Java file operations Daquan 1: the establishment of documents, checks and delete
Abstract: Java file operations Daquan 1: the establishment of documents, checks and delete
</ Td> </ tr> <tr> <td width="443" height="35" valign="top" class="ArticleTeitle"> <% @ page contentType = "text / html; gb2312 charset ="% >
<% @ Page import = "java.io. *"%>
<head>
</ Head>
<body>
<%
String path = request.getRealPath ( "/ article/article5a/example/filetest");
Out.println (path + "
");
File f = new File (path, "File.txt");
Out.println (f + "
");
/ / Out.println (f.exists ());
If (f.exists ()){// check whether there File.txt
F.delete ();// delete documents File.txt
Out.println (path + "\ \ File.txt exist, has been deleted.");
Else ()
F.createNewFile ();// under the current directory creation of a document entitled File.txt
Out.println (path + "\ \ File.txt did not exist, the current output has been established 。");// the directory path
)
%>
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Java file operations Daquan 4: read the paper
Abstract: Java file operations Daquan 4: read the paper
</ Td> </ tr> <tr> <td height="35" valign="top" class="ArticleTeitle"> <% @ page contentType = "text / html; gb2312 charset ="%>
<% @ Page import = "java.io. *"%>
<head>
</ Head>
<body>
<%
String path = request.getRealPath ( "/ article/article5a/example/filetest"); / / Get the current directory path
FileReader fr = new FileReader (path + "ReadData.txt ");// establish FileReader object, and examples into fr
BufferedReader br = new BufferedReader (fr); / / build BufferedReader object, and examples into br
String Line = br.readLine ();// his string read from the document
/ / Reader to judge whether the string is empty
While (Line! = Null) (
Out.println (Line + "
");// Read from the paper output data
Line = br.readLine ();// continue to read from the document in his data
)
Br.close ();// closed BufferedReader target
Fr.close ();// closing documents
%>
</ Body>
<table Width="730" border="0"> <tr> <td width="724"> </ td> </ tr> </ table> </ td> </ tr> <tr>
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Java file operations Daquan 2: directory establishment of checks and delete
Abstract: Java file operations Daquan 2: Contents of the establishment of checks and delete
</ Td> </ tr> <tr> <td height="35" valign="top" class="ArticleTeitle"> <table width="729" border="0"> <tr> <td width = " 723 "> </ td> </ tr> </ table>
<% @ Page contentType = "text / html; gb2312 charset ="%>
<% @ Page import = "java.io. *"%>
<head>
</ Head>
<body>
<%
String path = request.getRealPath ( "/ article/article5a/example/filetest");
Path = path + "\ \ Sub" / / will be established by the directory path
File d = new File (path); / / Sub directory that represents the File object, and a quote to get it
If (Sub d.exists ()){// check whether there directory
D.delete ();
Out.println ( "Sub directory exists, has been deleted");
Else ()
D.mkdir ();// establish Sub directory
Out.println ( "Sub directory does not exist, has been established");
)
%>
</ Body>
</ Td> </ tr> <tr>
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Properties file for use with mysql database connection pool proxool
Abstract: The paper attributes assigned to mysql database connection pool proxool
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1, to write a document attributes: Proxool.properties, Add to your application's WEB WEB-INF \ classes below, as follows:
Jdbc-0.proxool.alias = mysql
Jdbc-0.proxool.driver-class = org.gjt.mm.mysql.Driver
Jdbc-0.proxool.driver-url = jdbc: mysql: / / localhost: 3306/soft? User = root & password =
<table Width="673" border="0"> <tr> <td width="387"> PropertyFile WEB-INF/classes/Proxool.properties
Jdbc-0.proxool.maximum-connection-count = 20
Jdbc-0.proxool.prototype-count = 4
Jdbc-0.proxool.house-keeping-test-sql = select CURRENT_DATE
Jdbc-0.proxool.verbose = true
Jdbc-0.proxool.statistics = 10s, 1m, 1d
Jdbc-0.proxool.statistics-log-level = DEBUG
2, so write web.xml:
<? Xml version = "1.0" encoding = "ISO-8859-1">
Web-app
PUBLIC "- / / Sun Microsystems, Inc / / DTD Web Application 2.3 / / EN"
"Http://java.sun.com/dtd/web-app_2_3.dtd">
</ Td> <td width="276"> </ td> </ tr> </ table>
3, will be the driving procedures mm.mysql-2.0.14-bin.jar and proxool-0.8.3.jar Add WEB-INF \ lib directory.
4, Below is the test jsp documents:
<% @ Page import = "java.sql .*"%>
<% @ Page contentType = "text / html; charset = GB2312"%>
<head>
</ Head>
<body>
Use Proxool Connection Pool
<%
Connection con = null;
Statement stmt = null;
ResultSet rs = null;
Try (
Con = DriverManager.getConnection ( "proxool.mysql");
Stmt = con.createStatement ();
String query = "select * from count_num";
Rs = stmt.executeQuery (query);
While (rs.next ()) (
Out.print (rs.getLong (1 )+"– OK ");
)
Stmt.close ();
Con.close ();
) Catch (SQLException sqle) (
Out.println ( "sqle =" + sqle);
)
Finally (
Try (
If (con! = Null) (
Con.close ();
)
) Catch (SQLException sqle) (
Out.println ( "sqle =" + sqle);
)
)
%>
</ Body>
5, statistics and background information
Please go to: http://127.0.0.1:8080/testpxool/Admin
(Testpxool should read your application WEB) </ td> </ tr> <tr>
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Java file operations Daquan 6: Skip bytes do not read
Abstract: Java file operations Daquan 6: Skip bytes do not read
</ Td> </ tr> <tr> <td height="35" valign="top" class="ArticleTeitle"> <table width="730" border="0"> <tr> <td width = " 724 "> </ td> </ tr> </ table>
<% @ Page contentType = "text / html; gb2312 charset ="%>
<% @ Page import = "java.io. *"%>
<head>
</ Head>
<body>
<%
String path = request.getRealPath ( "/ article/article5a/example/filetest");
FileReader fr = new FileReader (new File (path, "ReadData.txt "));// establish FileReader object, and examples into fr
Out.println ( "the current directory:" + path + "
");
Fr.skip (2); / / Skip two bytes
Out.println ( "read out the contents of the documents:" + "
");
Int c = 1 byte read fr.read ();//
While (c! =- 1) (
Out.print ((char) c);
C = fr.read ();
)
Fr.close ();
%>
</ Body>
Attachment: ReadData.txt:
ASFFFAF
3234242 </ td> </ tr> <tr>
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Java file operations Daquan 5: directory listed in the document
Abstract: Java file operations Daquan 5: directory listed in the document
</ Td> </ tr> <tr> <td height="35" valign="top" class="ArticleTeitle"> <table width="734" border="0"> <tr> <td width = " 728 "> </ td> </ tr> </ table> ↑ Back Abstract: Java file operations Daquan 3: attributes of a document </ Td> </ tr> <tr> <td width="513" height="35" valign="top" class="ArticleTeitle"> <% @ page contentType = "text / html; gb2312 charset ="% > ↑ Back Abstract: Java file operations Daquan 8: how to write additional data to a file </ Td> </ tr> <tr> <td height="35" valign="top" class="ArticleTeitle"> <table width="731" border="0"> <tr> <td width = " 725 "> </ td> </ tr> </ table> ↑ Back Abstract: file upload Principle </ Td> </ tr> <tr> <td height="35" valign="top" class="ArticleTeitle"> <table width="664" border="0"> <tr> <td width = " 380 "> We know that the use of uploading files similar to the following form to file selection: ) After the implementation of the above documents will be produced the following results: (choice of different upload files, similar results) Here (1) (9) (20) is the boundary line. From paragraph (2) line with paragraph (10) to upload files in the full name and other information. (4) and (12) is empty row, followed by air after the upload the contents of the documents. So, you should understand how to write components upload! Extraction empty row after the contents of the documents, it will write FileOutputStream. (See ntsky upload source components). ↑ Back Abstract: another tomcat web application under the build.xml file </ Td> </ tr> <tr> <td width="513" height="35" valign="top" class="ArticleTeitle"> <? Xml version = "1.0"> ↑ Back
<% @ Page contentType = "text / html; gb2312 charset ="%>
<% @ Page import = "java.io. *"%>
<head>
</ Head>
<body>
<%
String path = request.getRealPath ( "/ article/article5a/example/filetest");
File d = new File (path); / / set up the current directory in the File object files
File list [] = d.listFiles ();// made on behalf of all the files in the directory object array File
Out.println ( "" + path + "directory paper:
");
For (int i = 0; i
Out.println (list [i]. GetName () + "
");
)
)
Out.println ( "
"+ Path +" directory under the directory:
");
For (int i = 0; i
Out.println (list [i]. GetName () + "
");
)
)
%>
</ Body>
</ Td> </ tr> <tr>
Java file operations Daquan 3: attributes of a document
<% @ Page import = "java.util.Date, java.io. *"%>
<head>
</ Head>
<body>
<%
String path = request.getRealPath ( "/ article/article5a/example/filetest");
File f = new File (path, "ReadData.txt");
If (f.exists ()) (
%>
<% = F.getName ()%> attributes are as follows:
Document length: <% = f.length ()%>
<% = F.isFile ()? "Document": "No documents"%>
<% = F.isDirectory ()? "Directory": "not a directory"%>
<% = F.canRead ()? "Can be read": "Do not read"%>
<% = F.canWrite ()? "Write": "Do not write"%>
<% = F.isHidden ()? "Hidden files": "no hidden files"%>
The document was last modified date: <% = new Date (f.lastModified ())%>
<%
Else ()
F.createNewFile ();// under the current directory creation of a document entitled ReaData.txt
%>
<% = F.getName ()%> attributes are as follows:
Document length: <% = f.length ()%>
% = F.isFile ()? "Document": "No documents"%>
<% = F.isDirectory ()? "Directory": "not a directory"%>
<% = F.canRead ()? "Can be read": "Do not read"%>
<% = F.canWrite ()? "Write": "Do not write"%>
<% = F.isHidden ()? "Hidden files": "no hidden files"%>
The document was last modified date: <% = new Date (f.lastModified ())%>
<%
)
%>
</ Body>
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Java file operations Daquan 8: how to write additional data to a file
<% @ Page contentType = "text / html; gb2312 charset ="%>
<% @ Page import = "java.io. *"%>
<head>
</ Head>
<body>
<%
String path = request.getRealPath ( "/ article/article5a/example/filetest");
RandomAccessFile rf = new RandomAccessFile (path + "\ \ WriteData.txt", "rw");
/ / Define a category RandomAccessFile targets, and examples of
Rf.seek (rf.length ());// mobile pointer at the end of the document
Rf.writeBytes ( "\ nAppend a line to the file!");
Rf.close ();// close the document flow
Out.println ( "writes the document says:
");
FileReader fr = new FileReader (path + "\ \ WriteData.txt");
BufferedReader br = new BufferedReader (fr); / / read the document object BufferedRead
String Line = br.readLine ();
While (Line! = Null) (
Out.println (Line + "
");
Line = br.readLine ();
)
Fr.close ();// closing documents
%>
</ Body>
</ Td> </ tr> <tr>
File upload Principle
Upload.html
<% @ Page contentType = "text / html; gb2312 charset ="%>
<body Bgcolor="white">
<form Action="doUpload.jsp" method="post" enctype="multipart/form-data">
<table>
<tr Align="center">
<td Width="55%" align="left"> <input type="file" name="text1"> </ td>
</ Tr>
<tr Align="center">
<td Width="55%" align="left"> <input type="file" name="text2"> </ td>
</ Tr>
<tr Align="center">
<td Colspan="2"> <input type="submit" value="ä¸Šä¼ "> </ td>
</ Tr>
</ Table> </ form> </ body> </ Td> <td width="274"> </ td> </ tr> </ table>
Form used enctype = "multipart / form-data" to identify the forms can file upload operation.
Then when we choose two small 1. Txt and 1. Zip and click the submit button, the form processing doUpload.jsp jsp pages can be received from the upload.html-what information?
Take a look: doUpload.jsp it obtained from the request object input flow, and will request the content branch output.
<% @ Page contentType = "text / html; gb2312 charset ="%>
<%
Int size = 0;
Byte readByte [] = new byte [4096];
Int j = 1;
ServletInputStream servletInputStream = request.getInputStream ();
While ((size = servletInputStream.readLine (readByte, 0, readByte.length ))!=- 1) (
String line = new String (readByte, 0, size);
Out.println ("("+ j + ")" + + line "
");
J + +;
%>
(1) ———————————————– 7d45a76025c
(2) Content-Disposition: form-data; name = "text1" filename = "C: \ Documents and Settings \ cwb \ Desktop \ 1. Txt"
(3) Content-Type: text / plain
(4)
(5) public static void main (String [] args) (
(6) FileUtil.makeDir ( "dir1/dir2/dir3/dir4", "c: / java /");
(7))
(8))
(9) ———————————————– 7d45a76025c
(10) Content-Disposition: form-data; name = "text2" filename = "C: \ Documents and Settings \ cwb \ Desktop \ 1. Zip"
(11) Content-Type: application / x-zip-compressed
(12)
(13) PK &? 1
(14) 6ex 1.txtSP ((M LV macrophages (I, Re?)
(15)??% E? Qing?
(16)? Fig?
(17) accounted for \
(18)? Basic guarantee Z ?????? Yd? $? 1? 0Q? Against J?, K? Ye - T - U PK & counselled? 1
(19) 6ex? 1.txtPK 3?
(20) ———————————————– 7d45a76025c –
</ Td> </ tr> <tr>
Another tomcat web application under the build.xml file
Build file for the JCatalog Project.
Derek Y. Shen
6 / 2004
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