java开发https请求ssl不受信任问题解决方法

本文主要讨论的是java开发https请求ssl不受信任的解决方法，具体分析及实现代码如下。

在java代码中请求https链接的时候，可能会报下面这个错误

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

原因是没有证书。在浏览器中直接使用url访问是可以的，应该是浏览器之前就保存过对应的.cer证书。

解决方法有两种，从目标机器获得有效证书或者忽略证书信任问题。

一、获得目标机器有效证书

1、编译安装证书程序 javac InstallCert.java（代码如下）

/* 
 * 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. 
 */
/** 
 * http://blogs.sun.com/andreas/resource/InstallCert.java 
 * Use: 
 * java InstallCert hostname 
 * Example: 
 *% java InstallCert ecc.fedora.redhat.com 
 */
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;
		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 [: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);
		}
	}
}

2、运行安装证书程序生成证书

java InstallCert my.hoolai.com

例如：java InstalCert smtp.zhangsan.com:465 admin
如果不加参数password和host的端口号，上面的获取证书程序中默认给的端口号是：443，密码是:changeit

3、根据运行提示信息，输入1，回车，在当前目录下生成名为： jssecacerts 的证书

将证书放置到$JAVA_HOME/jre/lib/security目录下， 切记该JDK的jre是工程所用的环境！！！

或者：

System.setProperty("javax.net.ssl.trustStore", "你的jssecacerts证书路径");

可以更改密码，在security目录下运行命令

keytool -storepasswd -new xxxcom -keystore cacerts

就可以修改密码，修改后使用命令

keytool -list -v -keystore cacerts

查看文件的信息，会提示需要密码才能查看，如果输入密码与修改后的密码匹配，说明修改成功了。

PS：至此这种方式可以成功使用ssl了，另外再补充一下，根据刚才生成的文件jssecacerts，可以生成cer文件，

命令如下

keytool -export -alias xxx.com-1 -keystore jssecacerts -rfc -file xxx.cer

如上，之前的工具类中默认命名别名是加上"-1"。使用InstallCert设置的密码需要跟cacerts文件中的密码一致，

如果修改过密码，就需要修改InstallCert类中对应的密码字符串，否则会有下面这个异常：

java.security.UnrecoverableKeyException: Password verification failed

二、忽略证书信任问题

源码：http://mengyang.iteye.com/blog/575671

一定要注意需要在connection创建之前调用文章里所述的方法，像这个样子：

trustAllHttpsCertificates();
HostnameVerifier hv = new HostnameVerifier() { 
    public boolean verify(String urlHostName, SSLSession session) { 
      return true; 
    } 
  };
HttpsURLConnection.setDefaultHostnameVerifier(hv);
connection = (HttpURLConnection) url.openConnection();

好吧，两种方法都试过有效。

总结

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