```public class http {
public String httpPost() {
URL url=null;
String result="";
try {
url = new URL("http://192.168.3.2:" +8088
+ "/transportservice/action/GetCarSpeed.do");
//请求连接 openConnection()有两个子类,分别是setDoInput()和setDoOutput()
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setDoInput(true); // 设置容许输入
conn.setDoOutput(true);// 设置容许输出
conn.setConnectTimeout(6000); //设置超时时间
conn.setRequestMethod("POST");//设置请求方式为post
conn.setRequestProperty("Charset", "UTF-8"); //设置请求的编码方式
conn.setUseCaches(false); //设置不使用缓存
//系统自动处理跳转,但是对于有多次跳转的情况,就只能处理第一次
conn.setInstanceFollowRedirects(true);
conn.setRequestProperty("Content-Type", "application/json"); //维持长连接
conn.connect(); //连接
DataOutputStream out = new DataOutputStream(conn.getOutputStream());
//这是请求的参数
JSONObject jsonObj = new JSONObject();
jsonObj.put("UserName", "user1");
//输出流写入请求参数
out.writeBytes(jsonObj.toString());
int responseCode = conn.getResponseCode();//请求的返回状态
if (responseCode == 200) {
// BufferedReader 是 缓冲字符输入流 conn.getInputStream() 输入流数据
BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String lines = reader.readLine(); //读取流
result =lines;
}
out.flush();
out.close();
conn.disconnect();
} catch (Exception e) {
e.printStackTrace();
}
return result;
}
}