Java中读文件操作

一、一次读取一行，从缓冲区中读取：

import java.awt.datatransfer.StringSelection;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;

public class BufferInputFile {

public static String read(String filename) throws IOException {
FileReader fr=new FileReader(filename);
BufferedReader in=new BufferedReader(fr);
String string;
StringBuilder sb =new StringBuilder();
while((string=in.readLine())!=null){
sb.append(string+"\n");
}
in.close();
return sb.toString();
}

public static void main(String[] args) throws IOException {
System.out.println(read("E:\\1.txt"));
}

}

二、一次读取一个字节，从内存中直接读：

import java.io.IOException;
import java.io.StringReader;

public class MemoryInput {

public static void main(String[] args) throws IOException{
StringReader in=new StringReader(BufferInputFile.read("E:\\1.txt"));
int c;
while((c=in.read())!=-1){
System.out.println((char)c);
}
in.close();
}
}

三、格式化的内存读文件

import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.IOException;

public class FormattedMeoryInput {

public static void main(String[] args) {
try {
DataInputStream in=new DataInputStream(new ByteArrayInputStream(BufferInputFile.read("E:\\1.txt").getBytes()));
while(true){
System.out.println((char)in.readByte());
}
} catch (IOException e) {
// TODO Auto-generated catch block
System.err.println("End of stream");
}
}

}