SpringBoot 01: JavaConfig + @ImportResource + @PropertyResource
- 2022 年 11 月 9 日
- 筆記
- springboot
springboot的前置知识:通过注解创建对象和读取配置文件
1. JavaConfig
设计思想
- 使用java类作为xml配置文件的替代,是配置spring容器的纯java的方式
- 可以创建java对象并把对象注入到spring容器中
注解实现
- @Configuration : 放在一个类的上面,表示这个类是作为配置文件使用的
- @Bean:放在返回值是对象的方法上,容器启动时,声明对象,并把对象注入到容器中
- 上面两个注解配套使用
代码实现
package com.example.springboot.configuration;
import com.example.springboot.model.Student;
import org.springframework.context.annotation.*;
@Configuration
public class SpringConfig {
@Bean
public Student getStudent(){
Student student = new Student();
student.setName("橘子");
student.setAge(18);
return student;
}
@Bean(name = "student")
public Student getStudentByBeanName(){
Student student = new Student();
student.setName("饺子");
student.setAge(21);
return student;
}
}
测试代码
package com.example.springboot.testspringconfig;
import com.example.springboot.configuration.SpringConfig;
import com.example.springboot.model.Student;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class TestSpringConfig {
@Test
public void testSpringConfig(){
ApplicationContext applicationContext = new AnnotationConfigApplicationContext(SpringConfig.class);
Student student = (Student) applicationContext.getBean("student");
//未在@Bean中指定对象名称时,从方法名(小驼峰命名规范)来获取对象
//Student student = (Student) applicationContext.getBean("getStudent");
System.out.println("获取到的对象: " + student);
}
}
2. @ImportResource
设计思想
- 导入其他的xml配置文件, 等于在xml 使用如下import标签
<import resources="其他配置文件"/>
代码实现
- SpringConfig类
package com.example.springboot.configuration;
import org.springframework.context.annotation.*;
@ImportResource(value = "classpath:applicationContext.xml")
public class SpringConfig {
}
- applicationContext.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="//www.springframework.org/schema/beans"
xmlns:xsi="//www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="//www.springframework.org/schema/beans //www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="cat" class="com.example.springboot.model.Cat">
<property name="catCard" value="0010"/>
<property name="catName" value="tomcat"/>
</bean>
</beans>
测试代码
package com.example.springboot.testspringconfig;
import com.example.springboot.configuration.SpringConfig;
import com.example.springboot.model.Cat;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class TestSpringConfig {
@Test
public void testImportResource(){
ApplicationContext applicationContext = new AnnotationConfigApplicationContext(SpringConfig.class);
Cat cat = (Cat) applicationContext.getBean("cat");
System.out.println("获取到的对象: " + cat);
}
}
3. @PropertyResource
设计思想
- 读取properties属性配置文件,使用属性配置文件可以实现外部化配置
使用步骤
- 在resources目录下,创建properties文件, 使用 key=value 的格式提供数据
- 在@PropertyResource 指定properties文件的位置
- 使用在待注入值的变量上使用@Value(value=”${key}”)
需要用的其他注解
- @Component:用在实体类上
- @ComponentScan:SpringConfig类上
- @Value:待注入值的属性上
代码实现
- SpringConfig类
package com.example.springboot.configuration;
import com.example.springboot.model.Student;
import org.springframework.context.annotation.*;
@PropertySource(value = "classpath:food.properties")
@ComponentScan(basePackages = "com.example.springboot.model")
public class SpringConfig {
}
- food.properties
food.name=饺子
food.price=13
- JiaoZi类
package com.example.springboot.model;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
@Component("jiaozi")
public class JiaoZi {
@Value("${food.name}")
private String name;
@Value("${food.price}")
private double price;
@Override
public String toString() {
return "JiaoZi{" +
"name='" + name + '\'' +
", price=" + price +
'}';
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
public JiaoZi(String name, double price) {
this.name = name;
this.price = price;
}
public JiaoZi() {
}
}
测试代码
package com.example.springboot.testspringconfig;
import com.example.springboot.configuration.SpringConfig;
import com.example.springboot.model.JiaoZi;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class TestSpringConfig {
@Test
public void testPropertiesSource(){
ApplicationContext applicationContext = new AnnotationConfigApplicationContext(SpringConfig.class);
JiaoZi jiaoZi = (JiaoZi) applicationContext.getBean("jiaozi");
System.out.println("food: " + jiaoZi);
}
}