Spring bean管理【基于注解】

Spring 关于bean的管理有几种方法，常见的有基于注解的javaConfig开发，XML开发，作为一名菜鸟XML开发会更适合，简单易懂，官方文档也写的清楚

不过最近看了Spring in action，学习了利用JavaConfig开发

package Model;

import org.springframework.stereotype.Component;

@Component
public class ClassRoom {
	private Student student;

	public Student getStudent() {
		return student;
	}

	public void setStudent(Student student) {
		this.student = student;
	}

	@Override
	public String toString() {
		return "ClassRoom [student=" + student + "]";
	}
	
}

package Model;

import org.springframework.stereotype.Component;

@Component
public class Student {
	private Integer id;
	private String name;
	private Integer age;
	private String major;
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Integer getAge() {
		return age;
	}
	public void setAge(Integer age) {
		this.age = age;
	}
	public String getMajor() {
		return major;
	}
	public void setMajor(String major) {
		this.major = major;
	}
	@Override
	public String toString() {
		return "Student [id=" + id + ", name=" + name + ", age=" + age + ", major=" + major + "]";
	}
	public void destory(){
		System.out.println("close...");
	}
}

package SpringConfig;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.context.annotation.Profile;
import org.springframework.context.annotation.PropertySource;
import org.springframework.context.annotation.Scope;
import org.springframework.core.env.Environment;

import Model.ClassRoom;
import Model.Student;

@Configuration
@ComponentScan(basePackages={"Model"})
@PropertySource("classpath:hello.properties")
@Import(value={javaConfigTo.class})
public class javaConfig {
	
	@Autowired
	Environment evn;
	
	@Bean(destroyMethod="destory",value="student")
	@Scope(scopeName=ConfigurableBeanFactory.SCOPE_SINGLETON)
	public Student returnStudent(){
		Student stu =  new Student();
		stu.setId(1);
		stu.setName(evn.getProperty("root"));//#利用spel表达式可以更强大，直接指定id获取bean
		return stu;
	}
	@Bean("classRoom")
	@Scope(scopeName=ConfigurableBeanFactory.SCOPE_SINGLETON)
	public ClassRoom returnClassRoom(){
		ClassRoom classRoom =  new ClassRoom();
		classRoom.setStudent(returnStudent());
		return classRoom;
	}
}

package SpringConfig;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import Model.Student;

@Configuration
public class javaConfigTo {
	@Bean("student2")
	public Student returnStudent(){
		Student stu = new Student();
		stu.setAge(11);
		return stu;
	}
}
package JunitTest;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.support.AbstractApplicationContext;

import Model.ClassRoom;
import Model.Student;
import SpringConfig.javaConfig;

public class Spring {
	private static ApplicationContext context;
	static{
		context = new AnnotationConfigApplicationContext(javaConfig.class);
	}
	@Test
	public void test() {
		Student student =(Student)context.getBean("student");
//		Student student2 = (Student) context.getBean("student2");
		System.out.println(student);
//		System.out.println(student2);
//		ClassRoom classRoom = (ClassRoom)context.getBean("classRoom");
//		((AnnotationConfigApplicationContext)context).close();
	}
}

@Configuration//配置注解
@ComponentScan(basePackages={"Model"})//扫描组件管理包
@PropertySource("classpath:hello.properties")//设置引入的属性文件，让我们动态注入，非硬编码
@Import(value={javaConfigTo.class})//有点像XML的import，可以分割多分xml配置文件，这里可以结合XML文件也可以多个javaConfig

@Scope(scopeName=ConfigurableBeanFactory.SCOPE_SINGLETON)//作用域

@Autowired
Environment evn;//这个类为我们封装了从引入属性文件获得属性

ps：记一个bean作用域管理的一个小知识点

一般单例模式就可以满足我们的开发，可是如果我们有时候需要基于会话或者请求来获得bean，那么得利用下面的注解

@Scope(value=WebApplicationContext.SCOPE_SESSION,proxyMode=ScopedProxyMode.INTERFACES)

比如购物车的接口，我们希望每个用户都拥有一个属于自己的购物车，所以不能是单例的，但是使用原型又显得过于浪费，性能不高，所以要利用这个注解，他用了代理模式。

当然，如果是类代理的话要使用CGLib代理，就把注解改为

@Scope(value=WebApplicationContext.SCOPE_SESSION,proxyMode=ScopedProxyMode.TARGET_CLASS)

他在对应xml的配置需要引入aop命名空间 <aop:scoped-proxy/> 或者  <aop:scoped-proxy proxy-target-class='false'/ >