java/java_autoload

Signed-off-by: lucasew <[email protected]>

Author: lucasew

java/java_autoload/.gitignore

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+*.class

java/java_autoload/InternalClassLoader.java

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+
+import java.net.URLClassLoader;
+import java.net.URL;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.URLConnection;
+import java.io.IOException;
+import java.io.File;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.io.InputStream;
+import java.io.FileOutputStream;
+
+public class InternalClassLoader extends URLClassLoader {
+  public InternalClassLoader(String name, ClassLoader parent) {
+    super(name, new URL[0], parent);
+    try {
+      System.out.println(getScriptPath());
+    } catch (Exception e) {}
+  }
+
+  private boolean isJarsLoaded = false;
+
+  public synchronized Class loadClass(String name) throws ClassNotFoundException {
+    System.out.println("Class " + name);
+    if (!isJarsLoaded) {
+      try {
+        add(new URL("https://repo1.maven.org/maven2/log4j/log4j/1.2.17/log4j-1.2.17.jar"));
+      } catch (Exception e) {e.printStackTrace();}
+      isJarsLoaded = true;
+    }
+    return super.loadClass(name);
+  }
+
+
+  public static String getScriptPath() {
+  	try {
+      return new File(InternalClassLoader.class.getProtectionDomain().getCodeSource().getLocation().getPath()).getCanonicalPath();
+  	} catch (IOException e) {
+  		e.printStackTrace();
+  		throw new RuntimeException("Can't find source file");
+  	}
+	}
+
+  public InternalClassLoader(ClassLoader parent) {
+    this("classpath", parent);
+  }
+
+  public InternalClassLoader() {
+    this(Thread.currentThread().getContextClassLoader());
+  }
+
+  public String downloadFromURL(URL url) throws IOException {
+        InputStream is = null;
+        FileOutputStream fos = null;
+        String localFilename = url.toString().substring(url.toString().lastIndexOf("/")+1, url.toString().length());
+        String tempDir = System.getProperty("java.io.tmpdir");
+        String outputPath = tempDir + "/" + localFilename;
+        System.out.printf("Downloading %s to %s\n", url, outputPath);
+
+        try {
+        	//connect
+            URLConnection urlConn = url.openConnection();
+
+            //get inputstream from connection
+            is = urlConn.getInputStream();               
+            fos = new FileOutputStream(outputPath);   
+
+            // 4KB buffer
+            byte[] buffer = new byte[4096];
+            int length;
+
+            // read from source and write into local file
+            while ((length = is.read(buffer)) > 0) {
+                fos.write(buffer, 0, length);
+            }
+            return outputPath;
+        } finally {
+            try {
+                if (is != null) {
+                    is.close();
+                }
+            } finally {
+                if (fos != null) {
+                    fos.close();
+                }
+            }
+            System.out.println("Downloading done");
+        }
+    }
+
+  void add(URL url) {
+    try {
+      URI uri = url.toURI();
+      if (uri.getScheme().equals("https")) {
+        System.out.println("scheme https");
+        url = new File(downloadFromURL(url)).toURI().toURL();
+        System.out.println(url);
+      }
+      System.out.println("aaaaaaaaaa");
+    
+      System.out.println(url);
+      addURL(url);
+      
+    }
+    catch (URISyntaxException e) {e.printStackTrace();}
+    catch (IOException e) {e.printStackTrace();}
+    for (URL u : this.getURLs()) {
+      System.out.println(u);
+    }
+  }
+
+  public static InternalClassLoader findAncestor(ClassLoader cl) {
+      do {
+
+          if (cl instanceof InternalClassLoader)
+              return (InternalClassLoader) cl;
+
+          cl = cl.getParent();
+      } while (cl != null);
+
+      return null;
+  }
+
+  /*
+   *  Required for Java Agents when this classloader is used as the system classloader
+   */
+  @SuppressWarnings("unused")
+  private void appendToClassPathForInstrumentation(String jarfile) throws IOException {
+    add(Paths.get(jarfile).toRealPath().toUri().toURL());
+  }
+}

java/java_autoload/README.md

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+TODO: find a way to dynamically load a class from the Internet
+
+BTW you need to javac the java file for this to "work"

java/java_autoload/main

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+#!/usr/bin/env -S java --source 11 -Djava.system.class.loader=InternalClassLoader
+// --class-path https://repo1.maven.org/maven2/log4j/log4j/1.2.17/log4j-1.2.17.jar
+// -verbose
+//  --class-path /tmp/log4j-1.2.17.jar
+
+import org.apache.log4j.Logger;
+class main {
+
+  final static Logger logger = Logger.getLogger(main.class);
+
+  public static void main(String []args) {
+    System.out.println("funciona?");
+    System.out.println(Thread.currentThread().getContextClassLoader());
+    System.out.println(System.getProperty("sun.java.command"));
+    System.out.println(System.getenv("JAVA_MAIN_CLASS"));
+    logger.info("Test");
+  }
+}
+
+