反射工具类——ReflectUtils

Posted 2020-07-23 panie2015

测试方法：根据已知的方法名，来反射调用方法

package com.redmoon.forum.job;

import java.util.ArrayList;
import java.util.List;

import com.common.utils.ReflectUtils;

public class Test
{
    private String name;
    public String getName()
    {
        return name;
    }
    public void setName(String name)
    {
        this.name = name;
    }
    public List<String> ff()
    {
        List<String> list = new ArrayList<String>();
        list.add("111");
        list.add("222");
        return list;
    }
    public static void main(String[] args)
    {
        Test test = new Test();
        Object list = ReflectUtils.invokeMethodByName(test, "ff", null);
        List<String> list2 = (List<String>)list;
        System.out.println(list);
        ReflectUtils.setFieldValue(test,"name","panie");
        String name = (String)ReflectUtils.getFieldValue(test,"name");
        System.out.println(name);
    }
}

　　

结果：

[111, 222]
panie

　　

反射工具类

package com.common.utils;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.Date;

import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.Validate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * 反射工具类.
 * 提供调用getter/setter方法, 访问私有变量, 调用私有方法, 获取泛型类型Class, 被AOP过的真实类等工具函数.
 * @author 
 * @version 
 */
public class ReflectUtils {
    
    private static final String SETTER_PREFIX = "set";

    private static final String GETTER_PREFIX = "get";

    private static final String CGLIB_CLASS_SEPARATOR = "$$";
    
    private static Logger logger = LoggerFactory.getLogger(ReflectUtils.class);

    /**
     * 调用Getter方法.
     * 支持多级，如：对象名.对象名.方法
     */
    public static Object invokeGetter(Object obj, String propertyName) {
        Object object = obj;
        for (String name : StringUtils.split(propertyName, ".")){
            String getterMethodName = GETTER_PREFIX + StringUtils.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
     */
    public static void invokeSetter(Object obj, String propertyName, Object value) {
        Object object = obj;
        String[] names = StringUtils.split(propertyName, ".");
        for (int i=0; i<names.length; i++){
            if(i<names.length-1){
                String getterMethodName = GETTER_PREFIX + StringUtils.capitalize(names[i]);
                object = invokeMethod(object, getterMethodName, new Class[] {}, new Object[] {});
            }else{
                String setterMethodName = SETTER_PREFIX + StringUtils.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.
     */
    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("不可能抛出的异常{}", e.getMessage());
        }
        return result;
    }

    /**
     * 直接设置对象属性值, 无视private/protected修饰符, 不经过setter函数.
     */
    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("不可能抛出的异常:{}", e.getMessage());
        }
    }

    /**
     * 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，
     */
    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);
        }
    }

    /**
     * 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。
     */
    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.
     */
    public static Field getAccessibleField(final Object obj, final String fieldName) {
        Validate.notNull(obj, "object can‘t be null");
        Validate.notBlank(fieldName, "fieldName can‘t be blank");
        for (Class<?> superClass = obj.getClass(); superClass != Object.class; superClass = superClass.getSuperclass()) {
            try {
                Field field = superClass.getDeclaredField(fieldName);
                makeAccessible(field);
                return field;
            } catch (NoSuchFieldException e) {//NOSONAR
                // Field不在当前类定义,继续向上转型
                continue;// new add
            }
        }
        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)
     */
    public static Method getAccessibleMethod(final Object obj, final String methodName,
            final Class<?>... parameterTypes) {
        Validate.notNull(obj, "object can‘t be null");
        Validate.notBlank(methodName, "methodName can‘t be blank");

        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
                continue;// new add
            }
        }
        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)
     */
    public static Method getAccessibleMethodByName(final Object obj, final String methodName) {
        Validate.notNull(obj, "object can‘t be null");
        Validate.notBlank(methodName, "methodName can‘t be blank");

        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。
     */
    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。
     */
    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<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> getClassGenricType(final Class clazz) {
        return getClassGenricType(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<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
     */
    public static Class getClassGenricType(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];
    }
    
    public static Class<?> getUserClass(Object instance) {
        Validate.notNull(instance, "Instance must not be null");
        Class clazz = instance.getClass();
        if (clazz != null && clazz.getName().contains(CGLIB_CLASS_SEPARATOR)) {
            Class<?> superClass = clazz.getSuperclass();
            if (superClass != null && !Object.class.equals(superClass)) {
                return superClass;
            }
        }
        return clazz;

    }
    
    /**
     * 将反射时的checked exception转换为unchecked 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);
    }
    
    /**
     * 判断属性是否为日期类型
     * 
     * @param clazz
     *            数据类型
     * @param fieldName
     *            属性名
     * @return 如果为日期类型返回true，否则返回false
     */
    public static <T> boolean isDateType(Class<T> clazz, String fieldName) {
        boolean flag = false;
        try {
            Field field = clazz.getDeclaredField(fieldName);
            Object typeObj = field.getType().newInstance();
            flag = typeObj instanceof Date;
        } catch (Exception e) {
            // 把异常吞掉直接返回false
        }
        return flag;
    }
 
    /**
     * 根据类型将指定参数转换成对应的类型
     * 
     * @param value
     *            指定参数
     * @param type
     *            指定类型
     * @return 返回类型转换后的对象
     */
    public static <T> Object parseValueWithType(String value, Class<?> type) {
        Object result = null;
        try { // 根据属性的类型将内容转换成对应的类型
            if (Boolean.TYPE == type) {
                result = Boolean.parseBoolean(value);
            } else if (Byte.TYPE == type) {
                result = Byte.parseByte(value);
            } else if (Short.TYPE == type) {
                result = Short.parseShort(value);
            } else if (Integer.TYPE == type) {
                result = Integer.parseInt(value);
            } else if (Long.TYPE == type) {
                result = Long.parseLong(value);
            } else if (Float.TYPE == type) {
                result = Float.parseFloat(value);
            } else if (Double.TYPE == type) {
                result = Double.parseDouble(value);
            } else {
                result = (Object) value;
            }
        } catch (Exception e) {
            // 把异常吞掉直接返回null
        }
        return result;
    }
}