课堂笔记之配置文件值的注入

通过配置文件来赋值有两个注解

@Value

@ConfigurationProperties

@Value如何注入值

package com.springboot.helloword.configuration;

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;

import javax.sql.DataSource;
@Configuration
@PropertySource("classpath:jdbc.properties")
public class JdbcConfig {
    DruidDataSource dataSource=null;
    @Value("${jdbc.driverClassName}")
    String driverClassName;
    @Value("${jdbc.url}")
    String url;
    @Value("${jdbc.username}")
    String username;
    @Value("${jdbc。password}")
    String password;
@Bean
    public DataSource dataSource(){
        new DruidDataSource();
        dataSource.setDriverClassName(driverClassName);
        dataSource.setUrl(url);
        dataSource.setName(username);
        dataSource.setPassword(password);
        return dataSource();

    }
}

代码部分注解的解释

@Configuration

1. 写在类上

2. 表示这个类是一个配置类

@PropertySource("classpath:jdbc.properties)

1. 相当于springboot中使用标签引入外部属性文件

2. 写在类上

@Bean

1. 将方法的返回值注入到bean 容器中 容器组件的id默认是方法名

2. 写在方法上

@Value

1. 用于配置文件值的注入

2. 建议写在属性名上

3. @Value相当于

---

Jdbc.Properties

jdbc.driverClassName=com。mysql。jdbc。Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/springboot
jdbc.username=root
jdbc.password=root

---

@Configuration值的注入

kage com.springboot.helloword.pojo;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

import javax.xml.crypto.Data;
import java.util.List;
import java.util.Map;
@Component
@ConfigurationProperties(prefix="person")
public class Person {

    private String lastName;
    private Integer age;
    private boolean boss;
    private Data birth;
    private Map maps;
    private List