【Java】使用 HttpURLConnection 发送 POST 和 GET 请求

古城微笑少年丶 2022-06-03 01:53 178阅读 0赞

## 实现代码 ##

/** * http 请求工具类 * Created by zhh on 2017/12/08. */
    public class HttpHelper { 
    
        // 每次读取大小
        private final static int READ_BODY_SIZE = 5120;
    
        /** * post 方式请求内容 * @param strUrl url地址 * @param paramMap 参数集 * @return */
        public static String post(String strUrl, Map<String, Object> paramMap) {
            StringBuffer sb = new StringBuffer();
            for (String strKey : paramMap.keySet()) {
                sb.append("&");
                sb.append(strKey);
                sb.append("=");
                sb.append(paramMap.get(strKey));
            }
            sb.replace(0, 1, "?");
            if (sb.length() > 0) {
                return post(strUrl + sb.toString(), "");
            }
            return post(strUrl + sb.toString(), "");
        }
    
        /** * get 方式请求内容 * @param strUrl url地址 * @param paramMap 参数集 * @return */
        public static String get(String strUrl, Map<String, Object> paramMap) {
            StringBuffer sb = new StringBuffer();
            for (String strKey : paramMap.keySet()) {
                sb.append("&");
                sb.append(strKey);
                sb.append("=");
                sb.append(paramMap.get(strKey));
            }
            sb.replace(0, 1, "?");
            if (sb.length() > 0) {
                return get(strUrl + sb.toString());
            }
            return get(strUrl + sb.toString());
        }
    
        /** * post 方式请求内容 * @param strUrl url地址 * @param content 输出内容 * @return */
        public static String post(String strUrl, String content) {
            return post(strUrl, content, 180);
        }
    
        /** * get 方式请求内容 * @param strUrl url地址 * @return */
        public static String get(String strUrl) {
            return get(strUrl, 180);
        }
    
        /** * post 方式请求内容 * @param strUrl url地址 * @param content 输出内容 * @param timeoutSecond 设置延时时间 * @return */
        public static String post(String strUrl, String content, int timeoutSecond) {
            try {
                URL url = new URL(strUrl);
                HttpURLConnection con = (HttpURLConnection) url.openConnection();
                // 连接主机超时 毫秒
                con.setConnectTimeout(timeoutSecond * 1000);
                // 从主机读取数据超时毫秒
                con.setReadTimeout(timeoutSecond * 1000);
                // 设置从HttpURLConnection读入
                con.setDoInput(true);
                // 设置是否向httpUrlConnection输出, 因为这个是post请求, 参数要放在http正文内, 因此需要设为true, 默认情况下是false
                con.setDoOutput(true);
                // 设置该URLConnection的allowUserInteraction请求头字段的值
                con.setAllowUserInteraction(false);
                con.setUseCaches(true);
                con.setRequestMethod("POST");
                con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded;charset=UTF-8");
                // 此处getOutputStream会隐含的进行connect,所以在开发中不调用上述的connect()也可以
                BufferedWriter bout = new BufferedWriter(new OutputStreamWriter(con.getOutputStream()));
                bout.write(content);
                bout.flush();
                bout.close();
                return streamReadHtml(con.getInputStream());
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return null;
        }
    
        /** * get 方式请求内容 * @param strUrl url地址 * @param timeoutSecond 设置延时时间 * @return */
        public static String get(String strUrl, int timeoutSecond) {
            try {
                URL url = new URL(strUrl);
                HttpURLConnection con = (HttpURLConnection) url.openConnection();
                // 连接主机超时 毫秒
                con.setConnectTimeout(timeoutSecond * 1000);
                // 从主机读取数据超时毫秒
                con.setReadTimeout(timeoutSecond * 1000);
                con.setRequestMethod("GET");
                con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded;charset=UTF-8");
                con.connect();
                return streamReadHtml(con.getInputStream());
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return null;
        }
    
        /** * 读取内容 * @param istream * @return * @throws UnsupportedEncodingException */
        public static String streamReadHtml(InputStream istream) throws UnsupportedEncodingException {
            String html = "";
            byte[] responseBody = new byte[READ_BODY_SIZE];
            int npos = 0;
            int nread = 0;
            try {
                while ((nread = istream.read(responseBody, npos, responseBody.length - npos)) >= 0) {
                    npos += nread;
                    byte[] tmpBuf = new byte[npos + READ_BODY_SIZE];
                    System.arraycopy(responseBody, 0, tmpBuf, 0, npos);
                    responseBody = tmpBuf;
                }
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    if (istream != null) {
                        istream.close();
                    }
                    istream = null;
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            html = new String(responseBody, 0, npos, "UTF-8");
            return html;
        }
    
    }

## 代码用例 ##

public static void main(String[] args) {
        String reqUrl = "https://www.baidu.com";
        Map<String, Object> paramMap = new HashMap<>();
        paramMap.put("wd", "测试test");
        System.out.println(HttpHelper.post(reqUrl, paramMap));
    }