net.lenni0451.reflect

Class Agents

java.lang.Object

net.lenni0451.reflect.Agents

public class Agents
extends java.lang.Object

This class contains some useful methods for working with agents.

Constructor Summary

Constructors

Constructor and Description
Agents()

Method Summary

Modifier and Type	Method and Description
static java.io.File	createDummyAgent(java.lang.Class<?> agentClass) Create a temp empty dummy agent jar for a given class.
static void	createDummyAgent(java.io.File agentJar, java.lang.String agentName) Create an empty dummy agent jar for a given class.
static java.lang.instrument.Instrumentation	getInstrumentation() Get an instrumentation instance by loading an agent during runtime.
static void	load(java.io.File agentJar) Load an agent from a jar during runtime.
static void	loadInternal(java.lang.Class<?> agentClass) Create a dummy agent jar for the given class and load it.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Agents

public Agents()

Method Detail

createDummyAgent

public static java.io.File createDummyAgent(java.lang.Class<?> agentClass)
                                     throws java.io.IOException

Create a temp empty dummy agent jar for a given class.

Parameters:

agentClass - The class to create the agent for

Returns:

The path to the agent jar

Throws:

java.io.IOException - If an I/O error occurs

createDummyAgent

public static void createDummyAgent(java.io.File agentJar,
                                    java.lang.String agentName)
                             throws java.io.IOException

Create an empty dummy agent jar for a given class.

Parameters:

agentJar - The path to the agent jar

agentName - The name of the agent class

Throws:

java.io.IOException - If an I/O error occurs

load

public static void load(java.io.File agentJar)
                 throws java.lang.ClassNotFoundException

Load an agent from a jar during runtime.
The method used was added in Java 9 and is not available in Java 8.

Parameters:

agentJar - The path to the agent jar

Throws:

java.lang.ClassNotFoundException - If the InstrumentationImpl class is not found

java.lang.IllegalStateException - If the loadAgent method does not exist

loadInternal

public static void loadInternal(java.lang.Class<?> agentClass)
                         throws java.io.IOException,
                                java.lang.ClassNotFoundException

Create a dummy agent jar for the given class and load it.
The method used was added in Java 9 and is not available in Java 8.

Parameters:

agentClass - The class to create the agent for

Throws:

java.io.IOException - If an I/O error occurs

java.lang.ClassNotFoundException - If the InstrumentationImpl class is not found

java.lang.IllegalStateException - If the loadAgent method does not exist

getInstrumentation

public static java.lang.instrument.Instrumentation getInstrumentation()
                                                               throws java.io.IOException,
                                                                      java.lang.ClassNotFoundException

Get an instrumentation instance by loading an agent during runtime.
The loaded agent stores the instrumentation instance in a static field which is accessed using reflection.
This solves many problems which can occur with class loaders.
The instrumentation instance is cached so that it is only loaded once.

Returns:

The instrumentation instance

Throws:

java.io.IOException - If an IO error occurs

java.lang.ClassNotFoundException - If the InstrumentationImpl class is not found

java.lang.IllegalStateException - If the loadAgent method does not exist