Spring的注解装配Bean
Spring2.5 引入使用注解去定义Bean
@Component 描述Spring框架中Bean
Spring的框架中提供了与@Component注解等效的三个注解:
@Repository 用于对DAO实现类进行标注
@Service 用于对Service实现类进行标注
@Controller 用于对Controller实现类进行标注
***** 三个注解为了后续版本进行增强的.Bean的属性注入:
普通属性;
@Value(value="itcast")
private String info;
对象属性:
@Autowired:自动装配默认使用类型注入.
@Autowired
@Qualifier("userDao") --- 按名称进行注入.
@Autowired
@Qualifier("userDao")
private UserDao userDao;
等价于
@Resource(name="userDao")
private UserDao userDao;Bean其他的属性的配置:
配置Bean初始化方法和销毁方法:
* init-method 和 destroy-method.
@PostConstruct 初始化
@PreDestroy 销毁
配置Bean的作用范围:
@Scope以下是测试案例：
<!-- 扫描多个目录方法两种
第一种：<context:component-scan base-package="cn.spring.demo1,cn.spring.demo2" />
第二种：<context:component-scan base-package="cn.spring" />
-->
<context:component-scan base-package="cn.spring" />UserService.java
package cn.spring.demo1;
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import javax.annotation.Resource;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Repository;
import org.springframework.stereotype.Service;
/*
* 注解的方式装配bean
*/
//在spring配置文件中<bean id="userservice" class="cn.spring.demo1.UserService">
//@Component("userservice")
@Service("userservice")
//scope默认是单实例
@Scope(value="prototype")
public class UserService {
@Value(value="测试1")
private String info;
//按类型注入的话@Autowired(required=false 忽略异常)
//@Autowired(required=true)
//按名称注入的话加@Qualifier("userdaoonly") 要跟userdao里面的@Repository("userdaoonly")一样（第二种）
//@Qualifier("userdaoonly")
//@[email protected][email protected]("userdaoonly")
@Resource(name="userdaoonly")
private UserDao userdao;
public void sayHello(){
System.out.println("Hello spring Annotation..."+info+userdao);
}
/* @Override
public String toString() {
return "UserService [info=" + info + ", userdao=" + userdao + "]";
}*/
@PostConstruct
public void setup(){
System.out.println("初始化……");
}
@PreDestroy
public void teardwon(){
System.out.println("销毁……");
}
}
--------------------------------------------------------------------------------------------------------------------------------------------
UserDao.java
package cn.spring.demo1;
import org.springframework.stereotype.Repository;
@Repository("userdaoonly")
public class UserDao {
}
-------------------------------------------------------------------------------------------------------------------------------------
package cn.spring.demo1;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
//注解的方式
public class SpringTest1 {
@Test
public void demo1() {
ClassPathXmlApplicationContext applicationcontext = new ClassPathXmlApplicationContext(
"applicationContext.xml");
UserService userservice = (UserService) applicationcontext
.getBean("userservice");
// userservice.sayHello();
System.out.println(userservice);
UserService userservice2 = (UserService) applicationcontext
.getBean("userservice");
//userservice.sayHello();
System.out.println(userservice2);
applicationcontext.close();
}
}
Spring3.0提供使用Java类定义Bean信息的方法
@Configuration
public class BeanConfig {
@Bean(name="car")
public Car showCar(){
Car car = new Car();
car.setName("长安");
car.setPrice(40000d);
return car;
}
@Bean(name="product")
public Product initProduct(){
Product product = new Product();
product.setName("空调");
product.setPrice(3000d);
return product;
}
}以下是测试案例：
//这个是java类定义bean信息的方式；
package cn.spring.demo2;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class BeanConfig {
@Bean(name="car")
public Car showCar() {
Car car = new Car();
car.setName("长安");
car.setPrice(123.00);
return car;
}
@Bean(name="product")
public Product showProduct() {
Product product = new Product();
product.setName("空调");
product.setPrice(1234.00);
return product;
}
}
-----------------------------------------------------------------------------------------------------------------
package cn.spring.demo2;
public class Car {
private String name;
private Double price;
public void setName(String name) {
this.name = name;
}
public void setPrice(Double price) {
this.price = price;
}
@Override
public String toString() {
return "Car [name=" + name + ", price=" + price + "]";
}
}
-----------------------------------------------------------------------------------------------------------------
package cn.spring.demo2;
public class Product {
private String name;
private Double price;
public void setName(String name) {
this.name = name;
}
public void setPrice(Double price) {
this.price = price;
}
@Override
public String toString() {
return "Product [name=" + name + ", price=" + price + "]";
}
}
-----------------------------------------------------------------------------------------------------------------
package cn.spring.demo2;
import org.junit.Test;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import cn.spring.demo1.UserService;
public class SpringTest {
@Test
public void demo1() {
ClassPathXmlApplicationContext applicationcontext = new ClassPathXmlApplicationContext(
"applicationContext.xml");
Car car = (Car) applicationcontext
.getBean("car");
Product product = (Product) applicationcontext
.getBean("product");
System.out.println(car);
System.out.println(product);
}
}
实际开发中使用XML还是注解?
XML:
* bean管理
注解;
* 注入属性的时候比较方便.
两种方式结合;一般使用XML注册Bean,使用注解进行属性的注入.
<context:annotation-config/>
@Autowired
@Qualifier("orderDao")
private OrderDao orderDao;最后一个整合一下，一个使用XML注册bean一个用注释bean
<context:annotation-config/>
<bean id="customerdao" class="cn.spring.demo3.CustomerDao"></bean>
<bean id="orderdao" class="cn.spring.demo3.OrderDao"></bean>
<bean id="customerservice" class="cn.spring.demo3.CustomerService">
<property name="customerdao" ref="customerdao"></property>
<!-- <property name="orderdao" ref="orderdao"></property>-->
</bean>package cn.spring.demo3;
public class CustomerDao {
}
-------------------------------------------
package cn.spring.demo3;
public class OrderDao {
}
--------------------------------------------
package cn.spring.demo3;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
public class CustomerService {
private CustomerDao customerdao;
@Autowired
@Qualifier("orderdao")
private OrderDao orderdao;
public void setCustomerdao(CustomerDao customerdao) {
this.customerdao = customerdao;
}
@Override
public String toString() {
return "CustomerService [customerdao=" + customerdao + ", orderdao="
+ orderdao + "]";
}
}
-----------------------------------------------
测试类写法
package cn.spring.demo3;
import org.junit.Test;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class SpringTest {
@Test
public void demo1() {
ClassPathXmlApplicationContext applicationcontext = new ClassPathXmlApplicationContext(
"applicationContext2.xml");
CustomerService customerservice = (CustomerService) applicationcontext
.getBean("customerservice");
System.out.println(customerservice);
}
}
原文地址：http://blog.51cto.com/4534309/2107862
时间： 2024-08-09 21:52:06