SpringBoot加载配置文件的几种方式（加载JDBC配置文件）

学习SpringBoot我们会使用JDBC来加载JDBC配置文件，这是有几种方式来进行文件的加载

Table of Contents

学习SpringBoot我们会使用JDBC来加载JDBC配置文件，这是有几种方式来进行文件的加载

前提：添加pom依赖

1:使用@PropertySource加载自定义配置文件。

2：@ConfigurationProperties注解的使用：一次加载到处使用。

3:@ConfigurationProperties的使用优化：

4：使用SpringBoot默认方式加载数据源（HikariDataSource）

5:SpringBoot中使用自己配置的数据源

---

前提：添加pom依赖

    4.0.0
    
        org.springframework.boot
        spring-boot-starter-parent
        2.2.4.RELEASE
         
    
    com.bjsxt
    springbootjdbc
    0.0.1-SNAPSHOT
    springbootjdbc
    Demo project for Spring Boot

    
        1.8
    

    
        
            org.springframework.boot
            spring-boot-starter-web
        

        
            org.springframework.boot
            spring-boot-starter-thymeleaf
        

        
        
            org.springframework.boot
            spring-boot-starter-jdbc
        
        
        
            com.alibaba
            druid
            1.1.12
        

        
        
            mysql
            mysql-connector-java
            5.1.38
        

        
            org.springframework.boot
            spring-boot-starter-test
            test
            
                
                    org.junit.vintage
                    junit-vintage-engine
                
            
        
    

    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
            
        
    

1:使用@PropertySource加载自定义配置文件。

   1.1：首先创建配置文件，设置配置文件的内容，我这里写的是连接数据库信息。

 

1.2：创建加载配置类。

package com.bjsxt.springbootjdbc.config;

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.annotation.Autowired;
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
//1.
@PropertySource("classpath:/jdbc.properties")
//2.
// @EnableConfigurationProperties(JdbcProperties.class)
public class JdbcConfiguration {
    /* //2:
    @Autowired
    private JdbcProperties jdbcProperties;
    */


    //1:
    @Value("${jdbc.driverClassName}")
    private String driverClassName;

    @Value("${jdbc.url}")
    private String url;

    @Value("${jdbc.username}")
    private String username;

    @Value("${jdbc.password}")
    private String password;

    //3
    // @ConfigurationProperties(prefix = "jdbc")
    @Bean
    public DataSource getDataSource(){
        DruidDataSource dataSource=new DruidDataSource();
        dataSource.setDriverClassName(this.driverClassName);
        dataSource.setUrl(this.url);
        dataSource.setUsername(this.username);
        dataSource.setPassword(this.password);
        return dataSource;
    }
}

1.3：创建控制器，打断点查看配置信息。

 

这样做有一些缺点，如果多次需要使用配置信息，我们都需要这样一步一步的来，代码就会十分的冗余。为此就有了第二种注解使用的方式。

 

2：@ConfigurationProperties注解的使用：一次加载到处使用。

在使用前我们需要知道，@ConfigurationProperties只能读取SpringBoot的Application的配置文件进行数据的读取加载的。

2.1：将数据配置文件复制到application.properties的文件中去

 

2.2：创建一个专门用于加载该配置的类。

package com.bjsxt.springbootjdbc.config;


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


//2.
 @ConfigurationProperties(prefix = "jdbc")
//只能读取springBoot Application注解文件
public class JdbcProperties {

    private String driverClassName;

    private String url;

    private String username;

    private String password;

    public String getDriverClassName() {
        return driverClassName;
    }

    public void setDriverClassName(String driverClassName) {
        this.driverClassName = driverClassName;
    }

    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;
    }
}

2.3：修改1.2的配置类。通过注入2.2专门加载配置类来通过get方法进行获取

package com.bjsxt.springbootjdbc.config;

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.annotation.Autowired;
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
//1.
//@PropertySource("classpath:/jdbc.properties")
//2.
@EnableConfigurationProperties(JdbcProperties.class)
public class JdbcConfiguration {
    //2:
    @Autowired
    private JdbcProperties jdbcProperties;


    /*
    //1:
    @Value("${jdbc.driverClassName}")
    private String driverClassName;

    @Value("${jdbc.url}")
    private String url;

    @Value("${jdbc.username}")
    private String username;

    @Value("${jdbc.password}")
    private String password;

    */

    //3
    // @ConfigurationProperties(prefix = "jdbc")
    @Bean
    public DataSource getDataSource(){
        DruidDataSource dataSource=new DruidDataSource();
        dataSource.setDriverClassName(this.jdbcProperties.getDriverClassName());
        dataSource.setUrl(this.jdbcProperties.getUrl());
        dataSource.setUsername(this.jdbcProperties.getUsername());
        dataSource.setPassword(this.jdbcProperties.getPassword());
        return dataSource;
    }
}

2.4：测试

 

3:@ConfigurationProperties的使用优化：

3.1：取消该专门加载配置类注解

package com.bjsxt.springbootjdbc.config;


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


//2.
// @ConfigurationProperties(prefix = "jdbc")
//只能读取springBoot Application注解文件
public class JdbcProperties {

    private String driverClassName;

    private String url;

    private String username;

    private String password;

    public String getDriverClassName() {
        return driverClassName;
    }

    public void setDriverClassName(String driverClassName) {
        this.driverClassName = driverClassName;
    }

    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;
    }
}

3.2：取消加载配置类，在该方法直接开启读取配置文件

package com.bjsxt.springbootjdbc.config;

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.annotation.Autowired;
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
//1.
//@PropertySource("classpath:/jdbc.properties")
//2.
//@EnableConfigurationProperties(JdbcProperties.class)
public class JdbcConfiguration {
    //2:
    /*
    @Autowired
    private JdbcProperties jdbcProperties;
    */


    /*
    //1:
    @Value("${jdbc.driverClassName}")
    private String driverClassName;

    @Value("${jdbc.url}")
    private String url;

    @Value("${jdbc.username}")
    private String username;

    @Value("${jdbc.password}")
    private String password;

    */

    //3
    @ConfigurationProperties(prefix = "jdbc")
    @Bean
    public DataSource getDataSource(){
        DruidDataSource dataSource=new DruidDataSource();
        /*
        dataSource.setDriverClassName(this.jdbcProperties.getDriverClassName());

        dataSource.setUrl(this.jdbcProperties.getUrl());
        dataSource.setUsername(this.jdbcProperties.getUsername());
        dataSource.setPassword(this.jdbcProperties.getPassword());
         */
        return dataSource;
    }
}

3.3：测试：

 

 

4：使用SpringBoot默认方式加载数据源（HikariDataSource）

4.1：配置application.properties

4.2:是注解配置类无效

package com.bjsxt.springbootjdbc.config;

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.annotation.Autowired;
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;

//4.
// @Configuration
//1.
//@PropertySource("classpath:/jdbc.properties")
//2.
//@EnableConfigurationProperties(JdbcProperties.class)
public class JdbcConfiguration {
    //2:
    /*
    @Autowired
    private JdbcProperties jdbcProperties;
    */


    /*
    //1:
    @Value("${jdbc.driverClassName}")
    private String driverClassName;

    @Value("${jdbc.url}")
    private String url;

    @Value("${jdbc.username}")
    private String username;

    @Value("${jdbc.password}")
    private String password;

    */

    //3
    @ConfigurationProperties(prefix = "jdbc")
    @Bean
    public DataSource getDataSource(){
        DruidDataSource dataSource=new DruidDataSource();
        /*
        dataSource.setDriverClassName(this.jdbcProperties.getDriverClassName());

        dataSource.setUrl(this.jdbcProperties.getUrl());
        dataSource.setUsername(this.jdbcProperties.getUsername());
        dataSource.setPassword(this.jdbcProperties.getPassword());
         */
        return dataSource;
    }
}

4.3：修改控制器代码，查看该类的位置：

 

5:SpringBoot中使用自己配置的数据源

5.1：修改pom文件，添加Druid数据源

5.2：修改数据源类型

5.3：重启项目进行测试：