java如何用反射將一個對象復制給另一個對象

更新時間：2023年09月25日 09:16:29 作者：YoungMirror

這篇文章主要介紹了java如何用反射將一個對象復制給另一個對象問題,具有很好的參考價值,希望對大家有所幫助,如有錯誤或未考慮完全的地方,望不吝賜教

java用反射將一個對象復制給另一個對象

@SneakyThrows
    public static Object objectClone(Object newObject,Object oldObject){
        Field[] oldFields = oldObject.getClass().getDeclaredFields();
        Field newField;
        for (Field oldField : oldFields){
            oldField.setAccessible(true);
            newField = newObject.getClass().getDeclaredField(oldField.getName());
            newField.setAccessible(true);
            newField.set(newObject,oldField.get(oldObject));
        }
        return newObject;
    }

java復制一個對象使新對象和源對象值相同，地址不同

1. 實體（3個模擬多層父級）支持多層父級和List，map的copy值

public class StudentDemo extends StudentF {
    private Integer stuId;
    private String stuName;
    private String stuPrice;
    private boolean flg;
    private List<String> listString;
    private HashMap<String, StuType> mapType;
    public HashMap<String, StuType> getMapType() {
        return mapType;
    }
    public void setMapType(HashMap<String, StuType> mapType) {
        this.mapType = mapType;
    }
    public List<String> getListString() {
        return listString;
    }
    public void setListString(List<String> listString) {
        this.listString = listString;
    }
    public boolean isFlg() {
        return flg;
    }
    public void setFlg(boolean flg) {
        this.flg = flg;
    }
    public StudentDemo(HashMap<String, StuType> mapType, List<StuType> listType, List<String> listString, Integer stuId, String stuName, String stuPrice, String stuSex, Integer stuAge, String stuNum, String stuTel, boolean isFlg) {
        this.stuId = stuId;
        this.stuName = stuName;
        this.stuPrice = stuPrice;
        super.setStudentSex(stuSex);
        super.setStudentAge(stuAge);
        super.setStuNum(stuNum);
        super.setTel(stuTel);
        this.flg = isFlg;
        this.listString = listString;
        super.setListType(listType);
        this.mapType = mapType;
    }
    public StudentDemo(){}
    @Override
    public String toString() {
        return "StudentDemo{" +
                "stuId=" + stuId +
                ", stuName='" + stuName + '\'' +
                ", stuPrice='" + stuPrice + '\'' +
                ", stuSex='" + super.getStudentSex() + '\'' +
                ", stuAge='" + super.getStudentAge() + '\'' +
                ", stuNum='" + super.getStuNum() + '\'' +
                ", stuTel='" + super.getTel() + '\'' +
                ", flg='" + flg + '\'' +
                ", listString='" + listString + '\'' +
                ", listType='" + super.getListType() + '\'' +
                ", mapType='" + mapType + '\'' +
                '}';
    }
    public Integer getStuId() {
        return stuId;
    }
    public void setStuId(Integer stuId) {
        this.stuId = stuId;
    }
    public String getStuName() {
        return stuName;
    }
    public void setStuName(String stuName) {
        this.stuName = stuName;
    }
    public String getStuPrice() {
        return stuPrice;
    }
    public void setStuPrice(String stuPrice) {
        this.stuPrice = stuPrice;
    }
}
public class StudentF extends StudentX {
    private String studentSex;
    private Integer studentAge;
    private List<StuType> listType;
    public List<StuType> getListType() {
        return listType;
    }
    public void setListType(List<StuType> listType) {
        this.listType = listType;
    }
    public String getStudentSex() {
        return studentSex;
    }
    public void setStudentSex(String studentSex) {
        this.studentSex = studentSex;
    }
    public Integer getStudentAge() {
        return studentAge;
    }
    public void setStudentAge(Integer studentAge) {
        this.studentAge = studentAge;
    }
}
public class StudentX {
    private String stuNum;
    private String Tel;
    public String getStuNum() {
        return stuNum;
    }
    public void setStuNum(String stuNum) {
        this.stuNum = stuNum;
    }
    public String getTel() {
        return Tel;
    }
    public void setTel(String tel) {
        Tel = tel;
    }
}

2. 工具類

package com.books.utils;
import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
/**
 *  復制一個實體對象
 *  修改新對象時不影響源對象的值
 * @param <T> 項目中任意類型
 */
public class CopyObjectEntity<T> {
	/**
     *  復制實體方法
     * @param orderEntity 源對象
     * @param newEntity 新對象
     * @return 新對象
     */
    public T newPojo(Object orderEntity, Object newEntity){
        // 新對象
        T newPojo = null;
        try {
            // 源對象
            T orderPojo = (T)orderEntity;
            newPojo = (T)newEntity;
            // 獲取所有方法，包括父類
            Method[] orderObject = orderPojo.getClass().getMethods();
            // 遍歷所有方法
            for(int a = 0; a < orderObject.length; a ++){
                // 得到每一個方法名稱
                String name = orderObject[a].getName();
                // 判斷獲取需要的（普通的字段都是get/set），這里獲取get方法因為get到值才能賦值
                if(!name.equals("setClass") && !name.equals("class") && !name.equals("getClass") && name.startsWith("get")){
                    // 獲取方法
                    Method method = orderPojo.getClass().getMethod(name, new Class[] {});
                    // 執(zhí)行方法
                    Object value = method.invoke(orderPojo, new Object[] {});
                    // 拼接set方法
                    String aa = orderObject[a].getName().substring(3);
                    String bb = aa.substring(0, 1).toUpperCase();
                    String setter = bb + aa.substring(1);
                    // 創(chuàng)建描述器
                    PropertyDescriptor pd = new PropertyDescriptor(setter, newPojo.getClass());
                    //為上面聲明的字段設置set方法（又稱內(nèi)?。?
                    Method setMethod = pd.getWriteMethod();
                    // 執(zhí)行set
                    setMethod.invoke(newPojo, value);
                }
                // 判斷是boolean的字段get時為is
                if(!name.equals("setClass") && !name.equals("class") && !name.equals("getClass") && name.startsWith("is")){
                    Method method = orderPojo.getClass().getMethod(name, new Class[] {});
                    Object value = method.invoke(orderPojo, new Object[] {});
                    String aa = orderObject[a].getName().substring(2);
                    String bb = aa.substring(0, 1).toUpperCase();
                    String setter = bb + aa.substring(1);
                    PropertyDescriptor pd = new PropertyDescriptor(setter, newPojo.getClass());
                    //為上面聲明的字段設置set方法（又稱內(nèi)省）
                    Method setMethod = pd.getWriteMethod();
                    // 執(zhí)行set
                    setMethod.invoke(newPojo, value);
                }
            }
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        } catch (IntrospectionException e) {
            e.printStackTrace();
        }catch (Exception e) {
            e.printStackTrace();
        }
        return newPojo;
    }
}

3. 測試

    public void test7(){
        List<String> ls = new ArrayList<>();
        ls.add("aa");
        ls.add("bb");
        ls.add("cc");
        List<StuType> listType = new ArrayList<>();
        listType.add(new StuType(1, "類型1"));
        listType.add(new StuType(2, "類型2"));
        HashMap<String, StuType> mapType = new HashMap<>();
        mapType.put("11", new StuType(11, "map1"));
        mapType.put("22", new StuType(22, "map2"));
        StudentDemo studentDemo = new StudentDemo(mapType, listType, ls,1, "aa" ,null, "男", 23, "010010", "15244669988", true);
        StudentDemo studentDemo1 = new StudentDemo();
        new CopyObjectEntity<StudentDemo>().newPojo(studentDemo, studentDemo1);
        System.out.println("復制完的新對象"+studentDemo1);
        studentDemo1.setStuId(22);
        studentDemo1.setStuName("你好啊");
        studentDemo1.setStuPrice("啦啦啦");
        studentDemo1.setStudentSex("女");
        studentDemo1.setStudentAge(20);
        studentDemo1.setStuNum("沒有學號");
        studentDemo1.setTel("沒有電話");
        studentDemo1.setFlg(false);
        List<String> ls1 = new ArrayList<>();
        ls1.add("33");
        ls1.add("44");
        ls1.add("55");
        List<StuType> listType1 = new ArrayList<>();
        listType1.add(new StuType(-1, "類型-1"));
        listType1.add(new StuType(-2, "類型-2"));
        HashMap<String, StuType> mapType1 = new HashMap<>();
        mapType1.put("11", new StuType(-11, "map-1"));
        mapType1.put("22", new StuType(-22, "map-2"));
        studentDemo1.setListType(listType1);
        studentDemo1.setMapType(mapType1);
        studentDemo1.setListString(ls1);
        System.out.println("源對象"+studentDemo);
        System.out.println("修改復制后對象"+studentDemo1);
        System.out.println("再次查看源對象"+studentDemo);
    }

4. 結(jié)果