一.错误原因
Java在访问SSL加密的网站时，需要从JDK的KeyStore 里面去查找相对应得可信证书，如果不能从默认或者指定的KeyStore 中找到可信证书，就会报这个错误。另外，Java所使用的证书仓库并不是Windows系统自带的证书管理。所以即使系统中包含此证书也不可以使用。
二.解决方案
只要将SSL的证书添加到KeyStore中即可，以下是两种解决方案。
1.Keytool工具导入证书
下载你所访问的SSL站点的证书, 执行以下命令导入（进入到JAVA JDK下的jrelibsecurity目录，打开命令行cmd）
keytool -import -file /data/test1.cer -keystore cacerts -alias server
接下来 会提示输入密码，默认密码为 changeit，输入之后，选择“是”将其安装到JDK 可信证书库中。如果看到以下结果，则导入成功。
2.执行java代码导入证书
/* * Copyright 2006 Sun Microsystems, Inc. All Rights Reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * - Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * - Neither the name of Sun Microsystems nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ import org.junit.Test; import java.io.*; import java.security.KeyStore; import java.security.MessageDigest; import java.security.cert.CertificateException; import java.security.cert.X509Certificate; import javax.net.ssl.SSLContext; import javax.net.ssl.SSLException; import javax.net.ssl.SSLSocket; import javax.net.ssl.SSLSocketFactory; import javax.net.ssl.TrustManager; import javax.net.ssl.TrustManagerFactory; import javax.net.ssl.X509TrustManager; /** * @description: 生成https服务端可信任证书，将证书加入到客户端jdk中 * @project: edsp-drs-parent * @version: 1.0 * @author: liyuan * @create: 2020-09-14 16:07 **/ public class InstallCert { @Test public void test() throws Exception { String arg = "www.baidu.com"; String[] args = arg.split(";"); use(args); } public static void main(String[] args) throws Exception { use(args); } public static void use(String[] args) throws Exception { String host; int port; char[] passphrase; if ((args.length == 1) || (args.length == 2)) { String[] c = args[0].split(":"); host = c[0]; port = (c.length == 1) ? 443 : Integer.parseInt(c[1]); String p = (args.length == 1) ? "changeit" : args[1]; passphrase = p.toCharArray(); } else { System.out.println("Usage: java InstallCert <host>[:port] [passphrase]"); return; } File file = new File("jssecacerts"); if (file.isFile() == false) { char SEP = File.separatorChar; File dir = new File(System.getProperty("java.home") + SEP + "lib" + SEP + "security"); file = new File(dir, "jssecacerts"); if (file.isFile() == false) { file = new File(dir, "cacerts"); } } System.out.println("Loading KeyStore " + file + "..."); InputStream in = new FileInputStream(file); KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType()); ks.load(in, passphrase); in.close(); SSLContext context = SSLContext.getInstance("TLS"); TrustManagerFactory tmf = TrustManagerFactory .getInstance(TrustManagerFactory.getDefaultAlgorithm()); tmf.init(ks); X509TrustManager defaultTrustManager = (X509TrustManager) tmf .getTrustManagers()[0]; SavingTrustManager tm = new SavingTrustManager(defaultTrustManager); context.init(null, new TrustManager[] { tm }, null); SSLSocketFactory factory = context.getSocketFactory(); System.out .println("Opening connection to " + host + ":" + port + "..."); SSLSocket socket = (SSLSocket) factory.createSocket(host, port); socket.setSoTimeout(10000); try { System.out.println("Starting SSL handshake..."); socket.startHandshake(); socket.close(); System.out.println(); System.out.println("No errors, certificate is already trusted"); } catch (SSLException e) { System.out.println(); e.printStackTrace(System.out); } X509Certificate[] chain = tm.chain; if (chain == null) { System.out.println("Could not obtain server certificate chain"); return; } BufferedReader reader = new BufferedReader(new InputStreamReader( System.in)); System.out.println(); System.out.println("Server sent " + chain.length + " certificate(s):"); System.out.println(); MessageDigest sha1 = MessageDigest.getInstance("SHA1"); MessageDigest md5 = MessageDigest.getInstance("MD5"); for (int i = 0; i < chain.length; i++) { X509Certificate cert = chain[i]; System.out.println(" " + (i + 1) + " Subject " + cert.getSubjectDN()); System.out.println(" Issuer " + cert.getIssuerDN()); sha1.update(cert.getEncoded()); System.out.println(" sha1 " + toHexString(sha1.digest())); md5.update(cert.getEncoded()); System.out.println(" md5 " + toHexString(md5.digest())); System.out.println(); } System.out .println("Enter certificate to add to trusted keystore or 'q' to quit: [1]"); String line = reader.readLine().trim(); int k; try { k = (line.length() == 0) ? 0 : Integer.parseInt(line) - 1; } catch (NumberFormatException e) { System.out.println("KeyStore not changed"); return; } X509Certificate cert = chain[k]; String alias = host + "-" + (k + 1); ks.setCertificateEntry(alias, cert); OutputStream out = new FileOutputStream("jssecacerts"); ks.store(out, passphrase); out.close(); System.out.println(); System.out.println(cert); System.out.println(); System.out .println("Added certificate to keystore 'jssecacerts' using alias '" + alias + "'"); } private static final char[] HEXDIGITS = "0123456789abcdef".toCharArray(); private static String toHexString(byte[] bytes) { StringBuilder sb = new StringBuilder(bytes.length * 3); for (int b : bytes) { b &= 0xff; sb.append(HEXDIGITS[b >> 4]); sb.append(HEXDIGITS[b & 15]); sb.append(' '); } return sb.toString(); } private static class SavingTrustManager implements X509TrustManager { private final X509TrustManager tm; private X509Certificate[] chain; SavingTrustManager(X509TrustManager tm) { this.tm = tm; } public X509Certificate[] getAcceptedIssuers() { throw new UnsupportedOperationException(); } public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException { throw new UnsupportedOperationException(); } public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException { this.chain = chain; tm.checkServerTrusted(chain, authType); } } }
执行test()，生成如下记录
java InstallCert www.twitter.com Loading KeyStore /usr/java/jdk1.6.0_16/jre/lib/security/cacerts... Opening connection to www.twitter.com:443... Starting SSL handshake... javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target at com.sun.net.ssl.internal.ssl.Alerts.getSSLException(Alerts.java:150) at com.sun.net.ssl.internal.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1476) at com.sun.net.ssl.internal.ssl.Handshaker.fatalSE(Handshaker.java:174) at com.sun.net.ssl.internal.ssl.Handshaker.fatalSE(Handshaker.java:168) at com.sun.net.ssl.internal.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:846) at com.sun.net.ssl.internal.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:106) at com.sun.net.ssl.internal.ssl.Handshaker.processLoop(Handshaker.java:495) at com.sun.net.ssl.internal.ssl.Handshaker.process_record(Handshaker.java:433) at com.sun.net.ssl.internal.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:815) at com.sun.net.ssl.internal.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1025) at com.sun.net.ssl.internal.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1038) at InstallCert.main(InstallCert.java:63) Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:221) at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:145) at sun.security.validator.Validator.validate(Validator.java:203) at com.sun.net.ssl.internal.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:172) at InstallCert$SavingTrustManager.checkServerTrusted(InstallCert.java:158) at com.sun.net.ssl.internal.ssl.JsseX509TrustManager.checkServerTrusted(SSLContextImpl.java:320) at com.sun.net.ssl.internal.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:839) ... 7 more Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:236) at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:194) at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:216) ... 13 more Server sent 2 certificate(s): 1 Subject CN=www.twitter.com, O=example.com, C=US Issuer CN=Certificate Shack, O=example.com, C=US sha1 2e 7f 76 9b 52 91 09 2e 5d 8f 6b 61 39 2d 5e 06 e4 d8 e9 c7 md5 dd d1 a8 03 d7 6c 4b 11 a7 3d 74 28 89 d0 67 54 2 Subject CN=Certificate Shack, O=example.com, C=US Issuer CN=Certificate Shack, O=example.com, C=US sha1 fb 58 a7 03 c4 4e 3b 0e e3 2c 40 2f 87 64 13 4d df e1 a1 a6 md5 72 a0 95 43 7e 41 88 18 ae 2f 6d 98 01 2c 89 68 Enter certificate to add to trusted keystore or 'q' to quit: [1]
输入1回车，然后会在当前的目录下产生一个名为"ssecacerts"的证书。将证书拷贝到JAVA_HOME/jre/lib/security目录下，或者通过以下方式：
System.setProperty("javax.net.ssl.trustStore", "你的jssecacerts证书路径");
注意：因为是静态加载，所以要重新启动你的Web Server，证书才能生效。
原文链接：https://blog.csdn.net/faye0412/article/details/6883879