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1 package fschmidt.util.java;
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2
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3 import java.lang.reflect.Method;
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4 import java.util.Arrays;
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5 import java.util.HashMap;
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6 import java.util.Map;
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7 import java.util.WeakHashMap;
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8
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9
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10 public final class ClassUtils {
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11
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12 private ClassUtils() {} // never
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13
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14 private static final class Key {
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15 private final String name;
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16 private final Class[] parameterTypes;
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17
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18 private Key(Method m) {
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19 this(m.getName(),m.getParameterTypes());
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20 }
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21
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22 private Key(String name,Class[] parameterTypes) {
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23 this.name = name;
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24 this.parameterTypes = parameterTypes;
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25 }
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26
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27 public boolean equals(Object obj) {
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28 if( !(obj instanceof Key) )
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29 return false;
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30 Key key = (Key)obj;
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31 return key.name.equals(name) && Arrays.equals(key.parameterTypes,parameterTypes);
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32 }
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33
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34 public int hashCode() {
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35 return name.hashCode()+31*Arrays.hashCode(parameterTypes);
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36 }
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37 }
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38
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39 private static final Map<Class,FutureValue<Map<Key,Method>>> cache = new WeakHashMap<Class,FutureValue<Map<Key,Method>>>();
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40
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41 // return null if not found
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42 public static Method getMethod(final Class cls,String name,Class... parameterTypes) {
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43 FutureValue<Map<Key,Method>> ft;
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44 synchronized(cache) {
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45 ft = cache.get(cls);
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46 if( ft==null ) {
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47 ft = new FutureValue<Map<Key,Method>>() {
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48 protected Map<Key,Method> compute() {
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49 Map<Key,Method> map = new HashMap<Key,Method>();
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50 for( Method m : cls.getMethods() ) {
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51 Method m2 = map.put(new Key(m),m);
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52 if( m2 != null )
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53 throw new RuntimeException("duplicate methods "+m+" and "+m2);
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54 }
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55 return map;
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56 }
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57 };
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58 cache.put(cls,ft);
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59 }
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60 }
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61 Key key = new Key(name,parameterTypes);
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62 return ft.get().get(key);
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63 }
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64
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65 }
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