SpringBoot中的bean管理示例详解

object getBean (String name)

<T> T getBean (Class<T> requiredType)

<T> TgetBean(String name,Class<T> requiredType)

package com.itheima;
import com.itheima.controller.DeptController;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.context.ApplicationContext;
@SpringBootTest
class SpringbootWebConfig2ApplicationTests {
    @Autowired
    private ApplicationContext applicationContext;  //IOC容器对象
    //获取bean对象
    @Test
    public void testGetBean() {
        //根据bean的名称获取     //声明一个bean对象没有指定名字时，默认是类名首字母小写
        DeptController bean1 = (DeptController) applicationContext.getBean("deptController");
        System.out.println(bean1);
        //根据bean的类型获取
        DeptController bean2 = applicationContext.getBean(DeptController.class);
        System.out.println(bean2);
        //根据bean的名称及类型获取
        DeptController bean3 = applicationContext.getBean("deptController", DeptController.class);
        System.out.println(bean3);
    }

//@Lazy   //延迟初始化 --延迟到第一次使用的时候
@Scope("prototype")  //将作用域设置为非单例的prototype--每次调用后bean对象都不同
@RestController
@RequestMapping("/depts")
public class DeptController {
}

<!--Dom4j-->
<dependency>
    <groupId>org.dom4j</groupId>
    <artifactId>dom4j</artifactId>
    <version>2.1.3</version>
</dependency>

    //第三方bean的管理
    @Test
    public void testThirdBean() throws Exception {
        SAXReader saxReader = new SAXReader();  //读取XML文件，下面逻辑是对XML文件的解析
        Document document = saxReader.read(this.getClass().getClassLoader().getResource("1.xml"));
        Element rootElement = document.getRootElement();
        String name = rootElement.element("name").getText();
        String age = rootElement.element("age").getText();
        System.out.println(name + " : " + age);
    }

//声明第三方bean
@Bean  //将当前方法的返回值对象交给Ioc容器管理，成为IOC容器bean
public SAXReader saxReader() {
    return new SAXReader();
}

    @Autowired
    private SAXReader saxReader;
    //第三方bean的管理
    @Test
    public void testThirdBean() throws Exception {
        /** 
		 * SAXReader saxReader = new SAXReader();  //读取XML文件，
		*/
		//下面逻辑是对XML文件的解析
        Document document = saxReader.read(this.getClass().getClassLoader().getResource("1.xml"));
        Element rootElement = document.getRootElement();
        String name = rootElement.element("name").getText();
        String age = rootElement.element("age").getText();
		//输出XML中的数据（解析后）
        System.out.println(name + " : " + age);
    }