1 package com.lovo.util;
 2
 3 import java.lang.reflect.Constructor;
 4 import java.lang.reflect.Field;
 5
 6 public class MyUtil {
 7     private MyUtil(){
 8         throw new AssertionError();
 9     }
10     /**
11      * 通过反射获取对象的字段值
12      * @param target 目标对象
13      * @param fieldName 字段名称
14      * @return 字段的值或null
15      */
16     public static Object getValue(Object target,String fieldName) {
17         Object value = null;
18         //用"."分割例如："car.engine"表示target对象的（Car类型）car属性的（Engine）engine属性值
19         String[] strs = fieldName.split("\\.");
20         for (int i = 0; i < strs.length; i++) {
21             if (target != null) {
22                 try {
23                     Class<?> clazz = target.getClass();//得到target对象类的类类型对象（描述target对象类的类对象）
24                     Field f = clazz.getDeclaredField(strs[i]);//得到属性
25                     f.setAccessible(true);
26                     if (i == strs.length - 1) {
27                         value = f.get(target);//得到属性值29                     } else {
30                         target = f.get(target);//修改target
31                     }
32                 } catch (Exception e) {
33                     throw new RuntimeException(e);
34                 }
35             }
36         }
37         return value;
38     }
39     /**
40      * 设置属性值
41      * @param target 目标对象
42      * @param fieldName 属性
43      * @param value 值
44      */
45     public static void setValue(Object target,String fieldName,Object value) {
46         Class<?> clazz = target.getClass();
47         String[] trs = fieldName.split("\\.");
48         for (int i = 0; i < trs.length - 1; i++) {
49             try {
50                 Field f = clazz.getDeclaredField(trs[i]);
51                 f.setAccessible(true);
52 //                Object tempTarget = target;
53 //                target = f.get(target);
54                 if (f.get(target) == null) {
55                     String type = f.getGenericType().toString();//得到值为null的属性的类型的字符串
56                     String[] typeSplits = type.split(" ");
57                     clazz = Class.forName(typeSplits[1]);//得到值为null的属性的类型的类类型对象
58                     Constructor<?> con = clazz.getDeclaredConstructor();//得到属性的无参构造器
59                     con.setAccessible(true); //有可能是private的所以设置可以访问
60                     f.set(target, con.newInstance());//给null属性赋值
61                 }
62                 target = f.get(target);
63                 clazz = target.getClass();
64
65             } catch (Exception e) {
66                 e.printStackTrace();
67                 throw new RuntimeException();
68             }
69         }
70         try {
71             Field f = clazz.getDeclaredField(trs[trs.length - 1]);
72             f.setAccessible(true);
73             f.set(target, value);
74
75         } catch (Exception e) {
76             throw new RuntimeException();
77         }
78     }
79 }