com.github.xphsc.lang.Reflections Maven / Gradle / Ivy
package com.github.xphsc.lang;
import com.github.xphsc.util.ClassUtil;
import com.github.xphsc.util.StringUtil;
import java.lang.reflect.*;
/**
* Created by ${huipei.x} on 2017-5-31.
*/
public class Reflections {
/**
* setter 前缀
*/
private static final String SETTER_PREFIX = "set";
/**
* getter 前缀
*/
private static final String GETTER_PREFIX = "get";
/**
* Logger
*/
private Reflections() {
throw new IllegalAccessError("Utility class");
}
public static T newInstance(Class clazz) {
Constructor[] constructors = getAllConstructorsOfClass(clazz, true);
if(constructors != null && constructors.length != 0) {
Object[] initParameters = getInitParameters(constructors[0].getParameterTypes());
try {
Object e = constructors[0].newInstance(initParameters);
return (T) e;
} catch (Exception var4) {
return null;
}
} else {
return null;
}
}
/**
* 调用Getter方法.
* 支持多级，如：对象名.对象名.方法
*
* @param obj the obj
* @param propertyName the property name
* @return the object
*/
public static Object invokeGetter(Object obj, String propertyName) {
Object object = obj;
for (String name : StringUtil.split(propertyName, ".")) {
String getterMethodName = GETTER_PREFIX + StringUtil.capitalize(name);
object = invokeMethod(object, getterMethodName, new Class[]{}, new Object[]{});
}
return object;
}
/**
* 调用Setter方法, 仅匹配方法名。
* 支持多级，如：对象名.对象名.方法
*
* @param obj the obj
* @param propertyName the property name
* @param value the value
*/
public static void invokeSetter(Object obj, String propertyName, Object value) {
Object object = obj;
String[] names = StringUtil.split(propertyName, ".");
for (int i = 0; i < names.length; i++) {
if (i < names.length - 1) {
String getterMethodName = GETTER_PREFIX + StringUtil.capitalize(names[i]);
object = invokeMethod(object, getterMethodName, new Class[]{}, new Object[]{});
} else {
String setterMethodName = SETTER_PREFIX + StringUtil.capitalize(names[i]);
invokeMethodByName(object, setterMethodName, new Object[]{value});
}
}
}
/**
* 直接读取对象属性值, 无视private/protected修饰符, 不经过getter函数.
*
* @param obj the obj
* @param fieldName the field name
* @return the field value
*/
public static Object getFieldValue(final Object obj, final String fieldName) {
Field field = getAccessibleField(obj, fieldName);
if (field == null) {
throw new IllegalArgumentException(String.format("Could not find field [%s] on target [%s]", fieldName, obj));
}
Object result = null;
try {
result = field.get(obj);
} catch (IllegalAccessException e) {
}
return result;
}
/**
* 直接设置对象属性值, 无视private/protected修饰符, 不经过setter函数.
*
* @param obj the obj
* @param fieldName the field name
* @param value the value
*/
public static void setFieldValue(final Object obj, final String fieldName, final Object value) {
Field field = getAccessibleField(obj, fieldName);
if (field == null) {
throw new IllegalArgumentException(String.format("Could not find field [%s] on target [%s]", fieldName, obj));
}
try {
field.set(obj, value);
} catch (IllegalAccessException e) {
}
}
/**
* 直接调用对象方法, 无视private/protected修饰符.
* 用于一次性调用的情况，否则应使用getAccessibleMethod()函数获得Method后反复调用.
* 同时匹配方法名+参数类型，
*
* @param obj the obj
* @param methodName the method name
* @param parameterTypes the parameter types
* @param args the args
* @return the object
*/
public static Object invokeMethod(final Object obj, final String methodName, final Class[] parameterTypes,
final Object[] args) {
Method method = getAccessibleMethod(obj, methodName, parameterTypes);
if (method == null) {
throw new IllegalArgumentException(String.format("Could not find method [%s] on target [%s]", methodName, obj));
}
try {
return method.invoke(obj, args);
} catch (Exception e) {
throw convertReflectionExceptionToUnchecked(e);
}
}
/**
* 直接调用对象方法, 无视private/protected修饰符，
* 用于一次性调用的情况，否则应使用getAccessibleMethodByName()函数获得Method后反复调用.
* 只匹配函数名，如果有多个同名函数调用第一个。
*
* @param obj the obj
* @param methodName the method name
* @param args the args
* @return the object
*/
public static Object invokeMethodByName(final Object obj, final String methodName, final Object[] args) {
Method method = getAccessibleMethodByName(obj, methodName);
if (method == null) {
throw new IllegalArgumentException("Could not find method [" + methodName + "] on target [" + obj + "]");
}
try {
return method.invoke(obj, args);
} catch (Exception e) {
throw convertReflectionExceptionToUnchecked(e);
}
}
/**
* 循环向上转型, 获取对象的DeclaredField, 并强制设置为可访问.
*
* 如向上转型到Object仍无法找到, 返回null.
*
* @param obj the obj
* @param fieldName the field name
* @return the accessible field
*/
public static Field getAccessibleField(final Object obj, final String fieldName) {
Validator.notNull(obj);
Validator.notBlank(fieldName);
for (Class superClass = obj.getClass(); superClass != Object.class; superClass = superClass.getSuperclass()) {
try {
Field field = superClass.getDeclaredField(fieldName);
makeAccessible(field);
return field;
} catch (NoSuchFieldException e) {
// Field不在当前类定义,继续向上转型
}
}
return null;
}
/**
* 循环向上转型, 获取对象的DeclaredMethod,并强制设置为可访问.
* 如向上转型到Object仍无法找到, 返回null.
* 匹配函数名+参数类型。
*
* 用于方法需要被多次调用的情况. 先使用本函数先取得Method,然后调用Method.invoke(Object obj, Object... args)
*
* @param obj the obj
* @param methodName the method name
* @param parameterTypes the parameter types
* @return the accessible method
*/
public static Method getAccessibleMethod(final Object obj, final String methodName,
final Class... parameterTypes) {
Validator.notNull(obj);
Validator.notBlank(methodName);
for (Class searchType = obj.getClass(); searchType != Object.class; searchType = searchType.getSuperclass()) {
try {
Method method = searchType.getDeclaredMethod(methodName, parameterTypes);
makeAccessible(method);
return method;
} catch (NoSuchMethodException e) {
// Method不在当前类定义,继续向上转型
}
}
return null;
}
/**
* 循环向上转型, 获取对象的DeclaredMethod,并强制设置为可访问.
* 如向上转型到Object仍无法找到, 返回null.
* 只匹配函数名。
*
* 用于方法需要被多次调用的情况. 先使用本函数先取得Method,然后调用Method.invoke(Object obj, Object... args)
*
* @param obj the obj
* @param methodName the method name
* @return the accessible method by name
*/
public static Method getAccessibleMethodByName(final Object obj, final String methodName) {
Validator.notNull(obj);
Validator.notBlank(methodName);
for (Class searchType = obj.getClass(); searchType != Object.class; searchType = searchType.getSuperclass()) {
Method[] methods = searchType.getDeclaredMethods();
for (Method method : methods) {
if (method.getName().equals(methodName)) {
makeAccessible(method);
return method;
}
}
}
return null;
}
/**
* 改变private/protected的方法为public，尽量不调用实际改动的语句，避免JDK的SecurityManager抱怨。
*
* @param method the method
*/
public static void makeAccessible(Method method) {
if ((!Modifier.isPublic(method.getModifiers()) || !Modifier.isPublic(method.getDeclaringClass().getModifiers()))
&& !method.isAccessible()) {
method.setAccessible(true);
}
}
/**
* 改变private/protected的成员变量为public，尽量不调用实际改动的语句，避免JDK的SecurityManager抱怨。
*
* @param field the field
*/
public static void makeAccessible(Field field) {
if ((!Modifier.isPublic(field.getModifiers()) || !Modifier.isPublic(field.getDeclaringClass().getModifiers()) || Modifier
.isFinal(field.getModifiers())) && !field.isAccessible()) {
field.setAccessible(true);
}
}
/**
* 通过反射, 获得Class定义中声明的泛型参数的类型, 注意泛型必须定义在父类处
* 如无法找到, 返回Object.class.
* eg.
* public UserDao extends HibernateDao
*
* @param the type parameter
* @param clazz The class to introspect
* @return the first generic declaration, or Object.class if cannot be determined
*/
@SuppressWarnings("unchecked")
public static Class getClassGenericType(final Class clazz) {
return getClassGenericType(clazz, 0);
}
/**
* 通过反射, 获得Class定义中声明的父类的泛型参数的类型.
* 如无法找到, 返回Object.class.
*
* 如public UserDao extends HibernateDao
*
* @param clazz clazz The class to introspect
* @param index the Index of the generic declaration,start from 0.
* @return the index generic declaration, or Object.class if cannot be determined
*/
public static Class getClassGenericType(final Class clazz, final int index) {
Type genType = clazz.getGenericSuperclass();
if (!(genType instanceof ParameterizedType)) {
return Object.class;
}
Type[] params = ((ParameterizedType) genType).getActualTypeArguments();
if (index >= params.length || index < 0) {
return Object.class;
}
if (!(params[index] instanceof Class)) {
return Object.class;
}
return (Class) params[index];
}
/**
* 将反射时的checked exception转换为unchecked exception.
*
* @param e the e
* @return the runtime exception
*/
public static RuntimeException convertReflectionExceptionToUnchecked(Exception e) {
if (e instanceof IllegalAccessException || e instanceof IllegalArgumentException
|| e instanceof NoSuchMethodException) {
return new IllegalArgumentException(e);
} else if (e instanceof InvocationTargetException) {
return new RuntimeException(((InvocationTargetException) e).getTargetException());
} else if (e instanceof RuntimeException) {
return (RuntimeException) e;
}
return new RuntimeException("Unexpected Checked Exception.", e);
}
public static Constructor[] getAllConstructorsOfClass(Class clazz, boolean accessible) {
if(clazz == null) {
return null;
} else {
Constructor[] constructors = clazz.getDeclaredConstructors();
if(constructors != null && constructors.length > 0) {
AccessibleObject.setAccessible(constructors, accessible);
}
return constructors;
}
}
private static Object[] getInitParameters(Class[] parameterTypes) {
int length = parameterTypes.length;
Object[] result = new Object[length];
for(int i = 0; i < length; ++i) {
if(parameterTypes[i].isPrimitive()) {
Object init = ClassUtil.getPrimitiveDefaultValue(parameterTypes[i]);
result[i] = init;
} else {
result[i] = null;
}
}
return result;
}
}