Spring之框架初探

Spring核心

IoC：控制反转Inversion of Control
AOP：Aspect Oriented programming

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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

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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。

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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]}