一、HttpClient

1、pom依赖

<!--HttpClient-->
<dependency><groupId>commons-httpclient</groupId><artifactId>commons-httpclient</artifactId><version>3.1</version>
</dependency>

2、HttpClient代码实现

public class HttpClientUtil {/*** httpClient的get请求方式* 使用GetMethod来访问一个URL对应的网页实现步骤：* 1.生成一个HttpClient对象并设置相应的参数；* 2.生成一个GetMethod对象并设置响应的参数；* 3.用HttpClient生成的对象来执行GetMethod生成的Get方法；* 4.处理响应状态码；* 5.若响应正常，处理HTTP响应内容；* 6.释放连接。* @param url* @param charset* @return*/public static String doGet(String url, String charset) {//1.生成HttpClient对象并设置参数HttpClient httpClient = new HttpClient();//设置Http连接超时为5秒httpClient.getHttpConnectionManager().getParams().setConnectionTimeout(5000);//2.生成GetMethod对象并设置参数GetMethod getMethod = new GetMethod(url);//设置get请求超时为5秒getMethod.getParams().setParameter(HttpMethodParams.SO_TIMEOUT, 5000);//设置请求重试处理，用的是默认的重试处理：请求三次getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler());String response = "";//3.执行HTTP GET 请求try {int statusCode = httpClient.executeMethod(getMethod);//4.判断访问的状态码if (statusCode != HttpStatus.SC_OK) {System.err.println("请求出错：" + getMethod.getStatusLine());}//5.处理HTTP响应内容//HTTP响应头部信息，这里简单打印Header[] headers = getMethod.getResponseHeaders();for(Header h : headers) {System.out.println(h.getName() + "---------------" + h.getValue());}//读取HTTP响应内容，这里简单打印网页内容//读取为字节数组byte[] responseBody = getMethod.getResponseBody();response = new String(responseBody, charset);System.out.println("-----------response:" + response);//读取为InputStream，在网页内容数据量大时候推荐使用//InputStream response = getMethod.getResponseBodyAsStream();} catch (HttpException e) {//发生致命的异常，可能是协议不对或者返回的内容有问题System.out.println("请检查输入的URL!");e.printStackTrace();} catch (IOException e) {//发生网络异常System.out.println("发生网络异常!");} finally {//6.释放连接getMethod.releaseConnection();}return response;}/*** post请求* @param url* @param json* @return*/public static String doPost(String url, JSONObject json){HttpClient httpClient = new HttpClient();PostMethod postMethod = new PostMethod(url);postMethod.addRequestHeader("accept", "*/*");postMethod.addRequestHeader("connection", "Keep-Alive");//设置json格式传送postMethod.addRequestHeader("Content-Type", "application/json;charset=GBK");//必须设置下面这个HeaderpostMethod.addRequestHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.81 Safari/537.36");//添加请求参数postMethod.addParameter("commentId", json.getString("commentId"));String res = "";try {int code = httpClient.executeMethod(postMethod);if (code == 200){res = postMethod.getResponseBodyAsString();System.out.println(res);}} catch (IOException e) {e.printStackTrace();}return res;}public static void main(String[] args) {System.out.println(doGet("http://tcc.taobao.com/cc/json/mobile_tel_segment.htm?tel=13026194071", "GBK"));System.out.println("-----------分割线------------");System.out.println("-----------分割线------------");System.out.println("-----------分割线------------");JSONObject jsonObject = new JSONObject();jsonObject.put("commentId", "13026194071");System.out.println(doPost("http://tcc.taobao.com/cc/json/mobile_tel_segment.htm?tel=13026194071", jsonObject));}
}

3、建议

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。

二、okhttp

1、简介

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。

2、pom依赖

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

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。

3、配置文件

@Configuration
public class OkHttpConfig {@Beanpublic 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();}@Beanpublic X509TrustManager x509TrustManager() {return new X509TrustManager() {@Overridepublic void checkClientTrusted(X509Certificate[] x509Certificates, String s) throws CertificateException {}@Overridepublic void checkServerTrusted(X509Certificate[] x509Certificates, String s) throws CertificateException {}@Overridepublic X509Certificate[] getAcceptedIssuers() {return new X509Certificate[0];}};}@Beanpublic 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*/@Beanpublic ConnectionPool pool() {return new ConnectionPool(200, 5, TimeUnit.MINUTES);}
}

4、客户端工具

@Slf4j
public class OkHttpClient {private static final MediaType JSON = MediaType.parse("application/json; charset=utf-8");private volatile static okhttp3.OkHttpClient client;private static final int MAX_IDLE_CONNECTION = Integer.parseInt(ConfigManager.get("httpclient.max_idle_connection"));private static final long KEEP_ALIVE_DURATION = Long.parseLong(ConfigManager.get("httpclient.keep_alive_duration"));private static final long CONNECT_TIMEOUT = Long.parseLong(ConfigManager.get("httpclient.connectTimeout"));private static final long READ_TIMEOUT = Long.parseLong(ConfigManager.get("httpclient. "));/*** 单例模式(双重检查模式) 获取类实例 ** @return client*/private static okhttp3.OkHttpClient getInstance() {if (client == null) {synchronized (okhttp3.OkHttpClient.class) {if (client == null) {client = new okhttp3.OkHttpClient.Builder().connectTimeout(CONNECT_TIMEOUT, TimeUnit.SECONDS).readTimeout(READ_TIMEOUT, TimeUnit.SECONDS).connectionPool(new ConnectionPool(MAX_IDLE_CONNECTION, KEEP_ALIVE_DURATION,TimeUnit.MINUTES)).build();}}}return client;}public static String syncPost(String url, String json) throws IOException {RequestBody body = RequestBody.create(JSON, json);Request request = new Request.Builder().url(url).post(body).build();try {Response response = OkHttpClient.getInstance().newCall(request).execute();if (response.isSuccessful()) {String result = response.body().string();log.info("syncPost response = {}, responseBody= {}", response, result);return result;}String result = response.body().string();log.info("syncPost response = {}, responseBody= {}", response, result);throw new IOException("三方接口返回http状态码为" + response.code());} catch (Exception e) {log.error("syncPost() url:{} have a ecxeption {}", url, e);throw new RuntimeException("syncPost() have a ecxeption {}" + e.getMessage());}}public static String syncGet(String url, Map<String, Object> headParamsMap) throws IOException {Request request;final Request.Builder builder = new Request.Builder().url(url);try {if (!CollectionUtils.isEmpty(headParamsMap)) {final Iterator<Map.Entry<String, Object>> iterator = headParamsMap.entrySet().iterator();while (iterator.hasNext()) {final Map.Entry<String, Object> entry = iterator.next();builder.addHeader(entry.getKey(), (String) entry.getValue());}}request = builder.build();Response response = OkHttpClient.getInstance().newCall(request).execute();String result = response.body().string();log.info("syncGet response = {},responseBody= {}", response, result);if (!response.isSuccessful()) {throw new IOException("三方接口返回http状态码为" + response.code());}return result;} catch (Exception e) {log.error("remote interface url:{} have a ecxeption {}", url, e);throw new RuntimeException("三方接口返回异常");}}}

三、RestTemplate

1、pom依赖

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

2、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);

3、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());
}