Spring 引導項目未綁定來自 application.properties 的 @Value

Question

I am in the process of migrating an existing multi-module maven project to spring boot 2.6.1 and I've populated application.properties in the resources folder of one of the modules (the one with the SpringBootApplication entry point and with the spring boot maven 插件）。 我可以通過應用程序環境從項目中的任何模塊訪問這些屬性。 但是使用 @Value 綁定屬性不起作用

以下是我的項目結構

PROJ
└── pom.xml
└── ModuleA
    └── src
        └── main
            └── java
                └── com.example
                    └── abc
                        └── configuration
                            └── TestConfig.java
                        └── MyApplication.java
            └── resources
                └── application.properties
    └── pom.xml
└── ModuleB     

為什么@ConfigurationProperties 或@Value 的屬性綁定會失敗？ （我正在嘗試使用 @ConfigurationProperties 將所有數據源屬性綁定到 ModuleB 中的 DataSourceProperties bean，如文檔中所述- 但這也不起作用。）

我嘗試過的事情：

• 將 application.properties 放在配置目錄中；
• 在 pom 文件中指定資源的位置；
• 創建一個具有相同結構的新多模塊項目（它確實在這個“干凈”項目中工作，所以問題必須在遷移項目的現有配置中。我試圖比較兩個項目之間的差異，但應用了相似的配置我仍然無法讓自動綁定在我遷移的項目中工作。）

編碼：

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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.example</groupId>
    <artifactId>PROJ</artifactId>
    <version>1.0</version>
    <packaging>pom</packaging>
    <name>PROJ</name>

    <modules>
        <module>ModuleA</module>
        <module>ModuleB</module>
        <!-- Other modules -->
    </modules>

    <profiles>
        <profile>
            <id>dev</id>
            <properties>
                <develop.mode>true</develop.mode>
            </properties>
        </profile>
        <profile>
            <id>prod</id>
            <activation>
                <activeByDefault>true</activeByDefault>
            </activation>
            <properties>
                <develop.mode>false</develop.mode>
            </properties>
        </profile>
    </profiles>

    <properties>
        <!-- Project Properties -->
    </properties>

    <dependencyManagement>
        <dependencies>
            <!-- In House Modules -->
            <dependency>
                <groupId>com.example</groupId>
                <artifactId>ModuleB</artifactId>
                <version>1.0</version>
            </dependency>
            <dependency>
                <groupId>com.example</groupId>
                <artifactId>ModuleA</artifactId>
                <version>1.0</version>
            </dependency>

            <!-- Spring -->
            <dependency>
                <!-- Import dependency management from Spring Boot -->
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>${spring-boot.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>

            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-instrument</artifactId>
                <version>${spring.version}</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-aspects</artifactId>
                <version>${spring.version}</version>
            </dependency>

            <dependency>
                <groupId>org.springframework.plugin</groupId>
                <artifactId>spring-plugin-core</artifactId>
                <version>${spring-plugin.version}</version>
            </dependency>
            <dependency>
                <groupId>org.springframework.plugin</groupId>
                <artifactId>spring-plugin</artifactId>
                <version>${spring-plugin.version}</version>
                <type>pom</type>
            </dependency>

            <dependency>
                <groupId>org.springframework.security</groupId>
                <artifactId>spring-security-saml2-service-provider</artifactId>
                <version>5.5.0-BETA</version>
                <classifier>BETA</classifier>
            </dependency>
            <dependency>
                <groupId>org.springframework.security.oauth</groupId>
                <artifactId>spring-security-oauth</artifactId>
                <version>${spring-security-oauth.version}</version>
            </dependency>
            <dependency>
                <groupId>org.springframework.security.oauth</groupId>
                <artifactId>spring-security-oauth2</artifactId>
                <version>${spring-security-oauth.version}</version>
                <exclusions>
                    <exclusion>
                        <groupId>org.springframework</groupId>
                        <artifactId>spring-webmvc</artifactId>
                    </exclusion>
                </exclusions>
            </dependency>

            <!-- Various other dependencies -->
            
        </dependencies>

    </dependencyManagement>

    <build>
        <pluginManagement>
            <plugins>
                <!-- Various plugins  -->
            </plugins>
        </pluginManagement>
    </build>

</project>

模塊A/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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <artifactId>PROJ</artifactId>
        <groupId>com.example</groupId>
        <version>1.0</version>
    </parent>

    <artifactId>ModuleA</artifactId>
    <packaging>jar</packaging>
    <name>ModuleA</name>

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

        <!-- In House Modules -->
        <dependency>
            <groupId>com.example</groupId>
            <artifactId>ModuleB</artifactId>
        </dependency>

    </dependencies>

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

應用程序屬性

# My datasource properties
app.datasource.myds.username=TestName

MyApplication.java

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

TestConfig.java

@Configuration
public class TestConfig {

    @Value("${app.datasource.myds.username}")
    public String un;

    @Bean(name = "testbean1")
    @Primary
    public Boolean testbean1() {
        System.out.println("Value un: " + un); // prints null
        return Boolean.FALSE;
    }

    @Bean(name = "testbean2")
    public Boolean testbean2(Environment env) {
        System.out.println("Env property: " + env.getProperty("app.datasource.myds.username")); // prints TestName 
        return Boolean.TRUE;
    }
}

Answer 1

我找到了 Spring Boot 沒有使用 @Value 或 @ConfigurationProperties 自動裝配我的屬性的原因。事實證明，我嘗試遷移的項目實現了一個無法正確初始化屬性的 PropertyPlaceholderConfigurer bean。 我已經取消了那個 bean，應用程序現在正在加載和自動裝配來自 application.properties 的所有屬性（來自所有模塊）