils.getStackTrace(e));
       } finally {
           if (response != null) {
               response.close();
           }
       }
       return responseBody;
   }

/**
    * get
    * @param url     请求的url
    * @param queries 请求的参数，在浏览器？后面的数据，没有可以传null
    * @return
    */
   public static String getForHeader(String url, Map<String, String> queries) {
       String responseBody = "";
       StringBuffer sb = new StringBuffer(url);
       if (queries != null && queries.keySet().size() > 0) {
           boolean firstFlag = true;
           Iterator iterator = queries.entrySet().iterator();
           while (iterator.hasNext()) {
               Map.Entry entry = (Map.Entry<String, String>) iterator.next();
               if (firstFlag) {
                   sb.append("?" + entry.getKey() + "=" + entry.getValue());
                   firstFlag = false;
               } else {
                   sb.append("&" + entry.getKey() + "=" + entry.getValue());
               }
           }
       }
       Request request = new Request.Builder()
               .addHeader("key", "value")
               .url(sb.toString())
               .build();
       Response response = null;
       try {
           response = okHttpClient.newCall(request).execute();
           int status = response.code();
           if (response.isSuccessful()) {
               return response.body().string();
           }
       } catch (Exception e) {
           logger.error("okhttp3 put error >> ex = {}", ExceptionUtils.getStackTrace(e));
       } finally {
           if (response != null) {
               response.close();
           }
       }
       return responseBody;
   }

/**
    * Post请求发送JSON数据....{"name":"zhangsan","pwd":"123456"}
    * 参数一：请求Url
    * 参数二：请求的JSON
    * 参数三：请求回调
    */
   public static String postJsonParams(String url, String jsonParams) {
       String responseBody = "";
       RequestBody requestBody = RequestBody.create(MediaType.parse("application/json; charset=utf-8"), jsonParams);
       Request request = new Request.Builder()
               .url(url)
               .post(requestBody)
               .build();
       Response response = null;
       try {
           response = okHttpClient.newCall(request).execute();
           int status = response.code();
           if (response.isSuccessful()) {
               return response.body().string();
           }
       } catch (Exception e) {
           logger.error("okhttp3 post error >> ex = {}", ExceptionUtils.getStackTrace(e));
       } finally {
           if (response != null) {
               response.close();
           }
       }
       return responseBody;
   }

/**
    * Post请求发送xml数据....
    * 参数一：请求Url
    * 参数二：请求的xmlString
    * 参数三：请求回调
    */
   public static String postXmlParams(String url, String xml) {
       String responseBody = "";
       RequestBody requestBody = RequestBody.create(MediaType.parse("application/xml; charset=utf-8"), xml);
       Request request = new Request.Builder()
               .url(url)
               .post(requestBody)
               .build();
       Response response = null;
       try {
           response = okHttpClient.newCall(request).execute();
           int status = response.code();
           if (response.isSuccessful()) {
               return response.body().string();
           }
       } catch (Exception e) {
           logger.error("okhttp3 post error >> ex = {}", ExceptionUtils.getStackTrace(e));
       } finally {
           if (response != null) {
               response.close();
           }
       }
       return responseBody;
   }
}

来源：https://www.cnblogs.com/wzk-0000/p/10955406.html