Java method of sending HTTP request through HttpClient

This article mainly introduces JAVA method examples of sending HTTP requests through HttpClient. It introduces the use of HttpClient in detail, which has certain reference value. Those who are interested can learn about it

HttpClient Introduction

HttpClient is not a browser. It is a client-side HTTP communication implementation library. The goal of HttpClient is to send and receive HTTP messages. HttpClient does not cache content, execute JavaScript code embedded in HTML pages, guess content types, reformat request/redirect URIs, or other functions unrelated to HTTP transport.

HttpClient use

You need to introduce the jar package. The maven project introduction is as follows:

##

<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>

How to use, the code is as follows:

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"));
  
  }
}

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