使用httpClient发送get\post请求

maven依赖

 <dependency>
       <groupId>org.apache.httpcomponents</groupId>
       <artifactId>httpclient</artifactId>
       <version>4.5.2</version>
     </dependency>

GET请求：

1、参数直接拼接到URL后面，即http://test.com?a=1&b=2的形式

 /**
      * get请求，参数拼接在地址上
      * @param url 请求地址加参数
      * @return 响应
      */
     public String get(String url)
     {
         String result = null;
         CloseableHttpClient httpClient = HttpClients.createDefault();
         HttpGet get = new HttpGet(url);
         CloseableHttpResponse response = null;
         try {
             response = httpClient.execute(get);
             if(response != null && response.getStatusLine().getStatusCode() == 200)
             {
                 HttpEntity entity = response.getEntity();
                 result = entityToString(entity);
             }
             return result;
         } catch (IOException e) {
             e.printStackTrace();
         }finally {
             try {
                 httpClient.close();
                 if(response != null)
                 {
                     response.close();
                 }
             } catch (IOException e) {
                 e.printStackTrace();
             }
         }
         return null;
     }

2、参数放置到一个map中

 /**
      * get请求，参数放在map里
      * @param url 请求地址
      * @param map 参数map
      * @return 响应
      */
     public String getMap(String url,Map<String,String> map)
     {
         String result = null;
         CloseableHttpClient httpClient = HttpClients.createDefault();
         List<NameValuePair> pairs = new ArrayList<NameValuePair>();
         for(Map.Entry<String,String> entry : map.entrySet())
         {
             pairs.add(new BasicNameValuePair(entry.getKey(),entry.getValue()));
         }
         CloseableHttpResponse response = null;
         try {
             URIBuilder builder = new URIBuilder(url);
             builder.setParameters(pairs);
             HttpGet get = new HttpGet(builder.build());
             response = httpClient.execute(get);
             if(response != null && response.getStatusLine().getStatusCode() == 200)
             {
                 HttpEntity entity = response.getEntity();
                 result = entityToString(entity);
             }
             return result;
         } catch (URISyntaxException e) {
             e.printStackTrace();
         } catch (ClientProtocolException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         }finally {
             try {
                 httpClient.close();
                 if(response != null)
                 {
                     response.close();
                 }
             } catch (IOException e) {
                 e.printStackTrace();
             }
         }

         return null;
     }

POST请求：

1、参数放到map中

 /**
      * 发送post请求，参数用map接收
      * @param url 地址
      * @param map 参数
      * @return 返回值
      */
     public String postMap(String url,Map<String,String> map) {
         String result = null;
         CloseableHttpClient httpClient = HttpClients.createDefault();
         HttpPost post = new HttpPost(url);
         List<NameValuePair> pairs = new ArrayList<NameValuePair>();
         for(Map.Entry<String,String> entry : map.entrySet())
         {
             pairs.add(new BasicNameValuePair(entry.getKey(),entry.getValue()));
         }
         CloseableHttpResponse response = null;
         try {
             post.setEntity(new UrlEncodedFormEntity(pairs,"UTF-8"));
             response = httpClient.execute(post);
             if(response != null && response.getStatusLine().getStatusCode() == 200)
             {
                 HttpEntity entity = response.getEntity();
                 result = entityToString(entity);
             }
             return result;
         } catch (UnsupportedEncodingException e) {
             e.printStackTrace();
         } catch (ClientProtocolException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         }finally {
             try {
                 httpClient.close();
                 if(response != null)
                 {
                     response.close();
                 }
             } catch (IOException e) {
                 e.printStackTrace();
             }

         }
         return null;
     }

2、参数是json字符串

 /**
      * post请求，参数为json字符串
      * @param url 请求地址
      * @param jsonString json字符串
      * @return 响应
      */
     public String postJson(String url,String jsonString)
     {
         String result = null;
         CloseableHttpClient httpClient = HttpClients.createDefault();
         HttpPost post = new HttpPost(url);
         CloseableHttpResponse response = null;
         try {
             post.setEntity(new ByteArrayEntity(jsonString.getBytes("UTF-8")));
             response = httpClient.execute(post);
             if(response != null && response.getStatusLine().getStatusCode() == 200)
             {
                 HttpEntity entity = response.getEntity();
                 result = entityToString(entity);
             }
             return result;
         } catch (UnsupportedEncodingException e) {
             e.printStackTrace();
         } catch (ClientProtocolException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         }finally {
             try {
                 httpClient.close();
                 if(response != null)
                 {
                     response.close();
                 }
             } catch (IOException e) {
                 e.printStackTrace();
             }
         }
         return null;
     }

entityToString方法：

 private String entityToString(HttpEntity entity) throws IOException {
         String result = null;
         if(entity != null)
         {
             long lenth = entity.getContentLength();
             if(lenth != -1 && lenth < 2048)
             {
                 result = EntityUtils.toString(entity,"UTF-8");
             }else {
                 InputStreamReader reader1 = new InputStreamReader(entity.getContent(), "UTF-8");
                 CharArrayBuffer buffer = new CharArrayBuffer(2048);
                 char[] tmp = new char[1024];
                 int l;
                 while((l = reader1.read(tmp)) != -1) {
                     buffer.append(tmp, 0, l);
                 }
                 result = buffer.toString();
             }
         }
         return result;
     }