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一、使用方法

使用HttpClient发送请求、接收响应很简单，一般需要如下几步即可。

1. 创建HttpClient对象。

2. 创建请求方法的实例，并指定请求URL。如果需要发送GET请求，创建HttpGet对象；如果需要发送POST请求，创建HttpPost对象。

3. 如果需要发送请求参数，可调用HttpGet、HttpPost共同的setParams(HetpParams params)方法来添加请求参数；对于HttpPost对象而言，也可调用setEntity(HttpEntity entity)方法来设置请求参数。

4. 调用HttpClient对象的execute(HttpUriRequest request)发送请求，该方法返回一个HttpResponse。

5. 调用HttpResponse的getAllHeaders()、getHeaders(String name)等方法可获取服务器的响应头；调用HttpResponse的getEntity()方法可获取HttpEntity对象，该对象包装了服务器的响应内容。程序可通过该对象获取服务器的响应内容。

6. 释放连接。无论执行方法是否成功，都必须释放连接

二、实例

1 import java.io.IOException;  2 import java.net.URI;  3 import java.util.ArrayList;  4 import java.util.List;  5 import java.util.Map;  6   7 import org.apache.http.NameValuePair;  8 import org.apache.http.client.entity.UrlEncodedFormEntity;  9 import org.apache.http.client.methods.CloseableHttpResponse; 10 import org.apache.http.client.methods.HttpGet; 11 import org.apache.http.client.methods.HttpPost; 12 import org.apache.http.client.utils.URIBuilder; 13 import org.apache.http.entity.ContentType; 14 import org.apache.http.entity.StringEntity; 15 import org.apache.http.impl.client.CloseableHttpClient; 16 import org.apache.http.impl.client.HttpClients; 17 import org.apache.http.message.BasicNameValuePair; 18 import org.apache.http.util.EntityUtils; 19  20  21 　　public static String doGet(String url, Map
     
       param) { 22  23         // 创建Httpclient对象 24         CloseableHttpClient httpclient = HttpClients.createDefault(); 25  26         String resultString = ""; 27         CloseableHttpResponse response = null; 28         try { 29             // 创建uri 30             URIBuilder builder = new URIBuilder(url); 31             if (param != null) { 32                 for (String key : param.keySet()) { 33                     builder.addParameter(key, param.get(key)); 34                 } 35             } 36             URI uri = builder.build(); 37  38             // 创建http GET请求 39             HttpGet httpGet = new HttpGet(uri); 40  41             // 执行请求 42             response = httpclient.execute(httpGet); 43             // 判断返回状态是否为200 44             if (response.getStatusLine().getStatusCode() == 200) { 45                 resultString = EntityUtils.toString(response.getEntity(), "UTF-8"); 46             } 47         } catch (Exception e) { 48             e.printStackTrace(); 49         } finally { 50             try { 51                 if (response != null) { 52                     response.close(); 53                 } 54                 httpclient.close(); 55             } catch (IOException e) { 56                 e.printStackTrace(); 57             } 58         } 59         return resultString; 60     } 61  62     public static String doGet(String url) { 63         return doGet(url, null); 64     } 65  66     public static String doPost(String url, Map
      
        param) { 67         // 创建Httpclient对象 68         CloseableHttpClient httpClient = HttpClients.createDefault(); 69         CloseableHttpResponse response = null; 70         String resultString = ""; 71         try { 72             // 创建Http Post请求 73             HttpPost httpPost = new HttpPost(url); 74             // 创建参数列表 75             if (param != null) { 76                 List
       
         paramList = new ArrayList<>(); 77                 for (String key : param.keySet()) { 78                     paramList.add(new BasicNameValuePair(key, param.get(key))); 79                 } 80                 // 模拟表单 81                 UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList); 82                 httpPost.setEntity(entity); 83             } 84             // 执行http请求 85             response = httpClient.execute(httpPost); 86             resultString = EntityUtils.toString(response.getEntity(), "utf-8"); 87         } catch (Exception e) { 88             e.printStackTrace(); 89         } finally { 90             try { 91                 response.close(); 92             } catch (IOException e) { 93                 // TODO Auto-generated catch block 94                 e.printStackTrace(); 95             } 96         } 97  98         return resultString; 99     }100 101     public static String doPost(String url) {102         return doPost(url, null);103     }104     105     public static String doPostJson(String url, String json) {106         // 创建Httpclient对象107         CloseableHttpClient httpClient = HttpClients.createDefault();108         CloseableHttpResponse response = null;109         String resultString = "";110         try {111             // 创建Http Post请求112             HttpPost httpPost = new HttpPost(url);113             // 创建请求内容114             StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);115             httpPost.setEntity(entity);116             // 执行http请求117             response = httpClient.execute(httpPost);118             resultString = EntityUtils.toString(response.getEntity(), "utf-8");119         } catch (Exception e) {120             e.printStackTrace();121         } finally {122             try {123                 response.close();124             } catch (IOException e) {125                 // TODO Auto-generated catch block126                 e.printStackTrace();127             }128         }129 130         return resultString;131     }
       
      
     

 3、用到的一些jar包

 https://pan.baidu.com/s/1kNZWQoZNyYEudL7DbotT0A　　　　k4yt