Spring基础知识

Posted 2021-03-16 wnlsq

spring简介

Spring是一个开放源代码的设计层面框架，他解决的是业务逻辑层和其他各层的松耦合问题，因此它将面向接口的编程思想贯穿整个系统应用。Spring是于2003 年兴起的一个轻量级的Java 开发框架，由Rod Johnson创建。简单来说，Spring是一个分层的JavaSE/EE full-stack(一站式) 轻量级开源框架。

 

Spring与解耦合

 

Spring根据功能的不同，将代码划分为两类：主业务逻辑与系统级服务（交叉业务逻辑）。主业务逻辑间，及主业务逻辑与系统级服务间的耦合度是较高的。Spring对于前述两种较高的耦合度，采用了两种不同的技术进行解耦。使用IoC解耦主业务逻辑间的耦合度，使用AOP解耦主业务逻辑与系统级服务间的耦合度。

spring框架的下载

下载地址：http://repo.spring.io 

官网：    http://spring.io 

spring程序

package com.kaikeba.beans;

public class Student {

private String sname;
private int age;
private Teacher teacher;

public Teacher getTeacher() {
return teacher;
}
public void setTeacher(Teacher teacher) {
this.teacher = teacher;
}
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}

}

package com.kaikeba.beans;

public class Teacher {
private String tname;

public String getTname() {
return tname;
}

public void setTname(String tname) {
this.tname = tname;
}

}

package com.kaikeba.util;

public class BeanDefined {
    
    private String beanId;
    private String classPath;
    public String getBeanId() {
        return beanId;
    }
    public void setBeanId(String beanId) {
        this.beanId = beanId;
    }
    public String getClassPath() {
        return classPath;
    }
    public void setClassPath(String classPath) {
        this.classPath = classPath;
    }
}

package com.kaikeba.util;

import java.util.List;

public class BeanFactory {
    
       private List<BeanDefined> beanDefinedList;

    public List<BeanDefined> getBeanDefinedList() {
        return beanDefinedList;
    }

    public void setBeanDefinedList(List<BeanDefined> beanDefinedList) {
        this.beanDefinedList = beanDefinedList;
    }
    
    public Object getBean(String beanId) throws Exception{
           Object instance;
           for(BeanDefined beanObj:beanDefinedList){
                 if(beanId.equals(beanObj.getBeanId())){
                     String classPath = beanObj.getClassPath();                     
                     Class classFile= Class.forName(classPath);
                     //在默认情况下，Spring工厂是通过调用当前类默认工作方法创建实例对象
                     instance= classFile.newInstance();
                     return instance;
                 }
           }
           return null;
    }
}

package com.kaikeba.test;

import java.util.ArrayList;
import java.util.List;

import com.kaikeba.beans.Teacher;
import com.kaikeba.util.BeanDefined;
import com.kaikeba.util.BeanFactory;

public class TestMain {

    public static void main(String[] args) throws Exception {
        
          //1.声明注册bean
          BeanDefined beanObj = new BeanDefined();
          beanObj.setBeanId("teacher");
          beanObj.setClassPath("com.kaikeba.beans.Teacher");
          
          List beanList = new ArrayList();
          beanList.add(beanObj);//spring核心配置
          
          //2.声明一个Spring提供BeanFacotory
          BeanFactory factory = new BeanFactory();
          factory.setBeanDefinedList(beanList);
          
          //3.开发人员向BeanFactory索要实例对象.
          Teacher t= (Teacher) factory.getBean("teacher");
          System.out.println(t);

    }

}