This article collects commonly used file operation methods, including file establishment / checking, deletion, catalog establish / check and delete, take out files in the directory, file properties, and read data by line by line.
File establishment / check and deletion
<% @ Page ContentType = "Text / HTML; Charset = GB2312"%> <% @ page import = "java.io. *"%>
file establishment, check and deletion </ 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 ()) {// checks if file.txt exists if f.delete (); // deletes the 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}%></p>
<p>Contents of the catalog / check and deletion</p>
<p><% @ Page ContentType = "Text / HTML; Charset = GB2312"%> <% @ page import = "java.io. *"%> <html> <head> <title> directory creation / check and deletion </ Title> </ head> <body> <% string path = request.getRealPath (""); path = path "// Sub"; // will be created directory path file d = new file (path); // Establish a File object representative of the SUB directory and get one reference IF (d.exists ()) {// check if the SUB directory exists (); out.println ("Sub directory, deleted"); } else {d.mkdir (); // Established subdirectory Out.println ("Sub directory does not exist, established");}%> </ body> </ html></p>
<p>How to handle virtual directories in JSP</p>
<p><% @ Page ContentType = "Text / HTML; Charset = GB2312"%> <% @ Page Import = "Java.io. *"%> <HTML> <HEAD> <Title> JSP How to Handle Virtual Directory </ Title > </ head> <body> Disk path to the virtual directory <br> WEB site main directory is <font color = # ff0000> <% = request.getRealPath ("/")%> </ font> < BR> JSP page location directory location <font color = # ff0000> <% = request.getRealPath ("./")" g et / </ / <上 上 "j j j 位置 目 位置 上 位置 上 位置 位置 位置# ff0000> <% = Request.getRealPath ("../")" "" "" "<br> </ body> </ html> file properties</p>
<p><% @ Page ContentType = "Text / HTML; Charset = GB2312"%> <% @ page import = "java.util.date, java.io. *"%> <html> <head> <title> file properties Obtain </ Title> </ head> <body> <% string path = request.getRealPath ("/"); file f = new file (path, "readdata.txt"); if (f.exists ()) { %> <% = f.getName ()%> following properties: <br> <br> file length is:? <% = f.length ()%> <% = f.isFile () "is a file": "Not a file"%> <br> <% = f.Indirectory ()? "Is a directory": "Not a directory"%> <br> <% = f.canread ()? "Read": "Unreadable Take "%> <br> <% = f.canwrite ()?" Can be written ":" Not writable "%> <br> <% = f.ishidden ()?" Is a hidden file: "Not hidden File "%> <br> File's last modification date is: <% = new date (f.lastmodified ())%> <br> <%} else {f.createNewFile (); // Create one in the current directory a file named ReaData.txt%> <% = f.getName ()%> following properties: <br> <br> file length is: <% = f.length ()%> <% = f.isFile ( "Yes File": "Not the file"%> <br> <% = f.Indirectory ()? "" Is a directory ":" Not a directory "%> <br> <% = f.canread ()?" Read ":" Do not read "%> <br> <% = f.canwrite ()?" Write ":" Not Write "%> <br> <% = f.ishidden ()?" Hidden file ":" Not hidden file "%> <br> File last modification date is: <% = new date (f.lastmodified ())%> <br> <%}%> </ body> </ html > Method for removing files in the directory</p>
<p><% @ Page ContentType = "Text / HTML; Charset = GB2312"%> <% @ page import = "java.io. *"%> <html> <head> <title> Remove the file in the directory - Column Files in the directory </ title> </ head> <body> <% string path = request.getRealPath ("/"); file d = new file (path); // Establish the file object file in the current directory. File. List [] = d.listfiles (); // acquire file object array of all files on behalf of the directory Out.println ("<font color = # ff0000>" PATH "directory: </ font> <br > "); for (int i = 0; i <list.Length; i ) {if (list <i> .isfile ()) {Out.Println (List <i> .Getname () " <br> " }}} out.println ("<br> <font color = # ff0000>" "directory: </ font> <br>"); for (int i = 0; i <list. Length; i ) {IF (List <i> .IsDirectory ()) {out.println (List <i> .Getname () "<br>");}}}%> </ body> </ html> judgment Is it blank file?</p>
<p><% @ 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") ;// established FileReader object And instantiate to the object generated by the FR // to use the read () method, which can read the next character from the character stream. if (fr.read () == - 1) // determines if the end of the file is read {OUT.PRINT ("There is no data <br>" in atend.txt file ");} else {Out.println (" Atend Data in .txt file ");} fr.close ();%> </ body> </ html> <b> Read all file data </ b> <ccid_nobr> <Table Width =" 400 "Border = "1" cellspacing = "0" cellpadding = "2" bordercolorlight = "black" bordercolordark = "#ffffff" align = "center"> <tr> <td bgcolor = "e6e6e6" class = "style =" font -Size: 9pt> <pre> <ccid_code> <% @ 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 during the reading process, to determine if 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.</p>
<p>INT c = fr.read (); // reads a character // from the file to determine if the file ends are read, while (c! = - 1) {Out.print ((char) c); // Output Data c = fr.read (); // Continue to read data IF from the file (c == 13) {// Judgment whether it is a broken character out.print ("<br>"); // Output Branch Label fr.skip (1); // Skose a character //c=fr.read();// read a character}} fr.close ();%> </ body> </ html> a line Read data</p>
<p><% @ 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 of the current directory FileReader fr = new fileReader (Path " //file/inc//t.txt "; Establish 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 line from the file // judgment Whether the character string read is not empty while (line! = Null) {outputln (line "<br>"); / / Output data read from the file line = br.readline (); / / Continue to read a line data from the file} br.close (); // Close the bufferedReader object fr.close (); // Turn file%> </ body> </ html></p>
<p>I'll not read the characters in the file</p>
<p><% @ Page ContentType = "Text / HTML; Charset = GB2312"%> <% @ page import = "java.io. *"%> <html> <head> <title> Slightly not reading </ Title> </ head> <body> <% string path = request.getRealPath ("."); fileReader fr = new fileReader (Path "//ReadData.txt"); fr.skip (2); // jump After 2 bytes INT C = fr.read (); // read a byte while (c! = - 1) {OUT.PRINT ((char) c); c = fr.read ();} fr .Close ();%> </ body> </ html></p>
<p>Write data into files</p>
<p><% @ 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 FileWriter object, and instantiate FW // Write string to file fw.write ("Hello!"); Fw.write ("This book is" JSP programming skill "); 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 instance BR string line = br.readline (); // read a line of data out.println (line "<br>"); br.close (); // Close BufferedReader object fr.close ();%> </ body> </ html> Write the data branch of the file</p>
<p><% @ 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 (); // break BW.WRITE ("Please give me more advice!"); bw. NewLine (); // Broken BW.WRITE ("email: stride@sina.com"); bw.flush (); // update data to file fw.close (); // Turn off file stream Out.println "Write file content: <br>"); 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 "<br>"); line = br.readline ();} fr.close ();%> </ body> </ html> How to add data to files</p></div><div class="text-center mt-3 text-grey">
转载请注明原文地址:https://www.9cbs.com/read-39531.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"><i class="icon-tags mr-2"></i><span class="badge border border-secondary mr-2"><h2 class="h6 mb-0 small"><a class="text-secondary" href="tag-2.html">9cbs</a></h2></span></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><b>New Post</b>(<span class="posts">0</span>)
</div><div></div></div></div><ul class="postlist list-unstyled">
</ul></div></div><div class="d-none threadlist"><input type="checkbox" name="modtid" value="39531" 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:
<b>0.043</b>, SQL:
<b>9</b></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);"><i class="icon-angle-up"></i></a><a class="scroll-to-bottom rounded" href="javascript:void(0);" style="display: inline;"><i class="icon-angle-down"></i></a></body></html><script>
var forum_url = 'list-1.html';
var safe_token = '11SeFnYIBiaNlGRC4ESJ0bPWrYwZhS5Zw4nUIeM6SpBa51bHr0n_2BufQ1wdwMsVImE0I3ObXhaOnQxoyHm9PoBg_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>
