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 <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);
		}
	}
}

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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