java中读写文本文件

转自http://zdq0426.blog.163.com/blog/static/22169094200881181026655/

写文本数据

方法 一：

import java.io.*;

public class A {

public static void main(String args[]) {
FileOutputStream out;
PrintStream ps;
try {
out = new FileOutputStream("a.txt");
ps = new PrintStream(out);
ps.println("qun qun.");
ps.println("fei fei");
ps.close();
} catch (Exception e) {
System.out.println(e.toString());
}
}
}

方法 二：

import java.io.*;

public class B {

public static void main(String args[]) {
FileWriter fw;
PrintWriter pw;
try {
fw = new FileWriter("b.txt");
pw = new PrintWriter(fw);
pw.print("qunqu n ");
pw.println("feiefi ss");
pw.print("qunqu n ");
pw.close();
fw.close();
} catch (IOException e) {
System.out.println(e.toString());
}
}
}

方法三：

import java.io.*;

public class C {

public static void main(String args[]) {
String str_written = "This is a simple example";
try {
FileWriter fwriter = new FileWriter("c.txt");
BufferedWriter bfwriter = new BufferedWriter(fwriter);
bfwriter.write(str_written, 0, str_written.length());
bfwriter.flush();
bfwriter.close();
} catch (IOException e) {
System.out.println(e.toString());
}
}
}
附注：方法一和方法二，方法三都是在操作文本文件不存在的时候将创建，否则，当覆盖之！

令；方法三

BufferedWriter将文本写入字符输出流，缓冲各个字符，从而提供单个字符、数组和字符串的高效写入。

附：追加写入：

import java.io.*;

public class C {

public static void main(String args[]) {
String str_written = "This is a simple example";
try {
FileWriter fwriter = new FileWriter("c.txt", true);
BufferedWriter bfwriter = new BufferedWriter(fwriter);
bfwriter.newLine();
bfwriter.write(str_written, 0, str_written.length());
bfwriter.flush();
bfwriter.close();
} catch (IOException e) {
System.out.println(e.toString());
}
}
}

读文本数据

方法一：

import java.io.*;

public class A {

public static void main(String args[]) {
try {
FileInputStream fstream = new FileInputStream("a.txt");
DataInputStream in = new DataInputStream(fstream);
while (in.available() != 0) {
String a = in.readLine();
System.out.println(a);
System.out.println(a.length());
}
in.close();
} catch (Exception e) {
System.out.println(e.toString());
}
}
}

方法二：

import java.io.*;

public class B {

public static void main(String args[]) {
try {
FileReader fr = new FileReader("a.txt");
BufferedReader br = new BufferedReader(fr);
String str;
int count = 0;
while ((str = br.readLine()) != null) {
count++;
System.out.println(count + " : " + str);
}
br.close();
fr.close();
} catch (Exception e) {
System.out.println(e.toString());
}
}
}

附：方法二的能够高效的实现文本数据的读出