Java课堂动手动脑
Posted 宋泊然
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1.使用Files. walkFileTree()找出指定文件夹下所有大于指定大小(比如1M)的文件:
代码:
package test; import java.io.IOException; import java.nio.file.FileSystems; import java.nio.file.FileVisitOption; import java.nio.file.FileVisitResult; import java.nio.file.FileVisitor; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.PathMatcher; import java.nio.file.Paths; import java.nio.file.attribute.BasicFileAttributes; import java.util.EnumSet; public class KnownSize implements FileVisitor { private final PathMatcher matcher; private final long accepted_size; public KnownSize(String glob,long accepted_size) { matcher= FileSystems.getDefault().getPathMatcher("glob:" +glob); this.accepted_size=accepted_size; } void search(Path file) throws IOException { long size = (Long) Files.getAttribute(file, "basic:size"); if(size ==accepted_size) { System.out.println(file); } } @Override public FileVisitResult postVisitDirectory(Object dir, IOException exc)throws IOException { return FileVisitResult.CONTINUE; } @Override public FileVisitResult preVisitDirectory(Object dir, BasicFileAttributes attrs)throws IOException { return FileVisitResult.CONTINUE; } @Override public FileVisitResult visitFile(Object file, BasicFileAttributes attrs)throws IOException { search((Path) file); return FileVisitResult.CONTINUE; } @Override public FileVisitResult visitFileFailed(Object file, IOException exc)throws IOException { return FileVisitResult.CONTINUE; } public static void main(String[] args) throws IOException{ String glob= "*.jpg"; long size = 1048576;//1M=1024k=1048576字节 Path fileTree = Paths.get("C:/"); KnownSize walk=new KnownSize(glob, size); EnumSet opts=EnumSet.of(FileVisitOption.FOLLOW_LINKS); System.out.println("C盘中大小等于1M的文件有"); Files.walkFileTree(fileTree, opts, Integer.MAX_VALUE, walk); } }
运行结果:
2.使用Files. walkFileTree()找出指定文件夹下所有扩展名为.txt和.java的文件。
package test; import java.io.IOException; import java.nio.file.FileSystems; import java.nio.file.FileVisitResult; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.PathMatcher; import java.nio.file.Paths; import java.nio.file.SimpleFileVisitor; import java.nio.file.attribute.BasicFileAttributes; public class WalkFileTree { public static void main(String[] args) throws IOException { String glob ="glob:**/*.{java,txt}";//采用组模式查找拓展名为.java和.txt的文件 String path ="E:/";//想要查询的目录 match(glob,path); } public static void match(String glob,String location)throws IOException{ final PathMatcher pathmatcher =FileSystems.getDefault().getPathMatcher(glob);//新建pathmatcher对象用FileSystems.getDefault().getPathMatcher()方法接收匹配的字符串,返回一个可用的pathmatcher对象,然后进行匹配工作 Files.walkFileTree(Paths.get(location), new SimpleFileVisitor<Path>() { @Override public FileVisitResult visitFile(Path path,BasicFileAttributes attrs)throws IOException{ if (pathmatcher.matches(path)) { System.out.println(path); } return FileVisitResult.CONTINUE; } @Override public FileVisitResult visitFileFailed(Path file, IOException exc) throws IOException { return FileVisitResult.CONTINUE; }}); } }
运行结果:
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