bean配置
一、bean的作用域
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bean的四大作用域
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singleton
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默认的配置方式
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每次getBean同一个id，获取同一个实例对象
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prototype
- 每次调用getBean方法，都会返回一个新的实例对象
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request
- 每次请求，都会产生一个新的bean实例对象
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session
- 每次会话都会产生新的bean实例对象
二、导入beans.xml文件
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在原先的bean xml文件导入其它的bean xml文件，其它归属同一个ioc容器管理
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使用import标签使用
<import resource="beans_import.xml" /> -
举例
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <import resource="beans_import.xml" /> <bean id="boss" class="com.gec.bean.Boss" > <property name="bossName" value="#{'马老板'}" /> <property name="car" ref="car"/> </bean> </beans>
三、FactoryBean类
1、简介
- 此工厂类，创建bean对象，此FactoryBean是Spring框架提供接口，可以自定义工厂bean对象
2、分析FactoryBean接口
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T getObject
- 产生bean对象
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getObjectType
- bean对象的类型
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isSingleton
- 指明bean的作用域
3、如何使用FactoryBean接口
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需求
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注入一个字符串属性，字符串属性格式：
品牌名,价格
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如何使用
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实现FactoryBean的接口
package com.gec.factory; import com.gec.bean.Car; import org.springframework.beans.factory.FactoryBean; public class CarFactoryBean implements FactoryBean<Car> { private String carprop; public void setCarprop(String carprop) { this.carprop = carprop; } /* * 产生bean对象 * */ @Override public Car getObject() throws Exception { //将属性字符串拆解到数组 String props[]=carprop.split(","); Car c=new Car(); c.setBrand(props[0]); c.setPrice(Double.parseDouble(props[1])); return c; } /* * bean的对象类型 * */ @Override public Class<?> getObjectType() { return Car.class; } /* * 指明作用域 * */ @Override public boolean isSingleton() { return true; } } -
配置FactoryBean
<?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"> <!-- 访问此bean对象，并不是访问CarFactoryBean对象，而是访问工厂bean所产生的bean对象 --> <bean id="carFactoryBean" class="com.gec.factory.CarFactoryBean"> <property name="carprop" value="特斯拉,1000000.00" /> </bean> </beans>
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四、如何注入外部文件的数据
1、简介
- 将外部文件的数据注入到bean对象属性里面
2、用法
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依赖context标签下的property-placeholder属性
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定义一个properties文件
url=jdbc:mysql://localhost:3306/hibernate_db username=root password=1111 -
定义一个Dbuitls类
package com.gec.bean; public class Dbuils { private String url; private String username; private String password; public String getUrl() { return url; } public void setUrl(String url) { this.url = url; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } @Override public String toString() { return "Dbuils{" + "url='" + url + '\'' + ", username='" + username + '\'' + ", password='" + password + '\'' + '}'; } } -
定义beans.xml
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd"> <!--导入外部配置文件--> <context:property-placeholder location="db.properties" /> <bean id="dbuils" class="com.gec.bean.Dbuils"> <property name="url" value="${url}" /> <property name="username" value="${username}" /> <property name="password" value="${password}" /> </bean> </beans>
五、如何通过注解配置bean对象
1、四大注解
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@Component
- 此注解是标注bean对象的基本注解
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@Repository
- 此注解是作用于DAO的bean对象配置
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@Service
- 此注解是作用于Service层的bean对象配置
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@Controller
- 此注解是作用于控制器的bean对象配置
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注意
- @Repository、@Service、@Controller都属于@Component的一种
2、如何使用上述注解配置成bean
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在bean类添加上述注解
- @Component、 @Repository、 @Service、 @Controller
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在此类进行扫描操作
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用法
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定义一个bean类，此类要添加注解，默认的bean的id值就是类名的头一个字母小写
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通过@Value注解对此属性赋值
package com.gec.bean;import org.springframework.beans.factory.annotation.Value;import org.springframework.stereotype.Component;@Componentpublic class Car { @Value("特斯拉") private String brand; @Value("100000.00") private Double price; public String getBrand() { return brand; } public void setBrand(String brand) { this.brand = brand; } public Double getPrice() { return price; } public void setPrice(Double price) { this.price = price; } @Override public String toString() { return "Car{" + "brand='" + brand + '\'' + ", price=" + price + '}'; }} -
扫描Car的bean对象
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd"> <context:component-scan base-package="com.gec.bean" /> </beans> -
配置扫描过滤条件
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设置context:componet-scan下的，此时指定的include-filter没有起到作用，只要把use-default-filter设置成false就可以
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include-filter：扫描目标类的过滤条件
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exclude-filter：将扫描到目标类排除之外
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六、如何实现注解自装配bean对象
1、简介
- 使用@Autowire实现自装配bean对象
2、@Autowire如何使用
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@Autowire
- 作用：查询IOC容器，将匹配的bean类型自动注入到bean的属性里面
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用法
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定义一个UserDao类
package com.gec.dao; import org.springframework.stereotype.Repository; @Repository public class UserDao { public void save() { System.out.println("user dao save"); } } -
定义一个UserService类
- @Autowried
- 查找ioc容器匹配bean对象类型自动注入到属性
package com.gec.service; import com.gec.dao.UserDao; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; @Service public class UserService { @Autowired private UserDao userDao; public void save() { System.out.println("user service save"); userDao.save(); } } - @Autowried
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配置beans.xml，实现扫描bean类
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd"> <context:component-scan base-package="com.gec" /> </beans> -
测试类
package com.gec.app; import com.gec.service.UserService; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class MainTest3 { public static void main(String[] args) { ApplicationContext ctx=new ClassPathXmlApplicationContext("beans3.xml"); UserService userService= (UserService) ctx.getBean("userService"); userService.save(); } }
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3、@Qualifier注解用法
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当注入数据类型，在一个IOC容器存在多个bean对象是属于相同的数据类型，则可以通过@Qualifier注解区分，具体导入那个bean对象
value属性：就是指明bean id值 -
用法
- 定义一个UserDao接口
package com.gec.dao; import org.springframework.stereotype.Repository; @Repository public interface UserDao { public void save(); }-
分别两个实现类，实现于此接口
package com.gec.dao.impl; import com.gec.dao.UserDao; import org.springframework.stereotype.Repository; @Repository public class UserDaoAImpl implements UserDao { @Override public void save() { System.out.println("UserDaoAImpl save"); } }
package com.gec.dao.impl; import com.gec.dao.UserDao; import org.springframework.stereotype.Repository; @Repository public class UserDaoBImpl implements UserDao { @Override public void save() { System.out.println("UserDaoBImpl save"); } }
package com.gec.service;
import com.gec.dao.UserDao;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Service;
@Service
public class UserService {
@Autowired
@Qualifier(value = "userDaoBImpl")
private UserDao userDao;
public void save()
{
System.out.println("user service save");
userDao.save();
}
}
七、java加注解方式配置bean对象
1、简介
- 通过纯的java+注解方式实现bean对象的配置
2、如何配置bean对象
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@Configuration
- 此注解修饰类，此类就是作用于配置bean的对象，此类就是之前beans.xml文件
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@Bean
- 此注解修饰方法，此方法就是配置bean对象，此方法名就是bean的id值
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用法
- 直接定义一个类即可，不需要添加任何注解
package com.gec.bean; public class Car { private String brand; private Double price; public String getBrand() { return brand; } public void setBrand(String brand) { this.brand = brand; } public Double getPrice() { return price; } public void setPrice(Double price) { this.price = price; } @Override public String toString() { return "Car{" + "brand='" + brand + '\'' + ", price=" + price + '}'; } }- 定义一个配置类
package com.gec.conf; import com.gec.bean.Car; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Configuration; @Configuration public class BeanConf { /* * 创建一个bean对象 * bean的id就是方法名 * */ @Bean public Car car() { Car c=new Car(); c.setBrand("QQ跑车"); c.setPrice(300000.00); return c; } }
3、注解+扫描方式实现bean的配置
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在类添加四大注解之一（@Repository、@Service、@Controller都属于@Component）
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在配置类添加@ComponentScan
- 实现扫描
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用法
package com.gec.bean; import org.springframework.stereotype.Component; @Component public class Person { }package com.gec.conf; import com.gec.bean.Car; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Configuration; @Configuration @ComponentScan(value = "com.gec.bean") public class BeanConf { /* * 创建一个bean对象 * bean的id就是方法名 * */ @Bean public Car car() { Car c=new Car(); c.setBrand("QQ跑车"); c.setPrice(300000.00); return c; } }- 测试类
package com.gec.app; import com.gec.bean.Car; import com.gec.bean.Person; import com.gec.conf.BeanConf; import org.springframework.context.ApplicationContext; import org.springframework.context.annotation.AnnotationConfigApplicationContext; public class MainTest { public static void main(String[] args) { ApplicationContext ctx=new AnnotationConfigApplicationContext(BeanConf.class); Car car= (Car) ctx.getBean("car"); System.out.println(car); Person p= (Person) ctx.getBean("person"); System.out.println(p); } }
八、如何java配置类引入xml配置
1、简介
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在java conf类导入xml配置
@ImportResource("classpath:beans.xml")
2、具体用法
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定义beans.xml文件
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <!--定义Car的bean对象--> <bean id="car" class="com.gec.bean.Car" p:brand="宝马" p:price="500000.00" /> </beans> -
编写java conf类
package com.gec.conf; import com.gec.bean.Boss; import com.gec.bean.Car; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.ImportResource; @Configuration @ImportResource("classpath:beans.xml") public class BeanConf2 { @Autowired private Car car; @Bean public Boss boss() { Boss boss=new Boss(); boss.setBossName("许老板"); boss.setCar(car); return boss; } } -
操作类
package com.gec.app; import com.gec.bean.Boss; import com.gec.conf.BeanConf2; import org.springframework.context.ApplicationContext; import org.springframework.context.annotation.AnnotationConfigApplicationContext; public class MainTest2 { public static void main(String[] args) { ApplicationContext ctx=new AnnotationConfigApplicationContext(BeanConf2.class); Boss boss= (Boss) ctx.getBean("boss"); System.out.println(boss.getBossName()); System.out.println(boss.getCar()); } }
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