springboot属性注入的四种方法

springBoot属性注入的四种方法：

以注入jdbc数据源为例

1.首先在resources下面创建application.properties文件，并添加jdbc数据源属性

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

2.配置需要读取数据源的properties类

创建类JdbcProperties

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

@ConfigurationProperties("jdbc")
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;
    }
}

这里需要引入@ConfigurationProperties("jdbc")，也就是你在applican中设置的前缀，也可以写成@ConfigurationProperties(prefix="jdbc")

在引入的文件中其实就是按照set方式注入的属性，同时取值的时候，通过get方法取值，所以get和set方法不能忘记添加。

3.然后就是四种注入属性的方式了：

3.1第一种方式就是按照自动注入的方式，也就是@Autowired

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.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 JbdcConfiguration {

   @Autowired
   private JdbcProperties jdbcProperties;

    

    @Bean
    public DataSource dataSource(){
        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;
    }
}

注意需要引入@EnableConfigurationProperties(JdbcProperties.class)，这个JdbcProperties是在上面创建的那个类

这样就实现了第一种属性注入的方式。

扫描二维码关注公众号，回复： 10695179 查看本文章

3.2第二种属性注入的方式为构造方法注入的方式

package com.w.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.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 JConfiguration {


   private JdbcProperties jdbcProperties;

    public JConfiguration(JdbcProperties jdbcProperties) {
        this.jdbcProperties = jdbcProperties;
    }

    @Bean
    public DataSource dataSource(){
        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第三种就是通过形参引入的方法注入属性

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.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 JdbcConfiguration {
    
    @Bean
    public DataSource dataSource(JdbcProperties jdbcProperties){
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setDriverClassName(jdbcProperties.getDriverClassName());
        dataSource.setUrl(jdbcProperties.getUrl());
        dataSource.setUsername(jdbcProperties.getUsername());
        dataSource.setPassword(jdbcProperties.getPassword());
        return dataSource;
    }
}

3.4第四种方式就是通过引入标签的方式，这是最简单的方式，但是前提是对应的类中需要有set方法将值可以注入进去才可以。

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
@EnableConfigurationProperties(JdbcProperties.class)
public class JdbcConfiguration {

    @Bean
    @ConfigurationProperties("jdbc")
    public DataSource dataSource(){
        DruidDataSource dataSource = new DruidDataSource();
        return dataSource;
    }
}