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：
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <!-- Bean的三种实例化方式================================================================================ -->
<!-- 2.1 使用无参的构造器 -->
<bean id="bean1" class="com.study.spring.b_instance.Bean1"></bean>
<!-- 2.2使用静态工厂方法 factory-method 是工厂提供的静态方法 -->
<bean id="bean2" class="com.study.spring.b_instance.Bean2" factory-method="createInstance"></bean>
<!-- 2.3配置实例化工厂的方法 -->
<bean id="bean3Factory" class="com.study.spring.b_instance.Bean3Factory"></bean>
<bean id="bean3" factory-bean="bean3Factory" factory-method="getInstance"></bean>
<!-- 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
public class Bean3Factory {
private Bean3Factory(){
}
public Bean3 getInstance(){
return new Bean3();
}
}
测试类InstanceDemo
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext; public class InstanceDemo { //实例化工厂方法
@Test
public void demo3(){
//加载配置文件 创建工厂
ApplicationContext applicationContext=new ClassPathXmlApplicationContext("applicationContext.xml"); Bean3 bean3 =(Bean3) applicationContext.getBean("bean3");
System.out.println(bean3); } //静态工厂方法
@Test
public void demo2(){
//加载配置文件 创建工厂
ApplicationContext applicationContext=new ClassPathXmlApplicationContext("applicationContext.xml"); Bean2 bean2 =(Bean2) applicationContext.getBean("bean2");
System.out.println(bean2); }
//构造方法得到bean对象
@Test
public void demo1(){
//加载配置文件 创建工厂
ApplicationContext applicationContext=new ClassPathXmlApplicationContext("applicationContext.xml"); Bean1 bean1 =(Bean1) applicationContext.getBean("bean1");
System.out.println(bean1); }
}
/*
* 这三个都得到类似于com.study.spring.b_instance.Bean1@7229c204 的内存地址
*/
(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
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <!-- Bean的依赖注入===================================================================================== -->
<!-- 4.1构造器注入 -->
<bean id="car" class="com.study.spring.e_di.Car">
<!-- 方式一.根据索引的位置 -->
<!-- <constructor-arg index="0" value="保时捷"></constructor-arg>
<constructor-arg index="1" value="1500000"></constructor-arg> -->
<!-- 方式二.根据名字配置 -->
<!-- <constructor-arg name="name" value="宝马"></constructor-arg>
<constructor-arg name="price" value="500000"></constructor-arg> -->
<!-- 方式三.根据类型配置 -->
<constructor-arg type="java.lang.String" value="奔驰"></constructor-arg>
<constructor-arg type="double" value="600000"></constructor-arg>
</bean> <!-- 4.2setter方法中注入 -->
<bean id="car2" class="com.study.spring.e_di.Car2">
<property name="name" value="雪佛兰"></property>
<property name="price" value="100000"></property>
</bean> <bean id="employee" class="com.study.spring.e_di.Employee">
<property name="name" value="张三"></property>
<property name="car2" ref="car2"></property>
</bean> <!-- 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"-->
<bean id="car22" class="com.study.spring.e_di.Car2" p:name="宝马" p:price="500000">
</bean>
<bean id="employee2" class="com.study.spring.e_di.Employee" p:name="李四" p:car2-ref="car22"></bean> <!-- 引入spEL表达式 -->
<bean id="carInfo" class="com.study.spring.e_di.CarInfo"></bean>
<bean id="car2_2" class="com.study.spring.e_di.Car2">
<property name="name" value="#{carInfo.name}"></property>
<property name="price" value="#{carInfo.caculatePrice()}"></property>
</bean> <!-- 复杂属性的依赖注入 -->
<bean id="collectionBean" class="com.study.spring.e_di.CollectionBean">
<!-- 简单属性的注入 -->
<property name="name" value="归谷"></property>
<property name="age" value="12"></property>
<!-- 注入list集合 -->
<property name="hobbies">
<list>
<value>吃饭</value>
<value>睡觉</value>
<value>敲代码</value>
</list>
</property> <!-- 注入set集合 -->
<property name="numbers">
<set>
<value>10</value>
<value>20</value>
<value>30</value>
<value>40</value>
<value>50</value>
</set>
</property>
<!-- 注入map集合 -->
<property name="map">
<map>
<entry key="birthday" value="2017-1-1"></entry>
<entry key="address" value="杭州西湖"></entry>
<entry key="sex" value="female"></entry>
</map>
</property> <!-- 注入Properties -->
<property name="properties">
<props>
<prop key="compamy">杭州余杭未来科技城</prop>
<prop key="pnum">200</prop>
</props>
</property>
</bean> <!-- end Bean的依赖注入===================================================================================== -->
<import resource="classpath:bean1.xml"/>
<import resource="classpath:bean2.xml"/>
<!-- 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 --> </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！