Saturday, 16 March 2013

Getting list of Jars loaded in SystemClassLoader (using Jni4Net)

I just created a couple extension methods for Jni4Net that allow (amongst other things) the listing of the jars currently loaded in the SystemClassLoader (see API_Jni4Net.cs for the code of these .NET Extension Methods)

The objective is to simplify the use of Jni4Net, and to hide the complexity in consuming Java code from .NET:

Here are a couple examples of these Extension Methods in action:

When you create a simple Jni4Net bridge there is only one jar loader:

image

Next lets load a jar dynamically and see it appear in the list of loaded jars

image

Note that once the jar is loaded we can access its classes:

image

create instances and invoke methods:

image

here is the script show above:
var jni4Net = new API_Jni4Net().setUpBride();
var env = jni4Net.jniEnv;

var classLoader = ClassLoader.getSystemClassLoader();
var beanShellJar = "http://www.beanshell.org/bsh-2.0b4.jar"
                        .uri()
                        .download(false);

classLoader.loadJar(beanShellJar);
var interpreter_Class = beanShellJar.java_Jar_Class("bsh.Interpreter");

return interpreter_Class.newInstance()
                        .java_Invoke_UsingSignature(
                            "eval",
                            "(Ljava/lang/String;)Ljava/lang/Object;",
                            "return \"hello from java: \" + (2 + 2); ".java_String()).str();
                        
return classLoader.jarsInClassPath();
//using java.lang;
//O2File:API_Jni4Net.cs
//O2Ref:jni4net.n-0.8.6.0.dll


Finally we can also load/add to the system class path, entire folders with jars. For example all ESAPI dependencies:

image
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