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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("<dt><b>"+byteread+"</b></dt>");
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.length;i++){
if(file[i].isfile()){
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("/upfile/2007-11/20071120224952890.gif");
byte[] buffer =new byte[1444];
while ((byteread=instream.read(buffer))!=-1)
{
out.println("<dt><b>"+byteread+"</b></dt>");
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+"<br>";
}
out.println(resultstring);
myfilereader.close();
%>
对word文档的处理（上传与下载）
<%@ page contenttype="application/msword" %>
<!-- 以上这行设定本网页为excel格式的网页 -->
<%
response.setheader("content-disposition","inline; filename=test1.doc"); //线上浏览方式
// response.setheader("content-disposition","attachment; filename=test1.doc");//下载方式
//以上这行设定传送到前端浏览器时的档名为test1.doc
//就是靠这一行，让前端浏览器以为接收到一个word档
%>
//然后输出动态内容就可以得到一个word文档了
1,打开：
1）文件头上加：<%@ page contenttype="application/msword"%>
xml文件里：
<mime-mapping>
<extension>doc</extension>
<mime-type>application/msword</mime-type>
</mime-mapping>
2）可以用js,以下代码来自引用：
<%@ page contenttype="text/html;charset=gb2312" import= "java.io.*"%>
<html>
<script>
var wrd=new activexobject("word.application")
wrd.visible=true
alert ("您的"+wrd.application.caption+"安装路径为：\n"+wrd.application.path+"\n版本号是："+ wrd.application.version+"\n注册使用者是："+wrd.application.username)
wrd.documents.add()
//wrd.documents.open("c:\\exam.doc")
wrd.selection.typetext("this is some text.")
wrd.application.activate()
wrd.activedocument.saveas("c:\\exam111.doc")
wrd=null
</script>
</html>
2，下载：
<%@ page contenttype="text/html;charset=gb2312" import= "java.io.*"%>
<%// 得到文件名字和路径
string filename = "jsp.doc";
string filepath = "c:\\";
// 设置响应头和下载保存的文件名
response.setcontenttype("application/octet-stream");
response.setheader("content-disposition","attachment; filename=\"" + filename + "\"");
// 打开指定文件的流信息
java.io.fileinputstream fileinputstream = new java.io.fileinputstream(filepath + filename);
//fileoutputstream out = new fileoutputstream(filepath+"测试\\" + filename);
// 写出流信息
int i;
while ((i=fileinputstream.read()) != -1) {
out.write(i);
}
fileinputstream.close();
out.close();
%>
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