java反射取对象中的各表量值

最新推荐文章于 2025-04-18 10:49:41 发布

liguiping2000

最新推荐文章于 2025-04-18 10:49:41 发布

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分类专栏： java 文章标签： java string bean null exception class

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本文介绍了一种方法，通过Java反射API获取并打印对象的所有属性，包括公有和私有属性，帮助开发者在测试阶段验证数据填充是否正确。

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package d;

import java.lang.reflect.Field;

public class bean01 {

   public static void main(String[] args) {
       bean02 bean = new bean02();bean.setId(222);
        System.out.println(getPojoLog(bean));

   }

    //列出一个pojo所有的内容，以便测试时检查数据
   public   static   String   getPojoLog(Object   pojo){
       Class   c   =   pojo.getClass();
       StringBuffer   out   =   new   StringBuffer(c.getName()   + ":   \n ");
       Field[]   fields   =   c.getDeclaredFields();//或者     Field[]   fields   =   c.getFields(); 2者的区别见附录
       Field.setAccessible(fields, true);
       for   (int   i   =   0;   i   <   fields.length;   i++)   {
           Field   field   =   fields[i];
           String   name   =   field.getName();
           if(name.startsWith( "SF_ ")){
               continue;
           }
           try   {
               Object   vo   =   field.get(pojo);
               String   value   =   " ";
               if   (vo   !=   null)   {
                   value   =   field.get(pojo).toString();
               }
               out.append( "         "+   name   + "   =   "   +   value   +   "\n ");

           }   catch   (Exception   e)   {
               e.printStackTrace();
           }
       }
       return   out.toString();
   }
}

package d;
public class bean02{

   public int id;

   public String[] love;

   public String[] getLove() {
       return love;
   }

   public void setLove(String[] love) {
       this.love = love;
   }

   public int getId() {
       return id;
   }

   public void setId(int id) {
       this.id = id;
   }
}

附录:

1.package study.reflection;
2.
3.public class People {
4.public String name = null;
5.private String sex = null;
6.private String age = null;
7.private String tel = null;
8.private String address = null;
9.public static String s = null;
10.static {
11. System.out.println("loading People");
12.}
13.
14.public static void showPeople() {
15.
16.}
17.
18.public People(String name) {
19. this.name = name;
20.}
21.
22.private People() {
23. this.name = name;
24.}
25.
26.private void showPeopleInfo() {
27. System.out.println(name + " " + sex + " " + age + " " + tel + " "
28. + address);
29.}
30.
31.public String getName() {
32. return name;
33.}
34.
35.public void setName(String name) {
36. this.name = name;
37.}
38.
39.public String getSex() {
40. return sex;
41.}
42.
43.public void setSex(String sex) {
44. this.sex = sex;
45.}
46.
47.public String getAge() {
48. return age;
49.}
50.
51.public void setAge(String age) {
52. this.age = age;
53.}
54.
55.public String getTel() {
56. return tel;
57.}
58.
59.public void setTel(String tel) {
60. this.tel = tel;
61.}
62.
63.public String getAddress() {
64. return address;
65.}
66.
67.public void setAddress(String address) {
68. this.address = address;
69.}
70.
71.}
72.
73.package esg;
74.
75.import java.lang.reflect.Constructor;
76.import java.lang.reflect.Field;
77.import java.lang.reflect.Method;
78.
79.import study.reflection.People;
80.
81.public class Esg {
82.
83.public static void main(String[] a) throws ClassNotFoundException {
84. Class c1 = People.class;
85.
86. Field[] fs = c1.getFields();
87. System.out.println("*******getFields()*********");
88. for (int i = 0; i < fs.length; i++) {
89. System.out.println(fs[i].getName());
90. }
91. System.out.println("*******getDeclaredFields()*********");
92. fs = c1.getDeclaredFields();
93. for (int i = 0; i < fs.length; i++) {
94. System.out.println(fs[i].getName());
95. }
96. System.out.println("*******getMethods()*********");
97. Method[] md = c1.getMethods();
98. for (int i = 0; i < md.length; i++) {
99. System.out.println(md[i].getName());
100. }
101. System.out.println("*******getDeclaredMethods()*********");
102. md = c1.getDeclaredMethods();
103. for (int i = 0; i < md.length; i++) {
104. System.out.println(md[i].getName());
105. }
106.
107. System.out.println("*******getConstructors()*********");
108. Constructor[] con = c1.getConstructors();
109. for (int i = 0; i < con.length; i++) {
110. System.out.println(con[i].getName());
111. }
112. System.out.println("*******getDeclaredConstructors()*********");
113. con = c1.getDeclaredConstructors();
114. for (int i = 0; i < con.length; i++) {
115. System.out.println(con[i].getName());
116. }
117.}
118.}

* getFields()与getDeclaredFields()区别:getFields()只能访问类中声明为公有的字段,私有的字段它无法访问.getDeclaredFields()能访问类中所有的字段,与public,private,protect无关

* getMethods()与getDeclaredMethods()区别:getMethods()只能访问类中声明为公有的方法,私有的方法它无法访问,能访问从其它类继承来的公有方法.getDeclaredFields()能访问类中所有的字段,与public,private,protect无关,不能访问从其它类继承来的方法

* getConstructors()与getDeclaredConstructors()区别:getConstructors()只能访问类中声明为public的构造函数.getDeclaredConstructors()能访问类中所有的构造函数,与public,private,protect无关