Or use above a small demo, test, verify a problem, ado, on to compare the code
. 1 Package service.impl;
2
. 3 Import service.UserService;
. 4 Import dao.UserDao;
. 5 Import entity.User;
. 6
. 7 / **
. 8 * user traffic class, to achieve business management User functions
. 9 * /
10 public class UserServiceImpl the implements UserService {
. 11
12 is // declaration of the interface reference type, and decoupling implementation class
13 is Private UserDao DAO;
14 Private String S1;
15 Private String S2;
16 Private int I1;
. 17
18 is
. 19 @ generated constructor with no arguments
20 is public UserServiceImpl () {
21 is
22 is }
23 is
24 // parameters as constructor assignment DAO
25 public UserServiceImpl (UserDao DAO) {
26 is the this .dao = DAO;
27 }
28 public UserServiceImpl (DAO UserDao, String S1) {
29 the this .dao = DAO;
30 the this .s1 = S1;
31 is }
32 public UserServiceImpl (String S2, UserDao DAO) {
33 is the this .dao =DAO;
34 is the this .s2 = S2;
35 }
36 public UserServiceImpl ( int I1, UserDao DAO) {
37 [ the this .dao = DAO;
38 is the this .i1 = I1;
39 }
40
41 is
42 is public UserDao getDao () {
43 is return DAO ;
44 is }
45
46 is // the setter accessor dao attribute is invoked Spring, setter injection to achieve
47 public void setDao (UserDao dao) {
48 the this .dao = dao;
49 }
50
51 is public void AddNewUser (the User User) {
52 is // method calls the user's user information stored DAO
53 is dao.save (User);
54 is System.out.println ( "S1 =" + S1);
55 the System.out. the println ( "S2 =" + S2);
56 is System.out.println ( "I1 =" + I1);
57 is }
58 }
Core configuration file:
<bean id="UserService" class="service.impl.UserServiceImpl">
<!--通过构造函数的方式，实现构造注入 -->
<constructor-arg>
<ref bean="userDao" />
</constructor-arg>
<constructor-arg>
<value>123</value>
</constructor-arg>
</bean>
运行结果：
保存用户信息到数据库
s1=null
s2=123
i1=0
由此可见，是没有附上值的 ，为i1变量
解决办法：对核心配置文件进行修改，使用type属性，指定数据类型
运行结果：
保存用户信息到数据库
s1=null
s2=null
i1=123