1.HttpURLConnection发送url请求
public class JavaRequest {private static final String BASE_URL = "http://localhost:8080/dsdemo/";public static String userToken = null;public static String problemName = null;public static String sendPost(String sufUrl, JSONObject params) {DataOutputStream out = null;BufferedReader in = null;String result = "";try {URL realUrl = new URL(BASE_URL+sufUrl);// 打开和URL之间的连接HttpURLConnection connection = (HttpURLConnection) realUrl.openConnection();connection.setDoOutput(true); connection.setDoInput(true); connection.setUseCaches(false); connection.setInstanceFollowRedirects(true); connection.setRequestMethod("POST"); // 设置请求方式 connection.setRequestProperty("Connection", "Keep-Alive");connection.connect();out = new DataOutputStream (connection.getOutputStream());// 发送请求参数，防止中文乱码out.write(jsonToUrlParams(params).getBytes("UTF-8"));// 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(connection.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.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();}}System.out.println(result);return result;} private static String jsonToUrlParams(JSONObject params){StringBuilder sb = new StringBuilder();sb.append("userToken=").append(userToken);for(Iterator<?> it = params.keys(); it.hasNext(); ){String key = (String) it.next();sb.append("&").append(key).append("=").append(params.get(key));}return sb.toString();} }
遗留问题：
a.按照网上说的发送 json格式的字符串，但是后台无法接收到。所以这里将jsonObject转化成 url 参数的形式。
b.jquery发送json格式的数据是可以接收到的。
<script type="text/javascript">var sendData = {username: "hjz",password: "123"};(function (){$.ajax({ type:'post', url:'http://localhost:8080/dsdemo/userRegister', data: sendData, dataType:'json', success:function(data){ alert(JSON.stringify(data));} ,error: function(data){alert(JSON.stringify(data));}}); })(); </script>
另外可能会出现中文乱码的问题：
a. 首先发送数据利用DataOutputStream out.write(jsonToUrlParams(params).getBytes("UTF-8"));
b. 接收后台 response.setCharacterEncoding("utf-8");
request.setCharacterEncoding("utf-8");
