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J2SE：Java对各种文件的操作详解
摘要: J2SE：Java对各种文件的操作详解
Java对各种文件的操作详解
</td> </tr> <tr> <td> </td> </tr> <tr> <td>java中提供了io类库，可以轻松的用java实现对文件的各种操作。下面就来说一下如何用java来实现这些操作。新建目录<%@ page contentType="text/html;charset=gb2312"%>
<%
//String URL = request.getRequestURI();
String filePath="C:\\测试\\";
filePath=filePath.toString();//中文转换
java.io.File myFilePath=new java.io.File(filePath);
if(!myFilePath.exists())
myFilePath.mkdir();
%>
新建文件
<%@ page contentType="text/html;charset=gb2312"%>
<%@ page import="java.io.*" %>
<%
String filePath="c:/测试/newFile.txt";
filePath=filePath.toString();
File myFilePath=new File(filePath);
if(!myFilePath.exists())
myFilePath.createNewFile();
FileWriter resultFile=new FileWriter(myFilePath);
PrintWriter myFile=new PrintWriter(resultFile);
String content ="这是测试数据";
String strContent = content.toString();
myFile.println(strContent);
resultFile.close();
%>
删除文件<%@ page contentType="text/html;charset=gb2312"%>
<%
String filePath="c://测试//newFile.txt";
filePath=filePath.toString();
java.io.File myDelFile=new java.io.File(filePath);
if(myDelFile.exists())
{
myDelFile.delete();
out.println(filePath+"删除成功！！！");
}
else
{
out.println(filePath+"该文件不存在");
}
%>
文件拷贝<%@ page contentType="text/html; charset=gb2312" %>
<%@ page import="java.io.*" %>
<%
int bytesum=0;
int byteread=0;
//file:读到流中
InputStream inStream=new FileInputStream("c://测试//newFile.txt");
FileOutputStream fs=new FileOutputStream( "c://测试//copyFile.txt");
byte[] buffer =new byte[1444];
int length;
while ((byteread=inStream.read(buffer))!=-1)
{
out.println("
bytesum+=byteread;
out.println(bytesum);
fs.write(buffer,0,byteread);
}
inStream.close();
%>
整个文件夹拷贝
<%@ page contentType="text/html;charset=gb2312"%>
<%@ page import="java.io.*" %>
<%String url1="C:/aaa";
String url2="d:/java/";
(new File(url2)).mkdirs();
File[] file=(new File(url1)).listFiles();
for(int i=0;i
file[i].toString();
FileInputStream input=new FileInputStream(file[i]);
FileOutputStream output=new FileOutputStream(url2+"/"+(file[i].getName()).toString());
byte[] b=new byte[1024*5];
int len;
while((len=input.read(b))!=-1){
output.write(b,0,len);
}
output.flush();
output.close();
input.close();
}
}
%>
文件下载
<%@ page contentType="text/html; charset=gb2312"%>
<%@ page import="java.io.*" %>
<%
String fileName = "newFile.txt".toString();
//读到流中
InputStream inStream=new FileInputStream("c://测试//newFile.txt");
//设置输出的格式
response.reset();
response.setContentType("text/plain");
response.addHeader("Content-Disposition","attachment; filename=\"" + fileName + "\"");
//循环取出流中的数据
byte[] b = new byte[100];
int len;
ServletOutputStream outStream = response.getOutputStream();
while((len=inStream.read(b)) >0)
outStream.write(b,0,len);
outStream.flush();
outStream.close();
inStream.close();
%>
数据库字段中的文件下载
<%@ page contentType="text/html;charset=gb2312"%>
<%@ page import="java.util.*,java.sql.*,java.io.*"%>
<%
String id = request.getParameter("id");
if(id==null)
{ throw new Exception ("没有找到图片");
}
else
{
try
{
com.gzrealmap.lib.jdbc.JDBCUtil SqlBean= com.gzrealmap.lib.jdbc.JDBCUtil.getInstance();
SqlBean.connect();
String sql = "select * from innernews where id = '"+79+"'";
ResultSet rs = SqlBean.queryforUpdate(sql);
rs.next();
//String fileNamedb = rs.getString("imageName");
String file= rs.getString("acc");
//String fileName = new String(fileNamedb.getBytes(),"iso-8859-1");
String fileName = "a.jpg";
response.setHeader("Content-Disposition", "inline; filename=\"" + fileName + "\"");
String filter = fileName.substring(fileName.lastIndexOf("."));
if(filter.equals(".txt"))
{
response.setContentType("text/plain");
}
else if(filter.equals(".doc")||filter.equals(".dot"))
{
response.setContentType("application/msword");
}
else
{
response.setContentType("image/jpeg;charset=GB2312");
}
ServletOutputStream o = response.getOutputStream();
//o.write(file);
out.println(file);
//o.flush();
//o.close();
SqlBean.disconnect();
}
catch(Exception ex)
{
out.println(ex.getMessage());
}
}
%>
把网页保存成文件<%@ page contentType="text/html;charset=gb2312"%>
<%@ page import="java.text.*,java.util.*,java.net.*,java.io.*"%>
<%
URL stdURL = null;
BufferedReader stdIn = null;
PrintWriter stdOut = null;
try {
stdURL = new URL("http://www.163.com/");
}
catch (MalformedURLException e) {
throw e;
}
try {
//将字节流转变成为字符流
stdIn = new BufferedReader(new InputStreamReader(stdURL.openStream()));
String theFileName = "c://测试//163.html";
stdOut = new PrintWriter(new BufferedWriter(new FileWriter(theFileName.toString())));
}
catch (IOException e) {
}
/***把URL指定的页面以流的形式读出，写成指定的文件***/
try {
String strHtml = "";
while((strHtml = stdIn.readLine())!=null) {
stdOut.println(strHtml);
}
}
catch (IOException e) {
throw e;
}
finally {
try {
if(stdIn != null)
stdIn.close();
if(stdOut != null)
stdOut.close();
}
catch (Exception e) {
System.out.println(e);
}
}
%>
直接下载网上的文件
<%@ page contentType="text/html;charset=gb2312"%>
<%@ page import="java.io.*"%>
<%@ page import="java.net.*"%>
<%
int bytesum=0;
int byteread=0;
URL url = new URL("http://image.21tx.com/image/20060513/10451.gif");
URLConnection conn = url.openConnection();
InputStream inStream = conn.getInputStream();
/**
String theFileName = "c:/测试/logo.gif";
theFileName = theFileName.toString();
File myFilePath=new File(theFileName);
if(!myFilePath.exists())
myFilePath.createNewFile();
**/
FileOutputStream fs=new FileOutputStream("c:/测试/logo2.gif");
byte[] buffer =new byte[1444];
while ((byteread=inStream.read(buffer))!=-1)
{
out.println("
bytesum+=byteread;
//System.out.println(bytesum);
fs.write(buffer,0,byteread);
}
%>
按行读文件 <%@ page contentType="text/html; charset=gb2312" %>
<%@ page import="java.io.*" %>
<%
FileReader myFileReader=new FileReader("c:/哈哈.txt");
BufferedReader myBufferedReader=new BufferedReader(myFileReader);
String myString=null;
String resultString=new String();
while((myString=myBufferedReader.readLine())!=null) {
resultString=resultString+myString+"
";
}
out.println(resultString);
myFileReader.close();
%>
对word文档的处理（上传与下载）<%@ page contentType="application/msword" %>