HttpClient入门示例

       如果你是使用maven来管理项目，你需要在pom.xml添加如下配置：

        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
            <version>4.5</version>
        </dependency>
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpmime</artifactId>
            <version>4.5</version>
        </dependency>
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpcore</artifactId>
            <version>4.4.1</version>
        </dependency>

 

 

示例代码如下：

package org.apache.http.examples.entity.mime;import java.io.IOException;import java.io.InterruptedIOException;import java.net.UnknownHostException;import java.util.HashMap;import java.util.List;import java.util.Map;import java.util.Map.Entry;import javax.net.ssl.SSLException;import org.apache.commons.codec.Charsets;import org.apache.http.Header;import org.apache.http.HttpEntityEnclosingRequest;import org.apache.http.HttpRequest;import org.apache.http.HttpResponse;import org.apache.http.client.HttpClient;import org.apache.http.client.HttpRequestRetryHandler;import org.apache.http.client.config.RequestConfig;import org.apache.http.client.methods.HttpGet;import org.apache.http.client.methods.HttpPost;import org.apache.http.client.protocol.HttpClientContext;import org.apache.http.client.utils.URIBuilder;import org.apache.http.config.SocketConfig;import org.apache.http.conn.ConnectTimeoutException;import org.apache.http.impl.client.HttpClients;import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;import org.apache.http.protocol.HttpContext;import org.apache.http.util.EntityUtils;/** * 使用HttpClient发送和接收Http请求 *  * @author manzhizhen * */public class HttpUtils {private static HttpClient httpClient;// 最大连接数private static final int MAX_CONNECTION = 100;// 每个route能使用的最大连接数，一般和MAX_CONNECTION取值一样private static final int MAX_CONCURRENT_CONNECTIONS = 100;// 建立连接的超时时间，单位毫秒private static final int CONNECTION_TIME_OUT = 200;// 请求超时时间，单位毫秒private static final int REQUEST_TIME_OUT = 200;// 最大失败重试次数private static final int MAX_FAIL_RETRY_COUNT = 3;// 请求配置，可以复用private static RequestConfig requestConfig;static {SocketConfig socketConfig = SocketConfig.custom().setSoTimeout(REQUEST_TIME_OUT).setSoKeepAlive(true).setTcpNoDelay(true).build();requestConfig = RequestConfig.custom().setSocketTimeout(REQUEST_TIME_OUT).setConnectTimeout(CONNECTION_TIME_OUT).build();/** * 每个默认的 ClientConnectionPoolManager 实现将给每个route创建不超过2个并发连接，最多20个连接总数。 */PoolingHttpClientConnectionManager connManager = new PoolingHttpClientConnectionManager();connManager.setMaxTotal(MAX_CONNECTION);connManager.setDefaultMaxPerRoute(MAX_CONCURRENT_CONNECTIONS);connManager.setDefaultSocketConfig(socketConfig);httpClient = HttpClients.custom().setConnectionManager(connManager)// 添加重试处理器.setRetryHandler(new MyHttpRequestRetryHandler()).build();}public static void main(String[] args) {testGet();}/** * 测试get方法 */private static void testGet() {String url = "http://restapi.amap.com/v3/place/text";Map<String, String> paramMap = new HashMap<String, String>();paramMap.put("key", "95708f902ac2428ea119ec99fb70e6a3");paramMap.put("keywords", "互联网金融大厦");paramMap.put("city", "330100");paramMap.put("extensions", "all");try {System.out.println(get(url, paramMap));} catch (Exception e) {e.printStackTrace();}}/** * post请求 *  * @param url * @param paramMap * @param headers * @return * @throws Exception */public static String post(String url, Map<String, String> paramMap,List<Header> headers) throws Exception {URIBuilder uriBuilder = new URIBuilder(url);if (paramMap != null) {// 添加请求参数for (Entry<String, String> entry : paramMap.entrySet()) {uriBuilder.addParameter(entry.getKey(), entry.getValue());}}HttpPost httpPost = new HttpPost(uriBuilder.build());if (headers != null) {// 添加请求首部for (Header header : headers) {httpPost.addHeader(header);}}httpPost.setConfig(requestConfig);// 执行请求HttpResponse response = httpClient.execute(httpPost);return EntityUtils.toString(response.getEntity(), Charsets.UTF_8);}/** * post请求，不带请求首部 *  * @param url * @param paramMap * @return * @throws Exception */public static String post(String url, Map<String, String> paramMap)throws Exception {return post(url, paramMap, null);}/** * get请求 *  * @param url * @param paramMap * @param headers * @return * @throws Exception */public static String get(String url, Map<String, String> paramMap,List<Header> headers) throws Exception {URIBuilder uriBuilder = new URIBuilder(url);if (paramMap != null) {// 添加请求参数for (Entry<String, String> entry : paramMap.entrySet()) {uriBuilder.addParameter(entry.getKey(), entry.getValue());}}HttpGet httpGet = new HttpGet(uriBuilder.build());if (headers != null) {// 添加请求首部for (Header header : headers) {httpGet.addHeader(header);}}httpGet.setConfig(requestConfig);// 执行请求HttpResponse response = httpClient.execute(httpGet);return EntityUtils.toString(response.getEntity(), Charsets.UTF_8);}/** * get请求，不带请求首部 *  * @param url * @param paramMap * @return * @throws Exception */public static String get(String url, Map<String, String> paramMap)throws Exception {return get(url, paramMap, null);}/** * 请求重试处理器 * @author manzhizhen * */private static class MyHttpRequestRetryHandler implementsHttpRequestRetryHandler {@Overridepublic boolean retryRequest(IOException exception, int executionCount,HttpContext context) {if (executionCount >= MAX_FAIL_RETRY_COUNT) {return false;}if (exception instanceof InterruptedIOException) {// 超时return false;}if (exception instanceof UnknownHostException) {// 未知主机return false;}if (exception instanceof ConnectTimeoutException) {// 连接被拒绝return false;}if (exception instanceof SSLException) {// SSL handshake exceptionreturn false;}HttpClientContext clientContext = HttpClientContext.adapt(context);HttpRequest request = clientContext.getRequest();boolean idempotent = !(request instanceof HttpEntityEnclosingRequest);if (idempotent) {// 如果请求被认为是幂等的，则重试return true;}return false;}}}