Reflector.java

  1. /*
  2.  *    Copyright 2009-2022 the original author or authors.
  3.  *
  4.  *    Licensed under the Apache License, Version 2.0 (the "License");
  5.  *    you may not use this file except in compliance with the License.
  6.  *    You may obtain a copy of the License at
  7.  *
  8.  *       http://www.apache.org/licenses/LICENSE-2.0
  9.  *
  10.  *    Unless required by applicable law or agreed to in writing, software
  11.  *    distributed under the License is distributed on an "AS IS" BASIS,
  12.  *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13.  *    See the License for the specific language governing permissions and
  14.  *    limitations under the License.
  15.  */
  16. package org.apache.ibatis.reflection;

  18. import java.lang.invoke.MethodHandle;
  19. import java.lang.invoke.MethodHandles;
  20. import java.lang.invoke.MethodType;
  21. import java.lang.reflect.Array;
  22. import java.lang.reflect.Constructor;
  23. import java.lang.reflect.Field;
  24. import java.lang.reflect.GenericArrayType;
  25. import java.lang.reflect.Method;
  26. import java.lang.reflect.Modifier;
  27. import java.lang.reflect.ParameterizedType;
  28. import java.lang.reflect.ReflectPermission;
  29. import java.lang.reflect.Type;
  30. import java.text.MessageFormat;
  31. import java.util.ArrayList;
  32. import java.util.Arrays;
  33. import java.util.Collection;
  34. import java.util.HashMap;
  35. import java.util.List;
  36. import java.util.Locale;
  37. import java.util.Map;
  38. import java.util.Map.Entry;

  40. import org.apache.ibatis.reflection.invoker.AmbiguousMethodInvoker;
  41. import org.apache.ibatis.reflection.invoker.GetFieldInvoker;
  42. import org.apache.ibatis.reflection.invoker.Invoker;
  43. import org.apache.ibatis.reflection.invoker.MethodInvoker;
  44. import org.apache.ibatis.reflection.invoker.SetFieldInvoker;
  45. import org.apache.ibatis.reflection.property.PropertyNamer;
  46. import org.apache.ibatis.util.MapUtil;

  48. /**
  49.  * This class represents a cached set of class definition information that
  50.  * allows for easy mapping between property names and getter/setter methods.
  51.  *
  52.  * @author Clinton Begin
  53.  */
  54. public class Reflector {

  56.   private static final MethodHandle isRecordMethodHandle = getIsRecordMethodHandle();
  57.   private final Class<?> type;
  58.   private final String[] readablePropertyNames;
  59.   private final String[] writablePropertyNames;
  60.   private final Map<String, Invoker> setMethods = new HashMap<>();
  61.   private final Map<String, Invoker> getMethods = new HashMap<>();
  62.   private final Map<String, Class<?>> setTypes = new HashMap<>();
  63.   private final Map<String, Class<?>> getTypes = new HashMap<>();
  64.   private Constructor<?> defaultConstructor;

  66.   private Map<String, String> caseInsensitivePropertyMap = new HashMap<>();

  68.   public Reflector(Class<?> clazz) {
  69.     type = clazz;
  70.     addDefaultConstructor(clazz);
  71.     Method[] classMethods = getClassMethods(clazz);
  72.     if (isRecord(type)) {
  73.       addRecordGetMethods(classMethods);
  74.     } else {
  75.       addGetMethods(classMethods);
  76.       addSetMethods(classMethods);
  77.       addFields(clazz);
  78.     }
  79.     readablePropertyNames = getMethods.keySet().toArray(new String[0]);
  80.     writablePropertyNames = setMethods.keySet().toArray(new String[0]);
  81.     for (String propName : readablePropertyNames) {
  82.       caseInsensitivePropertyMap.put(propName.toUpperCase(Locale.ENGLISH), propName);
  83.     }
  84.     for (String propName : writablePropertyNames) {
  85.       caseInsensitivePropertyMap.put(propName.toUpperCase(Locale.ENGLISH), propName);
  86.     }
  87.   }

  89.   private void addRecordGetMethods(Method[] methods) {
  90.     Arrays.stream(methods).filter(m -> m.getParameterTypes().length == 0)
  91.       .forEach(m -> addGetMethod(m.getName(), m, false));
  92.   }

  94.   private void addDefaultConstructor(Class<?> clazz) {
  95.     Constructor<?>[] constructors = clazz.getDeclaredConstructors();
  96.     Arrays.stream(constructors).filter(constructor -> constructor.getParameterTypes().length == 0)
  97.       .findAny().ifPresent(constructor -> this.defaultConstructor = constructor);
  98.   }

  100.   private void addGetMethods(Method[] methods) {
  101.     Map<String, List<Method>> conflictingGetters = new HashMap<>();
  102.     Arrays.stream(methods).filter(m -> m.getParameterTypes().length == 0 && PropertyNamer.isGetter(m.getName()))
  103.       .forEach(m -> addMethodConflict(conflictingGetters, PropertyNamer.methodToProperty(m.getName()), m));
  104.     resolveGetterConflicts(conflictingGetters);
  105.   }

  107.   private void resolveGetterConflicts(Map<String, List<Method>> conflictingGetters) {
  108.     for (Entry<String, List<Method>> entry : conflictingGetters.entrySet()) {
  109.       Method winner = null;
  110.       String propName = entry.getKey();
  111.       boolean isAmbiguous = false;
  112.       for (Method candidate : entry.getValue()) {
  113.         if (winner == null) {
  114.           winner = candidate;
  115.           continue;
  116.         }
  117.         Class<?> winnerType = winner.getReturnType();
  118.         Class<?> candidateType = candidate.getReturnType();
  119.         if (candidateType.equals(winnerType)) {
  120.           if (!boolean.class.equals(candidateType)) {
  121.             isAmbiguous = true;
  122.             break;
  123.           } else if (candidate.getName().startsWith("is")) {
  124.             winner = candidate;
  125.           }
  126.         } else if (candidateType.isAssignableFrom(winnerType)) {
  127.           // OK getter type is descendant
  128.         } else if (winnerType.isAssignableFrom(candidateType)) {
  129.           winner = candidate;
  130.         } else {
  131.           isAmbiguous = true;
  132.           break;
  133.         }
  134.       }
  135.       addGetMethod(propName, winner, isAmbiguous);
  136.     }
  137.   }

  139.   private void addGetMethod(String name, Method method, boolean isAmbiguous) {
  140.     MethodInvoker invoker = isAmbiguous
  141.         ? new AmbiguousMethodInvoker(method, MessageFormat.format(
  142.             "Illegal overloaded getter method with ambiguous type for property ''{0}'' in class ''{1}''. This breaks the JavaBeans specification and can cause unpredictable results.",
  143.             name, method.getDeclaringClass().getName()))
  144.         : new MethodInvoker(method);
  145.     getMethods.put(name, invoker);
  146.     Type returnType = TypeParameterResolver.resolveReturnType(method, type);
  147.     getTypes.put(name, typeToClass(returnType));
  148.   }

  150.   private void addSetMethods(Method[] methods) {
  151.     Map<String, List<Method>> conflictingSetters = new HashMap<>();
  152.     Arrays.stream(methods).filter(m -> m.getParameterTypes().length == 1 && PropertyNamer.isSetter(m.getName()))
  153.       .forEach(m -> addMethodConflict(conflictingSetters, PropertyNamer.methodToProperty(m.getName()), m));
  154.     resolveSetterConflicts(conflictingSetters);
  155.   }

  157.   private void addMethodConflict(Map<String, List<Method>> conflictingMethods, String name, Method method) {
  158.     if (isValidPropertyName(name)) {
  159.       List<Method> list = MapUtil.computeIfAbsent(conflictingMethods, name, k -> new ArrayList<>());
  160.       list.add(method);
  161.     }
  162.   }

  164.   private void resolveSetterConflicts(Map<String, List<Method>> conflictingSetters) {
  165.     for (Entry<String, List<Method>> entry : conflictingSetters.entrySet()) {
  166.       String propName = entry.getKey();
  167.       List<Method> setters = entry.getValue();
  168.       Class<?> getterType = getTypes.get(propName);
  169.       boolean isGetterAmbiguous = getMethods.get(propName) instanceof AmbiguousMethodInvoker;
  170.       boolean isSetterAmbiguous = false;
  171.       Method match = null;
  172.       for (Method setter : setters) {
  173.         if (!isGetterAmbiguous && setter.getParameterTypes()[0].equals(getterType)) {
  174.           // should be the best match
  175.           match = setter;
  176.           break;
  177.         }
  178.         if (!isSetterAmbiguous) {
  179.           match = pickBetterSetter(match, setter, propName);
  180.           isSetterAmbiguous = match == null;
  181.         }
  182.       }
  183.       if (match != null) {
  184.         addSetMethod(propName, match);
  185.       }
  186.     }
  187.   }

  189.   private Method pickBetterSetter(Method setter1, Method setter2, String property) {
  190.     if (setter1 == null) {
  191.       return setter2;
  192.     }
  193.     Class<?> paramType1 = setter1.getParameterTypes()[0];
  194.     Class<?> paramType2 = setter2.getParameterTypes()[0];
  195.     if (paramType1.isAssignableFrom(paramType2)) {
  196.       return setter2;
  197.     } else if (paramType2.isAssignableFrom(paramType1)) {
  198.       return setter1;
  199.     }
  200.     MethodInvoker invoker = new AmbiguousMethodInvoker(setter1,
  201.         MessageFormat.format(
  202.             "Ambiguous setters defined for property ''{0}'' in class ''{1}'' with types ''{2}'' and ''{3}''.",
  203.             property, setter2.getDeclaringClass().getName(), paramType1.getName(), paramType2.getName()));
  204.     setMethods.put(property, invoker);
  205.     Type[] paramTypes = TypeParameterResolver.resolveParamTypes(setter1, type);
  206.     setTypes.put(property, typeToClass(paramTypes[0]));
  207.     return null;
  208.   }

  210.   private void addSetMethod(String name, Method method) {
  211.     MethodInvoker invoker = new MethodInvoker(method);
  212.     setMethods.put(name, invoker);
  213.     Type[] paramTypes = TypeParameterResolver.resolveParamTypes(method, type);
  214.     setTypes.put(name, typeToClass(paramTypes[0]));
  215.   }

  217.   private Class<?> typeToClass(Type src) {
  218.     Class<?> result = null;
  219.     if (src instanceof Class) {
  220.       result = (Class<?>) src;
  221.     } else if (src instanceof ParameterizedType) {
  222.       result = (Class<?>) ((ParameterizedType) src).getRawType();
  223.     } else if (src instanceof GenericArrayType) {
  224.       Type componentType = ((GenericArrayType) src).getGenericComponentType();
  225.       if (componentType instanceof Class) {
  226.         result = Array.newInstance((Class<?>) componentType, 0).getClass();
  227.       } else {
  228.         Class<?> componentClass = typeToClass(componentType);
  229.         result = Array.newInstance(componentClass, 0).getClass();
  230.       }
  231.     }
  232.     if (result == null) {
  233.       result = Object.class;
  234.     }
  235.     return result;
  236.   }

  238.   private void addFields(Class<?> clazz) {
  239.     Field[] fields = clazz.getDeclaredFields();
  240.     for (Field field : fields) {
  241.       if (!setMethods.containsKey(field.getName())) {
  242.         // issue #379 - removed the check for final because JDK 1.5 allows
  243.         // modification of final fields through reflection (JSR-133). (JGB)
  244.         // pr #16 - final static can only be set by the classloader
  245.         int modifiers = field.getModifiers();
  246.         if (!(Modifier.isFinal(modifiers) && Modifier.isStatic(modifiers))) {
  247.           addSetField(field);
  248.         }
  249.       }
  250.       if (!getMethods.containsKey(field.getName())) {
  251.         addGetField(field);
  252.       }
  253.     }
  254.     if (clazz.getSuperclass() != null) {
  255.       addFields(clazz.getSuperclass());
  256.     }
  257.   }

  259.   private void addSetField(Field field) {
  260.     if (isValidPropertyName(field.getName())) {
  261.       setMethods.put(field.getName(), new SetFieldInvoker(field));
  262.       Type fieldType = TypeParameterResolver.resolveFieldType(field, type);
  263.       setTypes.put(field.getName(), typeToClass(fieldType));
  264.     }
  265.   }

  267.   private void addGetField(Field field) {
  268.     if (isValidPropertyName(field.getName())) {
  269.       getMethods.put(field.getName(), new GetFieldInvoker(field));
  270.       Type fieldType = TypeParameterResolver.resolveFieldType(field, type);
  271.       getTypes.put(field.getName(), typeToClass(fieldType));
  272.     }
  273.   }

  275.   private boolean isValidPropertyName(String name) {
  276.     return !(name.startsWith("$") || "serialVersionUID".equals(name) || "class".equals(name));
  277.   }

  279.   /**
  280.    * This method returns an array containing all methods
  281.    * declared in this class and any superclass.
  282.    * We use this method, instead of the simpler <code>Class.getMethods()</code>,
  283.    * because we want to look for private methods as well.
  284.    *
  285.    * @param clazz The class
  286.    * @return An array containing all methods in this class
  287.    */
  288.   private Method[] getClassMethods(Class<?> clazz) {
  289.     Map<String, Method> uniqueMethods = new HashMap<>();
  290.     Class<?> currentClass = clazz;
  291.     while (currentClass != null && currentClass != Object.class) {
  292.       addUniqueMethods(uniqueMethods, currentClass.getDeclaredMethods());

  294.       // we also need to look for interface methods -
  295.       // because the class may be abstract
  296.       Class<?>[] interfaces = currentClass.getInterfaces();
  297.       for (Class<?> anInterface : interfaces) {
  298.         addUniqueMethods(uniqueMethods, anInterface.getMethods());
  299.       }

  301.       currentClass = currentClass.getSuperclass();
  302.     }

  304.     Collection<Method> methods = uniqueMethods.values();

  306.     return methods.toArray(new Method[0]);
  307.   }

  309.   private void addUniqueMethods(Map<String, Method> uniqueMethods, Method[] methods) {
  310.     for (Method currentMethod : methods) {
  311.       if (!currentMethod.isBridge()) {
  312.         String signature = getSignature(currentMethod);
  313.         // check to see if the method is already known
  314.         // if it is known, then an extended class must have
  315.         // overridden a method
  316.         if (!uniqueMethods.containsKey(signature)) {
  317.           uniqueMethods.put(signature, currentMethod);
  318.         }
  319.       }
  320.     }
  321.   }

  323.   private String getSignature(Method method) {
  324.     StringBuilder sb = new StringBuilder();
  325.     Class<?> returnType = method.getReturnType();
  326.     if (returnType != null) {
  327.       sb.append(returnType.getName()).append('#');
  328.     }
  329.     sb.append(method.getName());
  330.     Class<?>[] parameters = method.getParameterTypes();
  331.     for (int i = 0; i < parameters.length; i++) {
  332.       sb.append(i == 0 ? ':' : ',').append(parameters[i].getName());
  333.     }
  334.     return sb.toString();
  335.   }

  337.   /**
  338.    * Checks whether can control member accessible.
  339.    *
  340.    * @return If can control member accessible, it return {@literal true}
  341.    * @since 3.5.0
  342.    */
  343.   public static boolean canControlMemberAccessible() {
  344.     try {
  345.       SecurityManager securityManager = System.getSecurityManager();
  346.       if (null != securityManager) {
  347.         securityManager.checkPermission(new ReflectPermission("suppressAccessChecks"));
  348.       }
  349.     } catch (SecurityException e) {
  350.       return false;
  351.     }
  352.     return true;
  353.   }

  355.   /**
  356.    * Gets the name of the class the instance provides information for.
  357.    *
  358.    * @return The class name
  359.    */
  360.   public Class<?> getType() {
  361.     return type;
  362.   }

  364.   public Constructor<?> getDefaultConstructor() {
  365.     if (defaultConstructor != null) {
  366.       return defaultConstructor;
  367.     } else {
  368.       throw new ReflectionException("There is no default constructor for " + type);
  369.     }
  370.   }

  372.   public boolean hasDefaultConstructor() {
  373.     return defaultConstructor != null;
  374.   }

  376.   public Invoker getSetInvoker(String propertyName) {
  377.     Invoker method = setMethods.get(propertyName);
  378.     if (method == null) {
  379.       throw new ReflectionException("There is no setter for property named '" + propertyName + "' in '" + type + "'");
  380.     }
  381.     return method;
  382.   }

  384.   public Invoker getGetInvoker(String propertyName) {
  385.     Invoker method = getMethods.get(propertyName);
  386.     if (method == null) {
  387.       throw new ReflectionException("There is no getter for property named '" + propertyName + "' in '" + type + "'");
  388.     }
  389.     return method;
  390.   }

  392.   /**
  393.    * Gets the type for a property setter.
  394.    *
  395.    * @param propertyName - the name of the property
  396.    * @return The Class of the property setter
  397.    */
  398.   public Class<?> getSetterType(String propertyName) {
  399.     Class<?> clazz = setTypes.get(propertyName);
  400.     if (clazz == null) {
  401.       throw new ReflectionException("There is no setter for property named '" + propertyName + "' in '" + type + "'");
  402.     }
  403.     return clazz;
  404.   }

  406.   /**
  407.    * Gets the type for a property getter.
  408.    *
  409.    * @param propertyName - the name of the property
  410.    * @return The Class of the property getter
  411.    */
  412.   public Class<?> getGetterType(String propertyName) {
  413.     Class<?> clazz = getTypes.get(propertyName);
  414.     if (clazz == null) {
  415.       throw new ReflectionException("There is no getter for property named '" + propertyName + "' in '" + type + "'");
  416.     }
  417.     return clazz;
  418.   }

  420.   /**
  421.    * Gets an array of the readable properties for an object.
  422.    *
  423.    * @return The array
  424.    */
  425.   public String[] getGetablePropertyNames() {
  426.     return readablePropertyNames;
  427.   }

  429.   /**
  430.    * Gets an array of the writable properties for an object.
  431.    *
  432.    * @return The array
  433.    */
  434.   public String[] getSetablePropertyNames() {
  435.     return writablePropertyNames;
  436.   }

  438.   /**
  439.    * Check to see if a class has a writable property by name.
  440.    *
  441.    * @param propertyName - the name of the property to check
  442.    * @return True if the object has a writable property by the name
  443.    */
  444.   public boolean hasSetter(String propertyName) {
  445.     return setMethods.containsKey(propertyName);
  446.   }

  448.   /**
  449.    * Check to see if a class has a readable property by name.
  450.    *
  451.    * @param propertyName - the name of the property to check
  452.    * @return True if the object has a readable property by the name
  453.    */
  454.   public boolean hasGetter(String propertyName) {
  455.     return getMethods.containsKey(propertyName);
  456.   }

  458.   public String findPropertyName(String name) {
  459.     return caseInsensitivePropertyMap.get(name.toUpperCase(Locale.ENGLISH));
  460.   }

  462.   /**
  463.    * Class.isRecord() alternative for Java 15 and older.
  464.    */
  465.   private static boolean isRecord(Class<?> clazz) {
  466.     try {
  467.       return isRecordMethodHandle != null && (boolean)isRecordMethodHandle.invokeExact(clazz);
  468.     } catch (Throwable e) {
  469.       throw new ReflectionException("Failed to invoke 'Class.isRecord()'.", e);
  470.     }
  471.   }

  473.   private static MethodHandle getIsRecordMethodHandle() {
  474.     MethodHandles.Lookup lookup = MethodHandles.lookup();
  475.     MethodType mt = MethodType.methodType(boolean.class);
  476.     try {
  477.       return lookup.findVirtual(Class.class, "isRecord", mt);
  478.     } catch (NoSuchMethodException | IllegalAccessException e) {
  479.       return null;
  480.     }
  481.   }
  482. }
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