cgb2106-day15

一,Spring

–1,概述

功能非常豐富,核心的功能是: IOC DI AOP
IOC : 是控制反轉,指 把創建物件的程序交給了Spring
DI : 是依賴注入,指把物件間的依賴關系 自動維護
AOP : 是補充了OOP的不足

–2,IOC的XML實作方式

是指把創建物件管理物件的程序交給了Spring框架

創建Maven Module

File-New-Module-Maven-next-輸入ModuleName-ok

匯入jar包(不需要了,被Spring Boot整合了)

創建Hello類

創建組態檔

<?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">
    <!--
        配置Bean的資訊
        id用來作為這個bean的唯一標識,class用來描述類的全路徑
    -->
    <bean id="hello" class="cn.tedu.spring.Hello"></bean>
</beans>

測驗

package cn.tedu.test;
import org.junit.jupiter.api.Test;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test1 {
    @Test
    public void get(){
        //1,讀取組態檔
        ClassPathXmlApplicationContext spring =
                        new ClassPathXmlApplicationContext(
                            "spring-config.xml");
        //2,直接getBean
        Object o = spring.getBean("hello");
        System.out.println(o);//cn.tedu.spring.Hello@45752059
    }
}

–3,IOC的注解實作方式

創建User類

package cn.tedu.ioc;

import org.springframework.stereotype.Component;
import org.springframework.stereotype.Controller;
import org.springframework.stereotype.Service;

@Component("a")//自動完成IOC,自己指定bean的名字a -> {"a",new User()}
//@Component  //默認的bean的名字,user
//@Component自動完成IOC, -> {"user",new User()}
//@Controller //spring提供的,用來ioc
//@Service //spring提供的,用來ioc
public class User {
    public void get(){
        System.out.println(123);
    }
}

修改組態檔

<?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.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">
    <!--
        配置Bean的資訊
        id用來作為這個bean的唯一標識,class用來描述類的全路徑
        IOC->{ "hello" , new Hello() }
    -->
    <bean id="hello" class="cn.tedu.spring.Hello"></bean>


    <!--
        配置包掃描
        base-package指定一個包的路徑,掃描范圍可以自己定
     -->
    <context:component-scan base-package="cn.tedu"></context:component-scan>

</beans>

測驗

package cn.tedu.test;
import cn.tedu.ioc.User;
import cn.tedu.spring.Hello;
import org.junit.jupiter.api.Test;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test1 {
    @Test
    public void get(){
        //1,讀取組態檔
        ClassPathXmlApplicationContext spring =
                        new ClassPathXmlApplicationContext(
                            "spring-config.xml");
        //2,直接getBean
        Object o = spring.getBean("hello");
        System.out.println(o);//cn.tedu.spring.Hello@45752059

        //呼叫子類的方法--向下轉型/造型
        Hello h = (Hello) o ;
        h.get();

        //獲取注解的bean
        User u = (User) spring.getBean("a");
        System.out.println(u);//cn.tedu.ioc.User@28f3b248

     
    }
}

總結

4,Spring的DI 依賴注入

–1,概述

是指物件間的依賴關系,可以由框架來完成

–2,簡單模擬

創建Dept類

package cn.tedu.di;

public class Dept {
    String name="java軟體開發一部";
    @Override
    public String toString() {
        return "Dept{" +
                "name='" + name + '\'' +
                '}';
    }
}

創建Emp類

package cn.tedu.di;

public class Emp {
    String name="jack";
    //系結兩個類間的關系
    private Dept d ;
    public Dept getD() {
        return d;
    }
    public void setD(Dept d) {
        this.d = d;
    }
    @Override
    public String toString() {
        return "Emp{" +
                "name='" + name + '\'' +
                ", d=" + d +
                '}';
    }
}

測驗

package cn.tedu.test;

import cn.tedu.di.Dept;
import cn.tedu.di.Emp;
import org.junit.jupiter.api.Test;
public class Test1 {
    @Test
    public void di(){
        Dept d = new Dept();
        System.out.println(d);//Dept{name='java軟體開發一部'}
        Emp e = new Emp();
        System.out.println(e);//Emp{name='jack', d=null}

        //di--把兩個物件間的關系依賴注入
        e.setD(d);
        System.out.println(e);
        //已經實作了di的效果,在查詢e把關聯的d的資訊也查到了
        //Emp{name='jack', d=Dept{name='java軟體開發一部'}}

    }
}

–3,使用Spring實作DI

創建Teacher類

package cn.tedu.di2;

import org.springframework.stereotype.Component;
@Component
public class Teacher {
    String name = "tony";
    @Override
    public String toString() {
        return "Teacher{" +
                "name='" + name + '\'' +
                '}';
    }
}

創建Student類

package cn.tedu.di2;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
@Component
public class Student {
    String name = "蔡徐坤";
    @Autowired //di
    Teacher t ;
    @Override
    public String toString() {
        return "Student{" +
                "t=" + t +
                ", name='" + name + '\'' +
                '}';
    }
}

創建組態檔,包掃描

<?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.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">

    <!--包掃描:掃描指定包路徑下的所有類,誰有ioc的注解就new誰  -->
    <context:component-scan base-package="cn.tedu.di2"></context:component-scan>
</beans>

測驗

 @Test
    public void di2(){
        //1,讀取xml檔案
        ClassPathXmlApplicationContext spring = new
                ClassPathXmlApplicationContext(
                        "spring-config.xml");
        //2,getBean
        Object o = spring.getBean("student");
//di:查學生資訊的同時也查到了老師資訊,兩個物件之間的依賴注入
        //Student{t=Teacher{name='tony'}, name='蔡徐坤'}
        System.out.println(o);
    }