spring的简单使用

好记性不如烂笔头
相信从事java后台开发的朋友们对这个框架都不陌生吧。
Spring的核心是控制反转(IOC)和面向切面(AOP)，本片博客主要是讲IOC的应用
什么是IOC，就我现在的理解就是将对象的生命周期交给了容器【如对象的创建…】

开始搭建环境【IDEA】
如图，new project的时候勾上Spring选项，然后下一步，填写好项目名称，然后确定就可以了

会自动帮你把jar下载好的

场景：创建一个User类，user包含id、name、age, 测试spring的容器是否会帮我们生成User的实例

public class User {

    public int id ;
    public String name ;
    public int age ;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    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;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

spring-config.xml [配置文件]
property 非必须的

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
       <!--scope="prototype" 表示使用原型模式【就是非单例模式，默认的是单例模式】-->
       <bean id="UserBean" class="User" scope="prototype">
              <!-- 注意 name="id" value="1"  是通过类的set方法设置进去的-->
              <property name="id" value="1"></property>
              <property name="name" value="Spring"></property>
              <property name="age" value="10"></property>
       </bean>
</beans>

测试代码

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test {

    public static void main(String[] args){
        //创建一个spring的IOC容器对象
        ApplicationContext context = new ClassPathXmlApplicationContext("spring-config.xml");
        //从IOC容器中获取Bean的实例
        User user = (User) context.getBean("UserBean"); 
        System.out.println(user.toString());
    }
}

输出  User{id=1, name='Spring', age=10}

此时增加一个user增加一个Phone的类

public class Phone {
    public int phoneNumber ;
    public String phoneName ;
    public long phonePay ;

    public int getPhoneNumber() {
        return phoneNumber;
    }

    public void setPhoneNumber(int phoneNumber) {
        this.phoneNumber = phoneNumber;
    }

    public String getPhoneName() {
        return phoneName;
    }

    public void setPhoneName(String phoneName) {
        this.phoneName = phoneName;
    }

    public long getPhonePay() {
        return phonePay;
    }

    public void setPhonePay(long phonePay) {
        this.phonePay = phonePay;
    }

    @Override
    public String toString() {
        return "Phone{" +
                "phoneNumber=" + phoneNumber +
                ", phoneName='" + phoneName + '\'' +
                ", phonePay=" + phonePay +
                '}';
    }
}

public class User {

    public int id ;
    public String name ;
    public int age ;

    public Phone phone ;

    public Phone getPhone() {
        return phone;
    }

    public void setPhone(Phone phone) {
        this.phone = phone;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    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;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", phone=" + phone +
                '}';
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
       <!--scope="prototype" 表示使用原型模式【就是非单例模式，默认的是单例模式】-->
       <bean id="UserBean" class="User" scope="prototype">
              <!-- 注意 name="id" value="1"  是通过类的set方法设置进去的-->
              <property name="id" value="1"></property>
              <property name="name" value="Spring"></property>
              <property name="age" value="10"></property>
              <!--注入一个Phone-->
              <property name="phone" ref="PhoneBean"/>
       </bean>

       <bean id="PhoneBean" class="Phone">
              <property name="phoneNumber" value="110"/>
              <property name="phoneName" value="小米"/>
              <property name="phonePay" value="2600"/>
       </bean>
</beans>

测试

User{id=1, name='Spring', age=10, phone=Phone{phoneNumber=110, phoneName='小米', phonePay=2600}}

~完~