Spring 中一个常用的反射类库ReflectionUtils

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在项目中部分方法采用反射，通过类访问类的属性，通过类反问方法，通过属性访问方法。以及常用异常的处理在等可以使用反射出处理。

public abstract class ReflectionUtils {  /**根据类和属性名称查找属性字段  * Attempt to find a {@link Field field} on the supplied {@link Class} with  * the supplied <code>name</code>. Searches all superclasses up to {@link Object}.  * @param clazz the class to introspect  * @param name the name of the field  * @return the corresponding Field object, or <code>null</code> if not found  */ public static Field findField(Class clazz, String name) {  return findField(clazz, name, null); }  /**根据类和属性名称查找属性字段  * Attempt to find a {@link Field field} on the supplied {@link Class} with  * the supplied <code>name</code> and/or {@link Class type}. Searches all  * superclasses up to {@link Object}.  * @param clazz the class to introspect  * @param name the name of the field (may be <code>null</code> if type is specified)  * @param type the type of the field (may be <code>null</code> if name is specified)  * @return the corresponding Field object, or <code>null</code> if not found  */ public static Field findField(Class clazz, String name, Class type) {  Assert.notNull(clazz, "Class must not be null");  Assert.isTrue(name != null || type != null, "Either name or type of the field must be specified");  Class searchType = clazz;  while (!Object.class.equals(searchType) && searchType != null) {   Field[] fields = searchType.getDeclaredFields();   for (int i = 0; i < fields.length; i++) {    Field field = fields;    if ((name == null || name.equals(field.getName()))      && (type == null || type.equals(field.getType()))) {     return field;    }   }   searchType = searchType.getSuperclass();  }  return null; }  /**根据属性字段和对象，设置对象的值  * Set the field represented by the supplied {@link Field field object} on  * the specified {@link Object target object} to the specified  * <code>value</code>. In accordance with  * {@link Field#set(Object, Object)} semantics, the new value is  * automatically unwrapped if the underlying field has a primitive type.  * <p>Thrown exceptions are handled via a call to  * {@link #handleReflectionException(Exception)}.  * @param field the field to set  * @param target the target object on which to set the field  * @param value the value to set; may be <code>null</code>  */ public static void setField(Field field, Object target, Object value) {  try {   field.set(target, value);  }  catch (IllegalAccessException ex) {   handleReflectionException(ex);   throw new IllegalStateException(     "Unexpected reflection exception - " + ex.getClass().getName() + ": " + ex.getMessage());  } }  /**根据属性字段和对象，获取的对象中字段的值  * Get the field represented by the supplied {@link Field field object} on  * the specified {@link Object target object}. In accordance with  * {@link Field#get(Object)} semantics, the returned value is  * automatically wrapped if the underlying field has a primitive type.  * <p>Thrown exceptions are handled via a call to  * {@link #handleReflectionException(Exception)}.  * @param field the field to get  * @param target the target object from which to get the field  * @return the field's current value  */ public static Object getField(Field field, Object target) {  try {   return field.get(target);  }  catch (IllegalAccessException ex) {   handleReflectionException(ex);   throw new IllegalStateException(     "Unexpected reflection exception - " + ex.getClass().getName() + ": " + ex.getMessage());  } }  /**根据类，方法名称和参数类型查找方法  * Attempt to find a {@link Method} on the supplied class with the supplied name  * and no parameters. Searches all superclasses up to <code>Object</code>.  * <p>Returns <code>null</code> if no {@link Method} can be found.  * @param clazz the class to introspect  * @param name the name of the method  * @return the Method object, or <code>null</code> if none found  */ public static Method findMethod(Class clazz, String name) {  return findMethod(clazz, name, new Class[0]); }  /**根据类，方法名称和参数类型查找方法  * Attempt to find a {@link Method} on the supplied class with the supplied name  * and parameter types. Searches all superclasses up to <code>Object</code>.  * <p>Returns <code>null</code> if no {@link Method} can be found.  * @param clazz the class to introspect  * @param name the name of the method  * @param paramTypes the parameter types of the method  * (may be <code>null</code> to indicate any signature)  * @return the Method object, or <code>null</code> if none found  */ public static Method findMethod(Class clazz, String name, Class[] paramTypes) {  Assert.notNull(clazz, "Class must not be null");  Assert.notNull(name, "Method name must not be null");  Class searchType = clazz;  while (!Object.class.equals(searchType) && searchType != null) {   Method[] methods = (searchType.isInterface() ? searchType.getMethods() : searchType.getDeclaredMethods());   for (int i = 0; i < methods.length; i++) {    Method method = methods;    if (name.equals(method.getName()) &&      (paramTypes == null || Arrays.equals(paramTypes, method.getParameterTypes()))) {     return method;    }   }   searchType = searchType.getSuperclass();  }  return null; }   /**调用方法的应用  * Invoke the specified {@link Method} against the supplied target object  * with no arguments. The target object can be <code>null</code> when  * invoking a static {@link Method}.  * <p>Thrown exceptions are handled via a call to {@link #handleReflectionException}.  * @param method the method to invoke  * @param target the target object to invoke the method on  * @return the invocation result, if any  * @see #invokeMethod(java.lang.reflect.Method, Object, Object[])  */ public static Object invokeMethod(Method method, Object target) {  return invokeMethod(method, target, null); }  /**调用方法的应用  * Invoke the specified {@link Method} against the supplied target object  * with the supplied arguments. The target object can be <code>null</code>  * when invoking a static {@link Method}.  * <p>Thrown exceptions are handled via a call to {@link #handleReflectionException}.  * @param method the method to invoke  * @param target the target object to invoke the method on  * @param args the invocation arguments (may be <code>null</code>)  * @return the invocation result, if any  */ public static Object invokeMethod(Method method, Object target, Object[] args) {  try {   return method.invoke(target, args);  }  catch (Exception ex) {   handleReflectionException(ex);  }  throw new IllegalStateException("Should never get here"); }  /**  * Invoke the specified JDBC API {@link Method} against the supplied  * target object with no arguments.  * @param method the method to invoke  * @param target the target object to invoke the method on  * @return the invocation result, if any  * @throws SQLException the JDBC API SQLException to rethrow (if any)  * @see #invokeJdbcMethod(java.lang.reflect.Method, Object, Object[])  */ public static Object invokeJdbcMethod(Method method, Object target) throws SQLException {  return invokeJdbcMethod(method, target, null); } /**  * Invoke the specified JDBC API {@link Method} against the supplied  * target object with the supplied arguments.  * @param method the method to invoke  * @param target the target object to invoke the method on  * @param args the invocation arguments (may be <code>null</code>)  * @return the invocation result, if any  * @throws SQLException the JDBC API SQLException to rethrow (if any)  * @see #invokeMethod(java.lang.reflect.Method, Object, Object[])  */ public static Object invokeJdbcMethod(Method method, Object target, Object[] args) throws SQLException {  try {   return method.invoke(target, args);  }  catch (IllegalAccessException ex) {   handleReflectionException(ex);  }  catch (InvocationTargetException ex) {   if (ex.getTargetException() instanceof SQLException) {    throw (SQLException) ex.getTargetException();   }   handleInvocationTargetException(ex);  }  throw new IllegalStateException("Should never get here"); } /**************************************************************** 处理异常的方法****************************************************************/ /** 使用反射处理异常的将异常信息输出但不抛出方法以外  * Handle the given reflection exception. Should only be called if  * no checked exception is expected to be thrown by the target method.  * <p>Throws the underlying RuntimeException or Error in case of an  * InvocationTargetException with such a root cause. Throws an  * IllegalStateException with an appropriate message else.  * @param ex the reflection exception to handle  */ public static void handleReflectionException(Exception ex) {  if (ex instanceof NoSuchMethodException) {   throw new IllegalStateException("Method not found: " + ex.getMessage());  }  if (ex instanceof IllegalAccessException) {   throw new IllegalStateException("Could not access method: " + ex.getMessage());  }  if (ex instanceof InvocationTargetException) {   handleInvocationTargetException((InvocationTargetException) ex);  }  if (ex instanceof RuntimeException) {   throw (RuntimeException) ex;  }  handleUnexpectedException(ex); }   /**    * Handle the given invocation target exception. Should only be called if  * no checked exception is expected to be thrown by the target method.  * <p>Throws the underlying RuntimeException or Error in case of such  * a root cause. Throws an IllegalStateException else.  * @param ex the invocation target exception to handle  */ public static void handleInvocationTargetException(InvocationTargetException ex) {  rethrowRuntimeException(ex.getTargetException()); }  /**  * Rethrow the given {@link Throwable exception}, which is presumably the  * <em>target exception</em> of an {@link InvocationTargetException}.  * Should only be called if no checked exception is expected to be thrown by  * the target method.  * <p>Rethrows the underlying exception cast to an {@link RuntimeException}  * or {@link Error} if appropriate; otherwise, throws an  * {@link IllegalStateException}.  * @param ex the exception to rethrow  * @throws RuntimeException the rethrown exception  */ public static void rethrowRuntimeException(Throwable ex) {  if (ex instanceof RuntimeException) {   throw (RuntimeException) ex;  }  if (ex instanceof Error) {   throw (Error) ex;  }  handleUnexpectedException(ex); } /**  * Rethrow the given {@link Throwable exception}, which is presumably the  * <em>target exception</em> of an {@link InvocationTargetException}.  * Should only be called if no checked exception is expected to be thrown by  * the target method.  * <p>Rethrows the underlying exception cast to an {@link Exception} or  * {@link Error} if appropriate; otherwise, throws an  * {@link IllegalStateException}.  * @param ex the exception to rethrow  * @throws Exception the rethrown exception (in case of a checked exception)  */ public static void rethrowException(Throwable ex) throws Exception {  if (ex instanceof Exception) {   throw (Exception) ex;  }  if (ex instanceof Error) {   throw (Error) ex;  }  handleUnexpectedException(ex); } /**  * Throws an IllegalStateException with the given exception as root cause.  * @param ex the unexpected exception  */ private static void handleUnexpectedException(Throwable ex) {  // Needs to avoid the chained constructor for JDK 1.4 compatibility.  IllegalStateException isex = new IllegalStateException("Unexpected exception thrown");  isex.initCause(ex);  throw isex; }     /**  * Determine whether the given method explicitly declares the given exception  * or one of its superclasses, which means that an exception of that type  * can be propagated as-is within a reflective invocation.  * @param method the declaring method  * @param exceptionType the exception to throw  * @return <code>true</code> if the exception can be thrown as-is;  * <code>false</code> if it needs to be wrapped  */ public static boolean declaresException(Method method, Class exceptionType) {  Assert.notNull(method, "Method must not be null");  Class[] declaredExceptions = method.getExceptionTypes();  for (int i = 0; i < declaredExceptions.length; i++) {   Class declaredException = declaredExceptions;   if (declaredException.isAssignableFrom(exceptionType)) {    return true;   }  }  return false; } /****************************************************************  判断方法，属性字段等的修饰符的方法*************************************************************/ /**  * Determine whether the given field is a "public static final" constant.  * @param field the field to check  */ public static boolean isPublicStaticFinal(Field field) {  int modifiers = field.getModifiers();  return (Modifier.isPublic(modifiers) && Modifier.isStatic(modifiers) && Modifier.isFinal(modifiers)); } /**  * Determine whether the given method is an "equals" method.  * @see java.lang.Object#equals  */ public static boolean isEqualsMethod(Method method) {  if (method == null || !method.getName().equals("equals")) {   return false;  }  Class[] paramTypes = method.getParameterTypes();  return (paramTypes.length == 1 && paramTypes[0] == Object.class); } /**  * Determine whether the given method is a "hashCode" method.  * @see java.lang.Object#hashCode  */ public static boolean isHashCodeMethod(Method method) {  return (method != null && method.getName().equals("hashCode") &&    method.getParameterTypes().length == 0); } /**  * Determine whether the given method is a "toString" method.  * @see java.lang.Object#toString()  */ public static boolean isToStringMethod(Method method) {  return (method != null && method.getName().equals("toString") &&    method.getParameterTypes().length == 0); }   /**  判断一个属性是否可以访问的方法    * Make the given field accessible, explicitly setting it accessible if necessary.  * The <code>setAccessible(true)</code> method is only called when actually necessary,  * to avoid unnecessary conflicts with a JVM SecurityManager (if active).  * @param field the field to make accessible  * @see java.lang.reflect.Field#setAccessible  */ public static void makeAccessible(Field field) {  if (!Modifier.isPublic(field.getModifiers()) ||    !Modifier.isPublic(field.getDeclaringClass().getModifiers())) {   field.setAccessible(true);  } }  /**  判断一个方法是否可以访问的方法    * Make the given method accessible, explicitly setting it accessible if necessary.  * The <code>setAccessible(true)</code> method is only called when actually necessary,  * to avoid unnecessary conflicts with a JVM SecurityManager (if active).  * @param method the method to make accessible  * @see java.lang.reflect.Method#setAccessible  */ public static void makeAccessible(Method method) {  if (!Modifier.isPublic(method.getModifiers()) ||    !Modifier.isPublic(method.getDeclaringClass().getModifiers())) {   method.setAccessible(true);  } }  /**  判断一个构造函数是否可以访问的方法    * Make the given constructor accessible, explicitly setting it accessible if necessary.  * The <code>setAccessible(true)</code> method is only called when actually necessary,  * to avoid unnecessary conflicts with a JVM SecurityManager (if active).  * @param ctor the constructor to make accessible  * @see java.lang.reflect.Constructor#setAccessible  */ public static void makeAccessible(Constructor ctor) {  if (!Modifier.isPublic(ctor.getModifiers()) ||    !Modifier.isPublic(ctor.getDeclaringClass().getModifiers())) {   ctor.setAccessible(true);  } } /**  * Perform the given callback operation on all matching methods of the  * given class and superclasses.  * <p>The same named method occurring on subclass and superclass will  * appear twice, unless excluded by a {@link MethodFilter}.  * @param targetClass class to start looking at  * @param mc the callback to invoke for each method  * @see #doWithMethods(Class, MethodCallback, MethodFilter)  */ public static void doWithMethods(Class targetClass, MethodCallback mc) throws IllegalArgumentException {  doWithMethods(targetClass, mc, null); }   /**  * Perform the given callback operation on all matching methods of the  * given class and superclasses.  * <p>The same named method occurring on subclass and superclass will  * appear twice, unless excluded by the specified {@link MethodFilter}.  * @param targetClass class to start looking at  * @param mc the callback to invoke for each method  * @param mf the filter that determines the methods to apply the callback to  */ public static void doWithMethods(Class targetClass, MethodCallback mc, MethodFilter mf)   throws IllegalArgumentException {  // Keep backing up the inheritance hierarchy.  do {   Method[] methods = targetClass.getDeclaredMethods();   for (int i = 0; i < methods.length; i++) {    if (mf != null && !mf.matches(methods)) {     continue;    }    try {     mc.doWith(methods);    }    catch (IllegalAccessException ex) {     throw new IllegalStateException(       "Shouldn't be illegal to access method '" + methods.getName() + "': " + ex);    }   }   targetClass = targetClass.getSuperclass();  }  while (targetClass != null); } /**获取类的所有的方法的  * Get all declared methods on the leaf class and all superclasses.  * Leaf class methods are included first.  */ public static Method[] getAllDeclaredMethods(Class leafClass) throws IllegalArgumentException {  final List list = new ArrayList(32);  doWithMethods(leafClass, new MethodCallback() {   public void doWith(Method method) {    list.add(method);   }  });  return (Method[]) list.toArray(new Method[list.size()]); }  /**调用字段时执行的回调的方法  * Invoke the given callback on all fields in the target class,  * going up the class hierarchy to get all declared fields.  * @param targetClass the target class to analyze  * @param fc the callback to invoke for each field  */ public static void doWithFields(Class targetClass, FieldCallback fc) throws IllegalArgumentException {  doWithFields(targetClass, fc, null); }  /**调用字段时执行的回调的并过滤的方法  * Invoke the given callback on all fields in the target class,  * going up the class hierarchy to get all declared fields.  * @param targetClass the target class to analyze  * @param fc the callback to invoke for each field  * @param ff the filter that determines the fields to apply the callback to  */ public static void doWithFields(Class targetClass, FieldCallback fc, FieldFilter ff)   throws IllegalArgumentException {  // Keep backing up the inheritance hierarchy.  do {   // Copy each field declared on this class unless it's static or file.   Field[] fields = targetClass.getDeclaredFields();   for (int i = 0; i < fields.length; i++) {    // Skip static and final fields.    if (ff != null && !ff.matches(fields)) {     continue;    }    try {     fc.doWith(fields);    }    catch (IllegalAccessException ex) {     throw new IllegalStateException(       "Shouldn't be illegal to access field '" + fields.getName() + "': " + ex);    }   }   targetClass = targetClass.getSuperclass();  }  while (targetClass != null && targetClass != Object.class); }   /**用于对象的拷贝的方法（类必须是同一类或子类）  * Given the source object and the destination, which must be the same class  * or a subclass, copy all fields, including inherited fields. Designed to  * work on objects with public no-arg constructors.  * @throws IllegalArgumentException if the arguments are incompatible  */ public static void shallowCopyFieldState(final Object src, final Object dest) throws IllegalArgumentException {  if (src == null) {   throw new IllegalArgumentException("Source for field copy cannot be null");  }  if (dest == null) {   throw new IllegalArgumentException("Destination for field copy cannot be null");  }  if (!src.getClass().isAssignableFrom(dest.getClass())) {   throw new IllegalArgumentException("Destination class [" + dest.getClass().getName() +     "] must be same or subclass as source class [" + src.getClass().getName() + "]");  }  doWithFields(src.getClass(), new FieldCallback() {   public void doWith(Field field) throws IllegalArgumentException, IllegalAccessException {    makeAccessible(field);    Object srcValue = field.get(src);    field.set(dest, srcValue);   }  }, COPYABLE_FIELDS); }  /**  * Action to take on each method.  */ public static interface MethodCallback {  /**   * Perform an operation using the given method.   * @param method the method to operate on   */  void doWith(Method method) throws IllegalArgumentException, IllegalAccessException; } /**  * Callback optionally used to method fields to be operated on by a method callback.  */ public static interface MethodFilter {  /**   * Determine whether the given method matches.   * @param method the method to check   */  boolean matches(Method method); } /**  * Callback interface invoked on each field in the hierarchy.  */ public static interface FieldCallback {  /**   * Perform an operation using the given field.   * @param field the field to operate on   */  void doWith(Field field) throws IllegalArgumentException, IllegalAccessException; } /**  * Callback optionally used to filter fields to be operated on by a field callback.  */ public static interface FieldFilter {  /**   * Determine whether the given field matches.   * @param field the field to check   */  boolean matches(Field field); } /**  * Pre-built FieldFilter that matches all non-static, non-final fields.  */ public static FieldFilter COPYABLE_FIELDS = new FieldFilter() {  public boolean matches(Field field) {   return !(Modifier.isStatic(field.getModifiers()) ||     Modifier.isFinal(field.getModifiers()));  } };}