新建Maven工程
修改pom文件
1 <?xml version="1.0" encoding="UTF-8"?> 2 <project xmlns="http://maven.apache.org/POM/4.0.0" 3 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 4 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> 5 <modelVersion>4.0.0</modelVersion> 6 <groupId>com.powernode</groupId> 7 <artifactId>spring6-002-dependency-injection</artifactId> 8 <version>1.0-SNAPSHOT</version> 9 <packaging>jar</packaging> 10 11 <!-- 依赖--> 12 <dependencies> 13 <dependency> 14 <groupId>org.springframework</groupId> 15 <artifactId>spring-context</artifactId> 16 <version>5.3.23</version> 17 </dependency> 18 19 <dependency> 20 <groupId>junit</groupId> 21 <artifactId>junit</artifactId> 22 <version>4.13.2</version> 23 <scope>test</scope> 24 </dependency> 25 <!--log4j2的依赖--> 26 <dependency> 27 <groupId>org.apache.logging.log4j</groupId> 28 <artifactId>log4j-core</artifactId> 29 <version>2.19.0</version> 30 </dependency> 31 <dependency> 32 <groupId>org.apache.logging.log4j</groupId> 33 <artifactId>log4j-slf4j2-impl</artifactId> 34 <version>2.19.0</version> 35 </dependency> 36 37 </dependencies> 38 <properties> 39 <maven.compiler.source>17</maven.compiler.source> 40 <maven.compiler.target>17</maven.compiler.target> 41 </properties> 42 43 44 </project>
UserDao.java
package com.lps.dao;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* ClassName: UserDao
* Description:
* Date: 2022/11/21 16:45
* <author> <time> <version> <desc>
* 刘品水 2022/11/21 16:45 @Version 1.0 描述
*/
public class UserDao {
public static final Logger LOGGER=LoggerFactory.getLogger(UserDao.class);
public void insert(){
// System.out.println("数据库正在保存用户信息。。。。");
LOGGER.info("数据库正在保存用户信息。。。。");
}
}
VipDao.java
package com.lps.dao;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* ClassName: vipDao
* Description:
* Date: 2022/11/21 17:16
* <author> <time> <version> <desc>
* 刘品水 2022/11/21 17:16 @Version 1.0 描述
*/
public class VipDao {
public static final Logger LOGGER= LoggerFactory.getLogger(UserDao.class);
public void insert(){
// System.out.println("数据库正在保存用户信息。。。。");
LOGGER.info("高级会员正在保存用户信息。。。。");
}
}
CostomerSercice.java
1 package com.lps.service;
2
3 import com.lps.dao.UserDao;
4 import com.lps.dao.VipDao;
5
6 /**
7 * ClassName: CostomerSercice
8 * Description:
9 * Date: 2022/11/21 17:35
10 * <author> <time> <version> <desc>
11 * 刘品水 2022/11/21 17:35 @Version 1.0 描述
12 */
13 public class CostomerSercice {
14 private UserDao userDao;
15 private VipDao vipDao;
16
17 public CostomerSercice(UserDao userDao, VipDao vipDao) {
18 this.userDao = userDao;
19 this.vipDao = vipDao;
20 }
21
22 public void save(){
23 userDao.insert();
24 vipDao.insert();
25 }
26 }
UserService.java
package com.lps.service;
import com.lps.dao.UserDao;
import com.lps.dao.VipDao;
/**
* ClassName: UserService
* Description:
* Date: 2022/11/21 16:48
* <author> <time> <version> <desc>
* 刘品水 2022/11/21 16:48 @Version 1.0 描述
*/
public class UserService {
private UserDao userDao;
private VipDao vipDao;
public void setVIP(VipDao vipDao){
this.vipDao=vipDao;
}
//为了显示差别 bane属性为：set方法的方法名去掉set 然后剩下单词的首字母变小写 为了展示出来set方法名我选择为setLpsHHH
public void setLpsHHH(UserDao ud) {
this.userDao = ud;
}
//正常用ait+insert直接生成的就很好了 符合规范了
/* public void setUserDao(UserDao userDao) {
this.userDao = userDao;
}*/
public void saveUser(){
userDao.insert();
vipDao.insert();
};
}
bean.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"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="userDao" class="com.lps.dao.UserDao"></bean>
<bean id="vipDao" class="com.lps.dao.VipDao"></bean>
<bean id="costomerSerciceBean1" class="com.lps.service.CostomerSercice">
<constructor-arg index="0" ref="userDao"></constructor-arg>
<constructor-arg index="1" ref="vipDao"></constructor-arg>
</bean>
<bean id="costomerSerciceBean2" class="com.lps.service.CostomerSercice">
<constructor-arg name="userDao" ref="userDao"></constructor-arg>
<constructor-arg name="vipDao" ref="vipDao"></constructor-arg>
</bean>
<bean id="costomerSerciceBean3" class="com.lps.service.CostomerSercice">
<constructor-arg ref="userDao"></constructor-arg>
<constructor-arg ref="vipDao"></constructor-arg>
</bean>
</beans>
log4j2.xml
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<loggers>
<!--
level指定日志级别，从低到高的优先级：
ALL < TRACE < DEBUG < INFO < WARN < ERROR < FATAL < OFF
-->
<root level="DEBUG">
<appender-ref ref="spring6log"/>
</root>
</loggers>
<appenders>
<!--输出日志信息到控制台-->
<console name="spring6log" target="SYSTEM_OUT">
<!--控制日志输出的格式-->
<PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss SSS} [%t] %-3level %logger{1024} - %msg%n"/>
</console>
</appenders>
</configuration>
spring.xml
实现原理：
通过property标签获取到属性名：userDao
通过属性名推断出set方法名：setUserDao
通过反射机制调用setUserDao()方法给属性赋值
property标签的name是属性名。
property标签的ref是要注入的bean对象的id。(通过ref属性来完成bean的装配，这是bean最简单的一种装配方式。装配指的是：创建系统组件之间关联的动作)
<?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="userDaoBean" class="com.lps.dao.UserDao"></bean>
<bean id="userServiceBean" class="com.lps.service.UserService">
<!-- 当需要spring调用对应的set方法 需要配置property属性-->
<!-- bane属性为：set方法的方法名去掉set 然后剩下单词的首字母变小写 为了展示出来set方法名我选择为setLpsHHH-->
<!-- ref翻译为引用 reference 后面指定要注入的bean的id-->
<property name="lpsHHH" ref="userDaoBean"></property>
<!-- <property name="userDao" ref="userDaoBean"></property>
建议别为难自己 直接用生成的更好 这里只是为了巩固记忆
-->
<property name="VIP" ref="vipDaoBean"></property>
</bean>
<bean name="vipDaoBean" class="com.lps.dao.VipDao"></bean>
</beans>
通过测试看到程序仍然可以正常执行，说明property标签的name是：setUserDao()方法名演变得到的。演变的规律是：
- setUsername() 演变为 username
- setPassword() 演变为 password
- setUserDao() 演变为 userDao
- setHaHaHa() 演变为 haHaHa
另外，对于property标签来说，ref属性也可以采用标签的方式，但使用ref属性是多数的：
总结：set注入的核心实现原理：通过反射机制调用set方法来给属性赋值，让两个对象之间产生关系。
测试类
package com.lps;
import com.lps.dao.VipDao;
import com.lps.service.CostomerSercice;
import com.lps.service.UserService;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
/**
* ClassName: test
* Description:
* Date: 2022/11/21 16:56
* <author> <time> <version> <desc>
* 刘品水 2022/11/21 16:56 @Version 1.0 描述
*/
public class test {
@Test
public void testConstructor(){
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("bean.xml");
CostomerSercice contextBean = context.getBean("costomerSerciceBean1", CostomerSercice.class);
contextBean.save();
System.out.println("=========");
CostomerSercice contextBean1 = context.getBean("costomerSerciceBean2", CostomerSercice.class);
contextBean1.save();
System.out.println("--------");
CostomerSercice contextBean2 = context.getBean("costomerSerciceBean3", CostomerSercice.class);
contextBean2.save();
}
@Test
public void testIoC01(){
ApplicationContext context = new ClassPathXmlApplicationContext("Spring.xml");
UserService userServiceBean = context.getBean("userServiceBean", UserService.class);
userServiceBean.saveUser();
// VipDao vipDaoBean = context.getBean("vipDaoBean", VipDao.class);
// vipDaoBean.insert();
}
}
通过测试 上述testConstructor（）得知，通过构造方法注入的时候：
- 可以通过下标
- 可以通过参数名
- 也可以不指定下标和参数名，可以类型自动推断。