Read all files under the folder in the jar package

The first thing to ask is ：

When the file is in resource In the middle of the day , If you read directly locally , Then you can read it , When it comes to success jar After package , No path , This problem is summarized as follows ：

We all know springboot The default method is to package into jar Package execution , At this time, if you need to traverse all folders and files under a certain path , Our usual way is to use File To deal with it , But this is because jar package , So use File Class will have an error that the path cannot be found , This article introduces a way to read all the contents of a folder

public static void main(String[] args) throws IOException {
        // TODO  Load current project classpath Next META-INF/folder And all files in its subfolders 
        Resource[] resources = new PathMatchingResourcePatternResolver().getResources(ResourceUtils.CLASSPATH_URL_PREFIX + "META-INF/folder/**/*.txt");

        // TODO  Load current project classpath Next META-INF/folder And all in its subfolders .txt Final document 
        Resource[] resources2 = new PathMatchingResourcePatternResolver().getResources(ResourceUtils.CLASSPATH_URL_PREFIX + "META-INF/folder/**/*.txt");

        // TODO  Load the current project and all jar in classpath All under META-INF/spring.factories file （springboot The main functions of automatic assembly ）
        Resource[] resources3 = new PathMatchingResourcePatternResolver().getResources(ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX + "META-INF/spring.factories");

        //  Traverse the contents of the file 
        for(Resource resource : resources) {
            StringBuffer script = new StringBuffer();
            try(InputStreamReader isr = new InputStreamReader(resource.getInputStream(), StandardCharsets.UTF_8);
                BufferedReader bufferReader = new BufferedReader(isr)) {
                String tempString;
                while ((tempString = bufferReader.readLine()) != null) {
                    script.append(tempString).append("\n");
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
            System.out.println("script:" + script.toString());
        }
    }

"META-INF/folder/**/*.txt" Change this path to your own path

// Because I need an array of output streams , It is amended as follows 
public InputStream[] getDirResource() throws IOException
  {
    Resource[] resources = new PathMatchingResourcePatternResolver().getResources(ResourceUtils.CLASSPATH_URL_PREFIX + "/Corpus/Chinese/*.xml");
    Resource[] resourcesPi = new PathMatchingResourcePatternResolver().getResources(ResourceUtils.CLASSPATH_URL_PREFIX + "/Corpus/pi/*.xml");

    int lengths = resources.length + resourcesPi.length;

    InputStream[] files = new InputStream[lengths];
    for (int i = 0, n = resources.length; i < n; i++)
      files[i] =resources[i].getInputStream();

    int count = 0;
    for (int i = resources.length, n = lengths; i < n; i++){
      files[i] =resourcesPi[count].getInputStream();
      count++;
    }
    return files;
  }

The following dependencies should be added to this （ Some automatically ignore ）

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter</artifactId>
	<version>2.1.0.RELEASE</version>
</dependency>
<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-cache</artifactId>
	<version>2.1.0.RELEASE</version>
</dependency>

That is to say springboot Regular... Should not be used in File To read the file , You can only use streaming to read ,

By the way, the traditional way ：

private String gossipPath = this.getClass().getResource("/gossip.txt").getPath();   // This kind of local can

InputStream is = this.getClass().getResourceAsStream("/conf/context.xml")  // This kind of jar You can also pack , Direct stream read , But what you read is a file , To read all the files in the folder , The above method , It's the best choice