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java文件读写
/**
*
*/
package com.struts2.other;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* @author Administrator
*
*/
public class WriteInText {
/**
* @param args
*/
public static void main(String[] args) {
try {
saveDataToFile("/conf/data.txt");
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 向指定路径的文件写入data中的内容
*
* @param fileName
* @param string
* @throws IOException
*/
public static void saveDataToFile(String str) throws IOException {
File f = new File("d:/data/data.txt");
if (!f.exists()) {
createFile();
}
BufferedReader br = new BufferedReader(new FileReader(f));
BufferedWriter bw = new BufferedWriter(new FileWriter(f));
// String s="你用方法或者session标记的用户名字和身份";
// bw = new java.io.BufferedWriter(new
// java.io.OutputStreamWriter(writerStream, "UTF-8"));
if (br.readLine() == null) {
//
byte[] midbytes = str.getBytes("UTF8");
//
String srt2 = new String(midbytes, "UTF-8");
bw.write(str);
br.close();
bw.flush();
bw.close();
}
}
/**
*
*/
public static void createFile() {
// path表示你所创建文件的路径
String path = "d:/data";
File f = new File(path);
if (!f.exists()) {
f.mkdirs();
}
// fileName表示你创建的文件名；为txt类型；
String fileName = "data.txt";
File file = new File(f, fileName);
if (!file.exists()) {
try {
file.createNewFile();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
/**
* 以行为单位读取文件，常用于读面向行的格式化文件
*/
public String readFileByLines(String fileName) {
File file = new File(fileName);
BufferedReader reader = null;
String data="";
try {
reader = new BufferedReader(new FileReader(file));
String tempString = null;
int line = 1;
// 一次读入一行，直到读入null为文件结束
while ((tempString = reader.readLine()) != null) {
// 显示行号
System.out.println(tempString);
data=tempString;
line++;
}
reader.close();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException e1) {
}
}
}
return data;
}
/**
* 以字符为单位读取文件，常用于读文本，数字等类型的文件
*
* @param fileName
*/
public static void readFileByChars(String fileName) {
File file = new File(fileName);
Reader reader = null;
try {
// 一次读多个字符
char[] tempchars = new char[30];
int charread = 0;
reader = new InputStreamReader(new FileInputStream(fileName));
// 读入多个字符到字符数组中，charread为一次读取字符数
while ((charread = reader.read(tempchars)) != -1) {
// 同样屏蔽掉\r不显示
if ((charread == tempchars.length)
&& (tempchars[tempchars.length - 1] != ' ')) {
System.out.print(tempchars);
} else {
for (int i = 0; i < charread; i++) {
if (tempchars[i] == '\r') {
continue;
} else {
System.out.print(tempchars[i]);
}
}
}
}
} catch (Exception e1) {
e1.printStackTrace();
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException e1) {
}
}
}
}
}
一.获得控制台用户输入的信息
public void StringBufferDemo() throws IOException......{
四.文件重命名