4_Spring_XML方式实现DI

4_Spring_XML方式实现DI

spring中的Bean的管理:

Bean(汉译咖啡豆). 又称JAVABean.其实就是JAVA程序程序中的一个个对象,所以Bean的管理其实就是spring对于JAVA程序中的对象的管理

管理的内容是什么

1 对象的创建   IOC

IOC   叫做控制反转,就是Spring给我们创建对象,然后我们直接用,不用自己NEW,前面已经解释过

IOC处理的是对象如何创建的问题

2 属性的赋值   DI

DI    Dependency Injection，即“依赖注入” 就是创建属性时给对象属性赋值

对象功能的实现往往要依赖属性的值,那么给对象属性赋值就可以说成是依赖注入

由于对象属性不仅仅是基本数据类型,还可能是其他类,或者引用类型

那么依赖注入将会把更多的对象之间的关系整理到一起,可以行程一个庞大的依赖关系

DI处理的是对象的属性赋值和互相依赖的关系

spring给我们提供了两种关于bean的方式

1 基于XML方式的Bean管理

2 基于注解方式的Bean管理

创建新的模块并导入以下依赖

依赖

2. org.springframework
3. spring-context
4. 5.3.5
7. junit
8. junit
9. 4.13.1
10. test

创建spring配置文件,一般spring的配置文件很多人约定俗称为application****.xml

准备一个要实例化的类

1. public class User {
2. private Integer userid;
3. private String username;
4. private String password;
5. @Override
6. public String toString() {
7. return "User{" +
8. "userid=" + userid +
9. ", username='" + username + ''' +
10. ", password='" + password + ''' +
11. '}';
12. }
13. public User() {
14. System.out.println("noArgConstructor");
15. }
16. public User(Integer userid, String username, String password) {
17. System.out.println("allArgConstructor");
18. this.userid = userid;
19. this.username = username;
20. this.password = password;
21. }
22. public void setUserid(Integer userid) {
23. System.out.println("setUserid");
24. this.userid = userid;
25. }
26. public void setUsername(String username) {
27. System.out.println("setUsername");
28. this.username = username;
29. }
30. public void setPassword(String password) {
31. System.out.println("setpassword");
32. this.password = password;
33. }
34. }

IOC创建对象

通过无参构造方法构造对象

标签的常见属性

id    对象的id

class 类的全路径名

name 和id类似,一般不用

scope 控制对象单例多例和使用范围

singleton作用域(scope 默认值), Spring IOC容器中只会存在一个共享的bean实例

prototype作用域部署的bean，每一次获取都会产生一个新的bean实例，相当与一个new的操作

request表示该针对每一次HTTP请求都会产生一个新的bean，同时该bean仅在当前HTTP request内有效

session作用域表示该针对每一次HTTP请求都会产生一个新的bean，同时该bean仅在当前HTTP session内有效

global session作用域类似于标准的HTTP Session作用域，不过它仅仅在基于portlet的web应用中才有意义

lazy-init 懒加载 调用getBean的时候再去实例化对象

DI给对象属性赋值

1 通过set方法给对象属性赋值

2 通过有参构造给对象属性赋值

测试代码

1. public class Test1 {
2. @Test
3. public void testGetBean(){
4. ApplicationContext context =new
   ClassPathXmlApplicationContext("applicationContext.xml");
5. User user1 = context.getBean("user1", User.class);
6. User user2 = context.getBean("user2", User.class);
7. User user3 = context.getBean("user3", User.class);
8. User user4 = context.getBean("user4", User.class);
9. User user5 = context.getBean("user5", User.class);
10. System.out.println(user1);
11. System.out.println(user2);
12. System.out.println(user3);
13. System.out.println(user4);
14. System.out.println(user5);
15. }
16. }

4 注入空值和特殊符号

10. ]]>

5 关于bean引用

实体类

1. package com.msb.bean;
2. import java.util.Date;
3. /**
4. • @Author: Ma HaiYang
5. • @Description: MircoMessage:Mark_7001
6. */
7. public class Mouse {
8. private String name;
9. private Date birthdate;
10. @Override
11. public String toString() {
12. return "Mouse{" +
13. "name='" + name + ''' +
14. ", birthdate=" + birthdate +
15. '}';
16. }
17. public Mouse() {
18. }
19. public Mouse(String name, Date birthdate) {
20. this.name = name;
21. this.birthdate = birthdate;
22. }
23. public String getName() {
24. return name;
25. }
26. public void setName(String name) {
27. this.name = name;
28. }
29. public Date getBirthdate() {
30. return birthdate;
31. }
32. public void setBirthdate(Date birthdate) {
33. this.birthdate = birthdate;
34. }
35. }
36. package com.msb.bean;
37. /**
38. • @Author: Ma HaiYang
39. • @Description: MircoMessage:Mark_7001
40. */
41. public class Cat {
42. private String name;
43. private Mouse mouse1;
44. @Override
45. public String toString() {
46. return "Cat{" +
47. "name='" + name + ''' +
48. ", mouse1=" + mouse1 +
49. '}';
50. }
51. public Cat() {
52. }
53. public Cat(String name, Mouse mouse1) {
54. this.name = name;
55. this.mouse1 = mouse1;
56. }
57. public String getName() {
58. return name;
59. }
60. public void setName(String name) {
61. this.name = name;
62. }
63. public Mouse getMouse1() {
64. return mouse1;
65. }
66. public void setMouse1(Mouse mouse1) {
67. this.mouse1 = mouse1;
68. }
69. }

xml 配置

6 关于集合注入

实体类

1. package com.msb.bean;
2. /**
3. • @Author: Ma HaiYang
4. • @Description: MircoMessage:Mark_7001
5. */
6. public class Book {
7. private String bname;
8. private String author;
9. @Override
10. public String toString() {
11. return "Book{" +
12. "bname='" + bname + ''' +
13. ", author='" + author + ''' +
14. '}';
15. }
16. public Book() {
17. }
18. public Book(String bname, String author) {
19. this.bname = bname;
20. this.author = author;
21. }
22. public String getBname() {
23. return bname;
24. }
25. public void setBname(String bname) {
26. this.bname = bname;
27. }
28. public String getAuthor() {
29. return author;
30. }
31. public void setAuthor(String author) {
32. this.author = author;
33. }
34. }
35. package com.msb.bean;
36. import java.util.Arrays;
37. import java.util.List;
38. import java.util.Map;
39. import java.util.Set;
40. /**
41. • @Author: Ma HaiYang
42. • @Description: MircoMessage:Mark_7001
43. */
44. public class Student {
45. private String[] books;
46. private Set bookSet;
47. private List bookList;
48. private Map<String,String> bookMap;
49. private List bookList2;
50. @Override
51. public String toString() {
52. return "Student{" +
53. "books=" + Arrays.toString(books) +
54. ", bookSet=" + bookSet +
55. ", bookList=" + bookList +
56. ", bookMap=" + bookMap +
57. ", bookList2=" + bookList2 +
58. '}';
59. }
60. public String[] getBooks() {
61. return books;
62. }
63. public void setBooks(String[] books) {
64. this.books = books;
65. }
66. public Set getBookSet() {
67. return bookSet;
68. }
69. public void setBookSet(Set bookSet) {
70. this.bookSet = bookSet;
71. }
72. public List getBookList() {
73. return bookList;
74. }
75. public void setBookList(List bookList) {
76. this.bookList = bookList;
77. }
78. public Map<String, String> getBookMap() {
79. return bookMap;
80. }
81. public void setBookMap(Map<String, String> bookMap) {
82. this.bookMap = bookMap;
83. }
84. public List getBookList2() {
85. return bookList2;
86. }
87. public void setBookList2(List bookList2) {
88. this.bookList2 = bookList2;
89. }
90. public Student() {
91. }
92. public Student(String[] books, Set bookSet, List
    bookList, Map<String, String> bookMap, List bookList2) {
93. this.books = books;
94. this.bookSet = bookSet;
95. this.bookList = bookList;
96. this.bookMap = bookMap;
97. this.bookList2 = bookList2;
98. }
99. }

配置文件

2. <beans xmlns="http://www.springframework.org/schema/beans"
3. xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4. xmlns:p="http://www.springframework.org/schema/p"
5. xmlns:c="http://www.springframework.org/schema/c"
6. xmlns:util="http://www.springframework.org/schema/util"
7. xsi:schemaLocation="
8. http://www.springframework.org/schema/beans
9. http://www.springframework.org/schema/beans/spring-beans.xsd
10. http://www.springframework.org/schema/util
11. http://www.springframework.org/schema/util/spring-util.xsd
12. ">
14. <util:list id="outerbookList">
19. </util:list>
24. JAVA
25. MySQL
26. Spring
32. JAVA
33. MySQL
34. Spring
40. JAVA
41. MySQL
42. Spring

7 工厂方式获取bean

特点 : bean标签中定义的class类不是返回的对象的类,而是生产该对象的工厂

工厂模式:GOF 设计模式

spring中给我们定义好了一个工厂接口,可以生产对象的接口,我们可以通过工厂来获取bean

定义工厂对象 实现 FactoryBean接口

1. package com.msb.bean;
2. import org.springframework.beans.factory.FactoryBean;
3. /**
4. • @Author: Ma HaiYang
5. • @Description: MircoMessage:Mark_7001
6. */
7. public class BookFactory implements FactoryBean {
8. @Override
9. public Book getObject() throws Exception {
10. Book book=new Book();
11. book.setBname("JAVA");
12. book.setAuthor("马士兵");
13. return book;
14. }
15. @Override
16. public Class<?> getObjectType() {
17. return null;
18. }
19. }

配置文件

测试代码

1. @Test
2. public void testGetBean(){
3. ApplicationContext applicationContext=new
   ClassPathXmlApplicationContext("applicationContext5.xml");
4. Book book = applicationContext.getBean("book", Book.class);
5. System.out.println(book);
6. }

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