https://wiki.chongtin.com/ 2026-04-09T00:48:36+00:00 https://wiki.chongtin.com/ https://wiki.chongtin.com/ttps://wiki.chongtin.com/lib/tpl/bootstrap3/images/favicon.ico text/html 2019-02-14T12:32:27+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.chongtin.com/java/apache_poi_check_if_file_contains_macros?do=revisions&rev=1550118747 Apache POI Check if File Contains Macros This code should work for all office file. In this code, we test the file 1.doc in the project root directory. Requirement: POI 3.15 or above. import org.apache.poi.poifs.macros.VBAMacroReader; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.util.Map; public class Main { private static boolean hasVBA(InputStream inputStream) throws IOException { boolean returnVal = f… text/html 2019-08-13T14:56:01+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.chongtin.com/java/basic_gson?do=revisions&rev=1565679361 Basic Gson Add Gson Dependency <dependency> <groupId>com.google.code.gson</groupId> <artifactId>gson</artifactId> <version>2.8.5</version> </dependency> Assumption Assume we have a Company class, and a Staff class such that Company has a name, a start date, and a list of staff, and the staff has a name, and a salary field. We use the following code to create the Java objects. text/html 2020-06-15T11:50:27+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.chongtin.com/java/byte_to_file?do=revisions&rev=1592193027 Byte Array to File Classic Way public static void main(String[] args) { byte[] b = "ABCDEFGHIJK".getBytes(); FileOutputStream fileOutputStream = null; try { fileOutputStream = new FileOutputStream("./out.txt"); fileOutputStream.write(b); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { if (fileOutputStream !… text/html 2020-07-29T17:45:31+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.chongtin.com/java/calling_native_windows_dll_api_with_jna?do=revisions&rev=1596015931 Calling Native Windows DLL API with JNA * Include the JNA library in your project * Create an interface that extents com.sun.jna.Library with the prototypes of the functions your need to call * Copy the DLL file to your project. * Load the library (in this case dll) with com.sun.jna.Native text/html 2019-12-16T09:59:47+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.chongtin.com/java/checking_memory_allocation?do=revisions&rev=1576461587 Checking Memory Allocation We can run the following code to estimate Java VM memory usage in run-time: (Original from StackOverFlow Jeremy answer <https://stackoverflow.com/questions/74674/how-do-i-check-cpu-and-memory-usage-in-java> with a little modification for console) To estimate the memory usage of a section, we can user 'System.gc() text/html 2020-12-10T12:29:08+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.chongtin.com/java/file_to_string?do=revisions&rev=1607574548 File to String Read the Whole File Change YOUR_FILE to your actual file. You might want to change to charset for your file. class Scratch { static String readFile(String path, Charset encoding) throws IOException { byte[] encoded = Files.readAllBytes(Paths.get(path)); return new String(encoded, encoding); } public static void main(String[] args) { try { String s = readFile("404357 1 - SOP AF WT 2019.json", Charset.defaultCharset()… text/html 2019-01-08T15:47:59+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.chongtin.com/java/jasper_report?do=revisions&rev=1546933679 Jasper Report Jasper report can help us to export a pdf file in Java. To make it simple, we will only focus on data source with JRBeanCollectionDataSource, and use only the Text Field, and Static Text basic elements to build this report. Code Assume we have already created a jasper template text/html 2021-07-22T16:30:10+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.chongtin.com/java/levenshtein_distance?do=revisions&rev=1626942610 Levenshtein Distance Levenshtein Distance is a method to check the similarity of wo string. If the string is very similar, we will get a small value for the distance. If the two strings are completely off, we get the value of max string lenth as the distance. text/html 2020-06-15T11:27:35+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.chongtin.com/java/resize_image_with_imageio_and_graphics2d?do=revisions&rev=1592191655 Resize Image with ImageIO and Graphics2D Here is how we do it. Note that the try catch exception is omitted here, you need to do it yourself. * Read the image file from storage as InputStream * Read it as BufferedImage * Create a new BufferedImage text/html 2019-10-18T11:33:33+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.chongtin.com/java/setting_truststore_and_keystore_in_runtime?do=revisions&rev=1571369613 Setting TrustStore and KeyStore in Runtime Sometime we might not want to mess up the Java JRE/JDK trust store and key store while we are testing some crazy shit like self-signed cert. We can do that in our application during running. Here is the code to do it: