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Architecture design principles
URL for downloading the Spring package
Open Spring's official website https://spring.io/
If there is no GitHub logo on the right, it may be that the ad blocking plug-in of your browser has been blocked, just open it in a different browser.
Or directly open the following URL
https://github.com/spring-projects/spring-framework
method 1
Method 2
Choose the middle one
https://repo.spring.io/libs-milestone-local/org/springframework/spring/5.3.0-M2/
Bean
Simple Demo
Create a Java project
- Start to guide the package
Find the compressed file downloaded above, unzip it, and select all the packages in the libs folder
Need a binding data source file, the name is generally called: beans.xml or applicationContext.xml
XML file-based approach
Engineering structure drawing
beans.xml
<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-4.0.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">
<!-- id名字随意，区分大小写。 class是包名 -->
<bean id="IntelCpu111" class="com.IntelCpu"></bean>
<bean id="Computer" class="com.Computer">
<!-- name=被注入的对象给注入者的属性，ref=注入的目标，是上面自定义的ID -->
<property name="intelCpu" ref="IntelCpu111"></property>
</bean>
</beans>
Computer.java
package com;
public class Computer {
//Computer类依赖CPU类。
private IntelCpu intelCpu;
//通过Set方法实现注入
public void setIntelCpu(IntelCpu intelCpu) {
this.intelCpu = intelCpu;
}
public void play() {
intelCpu.run();
System.out.println("pc is running");
}
}
IntelCpu.java
package com;
public class IntelCpu {
public void run() {
System.out.println("intel cpu is running");
}
}
Test.java
package com;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Test {
public static void main(String[] args) {
//1. 启动Spring容器，参数是数据配置的文件名，
ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");
//2. 从容器中拿到对象
Computer pc = (Computer)ctx.getBean("Computer");
pc.play();
}
}
Annotation-based approach
Project structure
Beans.xml
<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-4.0.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">
<!-- 这是注解方式配置 -->
<context:annotation-config />
<!-- 提示扫描那个包的注解 -->
<context:component-scan base-package="com">
</context:component-scan>
</beans>
Computer.java
package com;
import javax.annotation.Resource;
import org.springframework.stereotype.Component;
//@Component表示是Spring当中类的容器的组件
//括号代表着给此对象加上了Id，
//因为不加的话默认会认为此类的名字开头是小写，而实际是大写开头
@Component("Computer")
public class Computer {
//Computer类依赖CPU类。
//表明是一种资源，有了此注释可以省略相应的Set方法
@Resource
private IntelCpu intelCpu;
// //通过Set方法实现注入
// public void setIntelCpu(IntelCpu intelCpu) {
// this.intelCpu = intelCpu;
// }
public void play() {
intelCpu.run();
System.out.println("pc is running");
}
}
IntelCpu.java
package com;
import org.springframework.stereotype.Component;
@Component
public class IntelCpu {
public void run() {
System.out.println("intel cpu is running");
}
}
Test.java
package com;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Test {
public static void main(String[] args) {
//1. 启动Spring容器，参数是数据配置的文件名，
ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");
//2. 从容器中拿到对象
Computer pc = (Computer)ctx.getBean("Computer");
pc.play();
}
}
Configuration based on Java
Precautions
- On the basis of the above annotation configuration, the XML file is missing. Put the information that should be configured by the Xml file into the Test test class.
- The difference with the above annotation configuration is that the xml configuration file is deleted, and the annotation is added to the Test class
- Note: The test method of obtaining the Spring container is different
Project structure
Test.java
package com;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
@Configuration
@ComponentScan("com")
public class Test {
public static void main(String[] args) {
//1. 启动Spring容器，参数当前这个类
ApplicationContext ctx = new AnnotationConfigApplicationContext(Test.class);
//2. 从容器中拿到对象
Computer pc = (Computer)ctx.getBean("Computer");
pc.play();
}
}