java常见的 http 请求库比较

java常见的http请求库有httpclient，RestTemplate，OKhttp，更高层次封装的 feign、retrofit

##1、HttpClient 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 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：

1        <dependency>
2            <groupId>org.springframework.boot</groupId>
3            <artifactId>spring-boot-starter-web</artifactId>
4        </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

1package com.itunion.config;
2
3import org.springframework.context.annotation.Bean;
4import org.springframework.context.annotation.Configuration;
5import org.springframework.http.client.ClientHttpRequestFactory;
6import org.springframework.http.client.SimpleClientHttpRequestFactory;
7import org.springframework.web.client.RestTemplate;
8
9@Configuration
10public class ApiConfig {
11    @Bean
12    public RestTemplate restTemplate(ClientHttpRequestFactory factory) {
13        return new RestTemplate(factory);
14    }
15
16    @Bean
17    public ClientHttpRequestFactory simpleClientHttpRequestFactory() {
18        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。
19        factory.setReadTimeout(5000);//单位为ms
20        factory.setConnectTimeout(5000);//单位为ms
21        return factory;
22    }
23}

####(1）get请求（不带参的即把参数取消即可）

1// 1-getForObject()
2User user1 = this.restTemplate.getForObject(uri, User.class);
3
4// 2-getForEntity()
5ResponseEntity<User> responseEntity1 = this.restTemplate.getForEntity(uri, User.class);
6HttpStatus statusCode = responseEntity1.getStatusCode();
7HttpHeaders header = responseEntity1.getHeaders();
8User user2 = responseEntity1.getBody();
9  
10// 3-exchange()
11RequestEntity requestEntity = RequestEntity.get(new URI(uri)).build();
12ResponseEntity<User> responseEntity2 = this.restTemplate.exchange(requestEntity, User.class);
13User user3 = responseEntity2.getBody();

　　　　方式一：

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

　　　　方式二：

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

####(2）post请求：

1// 1-postForObject()
2User user1 = this.restTemplate.postForObject(uri, user, User.class);
3
4// 2-postForEntity()
5ResponseEntity<User> responseEntity1 = this.restTemplate.postForEntity(uri, user, User.class);
6
7// 3-exchange()
8RequestEntity<User> requestEntity = RequestEntity.post(new URI(uri)).body(user);
9ResponseEntity<User> responseEntity2 = this.restTemplate.exchange(requestEntity, User.class);

　　方式一：

1String url = "http://demo/api/book/";
2        HttpHeaders headers = new HttpHeaders();
3        MediaType type = MediaType.parseMediaType("application/json; charset=UTF-8");
4        headers.setContentType(type);
5        String requestJson = "{...}";
6        HttpEntity<String> entity = new HttpEntity<String>(requestJson,headers);
7        String result = restTemplate.postForObject(url, entity, String.class);
8        System.out.println(result);

　　方式二：

1@Test
2public void rtPostObject(){
3    RestTemplate restTemplate = new RestTemplate();
4    String url = "http://47.xxx.xxx.96/register/checkEmail";
5    HttpHeaders headers = new HttpHeaders();
6    headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
7    MultiValueMap<String, String> map= new LinkedMultiValueMap<>();
8    map.add("email", "844072586@qq.com");
9 
10    HttpEntity<MultiValueMap<String, String>> request = new HttpEntity<>(map, headers);
11    ResponseEntity<String> response = restTemplate.postForEntity( url, request , String.class );
12    System.out.println(response.getBody());
13}

其它：还支持上传和下载功能；

##3、okhttp 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：

1<dependency>
2    <groupId>com.squareup.okhttp3</groupId>
3    <artifactId>okhttp</artifactId>
4    <version>3.10.0</version>
5</dependency>

####(2）配置文件：

1import okhttp3.ConnectionPool;
2import okhttp3.OkHttpClient;
3import org.springframework.context.annotation.Bean;
4import org.springframework.context.annotation.Configuration;
5
6import javax.net.ssl.SSLContext;
7import javax.net.ssl.SSLSocketFactory;
8import javax.net.ssl.TrustManager;
9import javax.net.ssl.X509TrustManager;
10import java.security.KeyManagementException;
11import java.security.NoSuchAlgorithmException;
12import java.security.SecureRandom;
13import java.security.cert.CertificateException;
14import java.security.cert.X509Certificate;
15import java.util.concurrent.TimeUnit;
16
17@Configuration
18public class OkHttpConfiguration {
19
20    @Bean
21    public OkHttpClient okHttpClient() {
22        return new OkHttpClient.Builder()
23                //.sslSocketFactory(sslSocketFactory(), x509TrustManager())
24                .retryOnConnectionFailure(false)
25                .connectionPool(pool())
26                .connectTimeout(30, TimeUnit.SECONDS)
27                .readTimeout(30, TimeUnit.SECONDS)
28                .writeTimeout(30,TimeUnit.SECONDS)
29                .build();
30    }
31
32    @Bean
33    public X509TrustManager x509TrustManager() {
34        return new X509TrustManager() {
35            @Override
36            public void checkClientTrusted(X509Certificate[] x509Certificates, String s) throws CertificateException {
37            }
38            @Override
39            public void checkServerTrusted(X509Certificate[] x509Certificates, String s) throws CertificateException {
40            }
41            @Override
42            public X509Certificate[] getAcceptedIssuers() {
43                return new X509Certificate[0];
44            }
45        };
46    }
47
48    @Bean
49    public SSLSocketFactory sslSocketFactory() {
50        try {
51            //信任任何链接
52            SSLContext sslContext = SSLContext.getInstance("TLS");
53            sslContext.init(null, new TrustManager[]{x509TrustManager()}, new SecureRandom());
54            return sslContext.getSocketFactory();
55        } catch (NoSuchAlgorithmException e) {
56            e.printStackTrace();
57        } catch (KeyManagementException e) {
58            e.printStackTrace();
59        }
60        return null;
61    }
62
63    /**
64     * Create a new connection pool with tuning parameters appropriate for a single-user application.
65     * The tuning parameters in this pool are subject to change in future OkHttp releases. Currently
66     */
67    @Bean
68    public ConnectionPool pool() {
69        return new ConnectionPool(200, 5, TimeUnit.MINUTES);
70    }
71}

####(3）util工具：

1import okhttp3.*;
2import org.apache.commons.lang3.exception.ExceptionUtils;
3import org.slf4j.Logger;
4import org.slf4j.LoggerFactory;
5
6import java.io.File;
7import java.util.Iterator;
8import java.util.Map;
9
10public class OkHttpUtil{
11    private static final Logger logger = LoggerFactory.getLogger(OkHttpUtil.class);
12    
13    private static OkHttpClient  okHttpClient;
14
15    @Autowired
16    public OkHttpUtil(OkHttpClient  okHttpClient) {
17        OkHttpUtil.okHttpClient= okHttpClient;
18    } 
19    
20    /**
21     * get
22     * @param url     请求的url
23     * @param queries 请求的参数，在浏览器？后面的数据，没有可以传null
24     * @return
25     */
26    public static  String get(String url, Map<String, String> queries) {
27        String responseBody = "";
28        StringBuffer sb = new StringBuffer(url);
29        if (queries != null && queries.keySet().size() > 0) {
30            boolean firstFlag = true;
31            Iterator iterator = queries.entrySet().iterator();
32            while (iterator.hasNext()) {
33                Map.Entry entry = (Map.Entry<String, String>) iterator.next();
34                if (firstFlag) {
35                    sb.append("?" + entry.getKey() + "=" + entry.getValue());
36                    firstFlag = false;
37                } else {
38                    sb.append("&" + entry.getKey() + "=" + entry.getValue());
39                }
40            }
41        }
42        Request request = new Request.Builder()
43                .url(sb.toString())
44                .build();
45        Response response = null;
46        try { 
47            response = okHttpClient.newCall(request).execute();
48            int status = response.code();
49            if (response.isSuccessful()) {
50                return response.body().string();
51            }
52        } catch (Exception e) {
53            logger.error("okhttp3 put error >> ex = {}", ExceptionUtils.getStackTrace(e));
54        } finally {
55            if (response != null) {
56                response.close();
57            }
58        }
59        return responseBody;
60    }
61
62    /**
63     * post
64     *
65     * @param url    请求的url
66     * @param params post form 提交的参数
67     * @return
68     */
69    public static String post(String url, Map<String, String> params) {
70        String responseBody = "";
71        FormBody.Builder builder = new FormBody.Builder();
72        //添加参数
73        if (params != null && params.keySet().size() > 0) {
74            for (String key : params.keySet()) {
75                builder.add(key, params.get(key));
76            }
77        }
78        Request request = new Request.Builder()
79                .url(url)
80                .post(builder.build())
81                .build();
82        Response response = null;
83        try { 
84            response = okHttpClient.newCall(request).execute();
85            int status = response.code();
86            if (response.isSuccessful()) {
87                return response.body().string();
88            }
89        } catch (Exception e) {
90            logger.error("okhttp3 post error >> ex = {}", ExceptionUtils.getStackTrace(e));
91        } finally {
92            if (response != null) {
93                response.close();
94            }
95        }
96        return responseBody;
97    }
98
99    /**
100     * get
101     * @param url     请求的url
102     * @param queries 请求的参数，在浏览器？后面的数据，没有可以传null
103     * @return
104     */
105    public static String getForHeader(String url, Map<String, String> queries) {
106        String responseBody = "";
107        StringBuffer sb = new StringBuffer(url);
108        if (queries != null && queries.keySet().size() > 0) {
109            boolean firstFlag = true;
110            Iterator iterator = queries.entrySet().iterator();
111            while (iterator.hasNext()) {
112                Map.Entry entry = (Map.Entry<String, String>) iterator.next();
113                if (firstFlag) {
114                    sb.append("?" + entry.getKey() + "=" + entry.getValue());
115                    firstFlag = false;
116                } else {
117                    sb.append("&" + entry.getKey() + "=" + entry.getValue());
118                }
119            }
120        }
121        Request request = new Request.Builder()
122                .addHeader("key", "value")
123                .url(sb.toString())
124                .build();
125        Response response = null;
126        try { 
127            response = okHttpClient.newCall(request).execute();
128            int status = response.code();
129            if (response.isSuccessful()) {
130                return response.body().string();
131            }
132        } catch (Exception e) {
133            logger.error("okhttp3 put error >> ex = {}", ExceptionUtils.getStackTrace(e));
134        } finally {
135            if (response != null) {
136                response.close();
137            }
138        }
139        return responseBody;
140    }
141
142    /**
143     * Post请求发送JSON数据....{"name":"zhangsan","pwd":"123456"}
144     * 参数一：请求Url
145     * 参数二：请求的JSON
146     * 参数三：请求回调
147     */
148    public static String postJsonParams(String url, String jsonParams) {
149        String responseBody = "";
150        RequestBody requestBody = RequestBody.create(MediaType.parse("application/json; charset=utf-8"), jsonParams);
151        Request request = new Request.Builder()
152                .url(url)
153                .post(requestBody)
154                .build();
155        Response response = null;
156        try { 
157            response = okHttpClient.newCall(request).execute();
158            int status = response.code();
159            if (response.isSuccessful()) {
160                return response.body().string();
161            }
162        } catch (Exception e) {
163            logger.error("okhttp3 post error >> ex = {}", ExceptionUtils.getStackTrace(e));
164        } finally {
165            if (response != null) {
166                response.close();
167            }
168        }
169        return responseBody;
170    }
171
172    /**
173     * Post请求发送xml数据....
174     * 参数一：请求Url
175     * 参数二：请求的xmlString
176     * 参数三：请求回调
177     */
178    public static String postXmlParams(String url, String xml) {
179        String responseBody = "";
180        RequestBody requestBody = RequestBody.create(MediaType.parse("application/xml; charset=utf-8"), xml);
181        Request request = new Request.Builder()
182                .url(url)
183                .post(requestBody)
184                .build();
185        Response response = null;
186        try { 
187            response = okHttpClient.newCall(request).execute();
188            int status = response.code();
189            if (response.isSuccessful()) {
190                return response.body().string();
191            }
192        } catch (Exception e) {
193            logger.error("okhttp3 post error >> ex = {}", ExceptionUtils.getStackTrace(e));
194        } finally {
195            if (response != null) {
196                response.close();
197            }
198        }
199        return responseBody;
200    }
201}

java常见的 http 请求库比较

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