import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;

/** * http工具类 * */
public class HttpUtils { 

	/** * 发送http请求,返回BufferedReader流读取响应 * @param url * @return */
	public static BufferedReader doRequest(String url) { 
		
		BufferedReader in = null;
		try { 
			URL requestUrl = new URL(url);
			// 打开和URL之间的连接
            URLConnection connection = requestUrl.openConnection();
            // 设置通用的请求属性
            connection.setRequestProperty("accept", "*/*");
            connection.setRequestProperty("connection", "Keep-Alive");
            connection.setRequestProperty("user-agent",
                    "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            // 建立连接
            connection.connect();
            // 定义 BufferedReader输入流来读取URL的响应
            in = new BufferedReader(new InputStreamReader(
                    connection.getInputStream()));
		} catch (Exception e) { 
			e.printStackTrace();
		}
		return in;
	}
}

调用:

public static void main(String[] arg){ 
		BufferedReader in = HttpUtils.doRequest(tokenUrl);
        try { 
        	String line = null;
			while ((line = in.readLine()) != null) { 
			    JSONObject tokenObj = new JSONObject(line);
			    if (!tokenObj.isNull("access_token")) { 
			    	token = tokenObj.getString("access_token");
			    }
			}
		} catch (Exception e) { 
			e.printStackTrace();
		} finally { 
			try { 
                if (in != null) { 
                    in.close();
                }	
            } catch (Exception e2) { 
                e2.printStackTrace();
            }
		}
	}

本文地址:https://blog.csdn.net/iloki/article/details/113996723