springboot打成jar后获取classpath下文件失败

最新推荐文章于 2023-02-24 20:18:42 发布

SeaSky_Steven

最新推荐文章于 2023-02-24 20:18:42 发布

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文章标签： java 文件获取失败 jar

本文介绍在SpringBoot应用打包成Jar后，如何解决无法访问静态文件的问题，提供通过ClassPathResource.getInputStream()获取文件的解决方案，并附带三个具体实现场景。

背景：

springboot本地加载静态文件访问正常，打jar放到linux服务器报ileNotFoundException class path resource [static/taobao.dict] cannot be resolved to absolute file path because it does not reside in the file system: jar ..类似错误

原因：

通过

ResourceUtils.getFile("classpath:static/taobao.dict");//前缀有classpath

或

ClassPathResource resource = new ClassPathResource("static/taobao.dict");//前缀无classpath
InputStream inputStream = resource.getInputStream();
File file = resource.getFile();

只能获取类文件下文件，无法从jar包获取

解决方法：

通过ClassPathResource.getInputStream()获取

如：此处我将jieba切词词典作为静态文件放进内存读取
ClassPathResource resource = new ClassPathResource(“static/taobao.dict”);
InputStream inputStream = resource.getInputStream();
File taobaoDictFile = File.createTempFile("taobao", ".dict");
FileUtils.copyInputStreamToFile(inputStream, taobaoDictFile);
WordDictionary.getInstance().loadUserDict(taobaoDictFile.toPath(), StandardCharsets.UTF_8);

参考资料：https://www.oschina.net/question/2272552_2269641?sort=time

几个实现方式：

String data = "";
ClassPathResource cpr = new ClassPathResource("static/file.txt");
try {
    byte[] bdata = FileCopyUtils.copyToByteArray(cpr.getInputStream());
    data = new String(bdata, StandardCharsets.UTF_8);
} catch (IOException e) {
    LOG.warn("IOException", e);
}

场景二：

ClassPathResource classPathResource = new ClassPathResource("static/something.txt");

InputStream inputStream = classPathResource.getInputStream();
File somethingFile = File.createTempFile("test", ".txt");
try {
    FileUtils.copyInputStreamToFile(inputStream, somethingFile);
} finally {
    IOUtils.closeQuietly(inputStream);
}

场景三：

       Resource[] resources;

        try {
            resources = ResourcePatternUtils.getResourcePatternResolver(resourceLoader).getResources("classpath:" + location + "/*.json");
            for (int i = 0; i < resources.length; i++) {
                try {
                InputStream is = resources[i].getInputStream();
                byte[] encoded = IOUtils.toByteArray(is);
                String content = new String(encoded, Charset.forName("UTF-8"));
                }
            }
        } catch (IOException e) {
            throw new UncheckedIOException(e);
        }