SpringBoot读取properties配置文件中的数据的三种方法_Java

spring boot最常用的3种读取properties配置文件中数据的方法：

1、使用@value注解读取

读取properties配置文件时，默认读取的是application.properties。

application.properties：

demo.name=name
demo.age=18

java代码：

import org.springframework.beans.factory.annotation.value;
import org.springframework.web.bind.annotation.requestmapping;
import org.springframework.web.bind.annotation.restcontroller;

@restcontroller
public class gatewaycontroller {

    @value("${demo.name}")
    private string name;

    @value("${demo.age}")
    private string age;

    @requestmapping(value = "/gateway")
    public string gateway() {
        return "get properties value by ''@value'' :" +
                //1、使用@value注解读取
                " name=" + name +
                " , age=" + age;
    }
}

运行结果如下：

这里，如果要把

 @value("${demo.name}")
            private string name;
            @value("${demo.age}")
            private string age;

部分放到一个单独的类a中进行读取，然后在类b中调用，则要把类a增加@component注解，并在类b中使用@autowired自动装配类a，代码如下。

类a：

import org.springframework.beans.factory.annotation.value;
import org.springframework.stereotype.component;

@component
public class configbeanvalue {

    @value("${demo.name}")
    public string name;

    @value("${demo.age}")
    public string age;
}

类b：

import cn.wbnull.springbootdemo.config.configbeanvalue;
import org.springframework.beans.factory.annotation.autowired;
import org.springframework.web.bind.annotation.requestmapping;
import org.springframework.web.bind.annotation.restcontroller;

@restcontroller
public class gatewaycontroller {

    @autowired
    private configbeanvalue configbeanvalue;

    @requestmapping(value = "/gateway")
    public string gateway() {
        return "get properties value by ''@value'' :" +
                //1、使用@value注解读取
                " name=" + configbeanvalue.name +
                " , age=" + configbeanvalue.age;
    }
}

运行结果如下：

注意：如果@value${}所包含的键名在application.properties配置文件中不存在的话，会抛出异常：

org.springframework.beans.factory.beancreationexception: error creating bean with name 'configbeanvalue': injection of autowired dependencies failed; nested exception is java.lang.illegalargumentexception: could not resolve placeholder 'demo.name' in value "${demo.name}"

2、使用environment读取

application.properties：

demo.sex=男
demo.address=山东

java代码：

import cn.wbnull.springbootdemo.config.configbeanvalue;
import org.springframework.beans.factory.annotation.autowired;
import org.springframework.core.env.environment;
import org.springframework.web.bind.annotation.requestmapping;
import org.springframework.web.bind.annotation.restcontroller;

@restcontroller
public class gatewaycontroller {

    @autowired
    private configbeanvalue configbeanvalue;

    @autowired
    private environment environment;

    @requestmapping(value = "/gateway")
    public string gateway() {
        return "get properties value by ''@value'' :" +
                //1、使用@value注解读取
                " name=" + configbeanvalue.name +
                " , age=" + configbeanvalue.age +
                "<p>get properties value by ''environment'' :" +
                //2、使用environment读取
                " , sex=" + environment.getproperty("demo.sex") +
                " , address=" + environment.getproperty("demo.address");
    }
}

运行，发现中文乱码：

这里，我们在application.properties做如下配置：

server.tomcat.uri-encoding=utf-8
spring.http.encoding.charset=utf-8
spring.http.encoding.enabled=true
spring.http.encoding.force=true
spring.messages.encoding=utf-8

然后修改intellij idea，file --> settings --> editor --> file encodings ，将最下方default encoding for properties files设置为utf-8，并勾选transparent native-to-ascii conversion。

重新运行结果如下：

3、使用@configurationproperties注解读取

在实际项目中，当项目需要注入的变量值很多时，上述所述的两种方法工作量会变得比较大，这时候我们通常使用基于类型安全的配置方式，将properties属性和一个bean关联在一起，即使用注解@configurationproperties读取配置文件数据。

在src\main\resources下新建config.properties配置文件：

demo.phone=10086
demo.wife=self

创建configbeanprop并注入config.properties中的值：

import org.springframework.boot.context.properties.configurationproperties;
import org.springframework.context.annotation.propertysource;
import org.springframework.stereotype.component;

@component
@configurationproperties(prefix = "demo")
@propertysource(value = "config.properties")
public class configbeanprop {

    private string phone;

    private string wife;

    public string getphone() {
        return phone;
    }

    public void setphone(string phone) {
        this.phone = phone;
    }

    public string getwife() {
        return wife;
    }

    public void setwife(string wife) {
        this.wife = wife;
    }
}

@component 表示将该类标识为bean

@configurationproperties(prefix = "demo")用于绑定属性，其中prefix表示所绑定的属性的前缀。

@propertysource(value = "config.properties")表示配置文件路径。

使用时，先使用@autowired自动装载configbeanprop，然后再进行取值，示例如下：

import cn.wbnull.springbootdemo.config.configbeanprop;
import cn.wbnull.springbootdemo.config.configbeanvalue;
import org.springframework.beans.factory.annotation.autowired;
import org.springframework.core.env.environment;
import org.springframework.web.bind.annotation.requestmapping;
import org.springframework.web.bind.annotation.restcontroller;

@restcontroller
public class gatewaycontroller {

    @autowired
    private configbeanvalue configbeanvalue;

    @autowired
    private environment environment;

    @autowired
    private configbeanprop configbeanprop;

    @requestmapping(value = "/gateway")
    public string gateway() {
        return "get properties value by ''@value'' :" +
                //1、使用@value注解读取
                " name=" + configbeanvalue.name +
                " , age=" + configbeanvalue.age +
                "<p>get properties value by ''environment'' :" +
                //2、使用environment读取
                " sex=" + environment.getproperty("demo.sex") +
                " , address=" + environment.getproperty("demo.address") +
                "<p>get properties value by ''@configurationproperties'' :" +
                //3、使用@configurationproperties注解读取
                " phone=" + configbeanprop.getphone() +
                " , wife=" + configbeanprop.getwife();
    }
}

运行结果如下：