当同步块用于对象实例上的同步时,线程竞争进入对象的隐式监视器.一旦任何特定线程进入监视器,任何其他线程都必须等待进入它.然后
synchronized(object){
// some code here
// no function call
}
不得强制执行任何特定类型的对象.因此,这里可以使用任何对象类型,因为每个对象都有其隐式监视器.
请回复我是真的吗？
来自Carlo Scarioni的Pro Spring Security书籍,我正在尝试将Spring Application与CAS Server集成.我按照书中指示的每一步,仍然坚持这个错误.请帮帮我.
SEVERE: sun.security.validator.ValidatorException: PKIX path validation failed: java.security.cert.CertPathValidatorException: signature check failed
javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path validation failed: java.security.cert.CertPathValidatorException: signature check failed
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 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:1301)
at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:254)
at org.jasig.cas.client.util.CommonUtils.getResponseFromServer(CommonUtils.java:311)
at org.jasig.cas.client.util.CommonUtils.getResponseFromServer(CommonUtils.java:291)
at org.jasig.cas.client.validation.AbstractCasProtocolUrlBasedTicketValidator.retrieveResponseFromServer(AbstractCasProtocolUrlBasedTicketValidator.java:32)
at org.jasig.cas.client.validation.AbstractUrlBasedTicketValidator.validate(AbstractUrlBasedTicketValidator.java:187)
at org.springframework.security.cas.authentication.CasAuthenticationProvider.authenticateNow(CasAuthenticationProvider.java:140)
at org.springframework.security.cas.authentication.CasAuthenticationProvider.authenticate(CasAuthenticationProvider.java:126)
at org.springframework.security.authentication.ProviderManager.authenticate(ProviderManager.java:156)
at org.springframework.security.cas.web.CasAuthenticationFilter.attemptAuthentication(CasAuthenticationFilter.java:242)
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:195)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105) …请查看Joshua Bloch的Effective Java 链接.
在第二段中,作者说:
该类是私有的或包私有的,并且您确定它的equals方法永远不会被调用.可以说,在这些情况下应该覆盖该
equals方法,以防它被意外调用:Run Code Online (Sandbox Code Playgroud)@Override public boolean equals(Object o) { throw new AssertionError(); // Method is never called }
请解释一下.我对作者使用术语私有类感到困惑,并且当我们确定不会被调用时,为什么需要重写equals方法.
我有以下JSP:
<%@ page import="foo.*" %>
<html>
<body>
The page count is:
<%=Counter.getCount()%>
</body>
</html>
我有一个Counter包foo中的类,存储在:
C:\ Apache的Tomcat的6.0.32 \的webapps \神\ WEB-INF \班
容器可以从包中找到类foo.
但是,当我尝试直接添加一些其他类文件\WEB-INF\classes而不是在任何特定的包中foo,然后容器找不到该类.
这是怎么造成的,我该如何解决？
可能重复:
基本Java问题:字符串相等
特定
String s= "God";
String k= "God";
都将s和k被认为是指同一个String对象吗？是否有一个String对象实例？