RandomAccessFile
RandomAccessFile类同时实现了DataInput和DataOutput接口，提供了对文件随机存取的功能，利用这个类可以在文件的任何位置读取或写人数据；RandomAccessFile类提供了一个文件指针，用来标志要进行读写操作的下一数据的位置；该方法把文件的读入，写出，写到一起了，是操作文件比较好的方法；
import java.io.*;
class RandomAccessFileTest{
public static void main(String[] arg)
throws Exception{
Student s1 =
new Student(
1,
"zhangsan",
95.5);
Student s2 =
new Student(
2,
"lisi",
96.5);
Student s3 =
new Student(
3,
"wangwu",
94);
RandomAccessFile raf =
new RandomAccessFile(
"student.txt",
"rw");
s1.writeStudent(raf);
s2.writeStudent(raf);
s3.writeStudent(raf);
Student s =
new Student();
raf.seek(
0);
for(
long i=
0 ; i < raf.length();i=raf.getFilePointer()){
s.readStudent(raf);
System.out.println(
"num="+s.num+
"name="+s.name+
"score="+s.score);
}
raf.close();
}
}
class Student{
int num;
String name;
double score;
Student(){}
Student(
int num,String name,
double score){
this.num = num;
this.name = name;
this.score = score;
}
public void writeStudent(RandomAccessFile raf)
throws Exception{
raf.writeInt(num);
raf.writeUTF(name);
raf.writeDouble(score);
}
public void readStudent(RandomAccessFile raf)
throws Exception{
num = raf.readInt();
name = raf.readUTF();
score = raf.readDouble();
}
}
