java - 通过 Spring Boot 加载要映射的属性文件
问题描述
所以我正在尝试学习 Spring Boot,但我完全被困在这里。我正在尝试学习如何加载属性文件并通过 servlet 简单地打印结果。
这是我的application.properties
文件
example.mapProperty.key1=MapValue1
example.mapProperty.key2=MapValue2
属性类:
import org.springframework.boot.context.properties.ConfigurationProperties;
@PropertySource("classpath:application.properties")
@ConfigurationProperties(prefix = "example")
public class DemoProperty {
private Map<String, String> mapProperty;
public Map<String, String> getMapProperty() {
return mapProperty;
}
public void setMapProperty(Map<String, String> mapProperty) {
this.mapProperty = mapProperty;
}
}
小服务程序类:
public class HelloCountryServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private static final Logger logger = LogManager.getLogger(HelloCountryServlet.class);
@Autowired
private DemoProperty demoProperty;
public void setDemoProperty(DemoProperty demoProperty) {
this.demoProperty = demoProperty;
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
doGet(request, response);
}
public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
response.setContentType("text/html");
logger.info("Logger is running");
logger.info("demoProperty :: " + demoProperty);
PrintWriter out = response.getWriter();
for(Entry<String, String> i : demoProperty.getMapProperty().entrySet()) {
out.println("<h3>Property " + i.getKey() + " : " + i.getValue() + "</h3>");
}
}
}
入门级:
@SpringBootApplication
public class SpringBootAppStarter extends SpringBootServletInitializer {
@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
return application.sources(SpringBootAppStarter.class);
}
public static void main(String[] args) {
SpringApplication.run(SpringBootAppStarter.class, args);
}
}
pom.xml:
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.2.6.RELEASE</version>
<relativePath />
</parent>
<groupId>com.test</groupId>
<artifactId>SpringBootApp</artifactId>
<version>0.0.1</version>
<packaging>war</packaging>
<name>SpringBootApp Maven Webapp</name>
<properties>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
<java.version>1.8</java.version>
<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>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-logging</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-log4j2</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-configuration-processor</artifactId>
<optional>true</optional>
</dependency>
</dependencies>
<build>
<finalName>SpringBootApp</finalName>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
我在 sts 的 Wildfly 服务器上运行它。
战争结构:
META-INF
WEB-INF __
|
|_ lib
|_ classes__
|
|_ application.properties
|_ class files
不幸的是,我总是将 demoProperty 类设为空。
这是日志的一部分:
0:34:15,484 INFO [stdout] (default task-1) 2020-03-27 20:34:15.484 [INFO ] DispatcherServlet 547 - Completed initialization in 12 ms
20:34:22,454 INFO [stdout] (default task-1) 2020-03-27 20:34:22.453 [INFO ] HelloCountryServlet 35 - Logger is running
20:34:22,454 INFO [stdout] (default task-1) 2020-03-27 20:34:22.454 [INFO ] HelloCountryServlet 36 - demoProperty :: null
20:34:22,464 INFO [stdout] (default task-1) 2020-03-27 20:34:22.458 [ERROR] ErrorPageFilter 183 - Forwarding to error page from request [/country] due to exception [null]
20:34:22,464 INFO [stdout] (default task-1) java.lang.NullPointerException: null
20:34:22,464 INFO [stdout] (default task-1) at com.test.servlets.HelloCountryServlet.doGet(HelloCountryServlet.java:38) ~[classes:?]
20:34:22,464 INFO [stdout] (default task-1) at javax.servlet.http.HttpServlet.service(HttpServlet.java:503) ~[jboss-servlet-api_4.0_spec-2.0.0.Final.jar!/:2.0.0.Final]
我一直在使用这些链接作为参考: https ://mkyong.com/spring-boot/spring-boot-configurationproperties-example/
http://www.jcombat.com/spring/how-to-read-properties-using-spring-boot-configurationproperties
有人能帮我一下吗。提前致谢。
解决方案
您需要@Component
在 DemoProperty 类上添加注释。目前在应用程序启动期间它不被视为 bean。
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