如何获取Jar包中文件

最新推荐文章于 2025-04-12 11:21:44 发布

TheBlindM

最新推荐文章于 2025-04-12 11:21:44 发布

阅读量3.3k

点赞数 2

分类专栏： Java 文章标签： jar intellij-idea java

本文链接：https://blog.youkuaiyun.com/qq_40495860/article/details/122978701

版权

Java 专栏收录该内容

24 篇文章

订阅专栏

如何获取Jar包中文件

1.通过ClassLoader下的getResource

在java中获取resource文件一般可以通过 getResource 来获取，如果需要获取多个通过getResources

ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
URL resource = contextClassLoader.getResource("test.txt");
 System.out.println(resource.getPath());

idea中：

/D:/study/JarTest/target/classes/test.txt

Jar包中：

file:/D:/study/JarTest/target/JarTest-1.0-SNAPSHOT.jar!/test.txt

Jar中输出的路径不是常规的文件路径，所以通过File是无法获取的

2.JarURLConnection

 JarURLConnection jarConnection = (JarURLConnection) resource.openConnection();
  JarFile jarFile = jarConnection.getJarFile();
 JarEntry jarEntry = jarConnection.getJarEntry();
 InputStream in = jarFile.getInputStream(jarEntry);


 try(BufferedReader r = new BufferedReader(new InputStreamReader(jarFile.getInputStream(jarEntry)));){
           System.out.println(r.readLine());
}

老师老师，我这段代码在jar中运行是正常的，但是用idea 调试就报异常啊

sun.net.www.protocol.file.FileURLConnection cannot be cast to java.net.JarURLConnection

在调试时和jar中都能运行的代码

1.通过Url下的getProtocol

        ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
        URL resource = contextClassLoader.getResource("test.txt");
        //jar 包下 file:/D:/study/JarTest/target/JarTest-1.0-SNAPSHOT.jar!/test/JarTest.class

        File rootDir = new File(resource.getPath());

        System.out.println(resource.getPath());

        if("file".equals(resource.getProtocol())){
            String path = resource.getPath();
            File file = new File(path);
            FileInputStream in = new FileInputStream(file);
            try(BufferedReader r = new BufferedReader(new InputStreamReader(in));){
                System.out.println(r.readLine());
            }
        }else  if ("jar".equals(resource.getProtocol())){

            JarURLConnection jarConnection = (JarURLConnection) resource.openConnection();

            JarFile jarFile = jarConnection.getJarFile();
            JarEntry jarEntry = jarConnection.getJarEntry();

            System.out.println(jarFile.getName());
            System.out.println(jarEntry.getName());
            try(BufferedReader r = new BufferedReader(new InputStreamReader(jarFile.getInputStream(jarEntry)));){
                System.out.println(r.readLine());
            }


        }

这代码也太长了吧，有没有简单的啊！！！！

2.通过getResourceAsStream

        ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
        InputStream in = contextClassLoader.getResourceAsStream("test.txt");

        try(BufferedReader r = new BufferedReader(new InputStreamReader(in));){
            System.out.println(r.readLine());
        }

实际应用

手动向mybatis 注册xml


ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
        InputStream resourceAsStream = contextClassLoader.getResourceAsStream("mapper");
        
        IoUtil.readUtf8Lines(resourceAsStream, (LineHandler) (xmlName)->{
            InputStream in = contextClassLoader.getResourceAsStream(String.format("mapper/%s",xmlName));

            XMLMapperBuilder xmlMapperBuilder = new XMLMapperBuilder(in, configuration, xmlName, configuration.getSqlFragments());
            xmlMapperBuilder.parse();
        });