Apache HttpClient 5

最近要在非SpringBoot环境调用OpenFeign接口, 需要用到httpclient, 注意到现在 HttpClient 版本已经到 5.2.1 了. 之前在版本4中的一些方法已经变成 deprecated, 于是将之前的工具类升级一下, 顺便把中间遇到的问题记录一下

基础使用方法

首先参考Apache官方的快速开始 httpcomponents-client-5.2.x quickstart, 这是页面上给的例子

Post请求

try (CloseableHttpClient httpclient = HttpClients.createDefault()) { HttpPost httpPost = new HttpPost("http://httpbin.org/post"); List<NameValuePair> nvps = new ArrayList<>(); nvps.add(new BasicNameValuePair("username", "vip")); nvps.add(new BasicNameValuePair("password", "secret")); httpPost.setEntity(new UrlEncodedFormEntity(nvps)); try (CloseableHttpResponse response2 = httpclient.execute(httpPost)) { System.out.println(response2.getCode() + " " + response2.getReasonPhrase()); HttpEntity entity2 = response2.getEntity(); // do something useful with the response body // and ensure it is fully consumed EntityUtils.consume(entity2); }}

Get请求

try (CloseableHttpClient httpclient = HttpClients.createDefault()) { HttpGet httpGet = new HttpGet("http://httpbin.org/get"); try (CloseableHttpResponse response1 = httpclient.execute(httpGet)) { System.out.println(response1.getCode() + " " + response1.getReasonPhrase()); HttpEntity entity1 = response1.getEntity(); // do something useful with the response body // and ensure it is fully consumed EntityUtils.consume(entity1); }}

替换 Deprecated 的 execute 方法

上面的例子可以正常运行, 但是在HttpClient5中, CloseableHttpResponse execute(ClassicHttpRequest request) 这个方法已经被标记为 Deprecated

@DeprecatedHttpResponse execute(ClassicHttpRequest var1) throws IOException; @DeprecatedHttpResponse execute(ClassicHttpRequest var1, HttpContext var2) throws IOException; @DeprecatedClassicHttpResponse execute(HttpHost var1, ClassicHttpRequest var2) throws IOException; @DeprecatedHttpResponse execute(HttpHost var1, ClassicHttpRequest var2, HttpContext var3) throws IOException;

取而代之的, 是这四个带 HttpClientResponseHandler 参数的 execute 方法

<T> T execute(ClassicHttpRequest var1, HttpClientResponseHandler<? extends T> var2) throws IOException;<T> T execute(ClassicHttpRequest var1, HttpContext var2, HttpClientResponseHandler<? extends T> var3) throws IOException;<T> T execute(HttpHost var1, ClassicHttpRequest var2, HttpClientResponseHandler<? extends T> var3) throws IOException;<T> T execute(HttpHost var1, ClassicHttpRequest var2, HttpContext var3, HttpClientResponseHandler<? extends T> var4) throws IOException;}

这个 HttpClientResponseHandler 作为响应的处理方法, 里面只有一个接口方法(要注意到这是一个函数式接口)

@FunctionalInterfacepublic interface HttpClientResponseHandler<T> { T handleResponse(ClassicHttpResponse var1) throws HttpException, IOException;}

JDK中提供了一个默认的实现, BasicHttpClientResponseHandler(基于 AbstractHttpClientResponseHandler)

public abstract class AbstractHttpClientResponseHandler<T> implements HttpClientResponseHandler<T> { public AbstractHttpClientResponseHandler() { } public T handleResponse(ClassicHttpResponse response) throws IOException { HttpEntity entity = response.getEntity(); if (response.getCode() >= 300) { EntityUtils.consume(entity); throw new HttpResponseException(response.getCode(), response.getReasonPhrase()); } else { return entity == null ? null : this.handleEntity(entity); } } public abstract T handleEntity(HttpEntity var1) throws IOException;} public class BasicHttpClientResponseHandler extends AbstractHttpClientResponseHandler<String> { public BasicHttpClientResponseHandler() { } public String handleEntity(HttpEntity entity) throws IOException { try { return EntityUtils.toString(entity); } catch (ParseException var3) { throw new ClientProtocolException(var3); } } public String handleResponse(ClassicHttpResponse response) throws IOException { return (String)super.handleResponse(response); }}

这样基础的使用方式就改为了下面的形式

public static void main(final String[] args) throws Exception { final CloseableHttpClient httpClient = HttpClients.createDefault(); try (httpClient) { final HttpGet httpGet = new HttpGet("https://www.baidu.com/home/other/data/weatherInfo"); final String responseBody = httpClient.execute(httpGet, new BasicHttpClientResponseHandler()); System.out.println(responseBody); }}

使用自定义的函数式方法处理响应

可以看到, 上面的 BasicHttpClientResponseHandler 是一个比较简单的实现, 大于300的响应状态码直接抛出异常, 其它的读出字符串. 这样的处理方式对于更精细的使用场景是不够的

• 需要根据响应状态码判断时
• 需要对响应解析为Java类时
• 需要压住异常, 统一返回类对象时

之前在 HttpClient4 时, 可以通过CloseableHttpResponse response = client.execute(httpRequest), 对 response 进行判断, 现在response已经完全被handler 包裹, 需要通过自定义函数式方法处理响应, 看下面的例子

首先定义一个响应结果类, 数据部分使用泛型

@Datapublic class Client5Resp<T> implements Serializable { private int code; private String raw; private T data; public Client5Resp(int code, String raw, T data) { this.code = code; this.raw = raw; this.data = data; }}

然后对响应结果自定义 handler, 因为是函数式接口, 所以很方便在方法中直接定义, 处理的逻辑是:

1. 如果 T 泛型为String, 直接将 body 作为数据返回
2. 其它的 T 泛型, 用 Jackson 解开之后返回
3. 将 status code 一并返回

private static <T> Client5Resp<T> httpRequest( TypeReference<T> tp, HttpUriRequest httpRequest) { try (CloseableHttpClient client = HttpClients.createDefault()) { Client5Resp<T> resp = client.execute(httpRequest, response -> { if (response.getEntity() != null) { String body = EntityUtils.toString(response.getEntity()); if (tp.getType() == String.class) { return new Client5Resp<>(response.getCode(), body, (T)body); } // 当需要区分更多类型时可以增加定义 else { T t = JacksonUtil.extractByType(body, tp); return new Client5Resp<>(response.getCode(), body, t); } } else { return new Client5Resp<>(response.getCode(), null, null); } }); log.info("rsp:{}, body:{}", resp.getCode(), resp.getRaw()); return resp; } catch (IOException|NoSuchAlgorithmException|KeyStoreException|KeyManagementException e) { // 当异常也需要返回 Client5Resp 类型对象时可以在catch中封装 log.error(e.getMessage(), e); } return null;}

自定义请求设置和Header

首先是超时设置

RequestConfig defaultRequestConfig = RequestConfig.custom() .setConnectionRequestTimeout(60, TimeUnit.SECONDS) .setResponseTimeout(60, TimeUnit.SECONDS) .build();

然后是 Header

List<Header> headers = List.of( new BasicHeader(HttpHeaders.CONTENT_TYPE, "application/json"), new BasicHeader(HttpHeaders.ACCEPT, "application/json"));

在 HttpGet/HttpPost 中设置

HttpGet httpGet = new HttpGet(...);if (headers != null) { for (Header header : headers) { httpGet.addHeader(header); }}RequestConfig requestConfig = RequestConfig.copy(defaultRequestConfig).build();httpGet.setConfig(requestConfig);

自定义 HttpClient 增加 SSL TrustAllStrategy

在 HttpClient5 中, 增加 SSL TrustAllStrategy 的方法也有变化, 这是获取 CloseableHttpClient 的代码

final RequestConfig defaultRequestConfig = RequestConfig.custom() .setConnectionRequestTimeout(60, TimeUnit.SECONDS) .setResponseTimeout(60, TimeUnit.SECONDS) .build();final BasicCookieStore defaultCookieStore = new BasicCookieStore();final SSLContext sslcontext = SSLContexts.custom() .loadTrustMaterial(null, new TrustAllStrategy()).build();final SSLConnectionSocketFactory sslSocketFactory = SSLConnectionSocketFactoryBuilder.create() .setSslContext(sslcontext).build();final HttpClientConnectionManager cm = PoolingHttpClientConnectionManagerBuilder.create() .setSSLSocketFactory(sslSocketFactory).build();return HttpClients.custom() .setDefaultCookieStore(defaultCookieStore) .setDefaultRequestConfig(defaultRequestConfig) .setConnectionManager(cm) .evictExpiredConnections() .build();

增加 Http Proxy

固定的 Proxy

在 HttpClient5 中, RequestConfig.Builder.setProxy()方法已经 Deprecated

@Deprecatedpublic RequestConfig.Builder setProxy(HttpHost proxy) { this.proxy = proxy; return this;}

需要使用 HttpClientBuilder.setRoutePlanner(HttpRoutePlanner routePlanner) 进行设置, 和SSL一起, 获取client的代码变成

final HttpHost proxy = new HttpHost(proxyHost, proxyPort);final DefaultProxyRoutePlanner routePlanner = new DefaultProxyRoutePlanner(proxy);return HttpClients.custom() .setDefaultCookieStore(defaultCookieStore) .setDefaultRequestConfig(defaultRequestConfig) .setRoutePlanner(routePlanner) .setConnectionManager(cm) .evictExpiredConnections() .build();

如果需要用户名密码, 需要再增加一个 CredentialsProvider, 变成

final HttpHost proxy = new HttpHost(proxyHost, proxyPort);final DefaultProxyRoutePlanner routePlanner = new DefaultProxyRoutePlanner(proxy);final BasicCredentialsProvider credsProvider = new BasicCredentialsProvider();credsProvider.setCredentials( new AuthScope(proxyHost, proxyPort), new UsernamePasswordCredentials(authUser, authPasswd.toCharArray())); return HttpClients.custom() .setDefaultCookieStore(defaultCookieStore) .setDefaultRequestConfig(defaultRequestConfig) .setDefaultCredentialsProvider(credsProvider) .setRoutePlanner(routePlanner) .setConnectionManager(cm) .evictExpiredConnections() .build();

动态 Proxy

如果需要随时切换 proxy, 需要自己实现一个 HttpRoutePlanner

public static class DynamicProxyRoutePlanner implements HttpRoutePlanner { private DefaultProxyRoutePlanner planner; public DynamicProxyRoutePlanner(HttpHost host){ planner = new DefaultProxyRoutePlanner(host); } public void setProxy(HttpHost host){ planner = new DefaultProxyRoutePlanner(host); } public HttpRoute determineRoute(HttpHost target, HttpContext context) throws HttpException { return planner.determineRoute(target, context); }}

然后在代码中进行切换

HttpHost proxy = new HttpHost("127.0.0.1", 1080);DynamicProxyRoutePlanner routePlanner = new DynamicProxyRoutePlanner(proxy);CloseableHttpClient httpclient = HttpClients.custom() .setRoutePlanner(routePlanner) .build();// 换代理routePlanner.setProxy(new HttpHost("192.168.0.1", 1081));

构造 Multipart 文件上传请求

首先是构造 HttpEntity 的方法, 这个方法中设置请求为 1个文件 + 多个随表单参数

public static HttpEntity httpEntityBuild(NameValuePair fileNvp, List<NameValuePair> nvps) { File file = new File(fileNvp.getValue()); MultipartEntityBuilder builder = MultipartEntityBuilder.create().setMode(HttpMultipartMode.STRICT); if (nvps != null && nvps.size() > 0) { for (NameValuePair nvp : nvps) { builder.addTextBody(nvp.getName(), nvp.getValue(), ContentType.DEFAULT_BINARY); } } builder.addBinaryBody(fileNvp.getName(), file, ContentType.DEFAULT_BINARY, fileNvp.getValue()); return builder.build();}

// 构造一个文件参数, 其它参数留空NameValuePair fileNvp = new BasicNameValuePair("sendfile", filePath);HttpEntity entity = httpEntityBuild(fileNvp, null);HttpPost httpPost = new HttpPost(api);httpPost.setEntity(entity); try (CloseableHttpClient client = getClient(...)) { Client5Resp<T> resp = client.execute(httpPost, response->{ ... });

注意: 在使用 HttpMultipartMode 时对 HttpEntity 设置 Header 要谨慎, 因为 HttpClient 会对 Content-Type增加 Boundary 后缀, 而这个是服务端判断文件边界的重要参数. 如果设置自定义 Header, 需要检查 boundary 是否正确生成. 如果没有的话需要自定义 Content-Type 将 boundary 加进去, 并且通过 EntityBuilder.setBoundary() 将自定义的 boundary 值传给 HttpEntity.

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