如何通过类型签名搜索 Java API 方法? [英] How to search for Java API methods by type signature?
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问题描述
是否有任何可用的开源工具支持通过参数类型和返回类型集搜索 Java 方法?
Are there any open-source tools available which support searching for Java methods by the set of parameter types and return type?
举个例子，假设我正在寻找一种为整数数组生成哈希码的方法.我搜索了一个接受 int[] 参数并返回一个 int 的方法:
As an example, say I'm looking for a method to generate a hash code for an array of ints. I search for a method which takes an int[] parameter and returns an int:
int[] -> int
屈服
java.util.Arrays#hashCode(int[])
...
或者我可能想找到一种方法，它接受一个字符串、要替换的字符以及要替换的字符.所以我搜索了一个匹配的方法:
Or I may want to find a method which takes a String, and character to replace, and the character to replace it with. So I search for a matching method:
String, char, char -> String
屈服
java.lang.String#replace(char, char)
...
理想情况下，我想要一个相当于 Haskell 的 Hoogle 的 Java，它支持按类型签名搜索函数.
Ideally I'd like a Java equivalent to Haskell's Hoogle, which supports searching for functions by type signature.
我希望该工具能够:
- 忽略参数的顺序
- 包括接受更广泛"类型作为参数的方法(例如超类)
- 包括返回更窄"类型作为返回值的方法(例如子类)
- 将self"值视为实例方法的参数(例如，String -> int"将包括 String#hashCode)
我知道许多 IDE 支持搜索采用或返回给定类型的方法，但还没有看到通过参数类型和返回类型的组合来缩小搜索范围的工具.
I'm aware that many IDEs support searching for methods which take or return a given type, but haven't yet seen a tool to narrow the search by the combination of parameter types and return type.
推荐答案
解决方案评论:
- 忽略顺序，测试所有参数排列，直到找到给定函数的匹配项
- 原始类型是可以互换的(例如
Integer.class=Integer.TYPE) - 检查更广泛的参数
- 返回类型可以更窄
- Self 被视为
findMethod方法的第一个参数
- Ignoring order, all permutation of parameters are tested till a match of a given function is found
- Primitive types are interchangeable (eg
Integer.class=Integer.TYPE) - Checks wider parameters
- Return types can be narrower
- Self is treated as first of the arguments to the
findMethodmethod
<小时>
这是程序的输出:
int[] -> Integer
public native int java.lang.Object.hashCode()
public static native int java.lang.reflect.Array.getLength(java.lang.Object) throws java.lang.IllegalArgumentException
public static int java.util.Arrays.hashCode(int[])
public static native int java.lang.System.identityHashCode(java.lang.Object)
String, Character, Character -> String
public java.lang.String java.lang.String.replace(char,char)
String -> Integer
public int java.lang.String.hashCode()
public int java.lang.String.length()
public static native int java.lang.reflect.Array.getLength(java.lang.Object) throws java.lang.IllegalArgumentException
public static java.lang.Integer java.lang.Integer.decode(java.lang.String) throws java.lang.NumberFormatException
public static java.lang.Integer java.lang.Integer.valueOf(java.lang.String) throws java.lang.NumberFormatException
public static int java.lang.Integer.parseInt(java.lang.String) throws java.lang.NumberFormatException
public static java.lang.Integer java.lang.Integer.getInteger(java.lang.String)
public static native int java.lang.System.identityHashCode(java.lang.Object)
List -> Void
public abstract void java.util.List.clear()
public static void java.util.concurrent.locks.LockSupport.park(java.lang.Object)
public static void java.util.Collections.reverse(java.util.List)
public static void java.util.Collections.shuffle(java.util.List)
public static void java.util.Collections.sort(java.util.List)
代码:
public class MethodMatcher {
public static void main(String... args) throws Exception {
// where to load some classes from (could be a list of classes to
// search from)..
// String pathToJar = "/usr/lib/jvm/java-6-sun-1.6.0.22/jre/lib/rt.jar";
String pathToJar = "C:\Program Files\Java\jdk1.6.0_20\jre\lib\rt.jar";
MethodMatcher m = new MethodMatcher(pathToJar,
"java.io", "java.lang", "java.math", "java.net",
"java.nio", "java.text", "java.util");
// print some examples
m.printExampleSearch(Integer.class, new int[0].getClass());
m.printExampleSearch(String.class, String.class, Character.class, Character.class);
m.printExampleSearch(Integer.class, String.class);
m.printExampleSearch(Void.class, List.class);
}
public void printExampleSearch(Class<?> returnType, Class<?>... arguments) {
for (int i = 0; i < arguments.length; i++)
System.out.print((i == 0 ? "":", ") + arguments[i].getSimpleName());
System.out.println(" -> " + returnType.getSimpleName());
Set<Method> methods = findMethods(returnType, arguments);
for (Method method : methods)
System.out.println(" " + method);
System.out.println();
}
private final List<MethodFinder> klasses;
public MethodMatcher(String jarFile, String... allowedPackages)
throws IOException, ClassNotFoundException {
klasses = loadClasses(jarFile, allowedPackages);
}
/**
* Finds a set of methods
* @param returnType the return type
* @param arguments the arguments (in any order)
* @return a set of methods
*/
public Set<Method> findMethods(Class<?> returnType,
Class<?>... arguments) {
Set<Method> methods = new LinkedHashSet<Method>();
if (arguments.length > 0) {
MethodFinder instance = new MethodFinder(arguments[0]);
Class<?>[] rest = new Class<?>[arguments.length - 1];
System.arraycopy(arguments, 1, rest, 0, rest.length);
methods.addAll(instance.findInstanceMethods(returnType, rest));
}
else {
for (MethodFinder k : klasses)
methods.addAll(k.findInstanceMethods(returnType, arguments));
}
for (MethodFinder k : klasses)
methods.addAll(k.findStaticMethods(returnType, arguments));
return methods;
}
/**
* A method finder class
*/
static class MethodFinder {
public final Class<?> klass;
/**
* Constructs the method finder (doh)
* @param klass the class
*/
public MethodFinder(Class<?> klass) {
this.klass = klass;
}
/**
* Finds instance method matches
* @param returnType the return type
* @param arguments the arguments (in any order)
* @return
*/
public List<Method> findInstanceMethods(Class<?> returnType,
Class<?>... arguments) {
List<Method> matches = new LinkedList<Method>();
for (Method method : klass.getMethods()) {
if ((method.getModifiers() & Modifier.STATIC) == 0)
if (testMethod(method, returnType, arguments))
matches.add(method);
}
return matches;
}
/**
* Finds static method matches
* @param returnType the return type
* @param arguments the arguments (in any order)
* @return
*/
public List<Method> findStaticMethods(Class<?> returnType,
Class<?>... arguments) {
List<Method> matches = new LinkedList<Method>();
for (Method method : klass.getMethods())
if ((method.getModifiers() & Modifier.STATIC) != 0)
if (testMethod(method, returnType, arguments))
matches.add(method);
return matches;
}
/**
* Tests a method if it is a match
* @param method the method to test
* @param returnType the return type
* @param arguments the arguments (in any order)
* @return true if it matches
*/
private boolean testMethod(Method method,
Class<?> returnType,
Class<?>... arguments) {
boolean returnTypeIsOk = false;
for (Class<?> ic : getInterchangable(returnType))
if (ic.isAssignableFrom(method.getReturnType()))
returnTypeIsOk = true;
if (!returnTypeIsOk)
return false;
Class<?>[] methodArguments = method.getParameterTypes();
if (methodArguments.length != arguments.length)
return false;
if (methodArguments.length == 0) {
return true;
}
else {
Permutations permutations = new Permutations(arguments);
outer: for (Class<?>[] permutation : permutations) {
for (int i = 0; i < methodArguments.length; i++) {
boolean canAssign = false;
for (Class<?> ic : getInterchangable(permutation[i]))
if (methodArguments[i].isAssignableFrom(ic))
canAssign = true;
if (!canAssign)
continue outer;
}
return true;
}
return false;
}
}
/**
* Returns the autoboxing types
* @param type the type to autobox :)
* @return a list of types that it could be
*/
private static Class<?>[] getInterchangable(Class<?> type) {
if (type == Boolean.class || type == Boolean.TYPE)
return new Class<?>[] { Boolean.class, Boolean.TYPE };
if (type == Character.class || type == Character.TYPE)
return new Class<?>[] { Character.class, Character.TYPE };
if (type == Short.class || type == Short.TYPE)
return new Class<?>[] { Short.class, Short.TYPE };
if (type == Integer.class || type == Integer.TYPE)
return new Class<?>[] { Integer.class, Integer.TYPE };
if (type == Float.class || type == Float.TYPE)
return new Class<?>[] { Float.class, Float.TYPE };
if (type == Double.class || type == Double.TYPE)
return new Class<?>[] { Double.class, Double.TYPE };
if (type == Void.class || type == Void.TYPE)
return new Class<?>[] { Void.class, Void.TYPE };
return new Class<?>[] { type };
}
/**
* Creates a permutation list of all different combinations
*/
@SuppressWarnings("serial")
private class Permutations extends LinkedList<Class<?>[]> {
/**
* Creates a permutation list
* @param list the list to be permutated
*/
public Permutations(Class<?>[] list) {
permutate(new LinkedList<Class<?>>(Arrays.asList(list)),
new LinkedList<Class<?>>());
}
// ugly, there is better ways of doing this...
private void permutate(List<Class<?>> tail, List<Class<?>> choosen) {
if (tail.isEmpty()) {
add(choosen.toArray(new Class<?>[0]));
return;
}
ListIterator<Class<?>> it = tail.listIterator();
while (it.hasNext()) {
Class<?> current = it.next();
choosen.add(current);
it.remove();
permutate(new LinkedList<Class<?>>(tail), choosen);
choosen.remove(current);
it.add(current);
}
}
}
}
/**
* A hack to read some classes from some allowed packages
* @param jarFile the jar file to read from
* @param allowedPackages the allowed packages
* @return a list of MethodFinders
* @throws IOException
* @throws ClassNotFoundException
*/
private static List<MethodFinder> loadClasses(
String jarFile,
String... allowedPackages) throws IOException, ClassNotFoundException {
List<MethodFinder> klasses = new LinkedList<MethodFinder>();
JarFile file = new JarFile(jarFile);
try {
Enumeration<JarEntry> enumerator = file.entries();
while (enumerator.hasMoreElements()) {
String name = enumerator.nextElement().getName();
if (!name.endsWith(".class"))
continue;
name = name.substring(0, name.length() - 6).replace('/', '.');
boolean allowed = false;
for (String pkg : allowedPackages)
allowed |= name.startsWith(pkg);
if (allowed)
klasses.add(new MethodFinder(Class.forName(name)));
}
}
finally {
if (file != null)
file.close();
}
return klasses;
}
}
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