Java通過反射實現簡單對象的拷貝

代碼實現

package me.andy.practice.annotation;import java.lang.reflect.Constructor;import java.lang.reflect.Field;import java.lang.reflect.Method;public class ReflectUtils {    public static Object copy(Object resource) throws Exception {        Class<? extends Object> classType = resource.getClass();        Object newObject = classType.newInstance();        Field[] declaredFields = classType.getDeclaredFields();        for (Field filed : declaredFields) {            String firstLetter = filed.getName().substring(0, 1).toUpperCase();            String getMethodName = "get" + firstLetter + filed.getName().substring(1);            String setMethodName = "set" + firstLetter + filed.getName().substring(1);            Method getMethod = classType.getMethod(getMethodName, new Class[]{});            Method setMethod = classType.getMethod(setMethodName, new Class[]{filed.getType()});            Object value = getMethod.invoke(resource, new Object[]{});            setMethod.invoke(newObject, new Object[]{value});        }        return newObject;    }}

• 代碼解釋

Object newObject = classType.newInstance();

等價於

Constructor<? extends Object> constructor = classType.getConstructor(new Class[]{});

Object newObject = constructor.newInstance(new Object[]{});

Field[] declaredFields = classType.getDeclaredFields()返回當前類聲明的所有方法（包括私人共有）

classType.getFields()返回當前類共有方法，包括繼承父類的

測試代碼

package me.andy.practice.reflect;import me.andy.practice.annotation.ReflectUtils;import org.junit.Test;import java.lang.reflect.Constructor;import java.lang.reflect.Field;import java.lang.reflect.Method;import static junit.framework.Assert.assertEquals;public class ReflectTest {    @Test    public void test_copy() throws Exception {        Person person = new Person("andy", 1);        Person copyPerson = (Person) ReflectUtils.copy(person);        assertEquals("andy", copyPerson.getName());        assertEquals(Integer.valueOf(1), copyPerson.getAge());    }}

package me.andy.practice.reflect;public class Person {    private String name;    private Integer age;    public Person() {    }    public Person(String name, Integer age) {        this.name = name;        this.age = age;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public Integer getAge() {        return age;    }    public void setAge(Integer age) {        this.age = age;    }}