Spring Boot - 无法从application.properties解析xml中的属性

Question

我有一个春季启动应用程序

我@Configuration class加载了xml Configuration using @ImportResource("path/to/xml"),其中包含以下行

<property name="bla" value="${log.directory}/file.ext" />

在src/main/resources我有application.properties以下内容的文件:

log.directory=C:/path/I/Need

但是当我运行时它无法加载属性,如下所示:

Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'log.directory' in string value "${log.directory}/file.ext"

Answer 1

您可以解决它向您添加context:property-placeholder xml.这样你就会告诉Spring加载你的特定属性文件.

然而,另一个更符合Spring Boot解决方案的是使用application.properties作为属性文件的名称,将其置于其中一个预期位置,并使用@EnableAutoconfiguration批注.

Spring Boot期望application.properties按以下顺序排列在以下位置.

1. 当前目录的A/config子目录.
2. 当前目录
3. 一个classpath/config包
4. 类路径根

我试过这个并且它有效.

的pom.xml

<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>sample</groupId>
    <artifactId>sample</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>Sample</name>
    <description>Spring Boot sample</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.1.8.RELEASE</version>
    </parent>

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

    <!-- Package as an executable jar -->
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

Sample.java

package sample;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.ImportResource;

@Configuration
@EnableAutoConfiguration
@ComponentScan
@ImportResource("classpath:beans.xml")
public class Sample implements CommandLineRunner {

    @Value("${sample}")
    private String sample;

    @Autowired
    SampleService service;

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

    public void run(String... args) {
        System.out.println(service.greetings());
    }
}

SampleService.java

package sample;


public class SampleService {

    private String field;

    public String greetings() {
        return field;
    }

    public String getField() {
        return field;
    }

    public void setField(String field) {
        this.field = field;
    }
}

beans.xml中

<?xml version="1.0" encoding="UTF-8"?>
<beans
  xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:context="http://www.springframework.org/schema/context"
  xmlns:p="http://www.springframework.org/schema/p"
  xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">

    <bean class="sample.SampleService">
        <property name="field" value="${sample}-world"></property>
    </bean>
</beans>

application.properties

sample=hello

在输出中,如果运行程序,您将获得hello world.

确保已启用自动配置.如果你没有,它将无法按预期工作.为此,请添加@EnableAutoconfiguration批注,如示例中所示.

请注意您使用的是Spring Boot,因此建议您避免使用XML配置.您可以在没有beans.xml的情况下获得相同的结果.虽然,如果您仍然需要它,您可以将XML与注释混合使用.

我已将两个示例项目上传到GitHub,请检查.

https://github.com/plopcas/example-spring-boot/tree/master/spring-boot-xml

https://github.com/plopcas/example-spring-boot/tree/master/spring-boot

希望这可以帮助.