背景
java程序中有时需要我们发起http级别的请求，例如抓数据或者第三方对接时，一般分为两种：一种是只需我们发起请求，还有一种是我们不但要发起请求，还要拿到请求后的数据来进行下一步处理
实现
针对以上两种情况我们来给出简单的实现,对于在技术实现上一般分为两类：通过HttpClient方式和通过流的形式：
- 只发送get请求
- 通过httpclient方式
public static String httpGet(String url, String charset) throws HttpException, IOException { String json = null; HttpGet httpGet = new HttpGet(); // 设置参数 try { httpGet.setURI(new URI(url)); } catch (URISyntaxException e) { throw new HttpException("请求url格式错误。"+e.getMessage()); } // 发送请求 HttpResponse httpResponse = client.execute(httpGet); // 获取返回的数据 HttpEntity entity = httpResponse.getEntity(); byte[] body = EntityUtils.toByteArray(entity); StatusLine sL = httpResponse.getStatusLine(); int statusCode = sL.getStatusCode(); if (statusCode == 200) { json = new String(body, charset); entity.consumeContent(); } else { throw new HttpException("statusCode="+statusCode); } return json; }
- 通过流的方式
/** * 发送http get请求 * * @param getUrl * @return */ public String sendGetRequest(String getUrl) { StringBuffer sb = new StringBuffer(); InputStreamReader isr = null; BufferedReader br = null; try { URL url = new URL(getUrl); URLConnection urlConnection = url.openConnection(); urlConnection.setAllowUserInteraction(false); isr = new InputStreamReader(url.openStream()); br = new BufferedReader(isr); String line; while ((line = br.readLine()) != null) { sb.append(line); } } catch (IOException e) { e.printStackTrace(); } finally { fileOperator.closeResources(isr, br); } return sb.toString(); } }
- 只发送get请求获取请求结果
public static String httpGetRequest(String url, String param) { StringBuffer result = null; BufferedReader in = null; try { String urlNameString = url + "?" + param; System.out.println("请求url：" + urlNameString); URL realUrl = new URL(urlNameString); // 打开和URL之间的连接 URLConnection connection = realUrl.openConnection(); // 设置通用的请求属性 connection.setRequestProperty("accept", "application/json;charset=UTF-8"); connection.setRequestProperty("connection", "Keep-Alive"); connection.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)"); // 建立实际的连接 connection.connect(); // 获取所有响应头字段 Map<String, List<String>> map = connection.getHeaderFields(); // 遍历所有的响应头字段 for (String key : map.keySet()) { System.out.println(key + "--->" + map.get(key)); } // 定义 BufferedReader输入流来读取URL的响应 in = new BufferedReader(new InputStreamReader(connection.getInputStream())); String line; result = new StringBuffer(); while ((line = in.readLine()) != null) { result.append(line); } } catch (Exception e) { logger.info("发送GET请求出现异常！" + e); } finally { //释放资源 try { if (in != null) { in.close(); } } catch (Exception e) { logger.info("========get请求资源释放失败========"); } } return result.toString(); }
- 只发送post请求
public static JSONObject post(String url,JSONObject jsonObject){ HttpClient client = new DefaultHttpClient(); HttpPost post = new HttpPost(url); JSONObject response = null; try { StringEntity s = new StringEntity(jsonObject.toString(),"UTF-8"); s.setContentType("application/json"); post.setEntity(s); HttpResponse res = client.execute(post); if(res.getStatusLine().getStatusCode() == HttpStatus.SC_OK){ HttpEntity entity = res.getEntity(); String charset = EntityUtils.getContentCharSet(entity); response = new JSONObject(new JSONTokener(new InputStreamReader(entity.getContent(),charset))); } } catch (Exception e) { throw new RuntimeException(e); } return response; } //main方法测试 import org.json.JSONObject; import org.json.JSONTokener; public static void main(String[] rags) throws Exception{ String url="http://58.132.200.41:8280/teacher/discussion/add.json?token=58e86364c2654798a25038ae22e4e4f3"; String queryString="{"subjectId": 1,"title": "测试讨论1","sharedRange": 1,"type": 1,"same": false,"specialId": 0,"editPhone": false,"contents": ["测试讨论内容"]}"; //String content=httpPostWithJSON(url, queryString,"utf-8"); JSONObject json=post(url,new JSONObject(queryString)); System.out.println(json); }
- 发送post请求获取响应结果
/** * 向指定 URL 发送POST方法的请求 * * @param url * 发送请求的 URL * @param param * 请求参数，请求参数应该是 name1=value1&name2=value2 的形式。 * @return 所代表远程资源的响应结果 */ public static String sendPost(String url, String param) { PrintWriter out = null; BufferedReader in = null; String result = ""; try { URL realUrl = new URL(url); // 打开和URL之间的连接 URLConnection conn = realUrl.openConnection(); // 设置通用的请求属性 conn.setRequestProperty("accept", "*/*"); conn.setRequestProperty("connection", "Keep-Alive"); conn.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)"); // 发送POST请求必须设置如下两行 conn.setDoOutput(true); conn.setDoInput(true); // 获取URLConnection对象对应的输出流 out = new PrintWriter(conn.getOutputStream()); // 发送请求参数 out.print(param); // flush输出流的缓冲 out.flush(); // 定义BufferedReader输入流来读取URL的响应 in = new BufferedReader( new InputStreamReader(conn.getInputStream())); String line; while ((line = in.readLine()) != null) { result += line; } } catch (Exception e) { System.out.println("发送 POST 请求出现异常！"+e); e.printStackTrace(); } //使用finally块来关闭输出流、输入流 finally{ try{ if(out!=null){ out.close(); } if(in!=null){ in.close(); } } catch(IOException ex){ ex.printStackTrace(); } } return result; } }