Java对各种文件的操作详解

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
<%@ age 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
<%@ age contentType="text/html;charset=gb2312"%>
<%@ age 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 rintWriter(resultFile);
String content ="这是测试数据";
String trContent = content.toString();
myFile.println(strContent);
resultFile.close();
%>

删除文件
<%@ age 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<%@ age contentType="text/html charset=gb2312" %>
<%@ age import="java.io.*" %>
<%
int ytesum=0;
int yteread=0;
//file:读到流中
I utStream i tream=new FileI utStream("c://测试//newFile.txt");
FileOutputStream fs=new FileOutputStream( "c://测试//copyFile.txt");
byte[] uffer =new yte[1444];
int length;
while ((byteread=i tream.read(buffer))!=-1)
{
out.println("<DT> lt gt;"+byteread+"</ gt lt;/DT>");
ytesum+=byteread;
out.println(bytesum);
fs.write(buffer,0,byteread);
}
i tream.close();
%>

整个文件夹拷贝
<%@ age contentType="text/html;charset=gb2312"%>
<%@ age import="java.io.*" %>
<%String url1="C:/aaa";
tring 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();
FileI utStream i ut=new FileI utStream(file[i]);
FileOutputStream output=new FileOutputStream(url2+"/"+(file[i].getName()).toString());
yte[] =new yte[1024*5];
int le
while((len=i ut.read(b))!=-1){
output.write(b,0,len);
}
output.flush();
output.close();
i ut.close();
}
}
%>

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文件下载
<%@ age contentType="text/html charset=gb2312"%>
<%@ age import="java.io.*" %>
<%
tring fileName = "newFile.txt".toString();
//读到流中
I utStream i tream=new FileI utStream("c://测试//newFile.txt");
//设置输出的格式
re o e.reset();
re o e.setContentType("text/plain");
re o e.addHeader("Content-Di osition","attachment filename="" + fileName + """);
//循环取出流中的数据
yte[] = ew yte[100];
int le
ervletOutputStream outStream = re o e.getOutputStream();

while((len=i tream.read(b)) gt;0)
outStream.write(b,0,len);
outStream.flush();
outStream.close();
i tream.close();

%>

数据库字段中的文件下载
<%@ age contentType="text/html;charset=gb2312"%>
<%@ age import="java.util.*,java.sql.*,java.io.*"%>
<%
tring id = request.getParameter("id");
if(id==null)
{ throw ew Exceptio ("没有找到图片");
}
else
{
try
{
com.gzrealmap.lib.jdbc.JDBCUtil qlBean= com.gzrealmap.lib.jdbc.JDBCUtil.getI tance();
qlBean.co ect();
tring ql = "select * from i ernew where id = ""+79+""";
ResultSet r = qlBean.queryforUpdate(sql);
rs.next();
//String fileNamed = rs.getString("imageName");
tring file= rs.getString("acc");
//String fileName = ew tring(fileNamedb.getBytes(),"iso-8859-1");
tring fileName = "a.jpg";
re o e.setHeader("Content-Di osition", "inline filename="" + fileName + """)

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tring filter = fileName.su tring(fileName.lastIndexOf("."));

if(filter.equals(".txt"))
{
re o e.setContentType("text/plain");
}
else if(filter.equals(".doc")||filter.equals(".dot"))
{
re o e.setContentType("a lication/msword"); JAVA天堂
}
else
{
re o e.setContentType("image/jpeg;charset=GB2312");
}
ervletOutputStream o = re o e.getOutputStream();
//o.write(file);
out.println(file);
//o.flush();

//o.close();
qlBean.disco ect();
}
catch(Exceptio ex)
{
out.println(ex.getMe age());
}
}
%>

把网页保存成文件
<%@ age contentType="text/html;charset=gb2312"%>
<%@ age import="java.text.*,java.util.*,java.net.*,java.io.*"%>
<%
URL tdURL = ull;
ufferedReader tdI = ull;
rintWriter tdOut = ull;
try {
tdURL = ew URL("http://www.163.com");
}
catch (MalformedURLExceptio e) {
throw e;
}

try {
//将字节流转变成为字符流
tdI = ew ufferedReader(new I utStreamReader(stdURL.ope tream()));
tring theFileName = "c://测试//163.html";
tdOut = ew rintWriter(new ufferedWriter(new FileWriter(theFileName.toString())));
}
catch (IOExceptio e) {
}

/***把URL指定的页面以流的形式读出，写成指定的文件***/
try {
tring trHtml = "";
while((strHtml = tdIn.readLine())!=null) {
tdOut.println(strHtml);
}
}
catch (IOExceptio e) {
throw e;
}
finally {

try {
if(stdI != ull)
tdIn.close();
if(stdOut != ull)
tdOut.close();
}
catch (Exceptio e) {
ystem.out.println(e);
}
}
%>

直接下载网上的文件
<%@ age contentType="text/html;charset=gb2312"%>
<%@ age import="java.io.*"%>
<%@ age import="java.net.*"%>
<%
int ytesum=0;
int yteread=0;
URL url = ew URL("http://java./UploadFiles_8734/200611/20061116101405957.gif");
yte[] uffer =new yte[1444];
while ((byteread=i tream.read(buffer))!=-1)
{
out.println("<DT> lt gt;"+byteread+"</ gt lt;/DT>");
ytesum+=byteread;
//System.out.println(bytesum);
fs.write(buffer,0,byteread);
}
%>

按行读文件
<%@ age contentType="text/html charset=gb2312" %>
<%@ age import="java.io.*" %>
<%
FileReader myFileReader=new FileReader("c:/哈哈.txt");
BufferedReader myBufferedReader=new ufferedReader(myFileReader);
String myString=null;
String resultString=new tring();
while((myString=myBufferedReader.readLine())!=null) {
resultString=resultString+myString+"< r>";
}
out.println(resultString);
myFileReader.close();
%>

对word文档的处理（上传与下载）
<%@ age contentType="a lication/msword" %>

<%
re o e.setHeader("Content-di osition","inline filename=test1.doc") //线上浏览方式
// re o e.setHeader("Content-di osition","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：<%@ age contentType="a lication/msword"%>
xml文件里：
<mime-ma ing>
lt;exte io gt;doc</exte io gt;
lt;mime-type>a lication/msword</mime-type>
</mime-ma ing>
2）可以用js,以下代码来自引用：
<%@ age contentType="text/html;charset=gb2312" import= "java.io.*"%>
<HTML>
< cript>
var wrd=new ActiveXObject("Word.A lication")
wrd.visible=true
alert ("您的"+wrd.A lication.Caption+"安装路径为： "+wrd.A lication.Path+" 版本号是："+ wrd.A lication.version+" 注册使用者是："+wrd.A lication.UserName)
wrd.Documents.Add()
//wrd.Documents.Open("c:\exam.doc")
wrd.Selection.TypeText("Thi i ome text.")
wrd.A lication.Activate()
wrd.ActiveDocument.SaveAs("c:\exam111.doc")
wrd=null
</script>
</HTML>

2，下载：
<%@ age contentType="text/html;charset=gb2312" import= "java.io.*"%>
<%// 得到文件名字和路径
tring filename = "j .doc";
tring filepath = "C:\";

// 设置响应头和下载保存的文件名
re o e.setContentType("A LICATION/OCTET-STREAM");
re o e.setHeader("Content-Di osition","attachment filename="" + filename + """);

// 打开指定文件的流信息
java.io.FileI utStream fileI utStream = ew java.io.FileI utStream(filepath + filename);
//FileOutputStream out = ew FileOutputStream(filepath+"测试\" + filename);
// 写出流信息
int i;
while ((i=fileI utStream.read()) != -1) { JAVA天堂
out.write(i);
}
fileI utStream.close();
out.close();
%>
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