这段java代码是什么意思啊？

Question

public class ReadZipFile {
private static void mkdir(File file) {
if (!file.exists())
file.mkdir();
else if (!file.isDirectory()) {
throw new RuntimeException(String.format("因为%s已经存在，且不是目录，所以%<s目录无法创建", file.getPath()));
}
}

public static void main(String args[]) throws FileNotFoundException, IOException {
   File contextpath = new File("mybook");
   mkdir(contextpath);
   byte b[] = new byte[8 * 1024];
   try (ZipInputStream zipin = new ZipInputStream(ReadZipFile.class.getResourceAsStream("book.zip"),
          Charset.forName("gbk"));) {
       ZipEntry zipEntry = null;
       while ((zipEntry = zipin.getNextEntry()) != null) {
          File item = new File(contextpath, zipEntry.getName());
          if (zipEntry.isDirectory()) {
              System.out.println("创建了目录"+item.getAbsolutePath());
              mkdir(item);
          } else {
              try (FileOutputStream out = new FileOutputStream(item);) {
                 int n = -1;
                 System.out.println("创建了文件"+item.getAbsolutePath());
                 while ((n = zipin.read(b, 0, b.length)) != -1) {
                     out.write(b, 0, n);
                 }
              }
              try (FileInputStream in = new FileInputStream(item);){
                 byte[] allbytes = new byte[(int) item.length()];
                 in.read(allbytes);
                 System.out.println(new String(allbytes));
              }
          }
       }
   }
}

}

Answer 1