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HttpComponents HttpClient 简介
HttpClient属于Apache HttpComponents项目，基于HttpCore，支持HTTP代理实现，支持状态管理，连接管理，自定义结果处理等功能，代替原先的Commons HttpClient 3.x。
HttpClient是比较实用的Http请求客户端，相比HttpURLConnection来说封装性更好，也提供了许多用户自定义以及拓展的能力，下面简单来使用一下：
模拟服务
@RestController
@RequestMapping("/demo")
@SpringBootApplication
@Slf4j
public class DemoApplication {
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
private List foos = new CopyOnWriteArrayList<>();
@GetMapping("/list")
public ResponseEntity list(@RequestParam(value = "name") String name) {
log.info("accept a list request...");
return ResponseEntity.ok(foos.stream().filter(i -> i.getName().equals(name)).collect(Collectors.toList()));
}
@PostMapping
public ResponseEntity create(@RequestBody Foo foo) {
log.info("accept create request,foo:{}", foo);
foos.add(foo);
return ResponseEntity.ok(foo);
}
@GetMapping("/error")
public ResponseEntity error() {
return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body("error");
}
@GetMapping("/redirect")
public ResponseEntity redirect() {
return ResponseEntity.status(HttpStatus.FOUND).header(HttpHeaders.LOCATION, "http://www.baidu.com").build();
}
@Data
@AllArgsConstructor
public static class Foo {
private String name;
private int age;
}
}
发起POST请求
//request body
Map foo = new HashMap<>();
foo.put("name", "HTTP");
foo.put("age", "18");
HttpUriRequest request = RequestBuilder.post().setUri("http://localhost:8080/demo")
.setEntity(new StringEntity(JSONObject.toJSONString(foo), ContentType.APPLICATION_JSON)).build();
CloseableHttpClient httpClient = HttpClients.createDefault();
CloseableHttpResponse response = httpClient.execute(request);
int statusCode = response.getStatusLine().getStatusCode();
//错误判断
if (statusCode >= 200 & statusCode < 300) {
String body = IOUtils.toString(response.getEntity().getContent(), StandardCharsets.UTF_8.name());
log.info("请求结果:{}", body);
} else {
log.error("请求错误，statusCode={}", statusCode);
}
发起Get请求
HttpUriRequest request = RequestBuilder.get().setUri("http://localhost:8080/demo/list")
.addParameter("name", "HTTP").addHeader("Content-Type", "application/json").build();
//设置超时
RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(1000 * 5).build();
CloseableHttpClient httpClient = HttpClients.custom().setDefaultRequestConfig(requestConfig).build();
CloseableHttpResponse response = httpClient.execute(request);
System.out.println(response);
int statusCode = response.getStatusLine().getStatusCode();
if (statusCode >= 200 & statusCode < 300) {
String body = IOUtils.toString(response.getEntity().getContent(), StandardCharsets.UTF_8.name());
log.info("请求结果:{}", body);
} else {
log.error("请求错误，statusCode={}", statusCode);
}
使用BasicResponseHandler处理结果
HttpUriRequest request = RequestBuilder.get().setUri("http://localhost:8080/demo/error")
.addHeader("Content-Type", "application/json").build();
CloseableHttpClient httpClient = HttpClients.custom().build();
try {
String response = httpClient.execute(request, new BasicResponseHandler());
System.out.println(response);
} catch (HttpResponseException e) {
log.error("error,code={},message={}", e.getStatusCode(), e.getMessage(), e);
}
设置超时
// 备注，socketTimeout指接收数据时的超时，connectTimeout指的是建立连接的超时
RequestConfig.custom()
.setSocketTimeout(5 * 1000)//socket超时
.setConnectTimeout(10 * 1000)//连接超时
.setConnectionRequestTimeout(5000)//从连接池获取连接的超时时间
.build();
常用配置(官方例子)
/*
* ====================================================================
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* responseParserFactory = new DefaultHttpResponseParserFactory() {
@Override
public HttpMessageParser create(
SessionInputBuffer buffer, MessageConstraints constraints) {
LineParser lineParser = new BasicLineParser() {
@Override
public Header parseHeader(final CharArrayBuffer buffer) {
try {
return super.parseHeader(buffer);
} catch (ParseException ex) {
return new BasicHeader(buffer.toString(), null);
}
}
};
return new DefaultHttpResponseParser(
buffer, lineParser, DefaultHttpResponseFactory.INSTANCE, constraints) {
@Override
protected boolean reject(final CharArrayBuffer line, int count) {
// try to ignore all garbage preceding a status line infinitely
return false;
}
};
}
};
HttpMessageWriterFactory requestWriterFactory = new DefaultHttpRequestWriterFactory();
// Use a custom connection factory to customize the process of
// initialization of outgoing HTTP connections. Beside standard connection
// configuration parameters HTTP connection factory can define message
// parser / writer routines to be employed by individual connections.
HttpConnectionFactory connFactory = new ManagedHttpClientConnectionFactory(
requestWriterFactory, responseParserFactory);
// Client HTTP connection objects when fully initialized can be bound to
// an arbitrary network socket. The process of network socket initialization,
// its connection to a remote address and binding to a local one is controlled
// by a connection socket factory.
// SSL context for secure connections can be created either based on
// system or application specific properties.
SSLContext sslcontext = SSLContexts.createSystemDefault();
// Create a registry of custom connection socket factories for supported
// protocol schemes.
Registry socketFactoryRegistry = RegistryBuilder.create()
.register("http", PlainConnectionSocketFactory.INSTANCE)
.register("https", new SSLConnectionSocketFactory(sslcontext))
.build();
// Use custom DNS resolver to override the system DNS resolution.
DnsResolver dnsResolver = new SystemDefaultDnsResolver() {
@Override
public InetAddress[] resolve(final String host) throws UnknownHostException {
if (host.equalsIgnoreCase("myhost")) {
return new InetAddress[] { InetAddress.getByAddress(new byte[] {127, 0, 0, 1}) };
} else {
return super.resolve(host);
}
}
};
// Create a connection manager with custom configuration.
PoolingHttpClientConnectionManager connManager = new PoolingHttpClientConnectionManager(
socketFactoryRegistry, connFactory, dnsResolver);
// Create socket configuration
SocketConfig socketConfig = SocketConfig.custom()
.setTcpNoDelay(true)
.build();
// Configure the connection manager to use socket configuration either
// by default or for a specific host.
connManager.setDefaultSocketConfig(socketConfig);
connManager.setSocketConfig(new HttpHost("somehost", 80), socketConfig);
// Validate connections after 1 sec of inactivity
connManager.setValidateAfterInactivity(1000);
// Create message constraints
MessageConstraints messageConstraints = MessageConstraints.custom()
.setMaxHeaderCount(200)
.setMaxLineLength(2000)
.build();
// Create connection configuration
ConnectionConfig connectionConfig = ConnectionConfig.custom()
.setMalformedInputAction(CodingErrorAction.IGNORE)
.setUnmappableInputAction(CodingErrorAction.IGNORE)
.setCharset(Consts.UTF_8)
.setMessageConstraints(messageConstraints)
.build();
// Configure the connection manager to use connection configuration either
// by default or for a specific host.
connManager.setDefaultConnectionConfig(connectionConfig);
connManager.setConnectionConfig(new HttpHost("somehost", 80), ConnectionConfig.DEFAULT);
// Configure total max or per route limits for persistent connections
// that can be kept in the pool or leased by the connection manager.
connManager.setMaxTotal(100);
connManager.setDefaultMaxPerRoute(10);
connManager.setMaxPerRoute(new HttpRoute(new HttpHost("somehost", 80)), 20);
// Use custom cookie store if necessary.
CookieStore cookieStore = new BasicCookieStore();
// Use custom credentials provider if necessary.
CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
// Create global request configuration
RequestConfig defaultRequestConfig = RequestConfig.custom()
.setCookieSpec(CookieSpecs.DEFAULT)
.setExpectContinueEnabled(true)
.setTargetPreferredAuthSchemes(Arrays.asList(AuthSchemes.NTLM, AuthSchemes.DIGEST))
.setProxyPreferredAuthSchemes(Arrays.asList(AuthSchemes.BASIC))
.build();
// Create an HttpClient with the given custom dependencies and configuration.
CloseableHttpClient httpclient = HttpClients.custom()
.setConnectionManager(connManager)
.setDefaultCookieStore(cookieStore)
.setDefaultCredentialsProvider(credentialsProvider)
.setProxy(new HttpHost("myproxy", 8080))
.setDefaultRequestConfig(defaultRequestConfig)
.build();
try {
HttpGet httpget = new HttpGet("http://httpbin.org/get");
// Request configuration can be overridden at the request level.
// They will take precedence over the one set at the client level.
RequestConfig requestConfig = RequestConfig.copy(defaultRequestConfig)
.setSocketTimeout(5000)
.setConnectTimeout(5000)
.setConnectionRequestTimeout(5000)
.setProxy(new HttpHost("myotherproxy", 8080))
.build();
httpget.setConfig(requestConfig);
// Execution context can be customized locally.
HttpClientContext context = HttpClientContext.create();
// Contextual attributes set the local context level will take
// precedence over those set at the client level.
context.setCookieStore(cookieStore);
context.setCredentialsProvider(credentialsProvider);
System.out.println("executing request " + httpget.getURI());
CloseableHttpResponse response = httpclient.execute(httpget, context);
try {
System.out.println("----------------------------------------");
System.out.println(response.getStatusLine());
System.out.println(EntityUtils.toString(response.getEntity()));
System.out.println("----------------------------------------");
// Once the request has been executed the local context can
// be used to examine updated state and various objects affected
// by the request execution.
// Last executed request
context.getRequest();
// Execution route
context.getHttpRoute();
// Target auth state
context.getTargetAuthState();
// Proxy auth state
context.getProxyAuthState();
// Cookie origin
context.getCookieOrigin();
// Cookie spec used
context.getCookieSpec();
// User security token
context.getUserToken();
} finally {
response.close();
}
} finally {
httpclient.close();
}
}
}
总结
HttpClient是我们常用的Http客户端，了解熟悉API以及相关配置有利于我们更好的使用，一般场景下使用默认的配置都能满足要求，如果有特殊的要求也支持自定义配置。