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
<!-- 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=1234564、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