java操作txt文件

java操作文本文件个人认为最繁杂的是修改操作！需要重写整个文本！好了不说了先贴代码！

public class txtfile {

public void txtfileQ() throws IOException{ //txt文件的查询

FileReader fr =new FileReader("c://a.txt");

BufferedReader br = new BufferedReader(fr);

String Line=br.readLine();//从文件读取一行字符串

// 依据读取到的整行字符串是否不为空，来判断是够到达文件结尾

for (int i=0;Line !=null;i++){

if(Line.indexOf("测试")>-1){ // 使用indexof来实现模糊查询

System.out.println(Line+"1111111");

}

Line= br.readLine();

}

br.close();//关闭BufferedReader对象

fr.close();//关闭文件

}

//写txt文件 txtfile.getProperty("txtlist")为获得配置文件内的文件路径

public void txtfileW() throws IOException{

txtfile txtfile = new txtfile();

FileWriter fw=new FileWriter(txtfile.getProperty("txtlist"),true);//建立FileWriter对象，并实例化fw

// 将字符串写入文件

for (int i=0;i<20;i++){

fw.write("这是本文档的第"+i+"行"+"\r\n");

}

fw.write("测试耗费时间！");

fw.close();

}

//删除文件一行操作，可以类比为修改替换操作 txtfile.getProperty("newline")为配置文件内定义的回车换行符

public void txtfileD() throws IOException{

String line = "";

txtfile txtfile = new txtfile();

try {

File file = new File(txtfile.getProperty("txtlist"));

FileInputStream fis = new FileInputStream(file);

InputStreamReader isr = new InputStreamReader(fis);

BufferedReader br = new BufferedReader(isr);

StringBuffer buf = new StringBuffer();

// 保存该行前面的内容

for (int j = 1; (line = br.readLine()) != null

&& !line.equals("这是本文档的第6行"); j++) {

buf = buf.append(line);

buf = buf.append(txtfile.getProperty("newline"));

}

// 将内容替换为空

buf = buf.append("");

// 保存该行后面的内容

while ((line = br.readLine()) != null) {

buf = buf.append(line);

buf = buf.append(txtfile.getProperty("newline"));

}

br.close();

FileOutputStream fos = new FileOutputStream(file);

PrintWriter pw = new PrintWriter(fos);

pw.write(buf.toString().toCharArray());

pw.flush();

pw.close();

} catch (IOException e) {

e.printStackTrace();

}

}

//txt文件增加一行，追加到最后一行

public void txtfileA() throws IOException{

txtfile txtfile = new txtfile();

RandomAccessFile rf=new RandomAccessFile(txtfile.getProperty("txtlist"),"rw");

// 定义一个类RandomAccessFile的对象，并实例化。txtfile.getProperty("txtlist")为获得配置文件内的文件路径

rf.seek(rf.length());

rf.write("追加到文件最后一行！".getBytes());

rf.close();//关闭文件流

}

//读取配置文件获得文件路径

public String getProperty(String propertyname){

String propertyvalue = null;

Properties pro = new Properties ();

try {

FileInputStream fin = new FileInputStream("D://workspace//YNSMIMPL//WebRoot//WEB-INF//txt.properties");

pro.load(fin);

propertyvalue = pro.getProperty(propertyname);

} catch (FileNotFoundException e) {

// TODO Auto-generated catch block

e.printStackTrace();

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return propertyvalue;

}

/*

* 遍历文件夹内文件并判断文件大小！

*/

public String SelectPath(String path){

File dir = new File(path);

File[] tempf=dir.listFiles();

String filenameN="";

if(dir.isDirectory()){

if(tempf.length>1){

for (int n=1;n<tempf.length;n++){

filenameN = path+".getname/]\\"+tempf[0].getName();

File a = new File(filenameN);

File b = new File(path+"\\"+tempf
.getName());

if(a.length()>b.length()){

filenameN = path+"\\"+tempf
.getName();

}else{

filenameN = path+".getname/]\\"+tempf[0].getName();

}

}

}else{

filenameN = path+".getname/]\\"+tempf[0].getName();

}

}

System.out.println(filenameN);

return filenameN;

}