java中的文件操作

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。

生成文件时，可用下边的方法来设置流的编码

PrintWriter myFile =new PrintWriter(new OutputStreamWriter(new FileOutputStream(文件名),"gb2312"));
 
新建目录

1. <%@ page contentType="text/html;charset=gb2312"%>
2. <%
3. //String URL = request.getRequestURI();
4. String filePath="C:\\测试\\";
5. filePath=filePath.toString();//中文转换
6. java.io.File myFilePath=new java.io.File(filePath);
7. if(!myFilePath.exists())
8. myFilePath.mkdir();
9. %>

新建文件

1. <%@ page contentType="text/html;charset=gb2312"%>
2. <%@ page import="java.io.*" %>
3. <%
4. String filePath="c:/测试/newFile.txt";
5. filePath=filePath.toString();
6. File myFilePath=new File(filePath);
7. if(!myFilePath.exists())
8. myFilePath.createNewFile();
9. FileWriter resultFile=new FileWriter(myFilePath);
10. PrintWriter myFile=new PrintWriter(resultFile);
11. String content ="这是测试数据";
12. String strContent = content.toString();
13. myFile.println(strContent);
14. resultFile.close();
15. %>

 
删除文件

1. <%@ page contentType="text/html;charset=gb2312"%>
2. <%
3. String filePath="c://测试//newFile.txt";
4. filePath=filePath.toString();
5. java.io.File myDelFile=new java.io.File(filePath);
6. if(myDelFile.exists())
7. {  
8.     myDelFile.delete();
9.     out.println(filePath+"删除成功！！！");
10. }
11. else
12. {
13.     out.println(filePath+"该文件不存在");
14. }
15. %>

文件拷贝

1. <%@ page contentType="text/html; charset=gb2312" %>
2. <%@ page import="java.io.*" %>
3. <%
4. int bytesum=0;
5. int byteread=0;
6. //file:读到流中
7. InputStream inStream=new FileInputStream("c://测试//newFile.txt");
8. FileOutputStream fs=new FileOutputStream( "c://测试//copyFile.txt");
9. byte[]  buffer =new  byte[1444];
10. int length;
11. while ((byteread=inStream.read(buffer))!=-1)
12.  {
13.    out.println("<DT><B>"+byteread+"</B></DT>");
14.    bytesum+=byteread;
15.    out.println(bytesum);
16.    fs.write(buffer,0,byteread);
17.  }
18. inStream.close();
19. %>

整个文件夹拷贝

1. <%@ page contentType="text/html;charset=gb2312"%>
2. <%@ page import="java.io.*" %>
3. <%String url1="C:/aaa";
4.   String url2="d:/java/";
5.   (new File(url2)).mkdirs();
6.  File[] file=(new File(url1)).listFiles();
7.  for(int i=0;i<file.length;i++){
8.   if(file[i].isFile()){
9.    file[i].toString();
10.    FileInputStream input=new FileInputStream(file[i]);
11.    FileOutputStream output=new FileOutputStream(url2+"/"+(file[i].getName()).toString());
12.    byte[] b=new byte[1024*5];
13.     int len;
14.     while((len=input.read(b))!=-1){
15.     output.write(b,0,len);
16.     }
17.     output.flush();
18.     output.close();
19.     input.close();
20.   }
21.  }
22. %>

文件下载

1. <%@ page contentType="text/html; charset=gb2312"%>
2. <%@ page import="java.io.*" %>
3. <%
4.   String fileName = "newFile.txt".toString();
5.   //读到流中
6.   InputStream inStream=new FileInputStream("c://测试//newFile.txt");
7.   //设置输出的格式
8.   response.reset();
9.   response.setContentType("text/plain");
10.   response.addHeader("Content-Disposition","attachment; filename=\"" + fileName + "\"");
11.   //循环取出流中的数据
12.   byte[] b = new byte[100];
13.   int len;
14.   ServletOutputStream outStream = response.getOutputStream();
15.  
16.   while((len=inStream.read(b)) >0)
17.   outStream.write(b,0,len);
18.   outStream.flush();
19.   outStream.close();
20.   inStream.close();
21. %>

数据库字段中的文件下载

1. <%@ page contentType="text/html;charset=gb2312"%>
2. <%@ page import="java.util.*,java.sql.*,java.io.*"%>
3. <%
4.     String id = request.getParameter("id");
5.     if(id==null)
6.     {   throw new Exception ("没有找到图片");
7.     }
8.     else
9.     {
10.        try
11.        {
12. com.gzrealmap.lib.jdbc.JDBCUtil  SqlBean= com.gzrealmap.lib.jdbc.JDBCUtil.getInstance();
13.                SqlBean.connect();
14.                String sql = "select * from innernews where id = '"+79+"'";
15.                ResultSet rs = SqlBean.queryforUpdate(sql);
16.                rs.next();
17.                //String fileNamedb = rs.getString("imageName");
18.                String file= rs.getString("acc");
19.                //String fileName = new String(fileNamedb.getBytes(),"iso-8859-1");
20.                String fileName = "a.jpg";
21.                 response.setHeader("Content-Disposition",  "inline; filename=\"" + fileName + "\"");    
22.                String filter = fileName.substring(fileName.lastIndexOf("."));
23.               
24.                if(filter.equals(".txt"))
25.                {
26.                    response.setContentType("text/plain");
27.                }
28.                else if(filter.equals(".doc")||filter.equals(".dot"))
29.                {
30.                    response.setContentType("application/msword");
31.                }
32.                else
33.                {
34.                  response.setContentType("image/jpeg;charset=GB2312");
35.                }
36.                ServletOutputStream o = response.getOutputStream();
37.                //o.write(file);
38.                out.println(file);
39.                //o.flush();
40.                //o.close();
41.                SqlBean.disconnect();
42.        }
43.         catch(Exception ex)
44.        {
45.            out.println(ex.getMessage());
46.        }
47.     }  
48. %>
49.  

把网页保存成文件

1. <%@ page contentType="text/html;charset=gb2312"%>
2. <%@ page import="java.text.*,java.util.*,java.net.*,java.io.*"%>
3. <%
4.  URL stdURL = null;
5.  BufferedReader stdIn = null;
6.  PrintWriter stdOut = null;
7.  try {
8.   stdURL = new URL("<a href="http://www.163.com/">http://www.163.com</a>");
9.  }
10.  catch (MalformedURLException e) {
11.    throw e;
12.  }
13.  
14. try {
15.     //将字节流转变成为字符流
16.     stdIn = new BufferedReader(new InputStreamReader(stdURL.openStream()));
17.     String theFileName = "c://测试//163.html";
18.     stdOut = new PrintWriter(new BufferedWriter(new FileWriter(theFileName.toString())));
19.  }
20.  catch (IOException e) {
21.  }
22.  
23.  /***把URL指定的页面以流的形式读出，写成指定的文件***/
24.  try {
25.     String strHtml = "";
26.    while((strHtml = stdIn.readLine())!=null) {
27.    stdOut.println(strHtml);
28.    }
29.  }
30.  catch (IOException e) {
31.    throw e;
32.  }
33.  finally {  
34.    try {
35.      if(stdIn != null)
36.        stdIn.close();
37.      if(stdOut != null)
38.        stdOut.close();
39.        }
40.    catch (Exception e) {
41.      System.out.println(e);
42.    }
43.  }
44. %>

直接下载网上的文件

1. <%@ page contentType="text/html;charset=gb2312"%>
2. <%@ page import="java.io.*"%>
3. <%@ page import="java.net.*"%>
4. <%
5.   int bytesum=0;
6.   int byteread=0;
7.   URL url = new URL("<a href="http://pimg.163.com/sms/micheal/logo.gif">http://pimg.163.com/sms/micheal/logo.gif</a>");
8.   URLConnection conn = url.openConnection();
9.   InputStream inStream = conn.getInputStream();
10.  
11.   /**
12.   String theFileName = "c:/测试/logo.gif";
13.   theFileName = theFileName.toString();
14.   File myFilePath=new File(theFileName);
15.   if(!myFilePath.exists())
16.   myFilePath.createNewFile();
17.   **/
18.  
19.   FileOutputStream fs=new FileOutputStream("c:/测试/logo2.gif");
20.   byte[]  buffer =new  byte[1444];
21.     while ((byteread=inStream.read(buffer))!=-1)
22.     {
23.        out.println("<DT><B>"+byteread+"</B></DT>");
24.        bytesum+=byteread;
25.        //System.out.println(bytesum);
26.        fs.write(buffer,0,byteread);
27.      }
28. %>

按行读文件

1. <%@ page contentType="text/html; charset=gb2312" %>
2. <%@ page import="java.io.*" %>
3. <%
4. FileReader myFileReader=new FileReader("c:/哈哈.txt");
5. BufferedReader myBufferedReader=new BufferedReader(myFileReader);
6. String myString=null;
7. String resultString=new String();
8. while((myString=myBufferedReader.readLine())!=null) {
9. resultString=resultString+myString+"
10. ";
11. }
12. out.println(resultString);
13. myFileReader.close();
14. %>

对word文档的处理（上传与下载）

1. <%@ page contentType="application/msword" %>
2. <!-- 以上这行设定本网页为excel格式的网页 -->
3. <%
4.    response.setHeader("Content-disposition","inline; filename=test1.doc"); //线上浏览方式
5.   // response.setHeader("Content-disposition","attachment; filename=test1.doc");//下载方式
6.    //以上这行设定传送到前端浏览器时的档名为test1.doc
7.    //就是靠这一行，让前端浏览器以为接收到一个word档
8. %>
9. //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：

1. <%@ page  contentType="application/msword"%> 
2.  
3. xml文件里：
4. <mime-mapping>
5.         <extension>doc</extension>
6.         <mime-type>application/msword</mime-type>
7. </mime-mapping>

2）可以用js,以下代码来自引用：

<%@ page contentType="text/html;charset=gb2312" import= "java.io.*"%>




 
2，下载：

1. <%@ page contentType="text/html;charset=gb2312" import= "java.io.*"%>
2. <%// 得到文件名字和路径
3.   String filename = "jsp.doc";
4.   String filepath = "C:\\";
5.  
6.   // 设置响应头和下载保存的文件名
7.   response.setContentType("APPLICATION/OCTET-STREAM");
8.   response.setHeader("Content-Disposition","attachment; filename=\"" + filename + "\"");
9.  
10.   // 打开指定文件的流信息
11.   java.io.FileInputStream fileInputStream = new java.io.FileInputStream(filepath + filename);
12.   //FileOutputStream out  = new FileOutputStream(filepath+"测试\\" + filename);
13.   // 写出流信息
14.   int i;
15.   while ((i=fileInputStream.read()) != -1) {
16.    out.write(i);
17.   }
18.   fileInputStream.close();
19.   out.close()
20.  %>

 

分享到：

尽量不要从try区段中返回(return) | IE中打开UTF-8编码title为中文的网页会显 ...

• 2007-05-12 12:13
• 浏览 1203
• 评论(0)
• 查看更多