Java 信任所有SSL证书(解决PKIX path building failed问题)

Java在请求某些不受信任的https网站时会报：PKIX path building failed

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 sun.security.ssl.Alerts.getSSLException(Alerts.java:192)
	at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1884)
	at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:276)
	at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:270)
	at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1341)
	at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:153)
	at sun.security.ssl.Handshaker.processLoop(Handshaker.java:868)
	at sun.security.ssl.Handshaker.process_record(Handshaker.java:804)
	at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1016)
	at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1312)
	at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1339)
	at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1323)
	at sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:563)
	at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:185)
	at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1300)
	at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:254)
	at SslTest.getRequest(SslTest.java:16)
	at SslTest.main(SslTest.java:40)
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:385)
	at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:230)
	at sun.security.validator.Validator.validate(Validator.java:260)
	at sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:326)
	at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:231)
	at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:126)
	at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1323)
	... 13 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:196)
	at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:268)
	at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:380)
	... 19 more

解决办法：

1、导入证书到本地证书库

2、信任所有SSL证书

最好的解决办法或许是信任所有SSL证书，因为某些时候不能每次都手动的导入证书非常麻烦。现在封装了个方法，在连接openConnection的时候忽略掉证书就行了。

SslUtils.ignoreSsl();

import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSession;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;
public class SslUtils {
	private static void trustAllHttpsCertificates() throws Exception {
		TrustManager[] trustAllCerts = new TrustManager[1];
		TrustManager tm = new miTM();
		trustAllCerts[0] = tm;
		SSLContext sc = SSLContext.getInstance("SSL");
		sc.init(null, trustAllCerts, null);
		HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());
	}
	static class miTM implements TrustManager,X509TrustManager {
		public X509Certificate[] getAcceptedIssuers() {
			return null;
		}
		public boolean isServerTrusted(X509Certificate[] certs) {
			return true;
		}
		public boolean isClientTrusted(X509Certificate[] certs) {
			return true;
		}
		public void checkServerTrusted(X509Certificate[] certs, String authType)
				throws CertificateException {
			return;
		}
		public void checkClientTrusted(X509Certificate[] certs, String authType)
				throws CertificateException {
			return;
		}
	}
	/**
	 * 忽略HTTPS请求的SSL证书，必须在openConnection之前调用
	 * @throws Exception
	 */
	public static void ignoreSsl() throws Exception{
		HostnameVerifier hv = new HostnameVerifier() {
			public boolean verify(String urlHostName, SSLSession session) {
				System.out.println("Warning: URL Host: " + urlHostName + " vs. " + session.getPeerHost());
				return true;
			}
		};
		trustAllHttpsCertificates();
		HttpsURLConnection.setDefaultHostnameVerifier(hv);
	}
}

URL u = new URL(url);
		if("https".equalsIgnoreCase(u.getProtocol())){
			SslUtils.ignoreSsl();
		}
		URLConnection conn = u.openConnection();
		conn.setConnectTimeout(timeOut);
		conn.setReadTimeout(timeOut);
		return IOUtils.toString(conn.getInputStream());