java文件及读写操作

import java.io.File;
import java.io.FilenameFilter;

import java.io.FileInputStream;
import java.io.FileOutputStream;

import java.io.FileReader;
import java.io.FileWriter;

import java.io.BufferedReader;
import java.io.BufferedWriter;

public class FileTest{

public static void main(String[] args){

/*String parentPath = "c:/1";
File parent = new File(parentPath);

String child = "abc.txt";
File file = new File(parent, child);*/

/*String pathname = "c:/1/abc.txt";
File file = new File(pathname);*/

//第三种构造函数
/*String parent = "c:/1/";
String child = "abc.txt";
File file = new File(parent, child);

if(file.exists() == false){
file.createNewFile();
}*/

//File file = new File("c:/1/");
/*
String[] list = file.list();
for(String name : list){
System.out.println(name);
}*/

//File[] list = file.listFiles();
//for(File f : list){
//System.out.println(f.getName());
//System.out.println(f.getPath());
//System.out.println(f.getParent());
//System.out.println(f.getParentFile().getName());
//System.out.println(f.getParentFile().getPath());
//}
/*
File file = new File("c:/1/abc.txt");
file.delete();*/

/* 		File file = new File("c:" + File.separator + "1");
String[] list = file.list(new FilenameFilter(){

public boolean accept(File dir, String name){

if(name.endsWith(".java123")){
return true;
}
return false;
}
});

String[] list1 = {};
System.out.println(list1.length);

for(String item : list){
System.out.println(item);
} */
/*
File file = new File("c:/2");
System.out.println(file.isDirectory());

if(file.isDirectory()){
System.out.println("文件夹已存在");
}else{
file.mkdir();
}
*/
/*
FileInputStream fs = null;

try{

fs = new FileInputStream("c:/1/abc.txt");//abc.txt必须存在，否则Exception in thread "main" java.io.FileNotFoundException
byte[] bytes = new byte[1024];
bytes[0] = '$';

int realCount = 0;
while((realCount = fs.read(bytes, 1, 1023)) != -1){
String str = new String(bytes, 0, realCount);
System.out.println(str);
}

}catch(Exception e){

e.printStackTrace();
}finally{
try{

fs.close();
}catch(Exception e){

e.printStackTrace();
}

}*/
/*
FileOutputStream fo = null;
try{

String str = "关于南海问题，\r\n中国是有权抵制的。";
fo = new FileOutputStream("c:/1/abc.txt");

fo.write(str.getBytes());

}catch(Exception e){

e.printStackTrace();
}finally{
try{
fo.close();
}catch(Exception e){
e.printStackTrace();
}
}*/

/*
FileInputStream fis = null;
FileOutputStream fos = null;

try{
fis = new FileInputStream("c:/1/K.jpg");
fos = new FileOutputStream("c:/1/L.png");

byte[] bytes = new byte[2018];
int realCount = 0;

while((realCount = fis.read(bytes)) != -1){

fos.write(bytes, 0, realCount);
fos.flush();
}

}catch(Exception e){

e.printStackTrace();
}finally{
try{

fos.close();
fis.close();
}catch(Exception e){

e.printStackTrace();
}
}*/

/*
FileReader fr = null;
FileWriter fw = null;

try{

fr = new FileReader("c:/1/readme.txt");
fw = new FileWriter("c:/1/abc.txt");

char[] chars = new char[1024];
int realCount = 0;

while((realCount = fr.read(chars)) != -1){

fw.write(chars, 0, realCount);
fw.flush();
}

}catch(Exception e){

e.printStackTrace();
}finally{

try{

fr.close();
fw.close();
}catch(Exception e){

e.printStackTrace();
}
}*/

//如果字符文件比较小，可以通过使用BufferedReader, BufferedWriter提高读写速度
BufferedReader br = null;
BufferedWriter bw = null;

String str = null;

try{

br = new BufferedReader(new FileReader("c:/1/readme.txt"));
bw = new BufferedWriter(new FileWriter("c:/1/abc.txt"));

while((str = br.readLine()) != null){
bw.write(str + "\r\n");
bw.flush();
}

}catch(Exception e){

e.printStackTrace();
}finally{

try{

br.close();
bw.close();
}catch(Exception e){

e.printStackTrace();
}
}

}
}