JAVA通过HttpClient发送HTTP请求的方法示例

HttpClient介绍

HttpClient 不是一个浏览器。它是一个客户端的 HTTP 通信实现库。HttpClient的目标是发 送和接收HTTP 报文。HttpClient不会去缓存内容，执行 嵌入在 HTML 页面中的javascript 代码，猜测内容类型，重新格式化请求/重定向URI，或者其它和 HTTP 运输无关的功能。

HttpClient使用

使用需要引入jar包，maven项目引入如下：

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

<dependency>
     <groupId>org.apache.httpcomponents</groupId>
     <artifactId>httpcore</artifactId>
     <version>4.4.4</version>
   </dependency>

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

使用方法，代码如下：

package com.test;

import java.io.File;
import java.io.IOException;
import java.security.KeyManagementException;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.apache.http.HttpEntity;
import org.apache.http.HttpStatus;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.config.Registry;
import org.apache.http.config.RegistryBuilder;
import org.apache.http.conn.socket.ConnectionSocketFactory;
import org.apache.http.conn.socket.PlainConnectionSocketFactory;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.conn.ssl.SSLContextBuilder;
import org.apache.http.conn.ssl.TrustSelfSignedStrategy;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.entity.mime.MultipartEntityBuilder;
import org.apache.http.entity.mime.content.FileBody;
import org.apache.http.entity.mime.content.StringBody;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.DefaultHttpRequestRetryHandler;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.http.util.EntityUtils;

/**
*
* @author H__D
* @date 2016年10月19日 上午11:27:25
*
*/
public class HttpClientUtil {

// utf-8字符编码
 public static final String CHARSET_UTF_8 = "utf-8";

// HTTP内容类型。
 public static final String CONTENT_TYPE_TEXT_HTML = "text/xml";

// HTTP内容类型。相当于form表单的形式，提交数据
 public static final String CONTENT_TYPE_FORM_URL = "application/x-www-form-urlencoded";

// HTTP内容类型。相当于form表单的形式，提交数据
 public static final String CONTENT_TYPE_JSON_URL = "application/json;charset=utf-8";

// 连接管理器
 private static PoolingHttpClientConnectionManager pool;

// 请求配置
 private static RequestConfig requestConfig;

static {

try {
     //System.out.println("初始化HttpClientTest~~~开始");
     SSLContextBuilder builder = new SSLContextBuilder();
     builder.loadTrustMaterial(null, new TrustSelfSignedStrategy());
     SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(
         builder.build());
     // 配置同时支持 HTTP 和 HTPPS
     Registry<ConnectionSocketFactory> socketFactoryRegistry = RegistryBuilder.<ConnectionSocketFactory> create().register(
         "http", PlainConnectionSocketFactory.getSocketFactory()).register(
         "https", sslsf).build();
     // 初始化连接管理器
     pool = new PoolingHttpClientConnectionManager(
         socketFactoryRegistry);
     // 将最大连接数增加到200，实际项目最好从配置文件中读取这个值
     pool.setMaxTotal(200);
     // 设置最大路由
     pool.setDefaultMaxPerRoute(2);
     // 根据默认超时限制初始化requestConfig
     int socketTimeout = 10000;
     int connectTimeout = 10000;
     int connectionRequestTimeout = 10000;
     requestConfig = RequestConfig.custom().setConnectionRequestTimeout(
         connectionRequestTimeout).setSocketTimeout(socketTimeout).setConnectTimeout(
         connectTimeout).build();

//System.out.println("初始化HttpClientTest~~~结束");
   } catch (NoSuchAlgorithmException e) {
     e.printStackTrace();
   } catch (KeyStoreException e) {
     e.printStackTrace();
   } catch (KeyManagementException e) {
     e.printStackTrace();
   }

// 设置请求超时时间
   requestConfig = RequestConfig.custom().setSocketTimeout(50000).setConnectTimeout(50000)
       .setConnectionRequestTimeout(50000).build();
 }

public static CloseableHttpClient getHttpClient() {

CloseableHttpClient httpClient = HttpClients.custom()
       // 设置连接池管理
       .setConnectionManager(pool)
       // 设置请求配置
       .setDefaultRequestConfig(requestConfig)
       // 设置重试次数
       .setRetryHandler(new DefaultHttpRequestRetryHandler(0, false))
       .build();

return httpClient;
 }

/**
  * 发送Post请求
  *
  * @param httpPost
  * @return
  */
 private static String sendHttpPost(HttpPost httpPost) {

CloseableHttpClient httpClient = null;
   CloseableHttpResponse response = null;
   // 响应内容
   String responseContent = null;
   try {
     // 创建默认的httpClient实例.
     httpClient = getHttpClient();
     // 配置请求信息
     httpPost.setConfig(requestConfig);
     // 执行请求
     response = httpClient.execute(httpPost);
     // 得到响应实例
     HttpEntity entity = response.getEntity();

// 可以获得响应头
     // Header[] headers = response.getHeaders(HttpHeaders.CONTENT_TYPE);
     // for (Header header : headers) {
     // System.out.println(header.getName());
     // }

// 得到响应类型
     // System.out.println(ContentType.getOrDefault(response.getEntity()).getMimeType());

// 判断响应状态
     if (response.getStatusLine().getStatusCode() >= 300) {
       throw new Exception(
           "HTTP Request is not success, Response code is " + response.getStatusLine().getStatusCode());
     }

if (HttpStatus.SC_OK == response.getStatusLine().getStatusCode()) {
       responseContent = EntityUtils.toString(entity, CHARSET_UTF_8);
       EntityUtils.consume(entity);
     }

} catch (Exception e) {
     e.printStackTrace();
   } finally {
     try {
       // 释放资源
       if (response != null) {
         response.close();
       }
     } catch (IOException e) {
       e.printStackTrace();
     }
   }
   return responseContent;
 }

/**
  * 发送Get请求
  *
  * @param httpGet
  * @return
  */
 private static String sendHttpGet(HttpGet httpGet) {

CloseableHttpClient httpClient = null;
   CloseableHttpResponse response = null;
   // 响应内容
   String responseContent = null;
   try {
     // 创建默认的httpClient实例.
     httpClient = getHttpClient();
     // 配置请求信息
     httpGet.setConfig(requestConfig);
     // 执行请求
     response = httpClient.execute(httpGet);
     // 得到响应实例
     HttpEntity entity = response.getEntity();

// 可以获得响应头
     // Header[] headers = response.getHeaders(HttpHeaders.CONTENT_TYPE);
     // for (Header header : headers) {
     // System.out.println(header.getName());
     // }

// 得到响应类型
     // System.out.println(ContentType.getOrDefault(response.getEntity()).getMimeType());

// 判断响应状态
     if (response.getStatusLine().getStatusCode() >= 300) {
       throw new Exception(
           "HTTP Request is not success, Response code is " + response.getStatusLine().getStatusCode());
     }

if (HttpStatus.SC_OK == response.getStatusLine().getStatusCode()) {
       responseContent = EntityUtils.toString(entity, CHARSET_UTF_8);
       EntityUtils.consume(entity);
     }

} catch (Exception e) {
     e.printStackTrace();
   } finally {
     try {
       // 释放资源
       if (response != null) {
         response.close();
       }
     } catch (IOException e) {
       e.printStackTrace();
     }
   }
   return responseContent;
 }

/**
  * 发送 post请求
  *
  * @param httpUrl
  *      地址
  */
 public static String sendHttpPost(String httpUrl) {
   // 创建httpPost
   HttpPost httpPost = new HttpPost(httpUrl);
   return sendHttpPost(httpPost);
 }

/**
  * 发送 get请求
  *
  * @param httpUrl
  */
 public static String sendHttpGet(String httpUrl) {
   // 创建get请求
   HttpGet httpGet = new HttpGet(httpUrl);
   return sendHttpGet(httpGet);
 }

/**
  * 发送 post请求（带文件）
  *
  * @param httpUrl
  *      地址
  * @param maps
  *      参数
  * @param fileLists
  *      附件
  */
 public static String sendHttpPost(String httpUrl, Map<String, String> maps, List<File> fileLists) {
   HttpPost httpPost = new HttpPost(httpUrl);// 创建httpPost
   MultipartEntityBuilder meBuilder = MultipartEntityBuilder.create();
   if (maps != null) {
     for (String key : maps.keySet()) {
       meBuilder.addPart(key, new StringBody(maps.get(key), ContentType.TEXT_PLAIN));
     }
   }
   if (fileLists != null) {
     for (File file : fileLists) {
       FileBody fileBody = new FileBody(file);
       meBuilder.addPart("files", fileBody);
     }
   }
   HttpEntity reqEntity = meBuilder.build();
   httpPost.setEntity(reqEntity);
   return sendHttpPost(httpPost);
 }

/**
  * 发送 post请求
  *
  * @param httpUrl
  *      地址
  * @param params
  *      参数(格式:key1=value1&key2=value2)
  *
  */
 public static String sendHttpPost(String httpUrl, String params) {
   HttpPost httpPost = new HttpPost(httpUrl);// 创建httpPost
   try {
     // 设置参数
     if (params != null && params.trim().length() > 0) {
       StringEntity stringEntity = new StringEntity(params, "UTF-8");
       stringEntity.setContentType(CONTENT_TYPE_FORM_URL);
       httpPost.setEntity(stringEntity);
     }
   } catch (Exception e) {
     e.printStackTrace();
   }
   return sendHttpPost(httpPost);
 }

/**
  * 发送 post请求
  *
  * @param maps
  *      参数
  */
 public static String sendHttpPost(String httpUrl, Map<String, String> maps) {
   String parem = convertStringParamter(maps);
   return sendHttpPost(httpUrl, parem);
 }

/**
  * 发送 post请求 发送json数据
  *
  * @param httpUrl
  *      地址
  * @param paramsJson
  *      参数(格式 json)
  *
  */
 public static String sendHttpPostJson(String httpUrl, String paramsJson) {
   HttpPost httpPost = new HttpPost(httpUrl);// 创建httpPost
   try {
     // 设置参数
     if (paramsJson != null && paramsJson.trim().length() > 0) {
       StringEntity stringEntity = new StringEntity(paramsJson, "UTF-8");
       stringEntity.setContentType(CONTENT_TYPE_JSON_URL);
       httpPost.setEntity(stringEntity);
     }
   } catch (Exception e) {
     e.printStackTrace();
   }
   return sendHttpPost(httpPost);
 }

/**
  * 发送 post请求 发送xml数据
  *
  * @param httpUrl  地址
  * @param paramsXml 参数(格式 Xml)
  *
  */
 public static String sendHttpPostXml(String httpUrl, String paramsXml) {
   HttpPost httpPost = new HttpPost(httpUrl);// 创建httpPost
   try {
     // 设置参数
     if (paramsXml != null && paramsXml.trim().length() > 0) {
       StringEntity stringEntity = new StringEntity(paramsXml, "UTF-8");
       stringEntity.setContentType(CONTENT_TYPE_TEXT_HTML);
       httpPost.setEntity(stringEntity);
     }
   } catch (Exception e) {
     e.printStackTrace();
   }
   return sendHttpPost(httpPost);
 }

/**
  * 将map集合的键值对转化成：key1=value1&key2=value2 的形式
  *
  * @param parameterMap
  *      需要转化的键值对集合
  * @return 字符串
  */
 public static String convertStringParamter(Map parameterMap) {
   StringBuffer parameterBuffer = new StringBuffer();
   if (parameterMap != null) {
     Iterator iterator = parameterMap.keySet().iterator();
     String key = null;
     String value = null;
     while (iterator.hasNext()) {
       key = (String) iterator.next();
       if (parameterMap.get(key) != null) {
         value = (String) parameterMap.get(key);
       } else {
         value = "";
       }
       parameterBuffer.append(key).append("=").append(value);
       if (iterator.hasNext()) {
         parameterBuffer.append("&");
       }
     }
   }
   return parameterBuffer.toString();
 }

public static void main(String[] args) throws Exception {

System.out.println(sendHttpGet("http://www.baidu.com"));

}
}

来源：http://www.cnblogs.com/h--d/p/5976665.html