Java中對文件的操作

Java中對文件的操作

java中提供了io類庫，可以輕鬆的用java實現對文件的各種操作。

1。新建目錄
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
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
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
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
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
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","p_w_upload; 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

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

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

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);

}

10。按行讀文件

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();