生产环境业务流程走不通，查了es后以为请求其他服务器资源有错，错误如下：
[http-nio-9097-exec-1] sun.security.validator.ValidatorException: PKIX path building fai
led: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderExceptio
n: unable to find valid certification path to requested target
at sun.security.ssl.Alerts.getSSLException(Alerts.java:192) ~[?:1.8.0_201]
at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1946) ~[?:1.8.0_201]
at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:316) ~[?:1.8.0_201]
at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:310) ~[?:1.8.0_201]
at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1639) ~[?:1.8.0_201]
at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:223) ~[?:1.8.0_201]
at sun.security.ssl.Handshaker.processLoop(Handshaker.java:1037) ~[?:1.8.0_201]
at sun.security.ssl.Handshaker.process_record(Handshaker.java:965) ~[?:1.8.0_201]
at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1064) ~[?:1.8.0_201]
at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1367) ~[?:1.8.0_201]
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1395) ~[?:1.8.0_201]
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1379) ~[?:1.8.0_201]
at sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:559) ~[?:1.8.0_201]
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:185) ~[?:1.8.0_201]
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1564) ~[?:1.8.0_201]
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1492) ~[?:1.8.0_201]
at com.sun.net.ssl.internal.www.protocol.https.HttpsURLConnectionOldImpl.getInputStream(HttpsURLConnectionOldImpl.java:233) ~[?:1.8.0_201]
at org.apache.commons.io.FileUtils.copyURLToFile(FileUtils.java:1506) ~[commons-io-2.5.jar!/:2.5]
at com.cngongbao.basic.platform.util.FileUtil.copyURLToFile(FileUtil.java:139) ~[common-2.3-SNAPSHOT.jar!/:2.3-SNAPSHOT]
本以为请求其他服务器有证书错误，但是后面看日志发现copyURLToFile是自己服务器的资源，本质是java在访问https资源时的证书信任问题。Windos浏览器访问https资源，发现证书不可信任，一般会弹框告诉用户，对方的证书不可信任，是否继续或者无法进入之类这个大家经常遇到。
Java虚拟机并不直接使用操作系统的keyring，而是有自己的security manager。与操作系统类似，jdk的security manager默认有一堆的根证书信任。如果用java访问https资源，发现证书不可信任，就会有上述报错。网上查询后发现目前的两种解决办法。一种是对服务器添加证书导入到jdk的证书路径。两一种是代码加入忽略https信任代码块。
第一种的实现方案
编译：javac InstallCert.java
运行：java InstallCert 要访问的网址
最后面会输出：
Enter certificate to add to trusted keystore or 'q' to quit: [1]
输入1，然后直接回车，会在相应的目录下产生一个名为‘jssecacerts’的证书。将证书copy到$JAVA_HOME/jre/lib/security目录下
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);
}
}
}
第二种实现方案
HostnameVerifier hv = new HostnameVerifier() {
public boolean verify(String urlHostName, SSLSession session) {
System.out.println("Warning: URL Host: " + urlHostName + " vs. "
+ session.getPeerHost());
return true;
}
};
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;
}
}
在访问https资源前，调用trustAllHttpsCertificates();
欢迎有其他方案或问题留言交流
参考文档：
http://blog.csdn.net/mingli198611/article/details/8055261《HTTP和HTTPS详解》
http://www.cnblogs.com/wupher/archive/2012/08/05/2623561.html《使用Keytool为JDK添加https证书信任》
http://mengyang.iteye.com/blog/575671《解决PKIX path building failed的问题》
java在访问https资源时，忽略证书信任问题_lizeyang的博客-CSDN博客_java忽略证书《java在访问https资源时，忽略证书信任问题》
Java 和 HTTP 的那些事（四） HTTPS 和 证书相关_somnus_小凯的博客-CSDN博客《Java 和 HTTP 的那些事（四） HTTPS 和 证书相关》
