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。
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;
}
}