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[i];
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[i];
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[i];
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[i])) {
continue;
}
try {
mc.doWith(methods[i]);
}
catch (IllegalAccessException ex) {
throw new IllegalStateException(
"Shouldn't be illegal to access method '" + methods[i].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[i])) {
continue;
}
try {
fc.doWith(fields[i]);
}
catch (IllegalAccessException ex) {
throw new IllegalStateException(
"Shouldn't be illegal to access field '" + fields[i].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()));
}
};
}
