HttpClient使用流程

 使用流程

• 創建 HttpClient 對象
• 創建請求方法的實例，並指定請求 URL。如果需要發送 GET 請求，創建 HttpGet 對象；如果需要發送 POST 請求，創建 HttpPost 對象。
• 如果需要發送請求參數，可調用 HttpGet、HttpPost 共同的 setParams(HttpParams params) 方法來添加請求參數；對於 HttpPost 對象而言，也可調用 setEntity(HttpEntity entity) 方法來設置請求參數。
• 調用 HttpClient 對象的 execute(HttpUriRequest request) 發送請求，該方法返回一個 HttpResponse。
• 調用 HttpResponse 的 getAllHeaders()、getHeaders(String name) 等方法可獲取服務器的響應頭；調用 HttpResponse 的 getEntity() 方法可獲取 HttpEntity 對象，該對象包裝了服務器的響應內容。程序可通過該對象獲取服務器的響應內容。
• 釋放連接。無論執行方法是否成功，都必須釋放連接

 

案例

• pom.xml 配置如下：

  <!-- Apache Http Begin -->
  <dependency>
      <groupId>org.apache.httpcomponents</groupId>
      <artifactId>httpclient</artifactId>
      <version>4.5.5</version>
  </dependency>
  <dependency>
      <groupId>org.apache.httpcomponents</groupId>
      <artifactId>fluent-hc</artifactId>
      <version>4.5.5</version>
  </dependency>
  <dependency>
      <groupId>org.apache.httpcomponents</groupId>
      <artifactId>httpmime</artifactId>
      <version>4.5.5</version>
  </dependency>
  <!-- Apache Http End -->

   

• 創建 HttpGet 請求

  package com.funtl.hello.httpclient;
  
  import org.apache.http.HttpEntity;
  import org.apache.http.client.methods.CloseableHttpResponse;
  import org.apache.http.client.methods.HttpGet;
  import org.apache.http.impl.client.CloseableHttpClient;
  import org.apache.http.impl.client.HttpClients;
  import org.apache.http.util.EntityUtils;
  
  import java.io.IOException;
  
  public class MyTest {
      public static void main(String[] args) {
          get();
      }
  
      private static void get() {
          // 創建 HttpClient 客戶端
          CloseableHttpClient httpClient = HttpClients.createDefault();
  
          // 創建 HttpGet 請求
          HttpGet httpGet = new HttpGet("http://localhost:8080/content/page?draw=1&start=0&length=10");
          // 設置長連接
          httpGet.setHeader("Connection", "keep-alive");
          // 設置代理（模擬瀏覽器版本）
          httpGet.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36");
          // 設置 Cookie
          httpGet.setHeader("Cookie", "UM_distinctid=16442706a09352-0376059833914f-3c604504-1fa400-16442706a0b345; CNZZDATA1262458286=1603637673-1530123020-%7C1530123020; JSESSIONID=805587506F1594AE02DC45845A7216A4");
  
          CloseableHttpResponse httpResponse = null;
          try {
              // 請求並獲得響應結果
              httpResponse = httpClient.execute(httpGet);
              HttpEntity httpEntity = httpResponse.getEntity();
              // 輸出請求結果
              System.out.println(EntityUtils.toString(httpEntity));
          } catch (IOException e) {
              e.printStackTrace();
          }
  
          // 無論如何必須關閉連接
          finally {
              if (httpResponse != null) {
                  try {
                      httpResponse.close();
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
  
              if (httpClient != null) {
                  try {
                      httpClient.close();
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
          }
      }
  }

   

• 創建 HttpPost 請求

  package com.funtl.hello.httpclient;
  
  import org.apache.http.HttpEntity;
  import org.apache.http.client.ClientProtocolException;
  import org.apache.http.client.entity.UrlEncodedFormEntity;
  import org.apache.http.client.methods.CloseableHttpResponse;
  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;
  
  import java.io.IOException;
  import java.io.UnsupportedEncodingException;
  import java.util.ArrayList;
  import java.util.List;
  
  public class MyTest {
      public static void main(String[] args) {
          post();
      }
  
      private static void post() {
          // 創建 HttpClient 客戶端
          CloseableHttpClient httpClient = HttpClients.createDefault();
  
          // 創建 HttpPost 請求
          HttpPost httpPost = new HttpPost("http://localhost:8080/content/page");
          // 設置長連接
          httpPost.setHeader("Connection", "keep-alive");
          // 設置代理（模擬瀏覽器版本）
          httpPost.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36");
          // 設置 Cookie
          httpPost.setHeader("Cookie", "UM_distinctid=16442706a09352-0376059833914f-3c604504-1fa400-16442706a0b345; CNZZDATA1262458286=1603637673-1530123020-%7C1530123020; JSESSIONID=805587506F1594AE02DC45845A7216A4");
  
          // 創建 HttpPost 參數
          List<BasicNameValuePair> params = new ArrayList<BasicNameValuePair>();
          params.add(new BasicNameValuePair("draw", "1"));
          params.add(new BasicNameValuePair("start", "0"));
          params.add(new BasicNameValuePair("length", "10"));
  
          CloseableHttpResponse httpResponse = null;
          try {
              // 設置 HttpPost 參數
              httpPost.setEntity(new UrlEncodedFormEntity(params, "UTF-8"));
              httpResponse = httpClient.execute(httpPost);
              HttpEntity httpEntity = httpResponse.getEntity();
              // 輸出請求結果
              System.out.println(EntityUtils.toString(httpEntity));
          } catch (UnsupportedEncodingException e) {
              e.printStackTrace();
          } catch (ClientProtocolException e) {
              e.printStackTrace();
          } catch (IOException e) {
              e.printStackTrace();
          }
  
          // 無論如何必須關閉連接
          finally {
              try {
                  if (httpResponse != null) {
                      httpResponse.close();
                  }
              } catch (IOException e) {
                  e.printStackTrace();
              }
  
              try {
                  if (httpClient != null) {
                      httpClient.close();
                  }
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
      }
  }