Spring系列之——springboot解析resources.application.properties文件

　　摘要：本文通过讲解如何解析application.properties属性，介绍了几个注解的运用@value @configurationproperties @enableconfigurationproperties @autowired @conditionalonproperty

 

1 准备

1.1 

1.2 写一个controller类

package com.gbm.controller;

import org.springframework.stereotype.controller;
import org.springframework.web.bind.annotation.requestmapping;
import org.springframework.web.bind.annotation.responsebody;

/**
 * created by administrator on 2019/2/20.
 */

@controller
public class indexcontroller {
    @requestmapping("/index")
    @responsebody
    public string index() {
        return "我爱北京*！";
    }
}

view code

2 几种获取属性值方式

　　配置application.properties

value.local.province=zhejiang
value.local.city=hangzhou

complex.other.province=jiangsu
complex.other.city=suzhou
complex.other.flag=false

view code

2.1 使用注解@value("${xxx}")获取指定属性值

  2.1.1 在controller类中获取属性值

package com.gbm.controller;

import org.springframework.beans.factory.annotation.value;
import org.springframework.stereotype.controller;
import org.springframework.web.bind.annotation.requestmapping;
import org.springframework.web.bind.annotation.responsebody;

/**
 * created by administrator on 2019/2/20.
 */

@controller
public class indexcontroller {
    @value("${value.local.province}")
    private string province;

    @value("${value.local.city}")
    private string city;

    @requestmapping("/index")
    @responsebody
    public string index() {
        stringbuffer sb = new stringbuffer();
        sb.append(this.city);
        sb.append(",");
        sb.append(this.province);
        sb.append(" ");
        return sb.tostring();
    }
}

view code

  2.1.2 任何浏览器上运行 ，结果如下　　

　　

2.2 使用注解@configurationproperties(prefix = "xxx")获得前缀相同的一组属性，并转换成bean对象

  2.2.1 写一个实体类

package com.gbm.models;

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

/**
 * created by administrator on 2019/2/21.
 */
@component
@configurationproperties(prefix = "complex.other")
public class complex {
    private string province;
    private string city;
    private boolean flag;

    public string getprovince() {
        return province;
    }

    public void setprovince(string province) {
        this.province = province;
    }

    public string getcity() {
        return city;
    }

    public void setcity(string city) {
        this.city = city;
    }

    public boolean getflag() {
        return flag;
    }

    public void setflag(boolean flag) {
        this.flag = flag;
    }

    @override
    public string tostring() {
        return "complex{" +
                "province='" + province + '\'' +
                ", city='" + city + '\'' +
                ", flag=" + flag +
                '}';
    }
}

view code

  2.2.2 在controller类中获取属性值

package com.gbm.controller;

import com.gbm.models.complex;
import org.springframework.beans.factory.annotation.autowired;
import org.springframework.stereotype.controller;
import org.springframework.web.bind.annotation.requestmapping;
import org.springframework.web.bind.annotation.responsebody;

/**
 * created by administrator on 2019/2/20.
 */

@controller
public class indexcontroller {
    @autowired
    private complex complex;

    @requestmapping("/index")
    @responsebody
    public string index() {
        return complex.tostring();
    }
}

view code

  2.2.3 在springbootapplication中使configuration生效

package com.gbm.myspingboot;

import com.gbm.models.complex;
import org.springframework.boot.springapplication;
import org.springframework.boot.autoconfigure.springbootapplication;
import org.springframework.boot.autoconfigure.condition.conditionalonproperty;
import org.springframework.boot.context.properties.enableconfigurationproperties;
import org.springframework.context.annotation.componentscan;
import org.springframework.context.annotation.componentscans;

@springbootapplication
@componentscans({@componentscan("com.gbm.controller"), @componentscan("com.gbm.models")})
@enableconfigurationproperties(complex.class)
@conditionalonproperty(value = "complex.other.town", matchifmissing = true)
public class myspingbootapplication {

    public static void main(string[] args) {
        springapplication.run(myspingbootapplication.class, args);
    }
}

view code

  2.2.4 任何浏览器上运行 ，结果如下　

  

3 总结

　　关于解析application.properties文件，最重要的是对注解的使用，本文主要涉及到如下几个注解的运用

　　@value("${xxx}")——获取指定属性值

　　@configurationproperties(prefix = "xxx")——获得前缀相同的一组属性，并转换成bean对象

　　@enableconfigurationproperties(xxx.class)——使configuration生效，并从ioc容器中获取bean

　　@autowired——自动注入set和get方法

　　@conditionalonproperty(value = "complex.other.town", matchifmissing = true)——缺少该property时是否可以加载，如果是true，没有该property也会正常加载；如果是false则会抛出异常。例如

package com.gbm.myspingboot;

import com.gbm.models.complex;
import org.springframework.boot.springapplication;
import org.springframework.boot.autoconfigure.springbootapplication;
import org.springframework.boot.autoconfigure.condition.conditionalonproperty;
import org.springframework.boot.context.properties.enableconfigurationproperties;
import org.springframework.context.annotation.componentscan;
import org.springframework.context.annotation.componentscans;

@springbootapplication
@componentscans({@componentscan("com.gbm.controller"), @componentscan("com.gbm.models")})
@enableconfigurationproperties(complex.class)
@conditionalonproperty(value = "complex.other.town", matchifmissing = false)
public class myspingbootapplication {

    public static void main(string[] args) {
        springapplication.run(myspingbootapplication.class, args);
    }
}

matchifmissing=false代码

error starting applicationcontext. to display the conditions report re-run your application with 'debug' enabled.
2019-02-21 23:30:56.532 error 3152 --- [           main] o.s.boot.springapplication               : application run failed