Bean基本注解开发

 

创建一个空Maven项目:

创建完如下

 

之后在pom文件配置坐标

<dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.3.7</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.23</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.49</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.5</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.2.13.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.5</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
        </dependency>
    </dependencies>

不知道为啥 , 我的项目还要加一个maven插件才能跑起来 , 好奇怪

如下 , 不加就报错

<build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>8</source>
                    <target>8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

接着新建文件 , 和原来一样

 

二 . 开始进行Bean的注解开发 

在类前加@Component即可

代码如下

package com.itheima.dao.impl;

import com.itheima.dao.UserDao;
import org.springframework.stereotype.Component;

//<bean id="userDao" class="com.itheima.dao.impl.UserDaoImpl"></bean>
@Component("userDao")
public class UserDaoImpl implements UserDao {
}

之后再配置主文件applicationContext.xml

代码如下

<?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
       http://www.springframework.org/schema/context/spring-context.xsd">

        <!--注解组件扫描: 扫描的指定基本包及其包下的类,识别使用@component注解-->
        <context:component-scan base-package="com.itheima"/>


</beans>

然后即可测试

package com.itheima;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class ApplicationContextTest {
    public static void main(String[] args) {
        ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
        Object userDao = applicationContext.getBean("userDao");
        System.out.println(userDao);

    }
}