解决PKIX path building failed的问题

在一次调试中，出现了这个错误： 

[ERROR] http-8080-Processor25 2010-01-20 15:29:28,640 org.jasig.cas.client.validation.Cas20ServiceTicketValidator     - 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

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(Unknown Source)
at com.sun.net.ssl.internal.ssl.SSLSocketImpl.fatal(Unknown Source)
at com.sun.net.ssl.internal.ssl.Handshaker.fatalSE(Unknown Source)
at com.sun.net.ssl.internal.ssl.Handshaker.fatalSE(Unknown Source)
at com.sun.net.ssl.internal.ssl.ClientHandshaker.serverCertificate(Unknown Source)
at com.sun.net.ssl.internal.ssl.ClientHandshaker.processMessage(Unknown Source)
at com.sun.net.ssl.internal.ssl.Handshaker.processLoop(Unknown Source)
at com.sun.net.ssl.internal.ssl.Handshaker.process_record(Unknown Source)
at com.sun.net.ssl.internal.ssl.SSLSocketImpl.readRecord(Unknown Source)
at com.sun.net.ssl.internal.ssl.SSLSocketImpl.performInitialHandshake(Unknown Source)
at com.sun.net.ssl.internal.ssl.SSLSocketImpl.startHandshake(Unknown Source)
at com.sun.net.ssl.internal.ssl.SSLSocketImpl.startHandshake(Unknown Source)
at sun.net.www.protocol.https.HttpsClient.afterConnect(Unknown Source)
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(Unknown Source)
at org.jasig.cas.client.validation.AbstractCasProtocolUrlBasedTicketValidator.retrieveResponseFromServer(AbstractCasProtocolUrlBasedTicketValidator.java:58)
at org.jasig.cas.client.validation.AbstractUrlBasedTicketValidator.validate(AbstractUrlBasedTicketValidator.java:167)
at org.jasig.cas.client.validation.AbstractTicketValidationFilter.doFilter(AbstractTicketValidationFilter.java:141)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:137)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at org.jasig.cas.client.authentication.AuthenticationFilter.doFilter(AuthenticationFilter.java:149)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at org.jasig.cas.client.session.SingleSignOutFilter.doFilter(SingleSignOutFilter.java:78)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at com.web114.web.filter.UTF8EncoderFilter.doFilter(UTF8EncoderFilter.java:57)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:174)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:874)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
at java.lang.Thread.run(Unknown Source)

这个错误最终定位在这个方法： 

protected final String retrieveResponseFromServer(final
URL validationUrl,
final String ticket) {
HttpURLConnection connection = null;
try {
connection = (HttpURLConnection) validationUrl.openConnection();
final BufferedReader in = new BufferedReader(new InputStreamReader(
connection.getInputStream()));

String line;
final StringBuffer stringBuffer = new StringBuffer(255);

synchronized (stringBuffer) {
while ((line = in.readLine()) != null) {

4000
stringBuffer.append(line);
stringBuffer.append("\n");
}
return stringBuffer.toString();
}

} catch (final IOException e) {
log.error(e, e);
return null;
} catch (final Exception e1){
log.error(e1, e1);
return null;
}finally {
if (connection != null) {
connection.disconnect();
}
}
}

后来上网查了很久，说是证书出问题了，服务器不信任我们自己创建的证书，所以在代码中必须要忽略证书信任问题。只要在创建connection之前调用两个方法： 

trustAllHttpsCertificates();

HttpsURLConnection.setDefaultHostnameVerifier(hv);

具体的实现是： 

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;
}
}