java

问题 Is it possible to check any X509 Certificate if it is revoked or not? Actually, I made a Java application that just gets a regular https link and outputs the X509 certificate. I want to add a service in my application that check if this certificate has been revoked or not? Is there a tutorial or a simple code to start with that can guide me to do that. Thank you in advance 回答1: Yes, of course the revocation status can be checked. If you want to do this "by hand", you need to extract the

问题 I am aware of sub-pixel shapes, such as Rectangle2D.Double , Ellipse2D.Double and Line2D.Double - but I couldn't find information about drawing an Image / BufferedImage with sub-pixel accuracy. Perhaps something that would look like this - Image2D.Double ? Is there any way I can achieve this? 回答1: Images may be drawn with an AffineTransform, which can specify scaling and translation with floating point values. (See drawImage(Image, AffineTransform, ImageObserver) method) For example, to draw

问题 I used jssc library to read and write data from serial port. package serial; import jssc.*; public class Serial { public static void main(String[] args) { String[] portNames = null; portNames = SerialPortList.getPortNames(); for (String string : portNames) { System.out.println(string); } if (portNames.length == 0) { System.out.println("There are no serial-ports"); } else { SerialPort serialPort = new SerialPort("com2"); try { serialPort.openPort(); serialPort.setParams(SerialPort.BAUDRATE

问题 I am writing a Java multithreaded application that hits millions and sometimes billions of URLs of different web servers. The idea is to check if those URLs gives a valid 200OK response or 404/some other code. How can I know if my program is not causing high traffic on their servers? I don't want a DOS attack to happen.There are almost ~ 8 million URLs of each server . To check traffic this I created a simple webpage hosted at http://localhost:8089/ .My application is hitting this page 2

问题 I am using a cxf webservice which uses local transport and accessing the webservice from java application. Webservice is reading a file and sending through webservice call. I am using the byte size as 512. Suppose the file size is 1200. First two attempt of retrieving the file is success and for the last chunk i am getting org.apache.cxf.interceptor.Fault: Unmarshalling Error: Illegal character (NULL, unicode 0) encountered: not valid in any content. Here chunk represents 512 bytes. I am

问题 When I am trying to convert, I am getting below exception java.lang.ArrayStoreException: java.util.HashSet at java.util.AbstractCollection.toArray(Unknown Source) This is my code Map<String, Set<String>> map = new HashMap<>(); String[] keySet = map.keySet().toArray(new String[map.size()]); Collection<Set<String>> collections = map.values(); String[] values = collection.toArray(new String[collection.size()]);// In this line getting Exception 回答1: You can simply use Stream.flatMap as you stream

问题 When I am trying to convert, I am getting below exception java.lang.ArrayStoreException: java.util.HashSet at java.util.AbstractCollection.toArray(Unknown Source) This is my code Map<String, Set<String>> map = new HashMap<>(); String[] keySet = map.keySet().toArray(new String[map.size()]); Collection<Set<String>> collections = map.values(); String[] values = collection.toArray(new String[collection.size()]);// In this line getting Exception 回答1: You can simply use Stream.flatMap as you stream

问题 I am trying to call a function using a variable as String type dynamically i.e. variable will contain a function name as String. So, I need to call a function using that variable. So, I am using Scala Reflection. It is working if the function is accepting datatype as Sting, But it is throwing error List[Map[String, Double]] I used below link to refer a code Is there any Scala feature that allows you to call a method whose name is stored in a string? and below is a test program which I am

问题 I was thinking to use log4j for my standalone java project. Is it possible to use it for java project(not a web app). If its possible then how should I be able to initialize the properties file and where should I put the properties file(directory structure). Any help is appreciated. 回答1: Yes, it is possible, we do it all the time. You just need a log4j.properties file on your classpath, which in most cases means in the base directory of your jar file. If you wish to have multiple properties

问题 I have created a new Java 10 project in Eclipse 4.7.3a This is a maven project with some dependencies. The project is called "MyProject" and below is my module-info.java module myproject { exports myproject; requires commons.logging; requires htmlunit; requires htmlunit.cssparser; requires java.logging; requires java.xml; requires selenium.api; requires selenium.firefox.driver; requires selenium.remote.driver; } when I run the project I get the following Error occurred during initialization