目录

一、引入外部属性文件配置数据库连接池

1、创建外部properties文件

2、添加druid的pom依赖

3、添加druid.properties

4、创建beans.xml

二、注解的使用

1、非注解的方法

2、注解的方法

 三、依赖注入

 四、配置注解类

一、引入外部属性文件配置数据库连接池

1、创建外部properties文件

2、添加druid的pom依赖

        <!-- https://mvnrepository.com/artifact/com.alibaba/druid -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.1.24</version>
</dependency>

3、添加druid.properties

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/t2
name=root
password=123456

4、创建beans.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"
       xmlns:c="http://www.springframework.org/schema/c"
       xmlns:p="http://www.springframework.org/schema/p"
        xmlns:context="http://www.springframework.org/schema/context"
       xmlns:uitl="http://www.springframework.org/schema/util"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.3.xsd
       http://www.springframework.org/schema/context 
              http://www.springframework.org/schema/context/spring-context-4.2.xsd
       "
       >
          <context:property-placeholder location="classpath:druid.properties"></context:property-placeholder>
             <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
             	 <property name="driverClassName" value="${driverClassName}"></property>
       <property name="url" value="${url}"></property>
       <property name="username" value="${name}"></property>
       <property name="password" value="${password}"></property>
             	
             </bean>
</beans>

二、注解的使用

1、非注解的方法

主要通过<bean id=“”class=“”></bean>创建类的对象。

先创建一个对象Car类

import lombok.Getter;
import lombok.Setter;

@Setter
@Getter
public class Car {
private String brand;
private String car;
private double price;
private int maxpeed;
public Car() {
	System.out.println("无参的构造方法");
}
public Car(String brand,String car,double price,int maxpeed) {
	System.out.println("有参的构造方法");
	this.brand=brand;
	this.car=car;
	this.price=price;
	this.maxpeed=maxpeed;
}
}

通过<bean>利用构造方法实现对象的创建

<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="cars" class="com.DJX.bean.Car">
<constructor-arg name="brand" value="123"></constructor-arg>
<constructor-arg name="car" value="ddd"></constructor-arg>
<constructor-arg name="price" value="123"></constructor-arg>
<constructor-arg name="maxpeed" value="20"></constructor-arg>
</bean>
</beans>

测试类

	@Test
  public void test() {
		ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
		Car cars =   context.getBean("cars",Car.class);
		System.out.println(cars.getCar()+"\t"+cars.getBrand()+"\t"+cars.getMaxpeed()+"\t"+cars.getPrice()+"\t");
	}

效果展示 

2、注解的方法

注解是代码的特殊符号，格式：@注解名称

使用注解的目的：简化xml配置

在classpath中扫描组件：组件扫描（component scanning）：spring能够从classpath下自动扫描。侦测和实例化具有特定注解的组件。

扫描com.DJX.bean包，下面的所有类

<context:component-scan base-package="com.DJX.bean"></context:component-scan>

 通过注释来对Car类赋值

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import lombok.Getter;
import lombok.Setter;

@Setter
@Getter
@Component//标识为实体类

public class Car {
	@Value("321")
private String brand;
	@Value("汽车")
private String car;
	@Value("123")
private double price;
	@Value("20")
private int maxpeed;
public Car() {
	System.out.println("无参的构造方法");
}
public Car(String brand,String car,double price,int maxpeed) {
	System.out.println("有参的构造方法");
	this.brand=brand;
	this.car=car;
	this.price=price;
	this.maxpeed=maxpeed;
}
}

 测试类

	@Test
  public void test() {
		ApplicationContext context = new ClassPathXmlApplicationContext("bean4.xml");
		Car cars =   context.getBean(Car.class);
		System.out.println(cars.getCar()+"\t"+cars.getBrand()+"\t"+cars.getMaxpeed()+"\t"+cars.getPrice()+"\t");
	}

效果展示：

 三、依赖注入

给出三个类分别是DeptDao、DeptService、DeptAction

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;

@Repository
public class DeptDao {
	@Autowired
public void add() {
	System.out.println("Dao的add");
}
}

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.DJX.Dao.DeptDao;
@Service
public class DeptService {
	@Autowired
private DeptDao deptDao;
public void add() {
	System.out.println("service层的add");
	deptDao.add();
}

}

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;

import com.DJX.service.DeptService;
@Controller
public class DeptAction {
	@Autowired
	private DeptService service;
	public void add() {
		System.out.println("DeptAction的add");
		service.add();
	}
}

DeptAction依赖DeptService依赖DeptDao ,通过@Autowired注入

控制层：controller

业务层：service

数据访问层:respository

普通的：component四个方法效果一样，只是这样取名方便辨认

当然仍然扫描com.DJX包，下面的所有类

<context:component-scan base-package="com.DJX"></context:component-scan>

测试类

	public void test8() {
		ApplicationContext context = new ClassPathXmlApplicationContext("bean4.xml");
		DeptAction deptAction=context.getBean(DeptAction.class);
		deptAction.add();
//		DeptService deptService = context.getBean(DeptService.class);
//		deptService.add();
	}

效果展示

 四、配置注解类

不在通过xml实现配置，因为如果通过注释的话都是需要进行包的扫描，那我们为何不直接创建一个配置类呢？

所以下面我们通过配置类来实现

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@Configuration//告诉SPring是配置
@ComponentScan(basePackages= {"com.DJX"})//扫描的信息
public class SpringConfig {

}

因为我们采用的是配置类所以我们new的方法要改变，通过AnnotationConfigApplicationContext(SpringConfig.class)创建对象

测试类

@Test
	public void test5() {
		ApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);
		Dept dept=context.getBean(Dept.class);
		System.out.println(dept.getId()+"\t"+dept.getName());
	}

效果展示