webjars 是很方便，方式很多時候我們也需要讀取內容，ClassGraph 是一個高效的classpath 以及模塊掃描器
如果查看了webjars 提供的webjars-locator 內部實現也是基於此工具的，但是weebjars 默認提供的功能缺少
內容讀取的能力，我們可以基於ClassGraph提供讀取文件內容的能力
參考webjars 項目
webjars實際上就是利用了web 容器對於META-INF/resources下資源文件的自動加載處理，制作一個webjars 就是打包
資源到這個路徑下
- 項目結構
- 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.dalong-web</groupId>
<artifactId>webjars</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<java.version>1.8</java.version>
<package-version>1.0</package-version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<destinationDir>${project.build.outputDirectory}/META-INF/resources/webjars/dalongdemo/${package-version}</destinationDir>
</properties>
<build>
<resources>
<resource>
<directory>${project.basedir}/src/main/resources</directory>
<targetPath>${destinationDir}</targetPath>
</resource>
</resources>
</build>
</project>
- 構建
mvn clean package install
webjars 引用以及讀取內容
- 項目結構
就是基於spring start 的web 項目，很簡單
- 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>2.3.1.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.dalong</groupId>
<artifactId>wbjarsapps</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>wbjarsapps</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>io.micrometer</groupId>
<artifactId>micrometer-registry-prometheus</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>com.dalong-web</groupId>
<artifactId>webjars</artifactId>
<version>1.0-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>io.github.classgraph</groupId>
<artifactId>classgraph</artifactId>
<version>4.8.87</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
- 入口
package com.dalong.wbjarsapps;
import io.github.classgraph.ClassGraph;
import io.github.classgraph.Resource;
import io.github.classgraph.ScanResult;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.util.MultiValueMap;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;
@SpringBootApplication
@RestController
public class WbjarsappsApplication {
public static void main(String[] args) {
SpringApplication.run(WbjarsappsApplication.class, args);
}
@RequestMapping(value = {"/r"})
public Object listResources() {
List<String> resultContents = new ArrayList<>();
ClassGraph classGraph =new ClassGraph();
try (ScanResult scanResult = classGraph.acceptPaths("META-INF/resources/webjars").scan()) {
scanResult.getResourcesWithExtension(".js").forEachByteArrayIgnoringIOException((Resource res, byte[] content) -> {
resultContents.add(new String(content, StandardCharsets.UTF_8));
});
}
MultiValueMap<String,String> headers =new HttpHeaders();
headers.add("content-type","text/js");
return new ResponseEntity(resultContents.get(0),headers,HttpStatus.OK);
}
}
說明
以上是一個簡單的內容讀取，實際上我們基於webjars 的多版本能力可以靈活的用來進行配置管理（比如配置系統，我們可以靈活的管理）
同時結合ClassGraph強大高效的classpath 掃描能力，我們可以增強系統的擴展能力
參考資料
https://github.com/classgraph/classgraph
https://www.webjars.org/