Spring1.0——spring的IoC控制反转和DI依赖注入简单案例

JAVAWEB框架学习文章索引点这里
核心api：
BeanFactory:用于生成任意bean，采取延迟加载，第一次getBean的时候才会初始化Bean
ApplicationContext:是BeanFactory的子接口，功能更强大。当配置文件被加载时，就进行对象实例化。
ClassPathXmlApplicationContext :用于加载classpath(类路径、src)下的xml
FileSystemXmlApplicationContext:用于加载指定盘符下的xml

spring loC（控制反转）简单使用
1，导入jar包（beans,context,core,expression,logging）
2，编写配置文件

配置文件

<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">


    
    <bean id="Person" class="com.IocDemo.Person">bean>
beans>

测试

    @Test
    public void test1() {
        //1，获得spring容器
        String xmlPath = "com/IocDemo/beans.xml";
        ApplicationContext appCont = new ClassPathXmlApplicationContext(xmlPath);
        //2，获得内容
        Person person = (Person) appCont.getBean("Person");
        person.setId(20);
        System.out.println(person.getId());
    }

DI 依赖注入
分别创建StudentDao、StudentService接口
分别创建StudentDaoImpl、StudentServiceImpl实现类
在StudentServiceImpl中设置属性StudentDao并设置对于的setStudentDao方法（配置文件配置后自动调用进行赋值），由于StudentServiceImpl中并不知道StudentDao的实现类的内容（实际上调用setStudentDao方法的时候配置传入的是它的实现类），这是一种解耦。

几个接口，实现类

package com.b_DI;

public interface StudentDao {
    void info();
}

package com.b_DI;

public class StudentDaoImpl implements StudentDao {
    @Override
    public void info() {
        System.out.println("我是学生");
    }
}

package com.b_DI;

public interface StudentService {
    void study();
}

package com.b_DI;

public class StudentServiceImpl implements StudentService {
    private StudentDao studentDao;

    public void setStudentDao(StudentDao studentDao) {
        this.studentDao = studentDao;
    }
    @Override
    public void study() {
        System.out.println("学生学习");
        studentDao.info();
    }
}

配置文件：

<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">

    
    <bean id="StudentService" class="com.b_DI.StudentServiceImpl">
        <property name="studentDao" ref="StudentDao">property>
    bean>
    <bean id="StudentDao" class="com.b_DI.StudentDaoImpl">bean>
beans>

测试类

package com.b_DI;

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

import com.a_IocDemo.Person;

public class MyTest {
    @Test
    public void test1() {
        //1，获得spring容器
        String xmlPath = "com/b_DI/DITest.xml";
        ApplicationContext appCont = new ClassPathXmlApplicationContext(xmlPath);
        //依赖注入
        StudentService studentService = (StudentService) appCont.getBean("StudentService");
        studentService.study();
    }
}

结果：

学生学习
我是学生