Java實現Http請求的常用方式

一、使用Java自帶的java.io和java.net包。

　　實現方式如下：

public class HttpClient {
　　　　　//1、doGet方法　
	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，並指定字符集
				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;
	}
　　　　　//2、doPost方法
	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(150000);
			// 設置讀取主機服務器返回數據超時時間：60000毫秒
			connection.setReadTimeout(600000);

			// 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;
	}

　　

二、使用Apache的HttpClient-4.x.Jar包。

　　Jar包Maven下載地址：https://mvnrepository.com/artifact/org.apache.httpcomponents/httpclient。

　　實現方式如下：

package com.test.http;

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,並返回響應參數對象
			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;
	}
}

 

三、使用Apache的HttpClient-3.x.Jar包。

　　Jar包Maven下載地址：https://mvnrepository.com/artifact/commons-httpclient/commons-httpclient。

　　實現方式如下：

package com.test.http;

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;
	}
}