JAVA中的HTTP请求怎么利用HttpClient实现发送

JAVA中的HTTP请求怎么利用HttpClient实现发送？很多新手对此不是很清楚，为了帮助大家解决这个难题，下面小编将为大家详细讲解，有这方面需求的人可以来学习下，希望你能有所收获。

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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：


      org.apache.httpcomponents
      httpclient
      4.5
    

    
      org.apache.httpcomponents
      httpcore
      4.4.4
    

    
      org.apache.httpcomponents
      httpmime
      4.5

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 socketFactoryRegistry = RegistryBuilder. 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 maps, List 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 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"));
  
  }
}

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