读取同一文件夹中 JAR 之外的 application.properties 和其他属性文件

Question

我需要读取 JAR 外部的 application.properties 值和其他属性文件。在IDE中开发时，我将application.properties和其他属性文件放置在与src相同的根目录中。在IDE中运行时，一切正常。但是，当我制作一个 JAR 并将其与必要的属性文件一起放置在单独的文件夹中时，它无法读取相同的内容。我相信，我已经非常接近它了。需要帮助来解决我可能错的地方。分享必要的代码片段。

@SpringBootApplication
@EnableConfigurationProperties(AppProperties.class) // Load external properties
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);

        // Fetch the port from external properties
        String port = System.getProperty("server.port", "8081");
        // openLandingPageInBrowser("http://localhost:" + port);
    }
   }

我尝试读取 application.properties 的文件

@Configuration
@ConfigurationProperties(prefix = "application")
public class AppProperties {
    private String port;

    public String getPort() {
        return port;
    }

    public void setPort(String port) {
        this.port = port;
    }
}

我读取其他 .properties 文件的文件

@Service
public class DropdownPropertiesService {

    @Value("${dropdown1.file}")
    private String dropdown1File;

    @Value("${dropdown2.file}")
    private String dropdown2File;
}

application.properties 文件

spring.application.name=demo2
server.port=8084
dropdown1.file=./dropdown1.properties
dropdown2.file=./dropdown2.properties

Answer 1

项目树

demo-spring-boot-props
├── pom.xml
├── config1
│   └── application.properties
├── config2
│   └── application.properties
├── dropdown1.properties
├── dropdown2.properties
└── src
    └── main
        ├── java
        │   └── com
        │       └── example
        │           ├── AppConfig.java
        │           ├── DemoApplication.java
        │           └── HelloController.java
        └── resources
            └── application.properties

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.3.3</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo-spring-boot-props</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo-spring-boot-props</name>
    <description>demo-spring-boot-props project for Spring Boot</description>

    <properties>
            <maven.compiler.source>17</maven.compiler.source>
                <maven.compiler.target>17</maven.compiler.target>
                <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
                <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>        
        </dependency>
    </dependencies>

    <build>
        <finalName>app</finalName>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

资源/application.properties

spring.application.name=demo
# greeting=Hello
greeting=${GREETING:Hello}

演示应用程序.java

默认，模板。

package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

HelloController.java

测试班

package com.example;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {

    @Autowired
    AppConfig appConfig;

    //Inject greeting property from application.properties
    // If GREETING is set in the environment variable, this value will be used first; otherwise, the greeting value in application.properties will be used.
    @Value("${greeting:NotDefine}")
    private String greeting;

    @Value("${dropdown1.file:NotDefine}")
    private String dropdown1File;

    @Value("${dropdown2.file:NotDefine}")
    private String dropdown2File;

    // Create a GET request to receive parameters
    @GetMapping("/hello")
    public String sayHello(@RequestParam(value = "msg", defaultValue = "World") String msg) {
        return String.format("%s, %s!", greeting, msg);
    }

    @GetMapping("/getFile1")
    public String getFile1() {
        return dropdown1File;
    }

    @GetMapping("/getFile2")
    public String getFile2() {
        return dropdown2File;
    }

    @GetMapping("/dump")
    public String deump() {
        return appConfig.dump();
    }
}

AppConfig.java

package com.example;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;

@Configuration
//@PropertySource("classpath:config1.properties")
//@PropertySource("classpath:config2.properties")
//@PropertySource("classpath:${dropdown1.file:NotDefine}")
//@PropertySource("classpath:${dropdown2.file:NotDefine}")
// ERR java.io.FileNotFoundException: class path resource [dropdown1.properties] cannot be opened because it does not exist

@PropertySource("file:${dropdown1.file:NotDefine}")
@PropertySource("file:${dropdown2.file:NotDefine}")
public class AppConfig {
    @Value("${AAA1:NotDefine}")
    private String aaa1;
    @Value("${BBB1:NotDefine}")
    private String bbb1;
    @Value("${CCC1:NotDefine}")
    private String ccc1;
    @Value("${AAA2:NotDefine}")
    private String aaa2;
    @Value("${BBB2:NotDefine}")
    private String bbb2;
    @Value("${CCC2:NotDefine}")
    private String ccc2;

    @Value("${AAA3:NotDefine}")
    private String aaa3;
    @Value("${BBB3:NotDefine}")
    private String bbb3;
    @Value("${CCC3:NotDefine}")
    private String ccc3;

    public String dump() {
        String sb = "aaa1 = " + aaa1 + "\n" +
                "bbb1 = " + bbb1 + "\n" +
                "ccc1 = " + ccc1 + "\n" +
                "aaa2 = " + aaa2 + "\n" +
                "bbb2 = " + bbb2 + "\n" +
                "ccc2 = " + ccc2 + "\n" +
                "aaa3 = " + aaa3 + "\n" +
                "bbb3 = " + bbb3 + "\n" +
                "ccc3 = " + ccc3 + "\n";
        return sb;
    }
}

config1/application.properties

dropdown1.file=./dropdown1.properties

config2/application.properties

dropdown2.file=./dropdown2.properties

下拉1.属性

AAA1=XXXa1
BBB1=XXXb1
CCC1=XXXc1

dropdown2.属性

AAA2=YYYa2
BBB2=YYYb2
CCC2=YYYc2

构建

mvn clean package

奔跑

Linux

export SPRING_CONFIG_LOCATION=classpath:/application.properties,optional:file:`pwd`/config1/application.properties,optional:file:`pwd`/config2/application.properties

java -jar target/app.jar

您可以通过设置环境变量来配置application.properties：

SPRING_CONFIG_LOCATION

我配置了3个application.properties。

• (1)

  app.jar/application.properties

  阅读者

  clsspath

classpath:/application.properties

• (2) config1/application.properties 按文件路径

file:`pwd`/config1/application.properties

• (3) config2/application.properties 按文件路径

file:`pwd`/config2/application.properties

demo-spring-boot-props
├── target
│   └── app.jar/application.properties (classpath)
├── config1
│   └── application.properties
└── config2
    └── application.properties

测试

测试1

curl http://localhost:8080/hello?msg=Spring
>>> Hello, Spring!

curl http://localhost:8080/hello
>>> Hello, World!

按环境设置属性

greeting

GREETING

停止 Spring Boot 应用程序（Ctrl + C）

Linux

export GREETING=XYZ

java -jar target/app.jar

测试2

curl http://localhost:8080/hello?msg=Spring
>>> XYZ, Spring!

curl http://localhost:8080/hello
>>> XYZ, World!

greeting属性可以从application.perties中读取或者通过环境变量GREETING设置。

# application.properties
greeting=${GREETING:Hello}

测试3

curl http://localhost:8080/getFile1
>>> ./dropdown1.properties

curl http://localhost:8080/getFile2
>>> ./dropdown2.properties

HelloController.java读取dropdown1.file和dropdown2.file。

@Value("${dropdown1.file:NotDefine}")
private String dropdown1File;

@Value("${dropdown2.file:NotDefine}")
private String dropdown2File;

但是 dropdown1.file 和 dropdown2.file 属性的设置从何而来？

还记得这个吗？

export SPRING_CONFIG_LOCATION=classpath:/application.properties,optional:file:`pwd`/config1/application.properties,optional:file:`pwd`/config2/application.properties

config1/application.properties 和 config2/application.properties 提供

dropdown1.file

和

dropdown2.file

config

# config1/application.properties
dropdown1.file=./dropdown1.properties

config2/application.properties
dropdown2.file=./dropdown2.properties

demo-spring-boot-props
├── dropdown1.properties
└── dropdown2.properties

测试3

curl http://localhost:8080/dump

aaa1 = XXXa1
bbb1 = XXXb1
ccc1 = XXXc1
aaa2 = YYYa2
bbb2 = YYYb2
ccc2 = YYYc2
aaa3 = NotDefine
bbb3 = NotDefine
ccc3 = NotDefine

停止 Spring Boot 应用程序（Ctrl + C）

通过spring应用程序参数更改服务器端口。

java -jar target/app.jar --server.port=8888

测试4

curl http://localhost:8888/hello?msg=Spring
>>> XYZ, Spring!

总结：

(1) Spring Boot应用程序的属性可以从多个来源读取。

• 直接从application.properties读取
• 设置环境变量。
• 从 Spring Boot 应用程序 app 参数中读取。

(2) Spring Boot 的 application.properties 也来自多个来源。

• 可以从应用程序jar中的application.properties（类路径）获取
• 可以从外部目录命令路径。