Commons IO is a utility library that helps develop IO functions.

 


 
It mainly includes six aspects:

 


 

 

• Utility class - perform common tasks using static methods
• input - useful input stream and reader implementation
• output - useful output stream and writer implementation
• Filter Various implementations of file filter
• comparator Various implementations of java.util.Comparator for files
• File Watcher - Components for monitoring file system events

Official API address:
http://commons.apache.org/proper/commons-io/javadocs/api-release/index.html?org/apache/commons/io/FileUtils.html

User manual: http://commons.apache.org/proper/commons-io/description.html

/* Writing file
* 1.Only three full parameter forms are listed here. api provides method overloading of partial parameters
* 2.The last Boolean parameter is whether it is append mode or not
* 3.If the target file does not exist, FileUtils will be created automatically
* */
//static void:write(File file, CharSequence data, String encoding, boolean append)
FileUtils.write(new File("D:/a/b/cxyapi.txt"), "Program switching api","UTF-8",true);
//static void:writeLines(File file, Collection<?> lines, boolean append)
List lines=new ArrayList();
lines.add("Welcome to visit:");lines.add("blog.gzczy.top");
FileUtils.writeLines(new File("D:/a/b/cxyapi.txt"),lines,true);
//static void:writeStringToFile(File file, String data, String encoding, boolean append)
FileUtils.writeStringToFile(new File("D:/a/b/cxyapi.txt"), "Author: czy", "UTF-8",true);

//Read files or folders
//static String:readFileToString(File file, String encoding)
System.out.println(FileUtils.readFileToString(new File("D:/a/b/cxyapi.txt"), "UTF-8"));
//static List
   
    :readLines(File file, String encoding) System.out.println(FileUtils.readLines(new File("D:/a/b/cxyapi.txt"), "UTF-8")); //Return a list 
   

The common way we used to delete files / folders was to delete them recursively, repeatedly traverse subfolders to find and delete files one by one

//Delete directory
//static void:deleteDirectory(File directory)
FileUtils.deleteDirectory(new File("D:/not/cxyapi"));
//Note: when deleting files under path in this way, if the file read / write stream under path is not closed, it cannot be deleted;
//The second way (to solve the above problems, force deletion):
//static boolean:deleteQuietly(File file)
FileUtils.deleteQuietly(new File("D:/not/cxyapi")); //The folder is not empty and can be deleted without exception

//Move files or folders
//static void: moveDirectory(File srcDir, File destDir)
FileUtils.moveDirectory(new File("D:/cxyapi1"), new File("D:/cxyapi2")); //Note that if the second parameter file does not exist, an exception will be thrown
//static void:moveDirectoryToDirectory(File src, File destDir, boolean createDestDir)
FileUtils.moveDirectoryToDirectory(new File("D:/cxyapi2"), new File("D:/cxyapi3"), true);
/* The difference between the above two methods is:
* moveDirectory: D:/cxyapi2 The content in is the content of D / cxyapi1.
* moveDirectoryToDirectory: D:/cxyapi2 Move folder to D:/cxyapi3
*
* The following three are relatively simple, no examples are provided, only the api is provided
* The difference between moveToDirectory and others is that it can automatically identify operation files or folders
*/
//static void:moveFileToDirectory(srcFile, destDir, createDestDir)
//static void:moveFile(File srcFile, File destFile)
//static void:moveToDirectory(File src, File destDir, boolean createDestDir)

//The result is that cxyapi and cxyapi1 are in the same directory
FileUtils.copyDirectory(new File("D:/cxyapi"), new File("D:/cxyapi1"));
//The result is to copy cxyapi to cxyapi2
FileUtils.copyDirectoryToDirectory(new File("D:/cxyapi"), new File("D:/cxyapi2"));
//Copy file
FileUtils.copyFile(new File("d:/cxyapi.xml"), new File("d:/cxyapi.xml.bak"));
//Copy files to directory
FileUtils.copyFileToDirectory(new File("d:/cxyapi.xml"), new File("d:/cxyapi"));
//Copy url to file
FileUtils.copyURLToFile(new URL("https://blog.gzczy.topl"), new File("d:/cxyapi.xml"));

To view the original: https://blog.gzczy.top/index.php/2018/11/22/apache-commons-io%e4%bd%bf%e7%94%a8%e5%b0%8f%e6%8a%80%e5%b7%a7/