Spring之框架初探

Spring核心

IoC：控制反转Inversion of Control

AOP：Aspect Oriented programming

依赖注入配置文件介绍

1、 配置Bean的配置文件（文件名字叫什么都可以）

2、 在程序中利用context获取实例对象

如何实现依赖注入

使用IoC容器实现依赖注入DI。

DI依赖注入几种方法：

1. 构造注入（调用构造器）

2. set方法注入（常用）

3. 接口注入

即：在相应的组件里面提供set方法，spring自动调用set方法。

实际操作

如果想使用spring，首先导入jar；spring是一个非全有全无开源框架。spring可以用在普通的java程序，web程序，ejb程序。

1、 编写实体类

2、 在源包下创建文件夹并创建配置文件如：bean.xml，并做配置实体类。

3、 利用ClassPathXmlApplicationContext(“配置文件位置”)获取实体对象。

注意：配置文件中配置的bean，可以选择配置 scope=”prototype/singleton”

prototype：每次获取对象都是创建的新对象。

singleton：每次获取对象都是同一个对象。

bean.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:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd"> 
<bean id="address" class="com.justcrazy.www.model.Address">
<property name="city" value="北京" />
<property name="street" value="五棵松路26号" />
</bean>

<bean id="company" class="com.justcrazy.www.model.Company" scope="prototype">
<property name="name" value="嘿嘿嘿" />
<property name="age" value="1" />
<property name="address" ref="address" />
<property name="employees">
<list>
<value>帅哥</value>
<value>美女</value>
<value>女流氓</value>
</list>
</property>
<property name="department">
<set>
<value>耍流氓</value>
<value>服务</value>
</set>
</property>
</bean>
</beans>

Address 类

public class Address {
private String city;
private String street;

public Address() {
}

public String getCity() {
return city;
}

public void setCity(String city) {
this.city = city;
}

public String getStreet() {
return street;
}

public void setStreet(String street) {
this.street = street;
}

@Override
public String toString() {
return "Address{" + "city=" + city + ", street=" + street + '}';
}

}

Company类：

public class Company {
private String name;
private int age;
private Address address;
private List employees;
private Set department;

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public int getAge() {
return age;
}

public void setAge(int age) {
this.age = age;
}

public Address getAddress() {
return address;
}

public void setAddress(Address address) {
this.address = address;
}

public List getEmployees() {
return employees;
}

public void setEmployees(List employees) {
this.employees = employees;
}

public Set getDepartment() {
return department;
}

public void setDepartment(Set department) {
this.department = department;
}

@Override
public String toString() {
return "Company{" + "name=" + name + ", age=" + age + ", address=" + address + ", employees=" + employees + ", department=" + department + '}';
}

}

测试类

public class Test {

public static void main(String[] args) {
//配置文件所在位置为：src目录下config包内
ApplicationContext context = new ClassPathXmlApplicationContext("/config/beans.xml");

Company company = (Company)context.getBean("company");
System.out.println(company);
}
}

打印结果

Company{name=嘿嘿嘿, age=1, address=Address{city=北京, street=五棵松路26号}, employees=[帅哥, 美女, 女流氓], department=[耍流氓, 服务]}