如何解决java调dll报Unable to load library的错误

Posted 2023-03-29

1、必须确保设定的路径下有需要加载的dll文件；
2、jar是64位，则dll文件必须也是64位，如果jar是32位，则dll文件必须也是32位；
3、PlayCtrl INSTANCE = (PlayCtrl) Native.loadLibrary("soft\\hikvision\\PlayCtrl", PlayCtrl.class);
其中"soft\\hikvision\\PlayCtrl"可以是绝对路径，也可以是相对路径，但是，路径分隔符必须是\，不能是/，（这里使用\\是因为第一个\是转义字符）（别问我为什么，我也不知道，我就是这样改了之后就可以了）
4、在Tomcat中调用时，可将dll文件放在src目录下，编译后会自动存放到WebRoot\WEB-INF\classes\路径下，在调用时可使用如下方法：
String path = HCNetSDK.class.getResource("/").getPath()+"HCNetSDK.dll";
// 如何tomcat路径中有空格，加上这句path=path.replaceAll("%20", " ");
// 上述方法获取的path最前边第一个字符是/,如【/d:/RTSMS_x64/Servent/HCNetSDKCom/HCNetSDK.dll】
所以我用了以下方法
String path = (HCNetSDK.class.getResource("/").getPath()+"HCNetSDK.dll").replaceAll("%20", " ").substring(1).replace("/", "\\");
HCNetSDK INSTANCE = (HCNetSDK) Native.loadLibrary(path,HCNetSDK.class); 参考技术A DLL 文件不在搜索路径中

~~~~~~~~~~~~~~~~ 参考技术B 不能倒包库

Java调用https服务报错unable to find valid certification path to requested target的解决方法

我们网站要进行https改造，配置上购买的SSL证书后，浏览器访问正常，但是写了个java代码用httpcomponents调用https rest接口时报错：

Exception in thread "main" 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:1904)

at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:279)

at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:273)

at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1446)

at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:209)

at sun.security.ssl.Handshaker.processLoop(Handshaker.java:901)

at sun.security.ssl.Handshaker.process_record(Handshaker.java:837)

at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1023)

at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1332)

at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1359)

at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1343)

at org.apache.http.conn.ssl.SSLConnectionSocketFactory.createLayeredSocket(SSLConnectionSocketFactory.java:394)

at org.apache.http.conn.ssl.SSLConnectionSocketFactory.connectSocket(SSLConnectionSocketFactory.java:353)

at org.apache.http.impl.conn.DefaultHttpClientConnectionOperator.connect(DefaultHttpClientConnectionOperator.java:141)

at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.connect(PoolingHttpClientConnectionManager.java:353)

at org.apache.http.impl.execchain.MainClientExec.establishRoute(MainClientExec.java:380)

at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:236)

at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:184)

at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:88)

at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:110)

at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:184)

at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)

at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:107)

at com.duiba.activity.cmsweb.controller.DappConfigCtrl.main(DappConfigCtrl.java:1248)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.lang.reflect.Method.invoke(Method.java:606)

at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)

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:292)

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:1428)

... 25 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)

... 31 more

网上查了一堆资料，要么说要把网站证书放到某个目录下，要么要改代码，没有我想要的，因为不可能让其他开发者去做这些事情。

后来了解到证书链这回事，才知道如何解决这个问题。有关证书链可以读这里：http://blog.sina.com.cn/s/blog_53ed87c10102vn8b.html

此问题产生的原因是因为我们运维配置证书时只使用了签发的证书，java客户端无法找到可信任的上级证书，所以报错。解决方法也很简单，把中级证书、根证书附加到签发证书后面就可以了，具体方法参考这里：https://yq.aliyun.com/articles/26569

本文出自 “wolf” 博客，请务必保留此出处http://huangwq.blog.51cto.com/10299403/1859537