java建立HTTP請求的三種方式
阿新 • • 發佈：2018-12-27
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下操作遠端 url的工具包，雖然已不再更新，但實現工作中使用httpClient3.1的程式碼還是很多，HttpClient4.5是org.apache.http.client下操作遠端 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，也方便自己以後使用，話不多說上程式碼。
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; importjava.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;// 返回結果字串 try {// 建立遠端url連線物件 URL url = new URL(httpurl); // 通過遠端url連線物件開啟一個連線，強轉成httpURLConnection類 connection = (HttpURLConnection) url.openConnection(); // 設定連線方式：get connection.setRequestMethod("GET"); // 設定連線主機伺服器的超時時間：15000毫秒 connection.setConnectTimeout(15000); // 設定讀取遠端返回的資料時間：60000毫秒 connection.setReadTimeout(60000); // 傳送請求 connection.connect(); // 通過connection連線，獲取輸入流 if (connection.getResponseCode() == 200) { is = connection.getInputStream(); // 封裝輸入流is，並指定字符集 br = new BufferedReader(new InputStreamReader(is, "UTF-8")); // 存放資料 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();// 關閉遠端連線 } 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); // 通過遠端url連線物件開啟連線 connection = (HttpURLConnection) url.openConnection(); // 設定連線請求方式 connection.setRequestMethod("POST"); // 設定連線主機伺服器超時時間：15000毫秒 connection.setConnectTimeout(15000); // 設定讀取主機伺服器返回資料超時時間：60000毫秒 connection.setReadTimeout(60000); // 預設值為：false，當向遠端伺服器傳送資料/寫資料時，需要設定為true connection.setDoOutput(true); // 預設值為：true，當前向遠端服務讀取資料時，設定為true，該引數可有可無 connection.setDoInput(true); // 設定傳入引數的格式:請求引數應該是 name1=value1&name2=value2 的形式。 connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); // 設定鑑權資訊：Authorization: Bearer da3efcbf-0845-4fe3-8aba-ee040be542c0 connection.setRequestProperty("Authorization", "Bearer da3efcbf-0845-4fe3-8aba-ee040be542c0"); // 通過連線物件獲取一個輸出流 os = connection.getOutputStream(); // 通過輸出流物件將引數寫出去/傳輸出去,它是通過位元組陣列寫出的 os.write(param.getBytes()); // 通過連線物件獲取一個輸入流，向遠端讀取 if (connection.getResponseCode() == 200) { is = connection.getInputStream(); // 對輸入流物件進行包裝:charset根據工作專案組的要求來設定 br = new BufferedReader(new InputStreamReader(is, "UTF-8")); StringBuffer sbf = new StringBuffer(); String temp = null; // 迴圈遍歷一行一行讀取資料 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(); } } // 斷開與遠端地址url的連線 connection.disconnect(); } return result; } }
第二種方式：java原生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; // 建立httpClient例項 HttpClient httpClient = new HttpClient(); // 設定http連線主機服務超時時間：15000毫秒 // 先獲取連線管理器物件，再獲取引數物件,再進行引數的賦值 httpClient.getHttpConnectionManager().getParams().setConnectionTimeout(15000); // 建立一個Get方法例項物件 GetMethod getMethod = new GetMethod(url); // 設定get請求超時為60000毫秒 getMethod.getParams().setParameter(HttpMethodParams.SO_TIMEOUT, 60000); // 設定請求重試機制，預設重試次數：3次，引數設定為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,列印錯誤資訊 System.err.println("Method faild: " + getMethod.getStatusLine()); } else { // 通過getMethod例項，獲取遠端的一個輸入流 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(); } } // 釋放連線 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; // 建立httpClient例項物件 HttpClient httpClient = new HttpClient(); // 設定httpClient連線主機伺服器超時時間：15000毫秒 httpClient.getHttpConnectionManager().getParams().setConnectionTimeout(15000); // 建立post請求方法例項物件 PostMethod postMethod = new PostMethod(url); // 設定post請求超時時間 postMethod.getParams().setParameter(HttpMethodParams.SO_TIMEOUT, 60000); NameValuePair[] nvp = null; // 判斷引數map集合paramMap是否為空 if (null != paramMap && paramMap.size() > 0) {// 不為空 // 建立鍵值引數物件陣列，大小為引數的個數 nvp = new NameValuePair[paramMap.size()]; // 迴圈遍歷引數集合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建立鍵值物件存放到陣列中 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陣列是否為空 if (null != nvp && nvp.length > 0) { // 將引數存放到requestBody物件中 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()); } // 獲取遠端返回的資料 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(); } } // 釋放連線 postMethod.releaseConnection(); } return result; } }
第三種方式：java原生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 { // 通過址預設配置建立一個httpClient例項 httpClient = HttpClients.createDefault(); // 建立httpGet遠端連線例項 HttpGet httpGet = new HttpGet(url); // 設定請求頭資訊，鑑權 httpGet.setHeader("Authorization", "Bearer da3efcbf-0845-4fe3-8aba-ee040be542c0"); // 設定配置請求引數 RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(35000)// 連線主機服務超時時間 .setConnectionRequestTimeout(35000)// 請求超時時間 .setSocketTimeout(60000)// 資料讀取超時時間 .build(); // 為httpGet例項設定配置 httpGet.setConfig(requestConfig); // 執行get請求得到返回物件 response = httpClient.execute(httpGet); // 通過返回物件獲取返回資料 HttpEntity entity = response.getEntity(); // 通過EntityUtils中的toString方法將結果轉換為字串 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 = ""; // 建立httpClient例項 httpClient = HttpClients.createDefault(); // 建立httpPost遠端連線例項 HttpPost httpPost = new HttpPost(url); // 配置請求引數例項 RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(35000)// 設定連線主機服務超時時間 .setConnectionRequestTimeout(35000)// 設定連線請求超時時間 .setSocketTimeout(60000)// 設定讀取資料連線超時時間 .build(); // 為httpPost例項設定配置 httpPost.setConfig(requestConfig); // 設定請求頭 httpPost.addHeader("Content-Type", "application/x-www-form-urlencoded"); // 封裝post請求引數 if (null != paramMap && paramMap.size() > 0) { List<NameValuePair> nvps = new ArrayList<NameValuePair>(); // 通過map整合entrySet方法獲取entity Set<Entry<String, Object>> entrySet = paramMap.entrySet(); // 迴圈遍歷，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設定封裝好的請求引數 try { httpPost.setEntity(new UrlEncodedFormEntity(nvps, "UTF-8")); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } } try { // httpClient物件執行post請求,並返回響應引數物件 httpResponse = httpClient.execute(httpPost); // 從響應物件中獲取響應內容 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，可能傳入的引數是json或者其他格式，此時我們則需要更改請求頭及引數的設定資訊，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")。