java中文件操作大全

http://www.iteye.com/topic/196148


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import java.io.RandomAccessFile;

public class Test1 {
public static final String fileName = "c:/aaa.txt ";

public static void main(String[] args) {
try {
RandomAccessFile rF = new RandomAccessFile(fileName, "rw");
for (int i = 0; i < rF.length(); i++) {
rF.seek(i);
byte b = rF.readByte();
if (b == '2') {
rF.seek(i);
rF.writeByte(b + 3);
}
}
rF.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}

//在文件后面加入一行
String sitename = Struts2Utils.getRequest().getParameter("sitename");
// 在taglib中加入 网站名称的 变量
String filepath = ConfigManager.getConfigProperty("taglibs.tagpath");

RandomAccessFile raf = new RandomAccessFile(filepath, "rw");
long len = raf.length();
String lastLine = "";
if (len != 0L) {
long pos = len - 1;
while (pos > 0) {
pos--;
raf.seek(pos);
if (raf.readByte() == '\n') {
lastLine = raf.readLine();
break;
}
}
}

String ss = ("<c:set var=\"sitename\" value=\"" + sitename + "\"/>");

if (lastLine.startsWith("<c:set var=\"ctx\""))
raf.write(("\n<c:set var=\"sitename\" value=\"" + sitename + "\"/>")
.getBytes());
if (lastLine.startsWith("<c:set var=\"sitename\"")) {
raf.seek(len - lastLine.length());
raf.write(ss.getBytes());
}
raf.close();


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http://kennethf6986.iteye.com/blog/1064406