詳解java實現HTTP請求的三種方式

發布時間：2020-09-10 10:23:23 來源：腳本之家閱讀：158 作者：君臨-行者無界欄目：編程語言

目前JAVA實現HTTP請求的方法用的最多的有兩種：一種是通過HTTPClient這種第三方的開源框架去實現。HTTPClient對HTTP的封裝性比較不錯，通過它基本上能夠滿足我們大部分的需求，HttpClient3.1 是 org.apache.commons.httpclient下操作遠程 url的工具包，雖然已不再更新，但實現工作中使用httpClient3.1的代碼還是很多，HttpClient4.5是org.apache.http.client下操作遠程 url的工具包，最新的；另一種則是通過HttpURLConnection去實現，HttpURLConnection是JAVA的標準類，是JAVA比較原生的一種實現方式。

自己在工作中三種方式都用到過，總結一下分享給大家，也方便自己以后使用，話不多說上代碼。

第一種方式：java原生HttpURLConnection

package com.powerX.httpClient;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class HttpClient {
  public static String doGet(String httpurl) {
    HttpURLConnection connection = null;
    InputStream is = null;
    BufferedReader br = null;
    String result = null;// 返回結果字符串
    try {
      // 創建遠程url連接對象
      URL url = new URL(httpurl);
      // 通過遠程url連接對象打開一個連接，強轉成httpURLConnection類
      connection = (HttpURLConnection) url.openConnection();
      // 設置連接方式：get
      connection.setRequestMethod("GET");
      // 設置連接主機服務器的超時時間：15000毫秒
      connection.setConnectTimeout(15000);
      // 設置讀取遠程返回的數據時間：60000毫秒
      connection.setReadTimeout(60000);
      // 發送請求
      connection.connect();
      // 通過connection連接，獲取輸入流
      if (connection.getResponseCode() == 200) {
        is = connection.getInputStream();
        // 封裝輸入流is，并指定字符集
        br = new BufferedReader(new InputStreamReader(is, "UTF-8"));
        // 存放數據
        StringBuffer sbf = new StringBuffer();
        String temp = null;
        while ((temp = br.readLine()) != null) {
          sbf.append(temp);
          sbf.append("\r\n");
        }
        result = sbf.toString();
      }
    } catch (MalformedURLException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    } finally {
      // 關閉資源
      if (null != br) {
        try {
          br.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }

      if (null != is) {
        try {
          is.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }

      connection.disconnect();// 關閉遠程連接
    }

    return result;
  }

  public static String doPost(String httpUrl, String param) {

    HttpURLConnection connection = null;
    InputStream is = null;
    OutputStream os = null;
    BufferedReader br = null;
    String result = null;
    try {
      URL url = new URL(httpUrl);
      // 通過遠程url連接對象打開連接
      connection = (HttpURLConnection) url.openConnection();
      // 設置連接請求方式
      connection.setRequestMethod("POST");
      // 設置連接主機服務器超時時間：15000毫秒
      connection.setConnectTimeout(15000);
      // 設置讀取主機服務器返回數據超時時間：60000毫秒
      connection.setReadTimeout(60000);

      // 默認值為：false，當向遠程服務器傳送數據/寫數據時，需要設置為true
      connection.setDoOutput(true);
      // 默認值為：true，當前向遠程服務讀取數據時，設置為true，該參數可有可無
      connection.setDoInput(true);
      // 設置傳入參數的格式:請求參數應該是 name1=value1&name2=value2 的形式。
      connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
      // 設置鑒權信息：Authorization: Bearer da3efcbf-0845-4fe3-8aba-ee040be542c0
      connection.setRequestProperty("Authorization", "Bearer da3efcbf-0845-4fe3-8aba-ee040be542c0");
      // 通過連接對象獲取一個輸出流
      os = connection.getOutputStream();
      // 通過輸出流對象將參數寫出去/傳輸出去,它是通過字節數組寫出的
      os.write(param.getBytes());
      // 通過連接對象獲取一個輸入流，向遠程讀取
      if (connection.getResponseCode() == 200) {

        is = connection.getInputStream();
        // 對輸入流對象進行包裝:charset根據工作項目組的要求來設置
        br = new BufferedReader(new InputStreamReader(is, "UTF-8"));

        StringBuffer sbf = new StringBuffer();
        String temp = null;
        // 循環遍歷一行一行讀取數據
        while ((temp = br.readLine()) != null) {
          sbf.append(temp);
          sbf.append("\r\n");
        }
        result = sbf.toString();
      }
    } catch (MalformedURLException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    } finally {
      // 關閉資源
      if (null != br) {
        try {
          br.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
      if (null != os) {
        try {
          os.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
      if (null != is) {
        try {
          is.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
      // 斷開與遠程地址url的連接
      connection.disconnect();
    }
    return result;
  }
}

第二種方式：apache HttpClient3.1

package com.powerX.httpClient;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import org.apache.commons.httpclient.DefaultHttpMethodRetryHandler;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.NameValuePair;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.params.HttpMethodParams;

public class HttpClient3 {

  public static String doGet(String url) {
    // 輸入流
    InputStream is = null;
    BufferedReader br = null;
    String result = null;
    // 創建httpClient實例
    HttpClient httpClient = new HttpClient();
    // 設置http連接主機服務超時時間：15000毫秒
    // 先獲取連接管理器對象，再獲取參數對象,再進行參數的賦值
    httpClient.getHttpConnectionManager().getParams().setConnectionTimeout(15000);
    // 創建一個Get方法實例對象
    GetMethod getMethod = new GetMethod(url);
    // 設置get請求超時為60000毫秒
    getMethod.getParams().setParameter(HttpMethodParams.SO_TIMEOUT, 60000);
    // 設置請求重試機制，默認重試次數：3次，參數設置為true，重試機制可用，false相反
    getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler(3, true));
    try {
      // 執行Get方法
      int statusCode = httpClient.executeMethod(getMethod);
      // 判斷返回碼
      if (statusCode != HttpStatus.SC_OK) {
        // 如果狀態碼返回的不是ok,說明失敗了,打印錯誤信息
        System.err.println("Method faild: " + getMethod.getStatusLine());
      } else {
        // 通過getMethod實例，獲取遠程的一個輸入流
        is = getMethod.getResponseBodyAsStream();
        // 包裝輸入流
        br = new BufferedReader(new InputStreamReader(is, "UTF-8"));

        StringBuffer sbf = new StringBuffer();
        // 讀取封裝的輸入流
        String temp = null;
        while ((temp = br.readLine()) != null) {
          sbf.append(temp).append("\r\n");
        }

        result = sbf.toString();
      }

    } catch (IOException e) {
      e.printStackTrace();
    } finally {
      // 關閉資源
      if (null != br) {
        try {
          br.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
      if (null != is) {
        try {
          is.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
      // 釋放連接
      getMethod.releaseConnection();
    }
    return result;
  }

  public static String doPost(String url, Map<String, Object> paramMap) {
    // 獲取輸入流
    InputStream is = null;
    BufferedReader br = null;
    String result = null;
    // 創建httpClient實例對象
    HttpClient httpClient = new HttpClient();
    // 設置httpClient連接主機服務器超時時間：15000毫秒
    httpClient.getHttpConnectionManager().getParams().setConnectionTimeout(15000);
    // 創建post請求方法實例對象
    PostMethod postMethod = new PostMethod(url);
    // 設置post請求超時時間
    postMethod.getParams().setParameter(HttpMethodParams.SO_TIMEOUT, 60000);

    NameValuePair[] nvp = null;
    // 判斷參數map集合paramMap是否為空
    if (null != paramMap && paramMap.size() > 0) {// 不為空
      // 創建鍵值參數對象數組，大小為參數的個數
      nvp = new NameValuePair[paramMap.size()];
      // 循環遍歷參數集合map
      Set<Entry<String, Object>> entrySet = paramMap.entrySet();
      // 獲取迭代器
      Iterator<Entry<String, Object>> iterator = entrySet.iterator();

      int index = 0;
      while (iterator.hasNext()) {
        Entry<String, Object> mapEntry = iterator.next();
        // 從mapEntry中獲取key和value創建鍵值對象存放到數組中
        try {
          nvp[index] = new NameValuePair(mapEntry.getKey(),
              new String(mapEntry.getValue().toString().getBytes("UTF-8"), "UTF-8"));
        } catch (UnsupportedEncodingException e) {
          e.printStackTrace();
        }
        index++;
      }
    }
    // 判斷nvp數組是否為空
    if (null != nvp && nvp.length > 0) {
      // 將參數存放到requestBody對象中
      postMethod.setRequestBody(nvp);
    }
    // 執行POST方法
    try {
      int statusCode = httpClient.executeMethod(postMethod);
      // 判斷是否成功
      if (statusCode != HttpStatus.SC_OK) {
        System.err.println("Method faild: " + postMethod.getStatusLine());
      }
      // 獲取遠程返回的數據
      is = postMethod.getResponseBodyAsStream();
      // 封裝輸入流
      br = new BufferedReader(new InputStreamReader(is, "UTF-8"));

      StringBuffer sbf = new StringBuffer();
      String temp = null;
      while ((temp = br.readLine()) != null) {
        sbf.append(temp).append("\r\n");
      }

      result = sbf.toString();
    } catch (IOException e) {
      e.printStackTrace();
    } finally {
      // 關閉資源
      if (null != br) {
        try {
          br.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
      if (null != is) {
        try {
          is.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
      // 釋放連接
      postMethod.releaseConnection();
    }
    return result;
  }
}

第三種方式：apache httpClient4.5

package com.powerX.httpClient;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import org.apache.http.HttpEntity;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.entity.UrlEncodedFormEntity;
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.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;

public class HttpClient4 {

  public static String doGet(String url) {
    CloseableHttpClient httpClient = null;
    CloseableHttpResponse response = null;
    String result = "";
    try {
      // 通過址默認配置創建一個httpClient實例
      httpClient = HttpClients.createDefault();
      // 創建httpGet遠程連接實例
      HttpGet httpGet = new HttpGet(url);
      // 設置請求頭信息，鑒權
      httpGet.setHeader("Authorization", "Bearer da3efcbf-0845-4fe3-8aba-ee040be542c0");
      // 設置配置請求參數
      RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(35000)// 連接主機服務超時時間
          .setConnectionRequestTimeout(35000)// 請求超時時間
          .setSocketTimeout(60000)// 數據讀取超時時間
          .build();
      // 為httpGet實例設置配置
      httpGet.setConfig(requestConfig);
      // 執行get請求得到返回對象
      response = httpClient.execute(httpGet);
      // 通過返回對象獲取返回數據
      HttpEntity entity = response.getEntity();
      // 通過EntityUtils中的toString方法將結果轉換為字符串
      result = EntityUtils.toString(entity);
    } catch (ClientProtocolException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    } finally {
      // 關閉資源
      if (null != response) {
        try {
          response.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
      if (null != httpClient) {
        try {
          httpClient.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
    }
    return result;
  }

  public static String doPost(String url, Map<String, Object> paramMap) {
    CloseableHttpClient httpClient = null;
    CloseableHttpResponse httpResponse = null;
    String result = "";
    // 創建httpClient實例
    httpClient = HttpClients.createDefault();
    // 創建httpPost遠程連接實例
    HttpPost httpPost = new HttpPost(url);
    // 配置請求參數實例
    RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(35000)// 設置連接主機服務超時時間
        .setConnectionRequestTimeout(35000)// 設置連接請求超時時間
        .setSocketTimeout(60000)// 設置讀取數據連接超時時間
        .build();
    // 為httpPost實例設置配置
    httpPost.setConfig(requestConfig);
    // 設置請求頭
    httpPost.addHeader("Content-Type", "application/x-www-form-urlencoded");
    // 封裝post請求參數
    if (null != paramMap && paramMap.size() > 0) {
      List<NameValuePair> nvps = new ArrayList<NameValuePair>();
      // 通過map集成entrySet方法獲取entity
      Set<Entry<String, Object>> entrySet = paramMap.entrySet();
      // 循環遍歷，獲取迭代器
      Iterator<Entry<String, Object>> iterator = entrySet.iterator();
      while (iterator.hasNext()) {
        Entry<String, Object> mapEntry = iterator.next();
        nvps.add(new BasicNameValuePair(mapEntry.getKey(), mapEntry.getValue().toString()));
      }

      // 為httpPost設置封裝好的請求參數
      try {
        httpPost.setEntity(new UrlEncodedFormEntity(nvps, "UTF-8"));
      } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
      }
    }
    try {
      // httpClient對象執行post請求,并返回響應參數對象
      httpResponse = httpClient.execute(httpPost);
      // 從響應對象中獲取響應內容
      HttpEntity entity = httpResponse.getEntity();
      result = EntityUtils.toString(entity);
    } catch (ClientProtocolException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    } finally {
      // 關閉資源
      if (null != httpResponse) {
        try {
          httpResponse.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
      if (null != httpClient) {
        try {
          httpClient.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
    }
    return result;
  }
}

有時候我們在使用post請求時，可能傳入的參數是json或者其他格式，此時我們則需要更改請求頭及參數的設置信息，以httpClient4.5為例，更改下面兩列配置：httpPost.setEntity(new StringEntity("你的json串")); httpPost.addHeader("Content-Type", "application/json")。

以上所述是小編給大家介紹的java實現HTTP請求的三種方式詳解整合，希望對大家有所幫助，如果大家有任何疑問請給我留言，小編會及時回復大家的。在此也非常感謝大家對億速云網站的支持！

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