【2023】java常用HTTP客户端对比以及使用（HttpClient/OkHttp/WebClient）

1、介绍

现在java使用的http客户端主要包括以下几种

而这些中使用得最频繁的主要是：

1. Apache HttpClient：这是一个功能强大且广泛使用的第三方库，用于进行HTTP通讯。它提供了更高级的API和更丰富的功能，比如支持连接池、认证、重定向、Cookie管理等。Apache HttpClient可以作为独立的库使用，也可以作为Apache HttpComponents项目的一部分。

2. OkHttp：这是另一个流行的第三方库，用于进行HTTP通讯。OkHttp提供了简洁的API和高性能的特性，支持同步和异步请求，以及连接池、缓存、拦截器等功能。OkHttp也是Square公司的一个开源项目。

3. Spring WebClient：这是Spring框架中的一个模块，是RestTemplate的升级版，用于进行非阻塞的HTTP通讯。它基于Reactive Streams编程模型，适用于构建响应式的应用程序。Spring WebClient提供了简单的API来发送HTTP请求和处理响应，可以与Spring WebFlux等模块一起使用。

2、使用

下面展示了Apache HttpClient和OkHttp以及Spring WebClient的常用使用方式，包括get和post

2.1、添加配置

2.1.1、依赖

        <!-- https://mvnrepository.com/artifact/org.apache.httpcomponents.client5/httpclient5 --><dependency><groupId>org.apache.httpcomponents.client5</groupId><artifactId>httpclient5</artifactId></dependency><!--okhttp--><dependency><groupId>com.squareup.okhttp3</groupId><artifactId>okhttp</artifactId></dependency><dependency><groupId>cn.hutool</groupId><artifactId>hutool-all</artifactId><version>5.8.22</version></dependency><!--webClient--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-webflux</artifactId></dependency>

2.1.2、工具类

• Result：统一返回类

@Data
public class Result<T> {//状态码private Integer code;//信息private String message;//数据private T data;private Result(){}//设置数据,返回对象的方法public static <T> Result<T> build(T data, ResultCodeEnum resultCodeEnum) {//创建Result对象，设置值，返回对象Result<T> result = new Result<>();//判断返回结果中是否需要数据if (data != null) {//设置数据到result对象result.setData(data);}//设置其他值result.setCode(resultCodeEnum.getCode());result.setMessage(resultCodeEnum.getMessage());//返回设置值之后的对象return result;}//成功的方法public static <T> Result<T> ok(T data) {return build(data, ResultCodeEnum.SUCCESS);}//成功的方法public static <T> Result<T> ok() {return build(null, ResultCodeEnum.SUCCESS);}//失败的方法public static <T> Result<T> fail(T data) {return build(data, ResultCodeEnum.FAIL);}
}

• ResultCodeEnum：返回结果

@Getter
public enum  ResultCodeEnum {SUCCESS(200,"成功"),FAIL(201, "失败"),;private Integer code;private String message;ResultCodeEnum(Integer code, String message) {this.code = code;this.message = message;}
}

2.1.3、实体

• User

@Data
public class User {private String name;private Integer age;private Integer post;
}

• ProductInfo：返回数据

@Data
@AllArgsConstructor
@NoArgsConstructor
@ToString
public class ProductInfo implements Serializable {private Long id;/**销量*/private Integer sale;/**价格*/private Integer price;/**名称*/private String name;/**类型*/private Integer type;/**端口*/private Integer port;
}

2.1.4、Controller接口

@RestController
@RequestMapping("/productInfo/index")
public class ProductInfoController {@Resourceprivate ProductInfoService productInfoService;//    获取当前服务的端口@Value("${server.port}")private Integer port;@GetMapping("/get")public Result<?> get(Integer type){List<ProductInfo> productInfoList = getProductInfoList(type);System.out.println(productInfoList);return Result.ok(productInfoList);}@PostMapping("/post")public Result<?> post(@RequestBody User user){Integer post = user.getPost();List<ProductInfo> productInfoList = getProductInfoList(post);System.out.println(productInfoList);return Result.ok(productInfoList);}public List<ProductInfo> getProductInfoList(Integer type) {ProductInfo productInfo3 = new ProductInfo(3l,800,20,"哈密瓜1",1,port);ProductInfo productInfo1 = new ProductInfo(1l,50,8,"苹果1",1,port);ProductInfo productInfo2 = new ProductInfo(2l,200,13,"牛肉1",2,port);ProductInfo productInfo4 = new ProductInfo(4l,50,9,"青菜1",2,port);/*        实际项目中，会从数据库查出数据 */List<ProductInfo> productInfoList = Arrays.asList(productInfo1,productInfo2,productInfo3,productInfo4);//        根据传入的类型返回指定类型List<ProductInfo> result = productInfoList.stream().filter(productInfo -> productInfo.getType() == type).collect(Collectors.toList());return result;}
}

2.2、Apache HttpClient使用

• get使用
  默认只能同步异步需要加额外的依赖，get请求不能携带参数，只能通过拼接路径

        <!--异步请求--><dependency><groupId>org.apache.httpcomponents</groupId><artifactId>httpasyncclient</artifactId></dependency>

    public static void get(CloseableHttpClient httpClient,String url){
//            连接对象try {
//        HttpGet不能携带参数，如果需要参数只能通过拼接HttpGet httpGet = new HttpGet(url+"?type=1");String execute = httpClient.execute(httpGet, response -> {JSONObject entries = new JSONObject(EntityUtils.toString(response.getEntity()));Result result = JSONUtil.toBean(entries, Result.class);if (result.getCode() == 200) {String data = result.getData().toString();System.out.println(data);return data;} else {System.err.println(result.getMessage());return result.getMessage();}});System.out.println("get成功结果："+execute);} catch (Exception e) {e.printStackTrace();}}

• post
  post请求，通过setEntity()给HttpPost对象添加请求对象

    public static void post(CloseableHttpClient httpClient,String url){HttpPost httpPost = new HttpPost(url);User user = new User();user.setPost(1);
//        添加参数对象httpPost.setEntity(new StringEntity(JSONUtil.toJsonStr(user)));// 设置请求头httpPost.setHeader(HttpHeaders.CONTENT_TYPE, "application/json");try {String execute = httpClient.execute(httpPost, response -> {JSONObject entries = new JSONObject(EntityUtils.toString(response.getEntity()));Result result = JSONUtil.toBean(entries, Result.class);if (result.getCode() == 200) {String data = result.getData().toString();log.info(data);return data;} else {log.error(result.getMessage());return result.getMessage();}});log.info("HttpClient的post成功结果："+execute);} catch (IOException e) {e.printStackTrace();}}

• 全部代码

执行步骤：

1. 创建CloseableHttpClient对象
2. 创建get获取post请求对象
3. 通过execute()方法发送请求
4. 通过response.getEntity()获取响应回来的数据

@Slf4j
public class HttpClientUtil {private static String postUrl = "http://localhost:8202/productInfo/index/post";private static String getUrl = "http://localhost:8202/productInfo/index/get";public static void main(String[] args) {try {
//            创建客户端对象CloseableHttpClient client = HttpClients.createDefault();get(client,getUrl);post(client,postUrl);client.close();} catch (IOException e) {e.printStackTrace();}}public static void get(CloseableHttpClient httpClient,String url){
//            连接对象try {
//        HttpGet不能携带参数，如果需要参数只能通过拼接HttpGet httpGet = new HttpGet(url+"?type=1");String execute = httpClient.execute(httpGet, response -> {JSONObject entries = new JSONObject(EntityUtils.toString(response.getEntity()));Result result = JSONUtil.toBean(entries, Result.class);if (result.getCode() == 200) {String data = result.getData().toString();log.info(data);return data;} else {log.info(result.getMessage());return result.getMessage();}});log.info("HttpClient的get成功结果："+execute);} catch (Exception e) {e.printStackTrace();}}public static void post(CloseableHttpClient httpClient,String url){HttpPost httpPost = new HttpPost(url);User user = new User();user.setPost(1);
//        添加参数对象httpPost.setEntity(new StringEntity(JSONUtil.toJsonStr(user)));// 设置请求头httpPost.setHeader(HttpHeaders.CONTENT_TYPE, "application/json");try {String execute = httpClient.execute(httpPost, response -> {JSONObject entries = new JSONObject(EntityUtils.toString(response.getEntity()));Result result = JSONUtil.toBean(entries, Result.class);if (result.getCode() == 200) {String data = result.getData().toString();log.info(data);return data;} else {log.error(result.getMessage());return result.getMessage();}});log.info("HttpClient的post成功结果："+execute);} catch (IOException e) {e.printStackTrace();}}
}

2.3 、OkHttp使用

执行步骤：

1. 创建OkHttpClient对象，用于配置和管理HTTP请求的行为
2. 创建Request对象，用于描述要发送的HTTP请求。Request对象包含了URL、请求方法、请求头、请求体等信息。
3. 创建Call对象，使用OkHttpClient的newCall()方法，传入Request对象，创建一个Call对象，Call对象表示一次HTTP请求的调用，可以用于执行同步或异步的请求。
4. 执行请求，同步通过Call对象的execute()方法来；异步通过Call对象的enqueue()方法来执行请求，并通过回调函数处理响应
5. 解析响应，通过response.body()得到响应的内容在通过json解析。

@Slf4j
public class OkHttpUtil {private static String postUrl = "http://localhost:8202/productInfo/index/post";private static String getUrl = "http://localhost:8202/productInfo/index/get";public static void main(String[] args) {OkHttpClient client = new OkHttpClient().newBuilder().connectTimeout(30, TimeUnit.SECONDS) //连接超时时间.writeTimeout(30,TimeUnit.SECONDS)  //请求超时时间.readTimeout(30,TimeUnit.SECONDS)  //响应超时时间.build();
//        get(client);
//        asyncGet(client);
//        post(client);asyncPost(client);}/*** 同步get* @param client        * @return void*/public static void get(OkHttpClient client){
//        创建get请求对象Request request = new Request.Builder().url(getUrl+"?type=1").get().header("Content-Type", "application/json") // 设置Content-Type请求头.build();try {
//            返回响应对象Response response = client.newCall(request).execute();
//              验证响应是否成功if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);
//              解码对象Result result = JSONUtil.toBean(response.body().string(), Result.class);Object data = result.getData();System.out.println(data);} catch (IOException e) {e.printStackTrace();}}/*** 异步get* @param client* @return void*/public static void asyncGet(OkHttpClient client){//        创建get请求对象Request request = new Request.Builder().url(getUrl+"?type=1").get()   //不指定请求方式默认是get.build();
//           异步发送请求，没有返回结果client.newCall(request).enqueue(new Callback() {//               处理失败请求@Overridepublic void onFailure(Call call, IOException e) {log.debug("Unexpected code " + e.getMessage());e.printStackTrace();}//            处理成功请求@Overridepublic void onResponse(Call call, Response response) throws IOException {
//              验证响应是否成功if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);
//              解码对象Result result = JSONUtil.toBean(response.body().string(), Result.class);Object data = result.getData();System.out.println(data);}});}/*** 同步post* @param client* @return void*/public static void post(OkHttpClient client){User user = new User();user.setPost(1);String str = JSONUtil.toJsonStr(user);Request request = new Request.Builder().url(postUrl).post(RequestBody.create(MediaType.parse(ContentType.JSON.getValue()), str)).build();Call call = client.newCall(request);try {Response response = call.execute();//              验证响应是否成功if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);
//              解码对象Result result = JSONUtil.toBean(response.body().string(), Result.class);Object data = result.getData();log.info("post请求成功，返回结果:{}",data);} catch (IOException e) {e.printStackTrace();}}/*** 异步post请求* @param client        * @return void*/public static void asyncPost(OkHttpClient client){User user = new User();user.setPost(1);
//          把对象转为json字符串String str = JSONUtil.toJsonStr(user);Request request = new Request.Builder().url(postUrl).post(RequestBody.create(MediaType.parse(ContentType.JSON.getValue()), str)).build();Call call = client.newCall(request);
//       异步请求没返回call.enqueue(new Callback() {
//            请求异常@Overridepublic void onFailure(Call call, IOException e) {log.debug("Unexpected code " + e.getMessage());e.printStackTrace();}
//            请求成功@Overridepublic void onResponse(Call call, Response response) throws IOException {//              验证响应是否成功if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);
//              解码对象Result result = JSONUtil.toBean(response.body().string(), Result.class);Object data = result.getData();log.info("异步post请求成功，返回结果:{}",data);}});}
}

2.4、WebClient使用

执行步骤：

1. 创建WebClient对象，推荐使用WebClient.builder()的方式创建，因为可以自定义配置客户端的参数，直接new是只能使用默认的配置。

2. 构建请求，直接通过webClient对象，如get()、post()等，构建一个请求（如果没有指定请求方式），默认是get请求。

3. 处理响应：使用响应对象（如Mono、Flux等）来处理响应数据。你可以通过操作符（如map()、flatMap()等）对响应进行转换、过滤、合并等操作。

4. 订阅响应：使用subscribe()方法来订阅响应流，启动请求并处理响应数据。你可以通过回调函数或操作符链来处理响应数据。

@Component
@Slf4j
public class WebClientUtil {private static String postUrl = "http://localhost:8202/productInfo/index/post";private static String getUrl = "http://localhost:8202/productInfo/index/get";/*** 同步执行get请求* @param webClient* @return void*/public void get(WebClient webClient){Mono<Result> mono = webClient.get().uri(getUrl + "?type=2").retrieve().bodyToMono(Result.class);//        获取返回结果 block()会进行堵塞，等待返回结果Result result = mono.block();if (result.getCode()==200){log.info("get请求返回结果{}",result.getData());}}/*** 异步get* @return void*/public void asyncGet(){HttpClient client = HttpClient.create().option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 10000)  //设置连接超时.doOnConnected(conn -> conn.addHandler(new ReadTimeoutHandler(10, TimeUnit.SECONDS)) //写入超时.addHandler(new WriteTimeoutHandler(10))); //读取超时//        也可以以这种方式创建WebClient可以添加请求头和url以及一些参数；WebClient webClient = WebClient.builder().clientConnector(new ReactorClientHttpConnector(client)).baseUrl(getUrl).defaultHeader(HttpHeaders.USER_AGENT, "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko)")
//                .defaultCookie()  //添加请求Cookie.build();//        获取返回结果Mono<Result> mono = webClient.get().uri( "?type=2")// 请求路径，会拼接上面的.accept(MediaType.APPLICATION_JSON)//                .retrieve() //获取响应体
//                .bodyToMono(Result.class);  //指定获取的类型,直接获取结果。//                或者通过该方式手动处理结果.exchangeToMono(response->{if (response.statusCode().equals(HttpStatus.OK)) {
//                        成功返回return response.bodyToMono(Result.class);}else {
//                        失败返回return response.createException().flatMap(Mono::error);}});//        异步获取返回结果mono.subscribe(result -> {if (result.getCode() == 200) {log.info("get请求返回结果{}", result.getData());}});System.out.println("执行完成");}/*** 同步post* @return void*/public void post(){// 创建 WebClient 对象WebClient webClient = WebClient.builder().baseUrl(getUrl).build();User user = new User();user.setPost(2);Mono<Result> mono = webClient.post().uri(postUrl).contentType(MediaType.APPLICATION_JSON).header("token","12321412").body(BodyInserters.fromValue(user)).retrieve().bodyToMono(Result.class);Result result = mono.block();if (result.getCode()==200){log.info("post请求返回结果{}",result.getData());}}/*** WebClient异步请求* @return void*/public void asyncPost(){// 创建 WebClient 对象WebClient webClient = WebClient.builder().baseUrl(getUrl).build();User user = new User();user.setPost(2);Mono<Result> mono = webClient.post().uri(postUrl).contentType(MediaType.APPLICATION_JSON)  //指定类型.header("token","12321412")  //添加请求头.body(BodyInserters.fromValue(user)) //添加请求对象.retrieve().bodyToMono(Result.class);
//          异步请求mono.subscribe(result -> {if (result.getCode()==200){log.info("post异步请求返回结果{}",result.getData());}});}
}