一个简单的http请求

public  String sendMonitor(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
			HttpURLConnection conn = (HttpURLConnection) realUrl.openConnection();
			// 设置通用的请求属性
			conn.setRequestProperty("accept", "*/*");
			conn.setRequestProperty("Content-Type","application/json");  //设定 请求格式 json，也可以设定xml格式的 
			conn.setRequestProperty("Accept","application/json");//设定响应的信息的格式为 json，也可以设定xml格式的 
			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
			if (conn.getResponseCode() == 200) {
				in = new BufferedReader(
						new InputStreamReader(conn.getInputStream()));
			} else {
				in = new BufferedReader(
						new InputStreamReader(conn.getErrorStream()));
			}
			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;
	}