在项目中遇到java请求HTTPS，会报异常

javax.net.ssl.SSLHandshakeException: PKIX path building failed: 
sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

 在网上查了一堆资料，（忘记是哪位大佬的博客了）。然后写了一个类

public class httpUtils{


    public static void main(String[] args) {
        Map<String, String> headers = new HashMap<>(16);
        headers.put("Content-Type","application/x-www-form-urlencoded");
        String name = "sw";
        String url = "https://localhost:8080/v2/oauth/token";
        String sw = "grant_type=client_with_su&scope=all&slug="+name;
        JSONObject jsonObject = postFormUrlEncoded(url,sw,headers);
        System.out.println(jsonObject);
        String access_token = jsonObject.getString("access_token");
        System.out.println(access_token);

    }

    public static JSONObject postFormUrlEncoded(String targetUrl, String params,Map<String, String> headers) {
        HttpURLConnection urlConnection = null;
        try {
            URL url = new URL(targetUrl.trim());

            trustAllHttpsCertificates();
            HostnameVerifier hv = new HostnameVerifier() {
                public boolean verify(String urlHostName, SSLSession session) {
                    return true;
                }
            };
            HttpsURLConnection.setDefaultHostnameVerifier(hv);

            urlConnection = (HttpURLConnection) url.openConnection();
            // 设置请求方式
            urlConnection.setRequestMethod("POST");
            // 设置数据类型
            urlConnection.setRequestProperty("accept", "*/*");
            urlConnection.setRequestProperty("connection", "Keep-Alive");
            urlConnection.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            if (headers != null) {
                Set<String> keySet = headers.keySet();
                for (String key : keySet) {
                    urlConnection.setRequestProperty(key, headers.get(key));
                }
            }
            // 设置允许输入输出
            urlConnection.setDoOutput(true);
            urlConnection.setDoInput(true);
            // 设置不用缓存
            urlConnection.setUseCaches(false);

            urlConnection.connect();
            PrintWriter out = new PrintWriter(new OutputStreamWriter(urlConnection.getOutputStream(), StandardCharsets.UTF_8));
            // 写入传递参数,格式为a=b&c=d
            out.print(params);
            out.flush();
            int resultCode = urlConnection.getResponseCode();
            if (HttpURLConnection.HTTP_OK == resultCode) {
                StringBuffer stringBuffer = new StringBuffer();
                String readLine;
                BufferedReader responseReader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream(), StandardCharsets.UTF_8));
                while ((readLine = responseReader.readLine()) != null) {
                    stringBuffer.append(readLine);
                }
                responseReader.close();
                return JSONObject.parseObject(stringBuffer.toString());
            }
            out.close();
        } catch (Exception e) {
            return null;
        } finally {
            if (urlConnection != null) {
                urlConnection.disconnect();
            }
        }
        return null;
    }

    private static void trustAllHttpsCertificates() throws Exception {
        javax.net.ssl.TrustManager[] trustAllCerts = new javax.net.ssl.TrustManager[1];
        javax.net.ssl.TrustManager tm = new miTM();
        trustAllCerts[0] = tm;
        javax.net.ssl.SSLContext sc = javax.net.ssl.SSLContext
                .getInstance("SSL");
        sc.init(null, trustAllCerts, null);
        javax.net.ssl.HttpsURLConnection.setDefaultSSLSocketFactory(sc
                .getSocketFactory());
    }

    static class miTM implements javax.net.ssl.TrustManager,
            javax.net.ssl.X509TrustManager {
        public java.security.cert.X509Certificate[] getAcceptedIssuers() {
            return null;
        }

        public boolean isServerTrusted(
                java.security.cert.X509Certificate[] certs) {
            return true;
        }

        public boolean isClientTrusted(
                java.security.cert.X509Certificate[] certs) {
            return true;
        }

        public void checkServerTrusted(
                java.security.cert.X509Certificate[] certs, String authType)
                throws java.security.cert.CertificateException {
            return;
        }

        public void checkClientTrusted(
                java.security.cert.X509Certificate[] certs, String authType)
                throws java.security.cert.CertificateException {
            return;
        }
    }

调用https之前先调用

    trustAllHttpsCertificates();
    HostnameVerifier hv = new HostnameVerifier() {
        public boolean verify(String urlHostName, SSLSession session) {
            return true;
        }
    };
    HttpsURLConnection.setDefaultHostnameVerifier(hv);