Spring ClassPathResource 教程显示了如何在 Spring 应用中使用 ClassPathResource 读取资源。
Spring 是用于创建企业应用的流行 Java 应用框架。
Spring ClassPathResource
ClassPathResource允许从 Java 类路径获取资源。
Spring ClassPathResource示例
该应用从 Java 类路径中的文件读取文本数据。
src├───main│ ├───java│ │ └───com│ │ └───zetcode│ │ │ Application.java│ │ └───service│ │ ReadWordsService.java│ └───resources│ logback.xml│ my-beans.xml│ words.txt└───test └───java
这是项目结构。
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.zetcode</groupId> <artifactId>classpathres</artifactId> <version>1.0-SNAPSHOT</version> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.source>11</maven.compiler.source> <maven.compiler.target>11</maven.compiler.target> <spring-version>5.1.3.RELEASE</spring-version> </properties> <dependencies> <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-classic</artifactId> <version>1.2.3</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>{spring-version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>{spring-version}</version> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>exec-maven-plugin</artifactId> <version>1.6.0</version> <configuration> <mainClass>com.zetcode.Application</mainClass> </configuration> </plugin> </plugins> </build></project>在pom.xml文件中，我们具有基本的 Spring 依赖项spring-core和spring-context和日志记录logback-classic依赖项。
exec-maven-plugin用于在命令行上从 Maven 执行 Spring 应用。
resources/my-beans.xml
<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean name="readWordsService" class="com.zetcode.service.ReadWordsService"/></beans>
在my-beans.xml文件中，我们配置readWordsService bean。 它成为 Spring 托管的 bean。
resources/words.txt
skybluemountainfreshcloudrockwatermelon
resources目录包含在类路径中。 该应用从words.txt文件中读取单词。
resources/logback.xml
<?xml version="1.0" encoding="UTF-8"?><configuration> <logger name="org.springframework" level="ERROR"/> <logger name="com.zetcode" level="INFO"/> <appender name="consoleAppender" class="ch.qos.logback.core.ConsoleAppender"> <encoder> <Pattern>%d{HH:mm:ss.SSS} [%thread] %blue(%-5level) %magenta(%logger{36}) - %msg %n </Pattern> </encoder> </appender> <root> <level value="INFO" /> <appender-ref ref="consoleAppender" /> </root></configuration>logback.xml是 Logback 日志库的配置文件。
com/zetcode/service/ReadWordsService.java
package com.zetcode.service;import org.springframework.core.io.ClassPathResource;import java.io.IOException;import java.nio.file.Files;import java.util.List;public class ReadWordsService { public List<String> readWords() throws IOException { var res = new ClassPathResource("words.txt"); var myFile = res.getFile(); var lines = Files.readAllLines(myFile.toPath()); return lines; }}ReadWordsService将单词读入列表，并将列表返回给客户端。
var res = new ClassPathResource("words.txt");ClassPathResource用于定位文本文件。
com/zetcode/Application.java
package com.zetcode;import com.zetcode.service.ReadWordsService;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.context.support.GenericXmlApplicationContext;import java.io.IOException;public class Application { private static final Logger logger = LoggerFactory.getLogger(Application.class); public static void main(String[] args) throws IOException { var ctx = new GenericXmlApplicationContext("my-beans.xml"); var wordsService = (ReadWordsService) ctx.getBean("readWordsService"); var words = wordsService.readWords(); words.forEach(word -> logger.info(word)); ctx.close(); }}这是主要的应用类。
var wordsService = (ReadWordsService) ctx.getBean("readWordsService");var words = wordsService.readWords();words.forEach(word -> logger.info(word));我们从容器中检索readWordsService bean，并调用其readWords()方法。 文字将打印到控制台。
$ mvn -q exec:java00:25:49.008 [com.zetcode.Application.main()] INFO com.zetcode.Application - sky00:25:49.008 [com.zetcode.Application.main()] INFO com.zetcode.Application - blue00:25:49.008 [com.zetcode.Application.main()] INFO com.zetcode.Application - mountain00:25:49.008 [com.zetcode.Application.main()] INFO com.zetcode.Application - fresh00:25:49.008 [com.zetcode.Application.main()] INFO com.zetcode.Application - cloud00:25:49.008 [com.zetcode.Application.main()] INFO com.zetcode.Application - rock00:25:49.008 [com.zetcode.Application.main()] INFO com.zetcode.Application - water00:25:49.008 [com.zetcode.Application.main()] INFO com.zetcode.Application - melon
我们运行该应用。
在本教程中，我们使用了 Spring 的ClassPathResource。
