Java tutorial
/** * Copyright (c) 2005-2009 springside.org.cn * * Licensed under the Apache License, Version 2.0 (the "License"); * * $Id: ReflectionUtils.java 1112 2010-07-01 15:51:12Z calvinxiu $ */ package com.framework.infrastructure.utils; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.lang.reflect.ParameterizedType; import java.lang.reflect.Type; import java.util.ArrayList; import java.util.Collection; import java.util.List; import java.util.concurrent.locks.ReentrantLock; import org.apache.commons.beanutils.ConvertUtils; import org.apache.commons.beanutils.PropertyUtils; import org.apache.commons.lang.StringUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * . * * ,Class, , Util. * * @author calvin */ public class ReflectionUtils { private static Logger logger = LoggerFactory.getLogger(ReflectionUtils.class); // static { // DateConverter dc = new DateConverter(); // dc.setUseLocaleFormat(true); // dc.setPatterns(new String[] { "yyyy-MM-dd", "yyyy-MM-dd HH:mm:ss" }); // ConvertUtils.register(dc, Date.class); // } /** * Getter. */ public static Object invokeGetterMethod(Object obj, String propertyName) { String getterMethodName = "get" + StringUtils.capitalize(propertyName); return invokeMethod(obj, getterMethodName, new Class[] {}, new Object[] {}); } /** * Setter.valueClassSetter. */ public static void invokeSetterMethod(Object obj, String propertyName, Object value) { invokeSetterMethod(obj, propertyName, value, null); } /** * Setter. * * @param propertyType * Setter,valueClass. */ public static void invokeSetterMethod(Object obj, String propertyName, Object value, Class<?> propertyType) { Class<?> type = propertyType != null ? propertyType : value.getClass(); String setterMethodName = "set" + StringUtils.capitalize(propertyName); invokeMethod(obj, setterMethodName, new Class[] { type }, new Object[] { value }); } /** * , private/protected, getter. */ public static Object getFieldValue(final Object obj, final String fieldName) { Field field = getAccessibleField(obj, fieldName); if (field == null) { throw new IllegalArgumentException("Could not find field [" + fieldName + "] on target [" + obj + "]"); } Object result = null; try { result = field.get(obj); } catch (IllegalAccessException e) { logger.error("{}", e.getMessage()); } return result; } /** * , private/protected, setter. */ public static void setFieldValue(final Object obj, final String fieldName, final Object value) { Field field = getAccessibleField(obj, fieldName); if (field == null) { throw new IllegalArgumentException("Could not find field [" + fieldName + "] on target [" + obj + "]"); } try { field.set(obj, value); } catch (IllegalAccessException e) { logger.error(":{}", e.getMessage()); } } /** * , DeclaredField, . * * Object, null. */ public static Field getAccessibleField(final Object obj, final String fieldName) { for (Class<?> superClass = obj.getClass(); superClass != Object.class; superClass = superClass .getSuperclass()) { try { Field field = superClass.getDeclaredField(fieldName); field.setAccessible(true); return field; } catch (NoSuchFieldException e) {// NOSONAR // Field, } } return null; } /** * , private/protected. . */ 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( "Could not find method [" + methodName + "] on target [" + obj + "]"); } try { return method.invoke(obj, args); } catch (Exception e) { throw convertReflectionExceptionToUnchecked(e); } } /** * , DeclaredMethod,. Object, null. * * . Method,Method.invoke(Object obj, Object... * args) */ public static Method getAccessibleMethod(final Object obj, final String methodName, final Class<?>... parameterTypes) { for (Class<?> superClass = obj.getClass(); superClass != Object.class; superClass = superClass .getSuperclass()) { try { Method method = superClass.getDeclaredMethod(methodName, parameterTypes); method.setAccessible(true); return method; } catch (NoSuchMethodException e) {// NOSONAR // Method, } } return null; } /** * , Class. , Object.class. eg. public UserDao * extends HibernateDao<User> * * @param clazz * The class to introspect * @return the first generic declaration, or Object.class if cannot be * determined */ @SuppressWarnings("unchecked") public static <T> Class<T> getSuperClassGenricType(final Class clazz) { return getSuperClassGenricType(clazz, 0); } /** * , Class. , Object.class. * * public UserDao extends HibernateDao<User,Long> * * @param clazz * clazz The class to introspect * @param index * the Index of the generic ddeclaration,start from 0. * @return the index generic declaration, or Object.class if cannot be * determined */ @SuppressWarnings("unchecked") public static Class getSuperClassGenricType(final Class clazz, final int index) { Type genType = clazz.getGenericSuperclass(); if (!(genType instanceof ParameterizedType)) { logger.warn(clazz.getSimpleName() + "'s superclass not ParameterizedType"); return Object.class; } Type[] params = ((ParameterizedType) genType).getActualTypeArguments(); if (index >= params.length || index < 0) { logger.warn("Index: " + index + ", Size of " + clazz.getSimpleName() + "'s Parameterized Type: " + params.length); return Object.class; } if (!(params[index] instanceof Class)) { logger.warn(clazz.getSimpleName() + " not set the actual class on superclass generic parameter"); return Object.class; } return (Class) params[index]; } /** * (getter), List. * * @param collection * . * @param propertyName * . */ @SuppressWarnings("unchecked") public static List convertElementPropertyToList(final Collection collection, final String propertyName) { List list = new ArrayList(); try { for (Object obj : collection) { list.add(PropertyUtils.getProperty(obj, propertyName)); } } catch (Exception e) { throw convertReflectionExceptionToUnchecked(e); } return list; } // /** // * (getter), . // * // * @param collection . // * @param propertyName . // * @param separator . // */ // @SuppressWarnings("unchecked") // public static String convertElementPropertyToString(final Collection // collection, final String propertyName, // final String separator) { // List list = convertElementPropertyToList(collection, propertyName); // return StringUtils.join(list, separator); // } /** * . * * @param value * * @param toType * */ public static Object convertStringToObject(String value, Class<?> toType) { try { return ConvertUtils.convert(value, toType); } catch (Exception e) { throw convertReflectionExceptionToUnchecked(e); } } /** * checked exceptionunchecked exception. */ public static RuntimeException convertReflectionExceptionToUnchecked(Exception e) { if (e instanceof IllegalAccessException || e instanceof IllegalArgumentException || e instanceof NoSuchMethodException) { return new IllegalArgumentException("Reflection Exception.", e); } else if (e instanceof InvocationTargetException) { return new RuntimeException("Reflection Exception.", ((InvocationTargetException) e).getTargetException()); } else if (e instanceof RuntimeException) { return (RuntimeException) e; } return new RuntimeException("Unexpected Checked Exception.", e); } public static void main(String args[]) { Worker worker = new Worker(); Thread thread = new Thread(); thread.setName("nihao"); worker.setTask(thread); Thread thread2 = (Thread) ReflectionUtils.getFieldValue(worker, "firstTask"); System.out.println(thread2.getName()); } private static final class Worker implements Runnable { /** * The runLock is acquired and released surrounding each task execution. * It mainly protects against interrupts that are intended to cancel the * worker thread from instead interrupting the task being run. */ private final ReentrantLock runLock = new ReentrantLock(); /** * Initial task to run before entering run loop. Possibly null. */ private Runnable firstTask; private void setTask(Runnable firstTask) { this.firstTask = firstTask; } public void run() { } } }