解决报错：PKIX：unabletofindvalidcertificationpathtorequestedtarget！

一、简介
该错误主要是请求https网站时，服务端无法验证客户端信息。需要客户端安装证书。
目前博主是在使用Jenkins下载插件时遇到的该问题。
触类旁通，访问其他https网站时遇到该问题，也可使用如下方式解决

二、解决方案
2.1 创建InstallCert.java文件

import java.net.Proxy;
import java.net.Socket;
import java.net.InetSocketAddress;
import javax.net.ssl.*;
import java.io.*;
import java.security.KeyStore;
import java.security.MessageDigest;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
/**
* Class used to add the server's certificate to the KeyStore
* with your trusted certificates.
*/
public class InstallCert {
public static void main(String[] args) throws Exception {
String host = null;
int port = -1;
char[] passphrase = null;
// proxy
boolean useProxy = false;
String proxyHost = null;
int proxyPort = -1;
InetSocketAddress proxyAddr = null;
Socket underlying = null;
int numArg = 0;
int nbArgs = args.length;
boolean invalidArgs = false;
boolean isQuiet = false;
while (numArg < nbArgs) {
String arg = args[numArg++];
if (arg.startsWith("--proxy=")) {
String proxy = arg.substring("--proxy=".length());
useProxy = true;
String[] c = proxy.split(":");
proxyHost = c[0];
proxyPort = Integer.parseInt(c[1]); // proxy port is mandatory (we don't default to 8080)
}
else if (arg.startsWith("--quiet")) {
isQuiet = true;
}
else if (host == null) { // 1st argument is the "host:port"
String[] c = arg.split(":");
host = c[0];
port = (c.length == 1) ? 443 : Integer.parseInt(c[1]);
}
else if (passphrase == null) { // 2nd argument is the keystore passphrase
passphrase = arg.toCharArray();
}
else {
invalidArgs = true; // too many args
}
}
if (host == null) {
invalidArgs = true;
}
if (invalidArgs) {
System.out.println("Usage: java InstallCert [--proxy=proxyHost:proxyPort] host[:port] [passphrase] [--quiet]");
return;
}
// default values
if (port == -1 ) { port = 443; }
if (passphrase == null) { passphrase = "changeit".toCharArray(); }
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();
if (useProxy) {
proxyAddr = new InetSocketAddress(proxyHost, proxyPort);
underlying = new Socket(new Proxy(Proxy.Type.HTTP, proxyAddr));
}
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 + (useProxy ? (" via proxy "+proxyHost+":"+proxyPort) : "") + " ...");
SSLSocket socket;
if (useProxy) {
underlying.connect(new InetSocketAddress(host, port));
socket = (SSLSocket) factory.createSocket(underlying, host, port, true);
} else {
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();
}
int k;
if (isQuiet) {
System.out.println("Adding first certificate to trusted keystore");
k = 0;
}
else {
System.out.println("Enter certificate to add to trusted keystore or 'q' to quit: [1]");
String line = reader.readLine().trim();
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() {
// This change has been done due to the following resolution advised for Java 1.7+
// http://infposs.blogspot.kr/2013/06/installcert-and-java-7.html
return new X509Certificate[0];
//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);
}
}
}


2.2 生成证书文件
在该java文件所在的目录下，打开cmd界面

运行 `javac InstallCert.java`


会生成如下所示两个class文件

然后执行 `java InstallCert.java targetHost`
targetHost 为需要访问的域名地址
例如：博主这里要访问的是清华大学开源镜像网站(https://mirrors.tuna.tsinghua.edu.cn/)
执行 `java InstallCert.java mirrors.tuna.tsinghua.edu.cn`


然后在当前目录下会生成一个 jssecacerts 文件

2.3 复制 jssecacerts 文件
将 jssecacerts 文件复制到 $JAVA_HOME/jre/lib/security 目录下
$JAVA_HOME 为大家JDK安装的目录

然后重启Jenkins即可