java.io的日常用法

1。新建目錄 

<%@ page contentType="text/html;charset=gb2312"%> 
<% 
String filePath="c:/aaa/"; 
filePath=filePath.toString();//中文轉換 
java.io.File myFilePath=new java.io.File(filePath); 
if(!myFilePath.exists()) 
myFilePath.mkdir(); 
%> 

2。新建文件 

<%@ page contentType="text/html;charset=gb2312"%> 
<%@ page import="java.io.*" %> 
<% 
String filePath="c:/哈哈.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 strContent = "中文測試".toString(); 
myFile.println(strContent); 
resultFile.close(); 
%> 

3。刪除文件 

<%@ page contentType="text/html;charset=gb2312"%> 
<% 
String filePath="c:/支出證明單.xls"; 
filePath=filePath.toString(); 
java.io.File myDelFile=new java.io.File(filePath); 
myDelFile.delete(); 
%> 

4。文件拷貝 

<%@ 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:/aaa.doc"); 
FileOutputStream fs=new FileOutputStream( "d:/aaa.doc");byte[] buffer =new byte[1444]; 
int length; 
while ((byteread=inStream.read(buffer))!=-1) 
{ 
out.println("<DT><B>"+byteread+"</B></DT>"); 
bytesum+=byteread; 
System.out.println(bytesum); 
fs.write(buffer,0,byteread); 
} 
inStream.close(); 
%> 

5。整個文件夾拷貝 

<%@ 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(); 
} 
} 
%> 

6。文件下載 

<%@ page contentType="text/html; charset=gb2312" %> 
<%@ page import="java.io.*" %> 
<% 
String fileName = "zsc104.swf".toString(); 
//讀到流中 
InputStream inStream=new FileInputStream("c:/zsc104.swf"); 
//設置輸出的格式 
response.reset(); 
response.setContentType("bin"); 
response.addHeader("Content-Disposition","attachment; filename=\"" + fileName + "\""); 
//循環取出流中的數據 
byte[] b = new byte[100]; 
int len; 
while((len=inStream.read(b)) >0) 
response.getOutputStream().write(b,0,len); 
inStream.close(); 
%> 

7。數據庫字段中的文件下載 

<%@ page contentType="text/html; charset=gb2312" %> 
<%@ page import="java.sql.*"%> 
<%@ page import="java.lang.*" %> 
<%@ page import="java.io.*" %> 
<%@ page import="com.jspsmart.upload.*" %> 
<%@ page import="DBstep.iDBManager2000.*"%> 
<% 
int bytesum=0; 
int byteread=0; 
//打開數據庫 
ResultSet result=null; 
String Sql=null; 
PreparedStatement prestmt=null; 
DBstep.iDBManager2000 DbaObj=new DBstep.iDBManager2000(); 
DbaObj.OpenConnection(); 
//取得數據庫中的數據 
Sql="select * from t_local_zhongzhuan "; 
result=DbaObj.ExecuteQuery(Sql); 
result.next(); 

file://將數據庫中的數據讀到流中 
InputStream inStream=result.getBinaryStream("content"); 
FileOutputStream fs=new FileOutputStream( "c:/dffdsafd.doc"); 

byte[] buffer =new byte[1444]; 
int length; 
while ((byteread=inStream.read(buffer))!=-1) 
{ 
out.println("<DT><B>"+byteread+"</B></DT>"); 
bytesum+=byteread; 
System.out.println(bytesum); 
fs.write(buffer,0,byteread); 
} 
%> 

8。把網頁保存成文件 

<%@ page import="java.text.*"%> 
<%@ page import="java.util.*"%> 
<%@ page import="java.io.*"%> 
<%@ page import="java.net.*"%> 
<% 
URL stdURL = null; 
BufferedReader stdIn = null; 
PrintWriter stdOut = null; 
try { 
stdURL = new URL("http://www.163.com"); 
} 
catch (MalformedURLException e) { 
throw e; 
} 

try { 
stdIn = new BufferedReader(new InputStreamReader(stdURL.openStream())); 
stdOut = new PrintWriter(new BufferedWriter(new FileWriter("c:/163.html"))); 
} 
catch (IOException e) { 
} 

/***把URL指定的頁面以流的形式讀出，寫成指定的文件***/ 
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); 
} 
} 
%> 

9。直接下載網上的文件 

<%@ 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(); 
FileOutputStream fs=new FileOutputStream( "c:/abc.gif"); 

byte[] buffer =new byte[1444]; 
int length; 
while ((byteread=inStream.read(buffer))!=-1) 
{ 
out.println("<DT><B>"+byteread+"</B></DT>"); 
bytesum+=byteread; 
System.out.println(bytesum); 
fs.write(buffer,0,byteread); 
} 
%>