ReflectASM alternatives and similar libraries
Based on the "Introspection" category.
Alternatively, view ReflectASM alternatives based on common mentions on social networks and blogs.
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jOOR
jOOR - Fluent Reflection in Java jOOR is a very simple fluent API that gives access to your Java Class structures in a more intuitive way. The JDK's reflection APIs are hard and verbose to use. Other languages have much simpler constructs to access type meta information at runtime. Let us make Java reflection better. -
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Objenesis
Okay, it's pretty easy to instantiate objects in Java through standard reflection. However there are many cases where you need to go beyond what reflection provides. For example, if there's no public constructor, you want to bypass the constructor code, or set final fields. There are numerous clever (but fiddly) approaches to getting around this and this library provides a simple way to get at them. You will find the official site here. -
Mirror
Mirror was created to bring light to a simple problem, usually named ReflectionUtil, which is on almost all projects that rely on reflection to do advanced tasks.
WorkOS - The modern identity platform for B2B SaaS
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README
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Overview
ReflectASM is a very small Java library that provides high performance reflection by using code generation. An access class is generated to set/get fields, call methods, or create a new instance. The access class uses bytecode rather than Java's reflection, so it is much faster. It can also access primitive fields via bytecode to avoid boxing.
Performance
The source code for these benchmarks is included in the project. The above charts were generated on Oracle's Java 7u3, server VM.
Installation
To use reflectasm with maven, please use the following snippet in your pom.xml
<dependency>
<groupId>com.esotericsoftware</groupId>
<artifactId>reflectasm</artifactId>
<version>1.11.9</version>
</dependency>
Usage
Method reflection with ReflectASM:
SomeClass someObject = ...
MethodAccess access = MethodAccess.get(SomeClass.class);
access.invoke(someObject, "setName", "Awesome McLovin");
String name = (String)access.invoke(someObject, "getName");
Field reflection with ReflectASM:
SomeClass someObject = ...
FieldAccess access = FieldAccess.get(SomeClass.class);
access.set(someObject, "name", "Awesome McLovin");
String name = (String)access.get(someObject, "name");
Constructor reflection with ReflectASM:
ConstructorAccess<SomeClass> access = ConstructorAccess.get(SomeClass.class);
SomeClass someObject = access.newInstance();
Avoiding Name Lookup
For maximum performance when methods or fields are accessed repeatedly, the method or field index should be used instead of the name:
SomeClass someObject = ...
MethodAccess access = MethodAccess.get(SomeClass.class);
int addNameIndex = access.getIndex("addName");
for (String name : names)
access.invoke(someObject, addNameIndex, "Awesome McLovin");
Iterate all fields:
FieldAccess access = FieldAccess.get(SomeClass.class);
for(int i = 0, n = access.getFieldCount(); i < n; i++) {
access.set(instanceObject, i, valueToPut);
}
Visibility
ReflectASM can always access public members. An attempt is made to define access classes in the same classloader (using setAccessible) and package as the accessed class. If the security manager allows setAccessible to succeed, then protected and default access (package private) members can be accessed. If setAccessible fails, no exception is thrown, but only public members can be accessed. Private members can never be accessed.
Exceptions
Stack traces when using ReflectASM are a bit cleaner. Here is Java's reflection calling a method that throws a RuntimeException:
Exception in thread "main" java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.example.SomeCallingCode.doit(SomeCallingCode.java:22)
Caused by: java.lang.RuntimeException
at com.example.SomeClass.someMethod(SomeClass.java:48)
... 5 more
Here is the same but when ReflectASM is used:
Exception in thread "main" java.lang.RuntimeException
at com.example.SomeClass.someMethod(SomeClass.java:48)
at com.example.SomeClassMethodAccess.invoke(Unknown Source)
at com.example.SomeCallingCode.doit(SomeCallingCode.java:22)
If ReflectASM is used to invoke code that throws a checked exception, the checked exception is thrown. Because it is a compilation error to use try/catch with a checked exception around code that doesn't declare that exception as being thrown, you must catch Exception if you care about catching a checked exception in code you invoke with ReflectASM.