package com.alibaba.asyncload.impl.helper;
import java.lang.reflect.Array;
import java.lang.reflect.Constructor;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import net.sf.cglib.core.ReflectUtils;
import net.sf.cglib.reflect.FastClass;
import net.sf.cglib.reflect.FastMethod;
/**
* AyncLoad中常用的一些反射方法
*
* @author jianghang 2011-3-29 下午09:55:12
*/
public class AsyncLoadReflectionHelper {
private static final Map primitiveValueMap = new HashMap(16);
private static Map<String, FastClass> fastClassCache = new ConcurrentHashMap<String, FastClass>();
private static Map<String, FastMethod> fastMethodCache = new ConcurrentHashMap<String, FastMethod>();
static {
primitiveValueMap.put(Boolean.class, Boolean.FALSE);
primitiveValueMap.put(Byte.class, Byte.valueOf((byte) 0));
primitiveValueMap.put(Character.class, Character.valueOf((char) 0));
primitiveValueMap.put(Short.class, Short.valueOf((short) 0));
primitiveValueMap.put(Double.class, Double.valueOf(0));
primitiveValueMap.put(Float.class, Float.valueOf(0));
primitiveValueMap.put(Integer.class, Integer.valueOf(0));
primitiveValueMap.put(Long.class, Long.valueOf(0));
primitiveValueMap.put(boolean.class, Boolean.FALSE);
primitiveValueMap.put(byte.class, Byte.valueOf((byte) 0));
primitiveValueMap.put(char.class, Character.valueOf((char) 0));
primitiveValueMap.put(short.class, Short.valueOf((short) 0));
primitiveValueMap.put(double.class, Double.valueOf(0));
primitiveValueMap.put(float.class, Float.valueOf(0));
primitiveValueMap.put(int.class, Integer.valueOf(0));
primitiveValueMap.put(long.class, Long.valueOf(0));
}
/**
* 特殊处理，允许通过带参数的constructor创建对象
*
* @param type
* @return
*/
public static Object newInstance(Class type) {
Constructor _constructor = null;
Object[] _constructorArgs = new Object[0];
try {
_constructor = type.getConstructor(new Class[] {});// 先尝试默认的空构造函数
} catch (NoSuchMethodException e) {
// ignore
}
if (_constructor == null) {// 没有默认的构造函数，尝试别的带参数的函数
Constructor[] constructors = type.getConstructors();
if (constructors.length == 0) {
throw new UnsupportedOperationException("Class[" + type.getName() + "] has no public constructors");
}
_constructor = constructors[0];// 默认取第一个参数
Class[] params = _constructor.getParameterTypes();
_constructorArgs = new Object[params.length];
for (int i = 0; i < params.length; i++) {
_constructorArgs[i] = getDefaultValue(params[i]);
}
}
return ReflectUtils.newInstance(_constructor, _constructorArgs);
}
public static FastMethod getMethod(Class<?> clazz, String methodName) {
return getMethod(clazz, methodName, new Class[] {});
}
/**
* 根据信息查询FastMethod，已经有cache实现。
*
* @param clazz
* @param methodName
* @param parameterTypes
* @return
*/
public static FastMethod getMethod(Class<?> clazz, String methodName, Class... parameterTypes) {
String clazzName = clazz.getName();
String methodKey = clazzName + "#" + methodName;
FastMethod method = fastMethodCache.get(methodKey);
if (null == method) {
FastClass fc = fastClassCache.get(clazzName);
if (null == fc) {
fc = FastClass.create(clazz);
fastClassCache.put(clazzName, fc);
}
method = fc.getMethod(methodName, parameterTypes);
if (null == method) {
fastMethodCache.put(methodKey, method);
}
}
return method;
}
/**
* 根据class类型返回默认值值
*
* @param cl
* @return
*/
public static Object getDefaultValue(Class cl) {
if (cl.isArray()) {// 处理数组
return Array.newInstance(cl.getComponentType(), 0);
} else if (cl.isPrimitive() || primitiveValueMap.containsKey(cl)) { // 处理原型
return primitiveValueMap.get(cl);
} else {
return AsyncLoadReflectionHelper.newInstance(cl);
// return null;
}
}
}