一,概念
1,IOC/DI是一种编程思想,即控制反转/依赖注入。它主要用于解耦合,减少组件之间的耦合度,提高代码的灵活性和可维护性。在IOC/DI中,控制权由容器掌握,容器负责根据配置文件或注解来实例化对象,并将依赖关系注入到对象中。
2,在Spring中,IOC/DI主要通过注解和XML配置文件来实现。使用注解可以减少XML配置文件的编写量,使代码更加简洁和易读。常用的注解有@Component、@Service、@Autowired等,它们分别表示组件、服务和自动装配。同时,Spring也提供了一些工具类,如BeanUtils、ResourceLoader等,方便开发人员进行对象的初始化和属性注入等操作。
3,总之,反射和IOC/DI是Java编程中必不可少的两个重要特性,它们为开发人员提供了更多的灵活性和可扩展性,同时也使得代码更加清晰和易于维护。
二,代码示例
dao层
package com.yang.dao.impl;
import com.yang.dao.BookDao;
public class BookDaoImpl implements BookDao {
@Override
public void add() {
System.out.println("BookDaoImpl...add");
}
}
package com.yang.dao;
public interface BookDao {
public void add();
}
service层
package com.yang.service.impl;
import com.yang.dao.BookDao;
import com.yang.service.BookService;
public class BookServiceImpl implements BookService {
private BookDao bookDao;
public String name;
private int age;
public void setBookDao(BookDao bookDao) {
this.bookDao = bookDao;
}
public void setName(String name) {
this.name = name;
}
public void setAge(int age) {
this.age = age;
}
@Override
public void save() {
System.out.println("BookServiceImpl...save" + "姓名:" + name + "年龄:" + age);
bookDao.add();
}
}
package com.yang.service.impl;
import com.yang.service.BookService;
public class BookServiceVip implements BookService {
@Override
public void save() {
System.out.println("BookServiceVip...save");
}
}
package com.yang.service;
public interface BookService {
void save();
}
测试类
package com.yang.text;
import com.yang.service.BookService;
import org.junit.Test;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Text01 {
BookService bookService;
@Test
public void text01() {
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("spring.xml");
bookService = (BookService) context.getBean("bookService");
bookService.save();
}
}
<?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">
<bean id="bookDao" class="com.yang.dao.impl.BookDaoImpl"/>
<bean id="bookService" class="com.yang.service.impl.BookServiceImpl">
<property name="age" value="18"/>
<property name="name" value="梨子"/>
<property name="bookDao" ref="bookDao"/>
</bean>
</beans>
测试结果