Java file operation

xiaoxiao2021-03-06 71

File establishment / check and deletion

<% @ Page ContentType = "text / html; charset = GB2312"%>

<% @ Page Import = "java.io. *"%>

File Establishment, Check and Delete </ Title> </ hEAD> <body> <% String path = request.getRealPath (""); //out.println (PATH); FILE F = New File (Path, "File.txt"); //out.println (F); //out.println (f.exists ()); IF (F.Exists ()) {// Check if file.txt exists f.delete (); // Delete file.txt file Out.println (Path "//file.txt exists, deleted."); } else { f.createNewFile (); // Create a file named file.txt in the current directory Out.println (Path "//file.txt does not exist, established."); // Output current directory path } %> Contents of the catalog / check and deletion <% @ Page ContentType = "text / html; charset = GB2312"%> <% @ Page Import = "java.io. *"%> <html> <HEAD> <title> Directory Establish / Check and Delete </ Title> </ hEAD> <body> <% String path = request.getRealPath (""); Path = PATH "// Sub"; // will be created directory path FILE D = New File (PATH); / / Establish a file object representing the SUB directory and gets a reference to it IF (d.exists ()) {// check if the SUB directory exists D. Delete (); OUT.PRINTLN ("Sub directory, deleted"); } else { D.mkdir (); // Establish a SUB directory Out.println ("SUB directory does not exist, established"); } %> </ body> </ html> How to handle virtual directories in JSP <% @ Page ContentType = "text / html; charset = GB2312"%> <% @ Page Import = "java.io. *"%> <html> <HEAD> <Title> How to deal with virtual directory </ title> </ hEAD> <body> Take a disk path corresponding to the virtual directory The location of the main directory of the Web site is <% = request.getRealPath ("/")%> JSP page location <% = request.getRealPath ("./")" g g / / / t t "j j 网网目上位置上位置上位置上位置" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" " > <% = Request.getRealPath ("..") "=" " </ body> </ html> Document attribute <% @ Page ContentType = "text / html; charset = GB2312"%> <% @ Page Import = "java.util.date, java.io. *"%> <html> <HEAD> <Title> File Attributes </ Title> </ hEAD> <body> <% String path = Request.getRealPath ("/"); File f = new file (path, "readdata.txt"); IF (f.exists ()) { %> <% = F.getName ()%> following properties: The file length is: <% = f.length ()%> <% = f.isfile ()? "Yes File": "Not File"%> <% = f.IsDirectory ()? "is a directory": "Not a directory"%> <% = f.canread ()? "Readable": "Do not read"%> <% = f.canwrite ()? "writable": "Not Writing"%> <% = f.ishidden ()? "is a hidden file": "Not hidden file"%> The final modification date of the file is: <% = new Date (f.lastmodified ())%> <% } else { f.createNewFile (); // Create a file called readata.txt in the current directory %> <% = F.getName ()%> following properties: The file length is: <% = f.length ()%> <% = f.isfile ()? "Yes File": "Not File"%> <% = f.IsDirectory ()? "is a directory": "Not a directory"%> <% = f.canread ()? "Readable": "Do not read"%> <% = f.canwrite ()? "writable": "Not Writing"%> <% = f.ishidden ()? "is a hidden file": "Not hidden file"%> The final modification date of the file is: <% = new Date (f.lastmodified ())%> <%} %> </ body> </ html> Remove the method of files in the directory <% @ Page ContentType = "text / html; charset = GB2312"%> <% @ Page Import = "java.io. *"%> <html> <HEAD> <title> Remove the method in the directory - list files in the directory </ title> </ hEAD> <body> <% String path = Request.getRealPath ("/"); FILE D = New File (PATH); / / Establish the file object in the current directory File List [] = D.ListFiles (); // A number of file objects that represent all files in the directory Out.println ("" PATH "directory: "); For (int I = 0; i <list.length; i ) { IF (List .isfile ()) { Out.println (List .Getname () " "); } } Out.println (" " "directory: ); For (int I = 0; i <list.length; i ) { IF (List .Indirectory ()) { Out.println (List .Getname () " "); } } %> </ body> </ html> Judgment is a blank file <% @ Page ContentType = "text / html; charset = GB2312"%> <% @ Page Import = "java.io. *"%> <html> <HEAD> <title> Judging whether it is blank file </ title> </ hEAD> <body> <% String path = Request.getRealPath ("/"); Out.println (PATH); FileReader fr = new fileReader (path "//atend.txt" );// establishes FileReader object, and instantiates FR / / The object generated by the FileReader class uses the read () method, which can read the next character from the character stream. IF (fr.read () == - 1) // determine if the end of the file has been read { Out.print (no data "in atend.txt file); } else { Out.println ("ATEND.TXT file has data"); } Fr.close (); %> </ body> </ html> Read all file data <% @ Page ContentType = "Text / HTML; Charset = GB2312"%> <% @ page import = "java.io. *, Java.lang. *"%> <html> <HEAD> <Title> Read all file data </ title> </ hEAD> <body> <% String path = Request.getRealPath ("."); FileReader fr = new fileReader (Path "//ReadData.txt"); / / The key is that during the reading, it is to be determined whether the read characters have reached the end of the file, and this character is not a broken line in the file, ie it is determined whether the character value is 13. INT C = fr.read (); // Read a character from the file / / Judgment whether the end of the file has been read While (c! = - 1) { OUT.PRINT ((char) c); / / Output read data c = fr.read (); // Continue to read data from the file IF (c == 13) {// Judgment whether it is a broken character Out.print (" "); // Output Branch Tag Fr.skip (1); // Skose a character //c=fr.read ();// read a character } } Fr.close (); %> </ body> </ html> Read data a row <% @ Page ContentType = "text / html; charset = GB2312"%> <% @ Page Import = "java.io. *"%> <html> <HEAD> <title> file reading </ title> </ hEAD> <body> <% String path = request.getRealPath (""); // get the path to the current directory FileReader fr = new fileReader (Path "//file/inc///t.txt"" ;//> Establishing a FileReader object, and instantiate to FR BufferedReader Br = New BufferedReader (fr); // Establish a bufferedReader object and instantiate to BR String line = br.readline (); // read a string from the file / / Judgment whether the read string is not empty While (line! = null) { Out.println (Line " "); / / Output data read from the file LINE = br.readline (); // Continue to read a line of data from the file } Br.close (); // Close BufferedReader object fr.close (); // Turk %> </ body> </ html> I'll not read the characters in the file <% @ Page ContentType = "text / html; charset = GB2312"%> <% @ Page Import = "java.io. *"%> <html> <HEAD> <Title> Listening to bytes </ Title> </ hEAD> <body> <% String path = Request.getRealPath ("."); FileReader fr = new fileReader (Path "//ReadData.txt"); Fr.skip (2); // Skip 2 bytes INT C = fr.read (); // Read a byte While (c! = - 1) { Out.print (CHAR) C); C = fr.read (); } Fr.close (); %> </ body> </ html> Write data into files <% @ Page ContentType = "text / html; charset = GB2312"%> <% @ Page Import = "java.io. *"%> <html> <HEAD> <title> Write data into file </ title> </ hEAD> <body> <% String path = Request.getRealPath ("."); FileWriter FW = New FileWriter (Path "//WriteData.txt": // Established a FileWriter object, and instantiate FW // write a string to the file fw.write ("Hello!"); Fw.write ("This book is" JSP Programming Skills ""); fw.write ("Please give me a lot!"); Fw.write ("email: stride@sina.com"); Fw.close (); FileReader fr = new fileReader (Path "//writedata.txt"); BufferedReader Br = New BufferedReader (fr); // Establish a bufferedReader object and instantiate to BR String line = br.readline (); // read a line of data Out.println (Line " "); Br.close (); // Close BufferedReader object Fr.close (); %> </ body> </ html> Write the data branch of the file <% @ Page ContentType = "text / html; charset = GB2312"%> <% @ Page Import = "java.io. *"%> <html> <HEAD> <title> Write the data branch of the file </ title> </ hEAD> <body> <% String path = Request.getRealPath ("."); FileWriter FW = New FileWriter (Path "//writedata.txt"); BufferedWriter BW = New BufferedWriter (FW); BW.WRITE ("Hello!"); BW.WRITE ("This book is" JSP programming skills "."); Bw.newline (); // broken BW.WRITE ("Please pay more attention!"); BW.NEWLINE (); // Broken BW.WRITE ("email: stride@sina.com"); Bw.flush (); // update data to file fw.close (); // Turn off the file stream Out.println ("Write file content is: "); FileReader fr = new fileReader (Path "//writedata.txt"); BufferedReader Br = New BufferedReader (FR); String line = br.readline (); // read a line of data While (line! = null) { Out.println (Line " "); Line = br.readline (); } Fr.close (); %> </ body> </ html> How to add data to files <% @ Page ContentType = "text / html; charset = GB2312"%> <% @ Page Import = "java.io. *"%> <html> <HEAD> <title> Write the data branch of the file </ title> </ hEAD> <body> <% String path = Request.getRealPath ("."); RandomaccessFile Rf = new randomaccessfile (Path "//writedata.txt", "rw"), define a class randomaccessfile object, and instantiate Rf.seek (rf.Length ()); // Move the pointer to the end of the file Rf.writebytes ("/ NAPPEND A LINE to the File!"); Rf.close (); // Turn the file stream Out.println ("Write file content is: "); FileReader fr = new fileReader (Path "//writedata.txt"); BufferedReader Br = New BufferedReader (fr); // Read the bufferedRead object of the file String line = br.readline (); While (line! = null) { Out.println (Line " "); Line = br.readline (); } fr.close (); // Turk %> </ body> </ html> </div><div class="text-center mt-3 text-grey"> 转载请注明原文地址:https://www.9cbs.com/read-107082.html</div><div class="plugin d-flex justify-content-center mt-3"></div><hr><div class="row"><div class="col-lg-12 text-muted mt-2"><h2 class="h6 mb-0 small"><a class="text-secondary" href="tag-2.html">9cbs</a></h2></div></div></div></div><div class="card card-postlist border-white shadow"><div class="card-body"><div class="card-title"><div class="d-flex justify-content-between"><div>New Post(0) </div><div></div></div></div><ul class="postlist list-unstyled"> </ul></div></div><div class="d-none threadlist"><input type="checkbox" name="modtid" value="107082" checked /></div></div></div></div></div><footer class="text-muted small bg-dark py-4 mt-3" id="footer"><div class="container"><div class="row"><div class="col">CopyRight © 2020 All Rights Reserved </div><div class="col text-right">Processed: 0.047, SQL: 9</div></div></div></footer><script src="./lang/en-us/lang.js?2.2.0"></script><script src="view/js/jquery.min.js?2.2.0"></script><script src="view/js/popper.min.js?2.2.0"></script><script src="view/js/bootstrap.min.js?2.2.0"></script><script src="view/js/xiuno.js?2.2.0"></script><script src="view/js/bootstrap-plugin.js?2.2.0"></script><script src="view/js/async.min.js?2.2.0"></script><script src="view/js/form.js?2.2.0"></script><script> var debug = DEBUG = 0; var url_rewrite_on = 1; var url_path = './'; var forumarr = {"1":"Tech"}; var fid = 1; var uid = 0; var gid = 0; xn.options.water_image_url = 'view/img/water-small.png'; </script><script src="view/js/wellcms.js?2.2.0"></script><a class="scroll-to-top rounded" href="javascript:void(0);"></a><a class="scroll-to-bottom rounded" href="javascript:void(0);" style="display: inline;"></a></body></html><script> var forum_url = 'list-1.html'; var safe_token = 'GB3_2FbEgM9ypfXpYMbxcIYveC3UYNGMlruoekEQ8Sme2iLjBEuifZbLn6dxbG5_2Ba0P0oKjqF39e5RpzSEZ91KIA_3D_3D'; var body = $('body'); body.on('submit', '#form', function() { var jthis = $(this); var jsubmit = jthis.find('#submit'); jthis.reset(); jsubmit.button('loading'); var postdata = jthis.serializeObject(); $.xpost(jthis.attr('action'), postdata, function(code, message) { if(code == 0) { location.reload(); } else { $.alert(message); jsubmit.button('reset'); } }); return false; }); function resize_image() { var jmessagelist = $('div.message'); var first_width = jmessagelist.width(); jmessagelist.each(function() { var jdiv = $(this); var maxwidth = jdiv.attr('isfirst') ? first_width : jdiv.width(); var jmessage_width = Math.min(jdiv.width(), maxwidth); jdiv.find('img, embed, iframe, video').each(function() { var jimg = $(this); var img_width = this.org_width; var img_height = this.org_height; if(!img_width) { var img_width = jimg.attr('width'); var img_height = jimg.attr('height'); this.org_width = img_width; this.org_height = img_height; } if(img_width > jmessage_width) { if(this.tagName == 'IMG') { jimg.width(jmessage_width); jimg.css('height', 'auto'); jimg.css('cursor', 'pointer'); jimg.on('click', function() { }); } else { jimg.width(jmessage_width); var height = (img_height / img_width) * jimg.width(); jimg.height(height); } } }); }); } function resize_table() { $('div.message').each(function() { var jdiv = $(this); jdiv.find('table').addClass('table').wrap('<div class="table-responsive"></div>'); }); } $(function() { resize_image(); resize_table(); $(window).on('resize', resize_image); }); var jmessage = $('#message'); jmessage.on('focus', function() {if(jmessage.t) { clearTimeout(jmessage.t); jmessage.t = null; } jmessage.css('height', '6rem'); }); jmessage.on('blur', function() {jmessage.t = setTimeout(function() { jmessage.css('height', '2.5rem');}, 1000); }); $('#nav li[data-active="fid-1"]').addClass('active'); </script>