IOC装配Bean
（1）Spring框架Bean实例化的方式提供了三种方式实例化Bean
构造方法实例化(默认无参数，用的最多)
静态工厂实例化
实例工厂实例化
下面先写这三种方法的applicationContext.xml配置文件：
1 <?xml version="1.0" encoding="UTF-8"?> 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:context="http://www.springframework.org/schema/context" xsi:schemaLocation=" 6 http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd 7 http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> 8 9 <!-- Bean的三种实例化方式================================================================================ --> 10 <!-- 2.1 使用无参的构造器 --> 11 <bean id="bean1" class="com.study.spring.b_instance.Bean1"></bean> 12 <!-- 2.2使用静态工厂方法 factory-method 是工厂提供的静态方法 --> 13 <bean id="bean2" class="com.study.spring.b_instance.Bean2" factory-method="createInstance"></bean> 14 <!-- 2.3配置实例化工厂的方法 --> 15 <bean id="bean3Factory" class="com.study.spring.b_instance.Bean3Factory"></bean> 16 <bean id="bean3" factory-bean="bean3Factory" factory-method="getInstance"></bean> 17 <!-- end.Bean的三种实例化方式================================================================================ -->
Bean1类
public class Bean1 {
//必须提供无参的构造函数 系统有默认无参的构造函数
}
Bean2类
public class Bean2 {
private static Bean2 Bean2 = new Bean2();
private Bean2() {
}
public static Bean2 createInstance() {
return Bean2;
}
}
Bean3类
public class Bean3 {
}
Bean3Factory类
1 public class Bean3Factory {
2
3 private Bean3Factory(){
4
5 }
6
7 public Bean3 getInstance(){
8 return new Bean3();
9 }
10 }
测试类InstanceDemo
1 import org.junit.Test;
2 import org.springframework.context.ApplicationContext;
3 import org.springframework.context.support.ClassPathXmlApplicationContext;
4
5 public class InstanceDemo {
6
7 //实例化工厂方法
8 @Test
9 public void demo3(){
10 //加载配置文件 创建工厂
11 ApplicationContext applicationContext=new ClassPathXmlApplicationContext("applicationContext.xml");
12
13 Bean3 bean3 =(Bean3) applicationContext.getBean("bean3");
14 System.out.println(bean3);
15
16 }
17
18 //静态工厂方法
19 @Test
20 public void demo2(){
21 //加载配置文件 创建工厂
22 ApplicationContext applicationContext=new ClassPathXmlApplicationContext("applicationContext.xml");
23
24 Bean2 bean2 =(Bean2) applicationContext.getBean("bean2");
25 System.out.println(bean2);
26
27 }
28 //构造方法得到bean对象
29 @Test
30 public void demo1(){
31 //加载配置文件 创建工厂
32 ApplicationContext applicationContext=new ClassPathXmlApplicationContext("applicationContext.xml");
33
34 Bean1 bean1 =(Bean1) applicationContext.getBean("bean1");
35 System.out.println(bean1);
36
37 }
38 }
39 /*
40 * 这三个都得到类似于[email protected] 的内存地址
41 */
(2).Bean的其他配置:
一般情况下，装配一个Bean时，通过指定一个id属性作为Bean的名称
id 属性在IoC容器中必须是唯一的
id 的命名要满足XML对ID属性命名规范 必须以字母开始，可以使用字母、数字、连字符、下划线、句话、冒号
如果Bean的名称中含有特殊字符，就需要使用name属性 例如： <bean name="#person" class="cn.itcast.bean.Person"/>
因为name属性可以相同，所以后出现Bean会覆盖之前出现的同名的Bean
id和name的区别:
id遵守XML约束的id的约束.id约束保证这个属性的值是唯一的,而且必须以字母开始，可以使用字母、数字、连字符、下划线、句话、冒号
name没有这些要求
如果bean标签上没有配置id,那么name可以作为id.
Bean的scope属性
<!-- 3.Bean的scope属性===================================================================== -->
<bean id="product" class="com.study.spring.c_scope.Product" scope="singleton"></bean>
<!-- end.Bean的scope属性===================================================================== -->
* singleton :单例的.(默认的值.)
* prototype :多例的.
* request :web开发中.创建了一个对象,将这个对象存入request范围,request.setAttribute();
* session :web开发中.创建了一个对象,将这个对象存入session范围,session.setAttribute();
* globalSession :一般用于Porlet应用环境.指的是分布式开发.不是porlet环境,globalSession等同于session;
3.Bean属性的依赖注入
前面已经知道如何获得对象，那我们接下来要知道如果给对象对象的属性赋值。
下面通过举例说明：
public class Car {
private String name;
private double price;
public Car(String name, double price) {
super();
this.name = name;
this.price = price;
}
@Override
public String toString() {
return "Car [name=" + name + ", price=" + price + "]";
}
}
Car 类
public class Car2 {
private String name;
private double price;
public void setName(String name) {
this.name = name;
}
public void setPrice(double price) {
this.price = price;
}
@Override
public String toString() {
return "Car2 [name=" + name + ", price=" + price + "]";
}
}
Car2类
public class CarInfo {
public String getName(){
return "哈弗H6";
}
public double caculatePrice(){
return 110000;
}
}
CarInfo类
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
public class CollectionBean {
private String name;
private Integer age;
private List<String> hobbies;
private Set<Integer> numbers;
private Map<String, String> map;
private Properties properties;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public List<String> getHobbies() {
return hobbies;
}
public void setHobbies(List<String> hobbies) {
this.hobbies = hobbies;
}
public Set<Integer> getNumbers() {
return numbers;
}
public void setNumbers(Set<Integer> numbers) {
this.numbers = numbers;
}
public Map<String, String> getMap() {
return map;
}
public void setMap(Map<String, String> map) {
this.map = map;
}
public Properties getProperties() {
return properties;
}
public void setProperties(Properties properties) {
this.properties = properties;
}
@Override
public String toString() {
return "CollectionBean [name=" + name + ", age=" + age + ", hobbies=" + hobbies + ", numbers=" + numbers
+ ", map=" + map + ", properties=" + properties + "]";
}
}
CollectionBean类
public class Employee {
private String name;
private Car2 car2;
public void setName(String name) {
this.name = name;
}
public void setCar2(Car2 car2) {
this.car2 = car2;
}
@Override
public String toString() {
return "Employee [name=" + name + ", car2=" + car2 + "]";
}
}
Employee类
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class TestDi {
@Test
public void demo6() {
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
CollectionBean collectionBean = (CollectionBean) applicationContext.getBean("collectionBean");
System.out.println(collectionBean);
}
@Test
public void demo5() {
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
Car2 car2 = (Car2) applicationContext.getBean("car2_2");
System.out.println(car2);
}
@Test
public void demo4() {
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
Employee e = (Employee) applicationContext.getBean("employee2");
System.out.println(e);
}
@Test
public void demo3() {
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
Employee e = (Employee) applicationContext.getBean("employee");
System.out.println(e);
}
@Test
public void demo2() {
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
Car2 car2 = (Car2) applicationContext.getBean("car2");
System.out.println(car2);
}
@Test
public void demo1() {
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
Car car = (Car) applicationContext.getBean("car");
System.out.println(car);
}
}
TestDi测试类
上面这几个类都不是最主要的，我们主要是来看配置文件怎么写，这才是最关键的： applicationContext.xml
1 <?xml version="1.0" encoding="UTF-8"?>
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:context="http://www.springframework.org/schema/context" xsi:schemaLocation="
6 http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
7 http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
8
9
10 <!-- Bean的依赖注入===================================================================================== -->
11 <!-- 4.1构造器注入 -->
12 <bean id="car" class="com.study.spring.e_di.Car">
13 <!-- 方式一.根据索引的位置 -->
14 <!-- <constructor-arg index="0" value="保时捷"></constructor-arg>
15 <constructor-arg index="1" value="1500000"></constructor-arg> -->
16 <!-- 方式二.根据名字配置 -->
17 <!-- <constructor-arg name="name" value="宝马"></constructor-arg>
18 <constructor-arg name="price" value="500000"></constructor-arg> -->
19 <!-- 方式三.根据类型配置 -->
20 <constructor-arg type="java.lang.String" value="奔驰"></constructor-arg>
21 <constructor-arg type="double" value="600000"></constructor-arg>
22 </bean>
23
24 <!-- 4.2setter方法中注入 -->
25 <bean id="car2" class="com.study.spring.e_di.Car2">
26 <property name="name" value="雪佛兰"></property>
27 <property name="price" value="100000"></property>
28 </bean>
29
30 <bean id="employee" class="com.study.spring.e_di.Employee">
31 <property name="name" value="张三"></property>
32 <property name="car2" ref="car2"></property>
33 </bean>
34
35 <!-- 引用p命名空间 --><!-- 如果要引用p命名，那在最上面sxd中就要配置 xmlns:p="http://www.springframework.org/schema/p"-->
36 <bean id="car22" class="com.study.spring.e_di.Car2" p:name="宝马" p:price="500000">
37 </bean>
38 <bean id="employee2" class="com.study.spring.e_di.Employee" p:name="李四" p:car2-ref="car22"></bean>
39
40 <!-- 引入spEL表达式 -->
41 <bean id="carInfo" class="com.study.spring.e_di.CarInfo"></bean>
42 <bean id="car2_2" class="com.study.spring.e_di.Car2">
43 <property name="name" value="#{carInfo.name}"></property>
44 <property name="price" value="#{carInfo.caculatePrice()}"></property>
45 </bean>
46
47 <!-- 复杂属性的依赖注入 -->
48 <bean id="collectionBean" class="com.study.spring.e_di.CollectionBean">
49 <!-- 简单属性的注入 -->
50 <property name="name" value="归谷"></property>
51 <property name="age" value="12"></property>
52 <!-- 注入list集合 -->
53 <property name="hobbies">
54 <list>
55 <value>吃饭</value>
56 <value>睡觉</value>
57 <value>敲代码</value>
58 </list>
59 </property>
60
61 <!-- 注入set集合 -->
62 <property name="numbers">
63 <set>
64 <value>10</value>
65 <value>20</value>
66 <value>30</value>
67 <value>40</value>
68 <value>50</value>
69 </set>
70 </property>
71 <!-- 注入map集合 -->
72 <property name="map">
73 <map>
74 <entry key="birthday" value="2017-1-1"></entry>
75 <entry key="address" value="杭州西湖"></entry>
76 <entry key="sex" value="female"></entry>
77 </map>
78 </property>
79
80 <!-- 注入Properties -->
81 <property name="properties">
82 <props>
83 <prop key="compamy">杭州归谷</prop>
84 <prop key="pnum">200</prop>
85 </props>
86 </property>
87 </bean>
88
89 <!-- end Bean的依赖注入===================================================================================== -->
90 <import resource="classpath:bean1.xml"/>
91 <import resource="classpath:bean2.xml"/>
92 <!-- 这里导入是指如果在src下还有其它的beans.xml我们可以这样去调用 -->
93
94 </beans>
有关applicationContext.xml这个配置文件里的内容一定要看懂，我写的还是比较基础和全面的。
有关命名空间p的使用我这里在解释下：
p:<属性名>="xxx" 引入常量值
p:<属性名>-ref="xxx" 引用其它Bean对象
关于这篇文章，我就写到这里，不足之处，欢迎大家多多指点，谢谢！
时间： 2024-10-11 13:16:14