Spring Boot学习日志------连接数据库三方法之Springboot属性注入

目录

操作说明

操作详解

操作优缺点

代码优化

操作出现的问题

操作说明

• 创建application.properties（如果有jdbc.properties文件合并以下，然后删除jdbc.properties）
• 创建配置类文件
• 将配置类文件注入到对象中

操作详解

创建application.properties文件

#数据库连接配置
jdbc.driverClassNamr=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/ssm
jdbc.username=root
jdbc.password=root

创建配置类文件

package com.example.ycrk.config;

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

/**
 * ConfigurationProperties从application配置文件中读取配置
 * prefix配置项前缀
 * 配置项前缀的类变量名必须与前缀之后的配置项名称保持 松散绑定
 */
@Component
@ConfigurationProperties(prefix="jdbc")
public class JdbcProperties {
    private String driverClassNamr;
    private String url;
    private String username;
    private String password;

    public String getDriverClassNamr() {
        return driverClassNamr;
    }

    public void setDriverClassNamr(String driverClassNamr) {
        this.driverClassNamr = driverClassNamr;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

创建对象

package com.example.ycrk.config;

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

import javax.sql.DataSource;

@Configuration
@EnableConfigurationProperties(JdbcProperties.class)
public class JdbcConfig {
    @Bean
    public DataSource dataSource(JdbcProperties jdbcProperties){
        DruidDataSource druidDataSource=new DruidDataSource();
        druidDataSource.setDriverClassName(jdbcProperties.getDriverClassNamr());
        druidDataSource.setUrl(jdbcProperties.getUrl());
        druidDataSource.setUsername(jdbcProperties.getUsername());
        druidDataSource.setPassword(jdbcProperties.getPassword());
        return druidDataSource;
    }
}

调用

package com.example.ycrk.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.sql.DataSource;

@RestController
public class HelloController {
    @Autowired
    private DataSource dataSource;

    @GetMapping("hello")
    public String hello(){
        System.out.println("dataSource="+dataSource.toString());
        return "Hello,Spring Boot!";
    }
}

结果

操作优缺点

• 繁琐，如果变量过多不是很方便

代码优化

 将JdbcConfig 代码更换为以下代码

package com.example.ycrk.config;

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

import javax.sql.DataSource;

@Configuration
@EnableConfigurationProperties(JdbcProperties.class)
public class JdbcConfig {

    /***
     * 自动根据前缀调取相应的方法
     * @return
     */
    @Bean
    @ConfigurationProperties(prefix = "jdbc")
    public DataSource dataSource(){
        return new DruidDataSource();
    }
}

操作出现的问题

错误：ConfigurationProperties注入爆红

 解决方法

1、在pom.xml中添加以下依赖

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
  </dependency>

2、ConfigurationProperties注入方式上面添加@Component

@Component
@ConfigurationProperties(prefix="jdbc")