[Java] Idea工具中创建 SpringBoot工程及入门详解

package com.cy;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class Application {//Application.class
public static void main(String[] args) {//Main Thread
SpringApplication.run(Application.class, args);
}
}

package com.cy.pj.common.cache;
import org.springframework.stereotype.Component;
/**
* @Component 注解描述的类，表示此类交给Spring框架管理。
*/
@Component
public class DefaultCache {
}

package com.cy.pj.common.cache;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
@SpringBootTest
public class DefaultCacheTests {
/**
* @Autowired 注解描述的属性由spring框架按照一定规则为其注入值（赋值）
* 赋值过程是怎样的？
* 1)依赖查找？(请问查找规则是什么？)
* 2)依赖注入？(需要借助什么技术?)
*/ @Autowired
private DefaultCache defaultCache;
@Test
void testDefaultCache(){
System.out.println(defaultCache.toString());
//FAQ? defaultCache变量引用的对象是由谁创建的，存储 到了哪里？bean pool
}
}

package com.cy.pj.common.pool;
@Component
public class ObjectPool{//假设此对象为一个对象池
public ObjectPool(){//假设运行项目启动类，此构造方法执行了，说明此类对象构建了。
Systemd.out.println("ObjectPool()")
}
}

package com.cy.pj.pool;
import com.cy.pj.common.pool.ObjectPool;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
 
@SpringBootTest
public class ObjectPoolTests {
 
@Autowired
private ObjectPool objectPool01;
@Autowired
private ObjectPool objectPool02;
@Test
void testObjectPool01(){
System.out.println(objectPool01==objectPool02);
}
}

package com.cy.pj.common.pool;
@Lazy
@Component
public class ObjectPool{//假设此对象为一个对象池
public ObjectPool(){//假设运行项目启动类，此构造方法执行了，说明此类对象构建了。
Systemd.out.println("ObjectPool()")
}
}

package com.cy.pj.common.pool;
@Scope("singleton")
@Lazy
@Component
public class ObjectPool{//假设此对象为一个对象池
public ObjectPool(){//假设运行项目启动类，此构造方法执行了，说明此类对象构建了。
Systemd.out.println("ObjectPool()")
}
}

package com.cy.pj.common.pool;
@Scope("singleton")
@Lazy
@Component
public class ObjectPool{//假设此对象为一个对象池
public ObjectPool(){
Systemd.out.println("ObjectPool()")
}
@PostConstruct
public void init(){
System.out.println("init()");
}
@PreDestroy
public void destory(){
System.out.println("destory()");
}
}

package com.cy.pj.common.cache;
public interface Cache {
 
}

package com.cy.pj.common.cache;
 
@Component
public class SoftCache implements Cache{
 
}

package com.cy.pj.common.cache;
 
@Component
public class WeakCache implements Cache{
 
}

package com.cy.pj.common.cache;
import org.junit.jupiter.api.Test;
 
@SpringBootTest
public class CacheTests {
@Autowired
@Qualifier("softCache")
private Cache cache;
 
@Test
public void testCache() {
System.out.println(cache);
}
}