JDK自带的URLConnection

package com.example.demo.util;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;

public class HttpRequest {

    /**
     * 向指定URL发送GET方法的请求
     *
     * @param url 发送请求的URL
     * @return URL 所代表远程资源的响应结果
     */
    public static String sendGet(String url) {
        String result = "";
        BufferedReader in = null;
        try {
            URL httpUrl = new URL(url);
            // 打开和URL之间的连接
            HttpURLConnection connection = (HttpURLConnection) httpUrl.openConnection();
            connection.setRequestMethod("GET");
            connection.setConnectTimeout(5 * 1000);
            // 设置通用的请求属性
            connection.setRequestProperty("accept", "*/*");
            connection.setRequestProperty("connection", "Keep-Alive");
            connection.setRequestProperty("Charsert", "UTF-8"); //设置请求编码
            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();
            if (connection.getResponseCode() == 200) {
                // 定义 BufferedReader输入流来读取URL的响应
                in = new BufferedReader(new InputStreamReader(connection.getInputStream(), "GBK"));
                String line;
                while ((line = in.readLine()) != null) {
                    result += line;
                }
            } else {

            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        // 使用finally块来关闭输入流
        finally {
            try {
                if (in != null) {
                    in.close();
                }
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
        return result;
    }


    /**
     * 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("Charsert", "utf-8"); //设置请求编码
            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(), "utf-8"));
            String line;
            while ((line = in.readLine()) != null) {
                result += line;
            }
        } catch (Exception 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;
    }

/**
 * 参数存入body的post请求
 */
public static String sendPost(String serverURL, String parameters, Map<String, String> headers) throws Exception {
    StringBuffer sbf = new StringBuffer();
    String strRead = null;
    URL url = new URL(serverURL);
    HttpURLConnection connection = null;
    BufferedReader reader = null;
    try {
        connection = (HttpURLConnection) url.openConnection();
        // 请求post方式
        connection.setRequestMethod("POST");
        connection.setDoInput(true);
        connection.setDoOutput(true);
        // header内的的参数在这里
        if (headers != null) {
            for (Map.Entry<String, String> map : headers.entrySet()) {
                connection.setRequestProperty(map.getKey(), map.getValue());
            }
        }
        connection.setRequestProperty("Content-Type", "application/json");
        connection.connect();
        OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream(), "UTF-8");
        writer.write(parameters);
        writer.flush();
        InputStream is = connection.getInputStream();
        reader = new BufferedReader(new InputStreamReader(is, "UTF-8"));
        while ((strRead = reader.readLine()) != null) {
            sbf.append(strRead);
        }
    } finally {
        if (reader != null) {
            reader.close();
        }
        if (connection != null) {
            connection.disconnect();
        }
    }
    String results = sbf.toString();
    return results;
}

    public static void main(String[] args) {
      
    }
}