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>> 文件操作
>> JSP文件操作：读取，写入和追加
由 webmaster 发布于: 2001-01-20 16:54
来源 jsp中国论坛 http://jspbbs.yeah.net
作者： ASP3000
jsp文件操作之读取篇
Read.jsp
<html>
<head>
<title>Read a file</title>
</head>
<body bgcolor="#000000">
<jsp:useBean id="reader" class="DelimitedDataFile" scope="request">
<jsp:setProperty name="reader" property="path" value="/path/to/afile.txt" />
</jsp:useBean>
<h3>Contents of the file:</h3>
<p>
<% int count = 0; %>
<% while (reader.nextRecord() != -1) { %>
<% count++; %>
<b>Line <% out.print(count); %>:</b> <% out.print(reader.returnRecord()); %><br>
<% } %>
</p>
</body>
</html>
import java.io.*;
import java.util.StringTokenizer;
public class DelimitedDataFile
{
/**
* DelimitedDataFile.java
* Written by Morgan Catlin Email: mfcatlin@csclub2.stthomas.edu
* April 6, 1999
*
* Variables:
* String currentRecord = the record the bean is currently working on
* BufferedReader file = the file the bean is working with
* String path = the path to the file (ie. /home/you/afile.txt)
* StringTokenizer token = the currentRecord tokenized
*
* Methods:
* public void setPath() - creates a BufferedReader that reads the file in path
* public String getPath() - returns path
* public void fileClose() - closes the file that is being read
* public int nextRecord() - reads the next record(line) in the file,
* and returns the number of tokens in the record
* or else returns -1 if there aren't anymore records
* public double returnDouble() - returns the next token as a double
* public int returnInt() - returns the next token as an int
* public String returnString() - returns the next token as a String
* public String returnRecord() - returns the entire record as a String
*/
private String currentRecord = null;
private BufferedReader file;
private String path;
private StringTokenizer token;
public DelimitedDataFile()
{
file = new BufferedReader(new InputStreamReader(System.in),1);
} // constructor 1
public DelimitedDataFile(String filePath) throws FileNotFoundException
{
// gets file
path = filePath;
file = new BufferedReader(new FileReader(path));
} // constructor DelimitedDataFile
public void setPath(String filePath)
{
// sets the file
path = filePath;
try {
file = new BufferedReader(new
FileReader(path));
} catch (FileNotFoundException e) {
System.out.println("file not found");
}
} // method setPath
public String getPath() {
return path;
} // method getPath
public void fileClose() throws IOException
{
// closes file
file.close();
} // method fileClose
public int nextRecord()
{
// this method reads the next record and returns the number of
// tokens or else returns -1
int returnInt = -1;
try
{
currentRecord = file.readLine();
} // end try
catch (IOException e)
{
System.out.println("readLine problem, terminating.");
} // end catch
if (currentRecord == null)
returnInt = -1;
else
{
token = new StringTokenizer(currentRecord);
returnInt = token.countTokens();
} // end else
return returnInt;
} // method nextRecord
public double returnDouble()
{
// this method returns the next token as a double
double doubleReturn = Double.valueOf(token.nextToken()).doubleValue();
return doubleReturn;
} // method returnDouble
public int returnInt()
{
// this method returns the next token as an int
int returnint = Integer.parseInt(token.nextToken());
return returnint;
} // method returnInt
public String returnString()
{
// this method returns the next token as a String
String stringReturn = token.nextToken();
return stringReturn;
} // method returnString
public String returnRecord()
{
// this method returna the entire record as a string
return currentRecord;
} // method returnRecord
} // class DelimitedDataFile
jsp文件操作之写入篇
WriteOver.Jsp
<html>
<head>
<title>Write over a file</title>
</head>
<body bgcolor="#000000">
<jsp:useBean id="writer" class="WriteOver" scope="request">
<jsp:setProperty name="writer" property="path" value="/path/to/afile.txt" />
<jsp:setProperty name="writer" property="something" value="Something already set as a property in WriteOver" />
</jsp:useBean>
<h3>Write to the file</h3>
<p>
<% writer.setSomething("Something to write to the file"); %>
<% out.print(writer.getSomething()); %>
<% out.print(writer.writeSomething()); %>
</p>
</body>
</html>
import java.io.*;
/**
* WriteOver.java
* Written by Morgan Catlin Email: mfcatlin@csclub2.stthomas.edu
* August 19, 1999
*
* Variables:
* String path = path to file to write to (ie. /you/afile.txt)
* String something = something to write to the file
*
* Methods:
* void setPath() = sets path
* String getPath() = returns path
* void setSomething() = sets something
* String getSomething() = returns something
* String writeSomething() = writes something to the path,
* returns a message that indicates success or failure(an Exception)
*/
public class WriteOver {
private String path;
private String something;
public WriteOver() {
path = null;
something = "Default message";
} // constructor WriteOver
/**
* Mutator for the path property
*/
public void setPath(String apath) {
path = apath;
} // mutator setPath
/**
* Accessor for the path property
*/
public String getPath() {
return path;
} // accessor getPathClient
/**
* Mutator for the something property
*/
public void setSomething(String asomething) {
something = asomething;
} // mutator setSomething
/**
* Accessor for the something property
*/
public String getSomething() {
return something;
} // accessor getSomething
/**
* This method writes something to the path
*/
public String writeSomething() {
try {
File f = new File(path);
PrintWriter out = new PrintWriter(new FileWriter(f));
out.print(this.getSomething() + "\n");
out.close();
return "Alles ist Gut.";
} catch (IOException e) {
return e.toString();
}
} // method writeSomething
} // class WriteOver
jsp文件操作之追加篇
如何用jsp将数据追加到一个文件中，下面是实现方法
writeAppend.jsp
<html>
<head>
<title>Append a file</title>
</head>
<body bgcolor="#000000">
<jsp:useBean id="writer" class="WriteAppend" scope="request">
<jsp:setProperty name="writer" property="path" value="/path/to/afile.txt" />
<jsp:setProperty name="writer" property="something" value="Something already set as a property in WriteAppend" />
</jsp:useBean>
<h3>Write to the file</h3>
<p>
<% writer.setSomething("Something to write to the file"); %>
<% out.print(writer.getSomething()); %>
<% out.print(writer.writeSomething()); %>
</p>
</body>
</html>
WriteAppend.java
import java.io.*;
/**
* WriteAppend.java
* Written by Morgan Catlin Email: mfcatlin@csclub2.stthomas.edu
* August 19, 1999
*
* Variables:
* String path = path to file to write to (ie. /you/afile.txt)
* String something = something to write to the file
*
* Methods:
* void setPath() = sets path
* String getPath() = returns path
* void setSomething() = sets something
* String getSomething() = returns something
* String writeSomething() = writes something to the path,
* returns a message that indicates success or failure(an Exception)
*/
public class WriteAppend {
private String path;
private String something;
public WriteAppend() {
path = null;
something = "Default message";
} // constructor WriteAppend
/**
* Mutator for the path property
*/
public void setPath(String apath) {
path = apath;
} // mutator setPath
/**
* Accessor for the path property
*/
public String getPath() {
return path;
} // accessor getPathClient
/**
* Mutator for the something property
*/
public void setSomething(String asomething) {
something = asomething;
} // mutator setSomething
/**
* Accessor for the something property
*/
public String getSomething() {
return something;
} // accessor getSomething
/**
* This method writes something to the path
*/
public String writeSomething() {
try {
FileWriter theFile = new FileWriter(path,true);
PrintWriter out = new PrintWriter(theFile);
out.print(something + "\n");
out.close();
theFile.close();
return "Das war sehr gut!";
} catch (IOException e) {
return e.toString();
}
} // method writeSomething
} // class WriteAppend
（全文完）
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资料来源: JSP001.com
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