http://asm.ow2.io/: Usefull class adapters based on ASM, a very small and fast Java bytecode manipulation framework (OW2)
  • Eric Bruneton
  • Eugene Kuleshov
  • Remi Forax 
// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
// All rights reserved.
//
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package org.objectweb.asm.commons;

import java.util.HashMap;
import java.util.Map;
import org.objectweb.asm.Type;


A named method descriptor.

Author:Juozas Baliuka, Chris Nokleberg, Eric Bruneton
/**
 * A named method descriptor.
 *
 * @author Juozas Baliuka
 * @author Chris Nokleberg
 * @author Eric Bruneton
 */
public class Method {

  
The method name. 
/** The method name. */
  private final String name;

  
The method descriptor. 
/** The method descriptor. */
  private final String descriptor;

  
The descriptors of the primitive Java types (plus void). 
/** The descriptors of the primitive Java types (plus void). */
  private static final Map<String, String> PRIMITIVE_TYPE_DESCRIPTORS;

  static {
    HashMap<String, String> descriptors = new HashMap<>();
    descriptors.put("void", "V");
    descriptors.put("byte", "B");
    descriptors.put("char", "C");
    descriptors.put("double", "D");
    descriptors.put("float", "F");
    descriptors.put("int", "I");
    descriptors.put("long", "J");
    descriptors.put("short", "S");
    descriptors.put("boolean", "Z");
    PRIMITIVE_TYPE_DESCRIPTORS = descriptors;
  }

  
Constructs a new Method. 
Params:
  • name – the method's name.
  • descriptor – the method's descriptor.
/**
   * Constructs a new {@link Method}.
   *
   * @param name the method's name.
   * @param descriptor the method's descriptor.
   */
  public Method(final String name, final String descriptor) {
    this.name = name;
    this.descriptor = descriptor;
  }

  
Constructs a new Method. 
Params:
  • name – the method's name.
  • returnType – the method's return type.
  • argumentTypes – the method's argument types.
/**
   * Constructs a new {@link Method}.
   *
   * @param name the method's name.
   * @param returnType the method's return type.
   * @param argumentTypes the method's argument types.
   */
  public Method(final String name, final Type returnType, final Type[] argumentTypes) {
    this(name, Type.getMethodDescriptor(returnType, argumentTypes));
  }

  
Creates a new Method. 
Params:
  • method – a java.lang.reflect method descriptor
Returns:a Method corresponding to the given Java method declaration.
/**
   * Creates a new {@link Method}.
   *
   * @param method a java.lang.reflect method descriptor
   * @return a {@link Method} corresponding to the given Java method declaration.
   */
  public static Method getMethod(final java.lang.reflect.Method method) {
    return new Method(method.getName(), Type.getMethodDescriptor(method));
  }

  
Creates a new Method. 
Params:
  • constructor – a java.lang.reflect constructor descriptor
Returns:a Method corresponding to the given Java constructor declaration.
/**
   * Creates a new {@link Method}.
   *
   * @param constructor a java.lang.reflect constructor descriptor
   * @return a {@link Method} corresponding to the given Java constructor declaration.
   */
  public static Method getMethod(final java.lang.reflect.Constructor<?> constructor) {
    return new Method("<init>", Type.getConstructorDescriptor(constructor));
  }

  
Returns a Method corresponding to the given Java method declaration. 
Params:
  • method – a Java method declaration, without argument names, of the form "returnType name
    (argumentType1, ... argumentTypeN)", where the types are in plain Java (e.g. "int",
    "float", "java.util.List", ...). Classes of the java.lang package can be specified by their
    unqualified name; all other classes names must be fully qualified.
Throws:
Returns:a Method corresponding to the given Java method declaration.
/**
   * Returns a {@link Method} corresponding to the given Java method declaration.
   *
   * @param method a Java method declaration, without argument names, of the form "returnType name
   *     (argumentType1, ... argumentTypeN)", where the types are in plain Java (e.g. "int",
   *     "float", "java.util.List", ...). Classes of the java.lang package can be specified by their
   *     unqualified name; all other classes names must be fully qualified.
   * @return a {@link Method} corresponding to the given Java method declaration.
   * @throws IllegalArgumentException if <code>method</code> could not get parsed.
   */
  public static Method getMethod(final String method) {
    return getMethod(method, false);
  }

  
Returns a Method corresponding to the given Java method declaration. 
Params:
  • method – a Java method declaration, without argument names, of the form "returnType name
    (argumentType1, ... argumentTypeN)", where the types are in plain Java (e.g. "int",
    "float", "java.util.List", ...). Classes of the java.lang package may be specified by their
    unqualified name, depending on the defaultPackage argument; all other classes names must be
    fully qualified.
  • defaultPackage – true if unqualified class names belong to the default package, or false
    if they correspond to java.lang classes. For instance "Object" means "Object" if this
    option is true, or "java.lang.Object" otherwise.
Throws:
Returns:a Method corresponding to the given Java method declaration.
/**
   * Returns a {@link Method} corresponding to the given Java method declaration.
   *
   * @param method a Java method declaration, without argument names, of the form "returnType name
   *     (argumentType1, ... argumentTypeN)", where the types are in plain Java (e.g. "int",
   *     "float", "java.util.List", ...). Classes of the java.lang package may be specified by their
   *     unqualified name, depending on the defaultPackage argument; all other classes names must be
   *     fully qualified.
   * @param defaultPackage true if unqualified class names belong to the default package, or false
   *     if they correspond to java.lang classes. For instance "Object" means "Object" if this
   *     option is true, or "java.lang.Object" otherwise.
   * @return a {@link Method} corresponding to the given Java method declaration.
   * @throws IllegalArgumentException if <code>method</code> could not get parsed.
   */
  public static Method getMethod(final String method, final boolean defaultPackage) {
    final int spaceIndex = method.indexOf(' ');
    int currentArgumentStartIndex = method.indexOf('(', spaceIndex) + 1;
    final int endIndex = method.indexOf(')', currentArgumentStartIndex);
    if (spaceIndex == -1 || currentArgumentStartIndex == 0 || endIndex == -1) {
      throw new IllegalArgumentException();
    }
    final String returnType = method.substring(0, spaceIndex);
    final String methodName =
        method.substring(spaceIndex + 1, currentArgumentStartIndex - 1).trim();
    StringBuilder stringBuilder = new StringBuilder();
    stringBuilder.append('(');
    int currentArgumentEndIndex;
    do {
      String argumentDescriptor;
      currentArgumentEndIndex = method.indexOf(',', currentArgumentStartIndex);
      if (currentArgumentEndIndex == -1) {
        argumentDescriptor =
            getDescriptorInternal(
                method.substring(currentArgumentStartIndex, endIndex).trim(), defaultPackage);
      } else {
        argumentDescriptor =
            getDescriptorInternal(
                method.substring(currentArgumentStartIndex, currentArgumentEndIndex).trim(),
                defaultPackage);
        currentArgumentStartIndex = currentArgumentEndIndex + 1;
      }
      stringBuilder.append(argumentDescriptor);
    } while (currentArgumentEndIndex != -1);
    stringBuilder.append(')').append(getDescriptorInternal(returnType, defaultPackage));
    return new Method(methodName, stringBuilder.toString());
  }

  
Returns the descriptor corresponding to the given type name.

Params:
  • type – a Java type name.
  • defaultPackage – true if unqualified class names belong to the default package, or false
    if they correspond to java.lang classes. For instance "Object" means "Object" if this
    option is true, or "java.lang.Object" otherwise.
Returns:the descriptor corresponding to the given type name.
/**
   * Returns the descriptor corresponding to the given type name.
   *
   * @param type a Java type name.
   * @param defaultPackage true if unqualified class names belong to the default package, or false
   *     if they correspond to java.lang classes. For instance "Object" means "Object" if this
   *     option is true, or "java.lang.Object" otherwise.
   * @return the descriptor corresponding to the given type name.
   */
  private static String getDescriptorInternal(final String type, final boolean defaultPackage) {
    if ("".equals(type)) {
      return type;
    }

    StringBuilder stringBuilder = new StringBuilder();
    int arrayBracketsIndex = 0;
    while ((arrayBracketsIndex = type.indexOf("[]", arrayBracketsIndex) + 1) > 0) {
      stringBuilder.append('[');
    }

    String elementType = type.substring(0, type.length() - stringBuilder.length() * 2);
    String descriptor = PRIMITIVE_TYPE_DESCRIPTORS.get(elementType);
    if (descriptor != null) {
      stringBuilder.append(descriptor);
    } else {
      stringBuilder.append('L');
      if (elementType.indexOf('.') < 0) {
        if (!defaultPackage) {
          stringBuilder.append("java/lang/");
        }
        stringBuilder.append(elementType);
      } else {
        stringBuilder.append(elementType.replace('.', '/'));
      }
      stringBuilder.append(';');
    }
    return stringBuilder.toString();
  }

  
Returns the name of the method described by this object.

Returns:the name of the method described by this object.
/**
   * Returns the name of the method described by this object.
   *
   * @return the name of the method described by this object.
   */
  public String getName() {
    return name;
  }

  
Returns the descriptor of the method described by this object.

Returns:the descriptor of the method described by this object.
/**
   * Returns the descriptor of the method described by this object.
   *
   * @return the descriptor of the method described by this object.
   */
  public String getDescriptor() {
    return descriptor;
  }

  
Returns the return type of the method described by this object.

Returns:the return type of the method described by this object.
/**
   * Returns the return type of the method described by this object.
   *
   * @return the return type of the method described by this object.
   */
  public Type getReturnType() {
    return Type.getReturnType(descriptor);
  }

  
Returns the argument types of the method described by this object.

Returns:the argument types of the method described by this object.
/**
   * Returns the argument types of the method described by this object.
   *
   * @return the argument types of the method described by this object.
   */
  public Type[] getArgumentTypes() {
    return Type.getArgumentTypes(descriptor);
  }

  @Override
  public String toString() {
    return name + descriptor;
  }

  @Override
  public boolean equals(final Object other) {
    if (!(other instanceof Method)) {
      return false;
    }
    Method otherMethod = (Method) other;
    return name.equals(otherMethod.name) && descriptor.equals(otherMethod.descriptor);
  }

  @Override
  public int hashCode() {
    return name.hashCode() ^ descriptor.hashCode();
  }
}