这两天在twitter服务器上突然遇到这样的异常：html
e: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
java
通过检查确认，完整的异常信息应该以下：web
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
安全
后来到twitter开发者网站上去看到了也有人遇到了相似的问题，连接以下：https://dev.twitter.com/discussions/533服务器
可是都没说明具体的解决方法，郁闷啊！！oracle
在oracle某一博客上说是能够这样解决的：http://blogs.oracle.com/gc/entry/unable_to_find_valid_certificationapp
可是悲催的是那个java类已经没法下载了。。。。历经N次的google，终于找到该文件了，不敢独享，记录于此。socket
问题的根本是：ide
缺乏安全证书时出现的异常。
oop
解决问题方法：
将你要访问的webservice/url....的安全认证证书导入到客户端便可。
如下是获取安全证书的一种方法，经过如下程序获取安全证书：
/*
* 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 java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
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;
public class InstallCert {
public static void main(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);
}
}
}
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$SavingTrustManager.checkServerTrusted(InstallCert.java:158) at com.sun.net.ssl.internal.ssl.JsseX509TrustManager.checkServerTrusted(SSLContextImpl.java:320) at com.sun.net.ssl.internal.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:839) ... 7 more Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:236) at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:194) at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:216) ... 13 more Server sent 2 certificate(s): 1 Subject CN=www.twitter.com, O=example.com, C=US Issuer CN=Certificate Shack, O=example.com, C=US sha1 2e 7f 76 9b 52 91 09 2e 5d 8f 6b 61 39 2d 5e 06 e4 d8 e9 c7 md5 dd d1 a8 03 d7 6c 4b 11 a7 3d 74 28 89 d0 67 54 2 Subject CN=Certificate Shack, O=example.com, C=US Issuer CN=Certificate Shack, O=example.com, C=US sha1 fb 58 a7 03 c4 4e 3b 0e e3 2c 40 2f 87 64 13 4d df e1 a1 a6 md5 72 a0 95 43 7e 41 88 18 ae 2f 6d 98 01 2c 89 68 Enter certificate to add to trusted keystore or 'q' to quit: [1]
将证书拷贝到$JAVA_HOME/jre/lib/security目录下，或者经过如下方式：
System.setProperty("javax.net.ssl.trustStore", "你的jssecacerts证书路径");
注意：由于是静态加载，因此要从新启动你的Web Server，证书才能生效。