這裡在網上找了一份ReflectionUtils

package com.litian.jdbc;

/**
 * @author: Li Tian
 * @contact: [email protected]
 * @software: IntelliJ IDEA
 * @file: ReflectionUtils.java
 * @time: 2020/3/26 18:57
 * @desc: |JDBC 查詢得到屬性欄位 反射機制返回到 JavaBean中相同類屬性名的物件中
 */

import java.lang.reflect.*;


public class ReflectionUtils {

    
 
/**
     * 使 filed 變為可訪問
     *
     * @param field
     */
    public static void makeAccessible(Field field) {
        if (!Modifier.isPublic(field.getModifiers())) {
            field.setAccessible(true);
        }
    }

    /**
     * 直接設定物件的屬性，忽略 private/protected 修飾符, 也不經過 setter
     *
     * @param
 
 object
     * @param fieldName 屬性名稱
     * @param value
     */
    public static void setFieldValue(Object object, String fieldName, Object value) {

        Field field = getDeclaredField(object, fieldName);
        if (field == null)
            throw new IllegalArgumentException("Could not find field [" + fieldName + "] on target [" + object + "]");

        
 
// 讓 private 元素變得可以訪問,field.setAccessible();
        makeAccessible(field);

        try {
            field.set(object, value);
        } catch (IllegalArgumentException | IllegalAccessException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    /**
     * 迴圈向上轉型, 獲取物件的 DeclaredField
     *
     * @param object
     * @param filedName
     * @return
     */
    public static Field getDeclaredField(Object object, String filedName) {
        // 一步步的迴圈得到 獲取宣告物件的祖宗類
        for (Class<?> superClass = object.getClass(); superClass != Object.class; superClass = superClass.getSuperclass()) {
            try {
                return superClass.getDeclaredField(filedName);
            } catch (NoSuchFieldException | SecurityException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        return null;
    }

    /**
     * 直接讀取物件的屬性值, 忽略 private/protected 修飾符, 也不經過 getter
     *
     * @param object
     * @param fieldName
     * @return
     */
    public static Object getFieldValue(Object object, String fieldName) {
        Field field = getDeclaredField(object, fieldName);

        if (field == null)
            throw new IllegalArgumentException("Could not find field [" + fieldName + "] on target [" + object + "]");

        makeAccessible(field);
        Object result = null;

        try {
            result = field.get(object);
        } catch (IllegalArgumentException | IllegalAccessException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return result;
    }

    /**
     * 迴圈向上轉型, 獲取物件的 DeclaredMethod
     *
     * @param object
     * @param methodName
     * @param parameterTypes: 指定特定成員方法有過載可能性，必須指定特定的型別變數
     * @return
     */
    public static Method getDeclaredMethod(Object object, String methodName, Class<?>[] parameterTypes) {
        for (Class<?> superClass = object.getClass(); superClass != Object.class; superClass = superClass.getSuperclass()) {
            try {
                //superClass.getMethod(methodName, parameterTypes);
                return superClass.getDeclaredMethod(methodName, parameterTypes);
            } catch (NoSuchMethodException e) {
                //Method 不在當前類定義, 繼續向上轉型
            }
            //..
        }

        return null;
    }

    /**
     * 直接呼叫物件方法, 而忽略修飾符(private, protected)
     *
     * @param object
     * @param methodName
     * @param parameterTypes
     * @param parameters
     * @return
     * @throws InvocationTargetException
     * @throws IllegalArgumentException
     */
    public static Object invokeMethod(Object object, String methodName, Class<?>[] parameterTypes,
                                      Object[] parameters) throws InvocationTargetException {
        Method method = getDeclaredMethod(object, methodName, parameterTypes);

        if (method == null)
            throw new IllegalArgumentException("Could not find method [" + methodName + "] on target [" + object + "]");
        method.setAccessible(true);

        // 使用 method.invoke()方法進行執行
        try {
            method.invoke(object, parameters);
        } catch (IllegalAccessException | IllegalArgumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return method;
    }

    /**
     * 通過反射, 獲得定義 Class 時宣告的父類的泛型引數的型別
     * 如: public EmployeeDao extends BaseDao<Employee, String>
     *
     * @param clazz
     * @return
     */
    public static Class getSuperClassGenricType(Class clazz, int index) {
        Type genType = clazz.getGenericSuperclass();

        // 判定s是否是ParameterType相對應的
        if (!(genType instanceof ParameterizedType))
            return Object.class;

        // 強制轉換 獲取超類泛型引數實際型別，返回genType 是類的介面，基本型別或者void
        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];
    }

    /**
     * 通過反射,獲得Class定義中宣告的父類的泛型引數的型別.
     * 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);
    }
}

JAVA類屬性

在JAVAEE中，JAVA類的屬性通過getter，setter來定義：get（set）方法：去除get（或set）後，首字母小寫即為該類的屬性。

而之前的屬性，即成員變數稱之為欄位。

操作java類的屬性有一個工具包：beanutils（需要結合logging來用）

BeanUtils.setProperty()
BeanUtils.getProperty()
一般情況下，欄位名和屬性名都一致

通過該工具包可以將之前的ReflectionUtil替換為：BeanUtils.setProperty(entity, propertyName, value);

BeanUtils測試程式碼

package com.litian.jdbc;

import org.apache.commons.beanutils.BeanUtils;

import java.lang.reflect.InvocationTargetException;

/**
 * @author: Li Tian
 * @contact: [email protected]
 * @software: IntelliJ IDEA
 * @file: BeanUtilsTest.java
 * @time: 2020/3/27 15:37
 * @desc: |測試工具包beanutils
 */

public class BeanUtilsTest {
    public static void main(String[] args) throws InvocationTargetException, IllegalAccessException, NoSuchMethodException {
        // 測試賦值操作
        Object obj = new User();
        System.out.println(obj);

        BeanUtils.setProperty(obj, "username", "二哈");
        System.out.println(obj);

        // 測試獲取操作
        Object val = BeanUtils.getProperty(obj, "username");
        System.out.println(val);

    }
}

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原文連結：https://blog.csdn.net/qq_21579045/article/details/105386353