Java對各種檔案的操作詳解

java中提供了io類庫，可以輕鬆的用java實現對檔案的各種操作。下面就來說一下如何用java來實現這些操作。
 
新建目錄<%@ page contentType="text/html;charset=gb2312"%>
<%
//String URL = request.getRequestURI();
String filePath="C://測試//";
filePath=filePath.toString();//中文轉換
java.io.File myFilePath=new java.io.File(filePath);
if(!myFilePath.exists())
myFilePath.mkdir();
%>
 
新建檔案
<%@ page contentType="text/html;charset=gb2312"%>
<%@ page import="java.io.*" %>
<%
String filePath="c:/測試/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 ="這是測試資料";
String strContent = content.toString();
myFile.println(strContent);
resultFile.close();
%>
 
刪除檔案<%@ page contentType="text/html;charset=gb2312"%>
<%
String filePath="c://測試//newFile.txt";
filePath=filePath.toString();
java.io.File myDelFile=new java.io.File(filePath);
if(myDelFile.exists())
{  
    myDelFile.delete();
    out.println(filePath+"刪除成功！！！");
}
else
{
    out.println(filePath+"該檔案不存在");
}
%>
檔案拷貝<%@ page contentType="text/html; charset=gb2312" %>
<%@ page import="java.io.*" %>
<%
int bytesum=0;
int byteread=0;
//file:讀到流中
InputStream inStream=new FileInputStream("c://測試//newFile.txt");
FileOutputStream fs=new FileOutputStream( "c://測試//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();
%>
 
整個資料夾拷貝
<%@ 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();
  }
 }
%>
 
檔案下載
<%@ page contentType="text/html; charset=gb2312"%>
<%@ page import="java.io.*" %>
<%
  String fileName = "newFile.txt".toString();
  //讀到流中
  InputStream inStream=new FileInputStream("c://測試//newFile.txt");
  //設定輸出的格式
  response.reset();
  response.setContentType("text/plain");
  response.addHeader("Content-Disposition","attachment; filename=/"" + fileName + "/"");
  //迴圈取出流中的資料
  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();
%>
 
資料庫欄位中的檔案下載
<%@ 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 ("沒有找到圖片");
    }
    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());
       }
    }  
%>
 
把網頁儲存成檔案<%@ 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 {
    //將位元組流轉變成為字元流
    stdIn = new BufferedReader(new InputStreamReader(stdURL.openStream()));
    String theFileName = "c://測試//163.html";
    stdOut = new PrintWriter(new BufferedWriter(new FileWriter(theFileName.toString())));
 }
 catch (IOException e) {
 }
 
 /***把URL指定的頁面以流的形式讀出，寫成指定的檔案***/
 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);
   }
 }
%>
 
直接下載網上的檔案
<%@ 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://pimg.163.com/sms/micheal/logo.gif");
  URLConnection conn = url.openConnection();
  InputStream inStream = conn.getInputStream();
 
  /**
  String theFileName = "c:/測試/logo.gif";
  theFileName = theFileName.toString();
  File myFilePath=new File(theFileName);
  if(!myFilePath.exists())
  myFilePath.createNewFile();
  **/
 
  FileOutputStream fs=new FileOutputStream("c:/測試/logo2.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);
     }
%>
 
按行讀檔案 <%@ 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();
%>
 
對word文件的處理（上傳與下載）<%@ page contentType="application/msword" %>
<!-- 以上這行設定本網頁為excel格式的網頁 -->
<%
   response.setHeader("Content-disposition","inline; filename=test1.doc"); //線上瀏覽方式
  // response.setHeader("Content-disposition","attachment; filename=test1.doc");//下載方式
   //以上這行設定傳送到前端瀏覽器時的檔名為test1.doc
   //就是靠這一行，讓前端瀏覽器以為接收到一個word檔
%>
//然後輸出動態內容就可以得到一個word文件了
 
1,開啟：
1）檔案頭上加：<%@ page  contentType="application/msword"%> 
xml檔案裡：
<mime-mapping>
        <extension>doc</extension>
        <mime-type>application/msword</mime-type>
</mime-mapping>
2）可以用js,以下程式碼來自引用：
<%@ 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+"安裝路徑為：/n"+wrd.Application.Path+"/n版本號是："+wrd.Application.version+"/n註冊使用者是："+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，下載：
<%@ page contentType="text/html;charset=gb2312" import= "java.io.*"%>
<%// 得到檔名字和路徑
  String filename = "jsp.doc";
  String filepath = "C://";
 
  // 設定響應頭和下載儲存的檔名
  response.setContentType("APPLICATION/OCTET-STREAM");
  response.setHeader("Content-Disposition","attachment; filename=/"" + filename + "/"");
 
  // 開啟指定檔案的流資訊
  java.io.FileInputStream fileInputStream = new java.io.FileInputStream(filepath + filename);
  //FileOutputStream out  = new FileOutputStream(filepath+"測試//" + filename);
  // 寫出流資訊
  int i;
  while ((i=fileInputStream.read()) != -1) {
   out.write(i);
  }
  fileInputStream.close();
  out.close();
 %>