readfromfile.java

本书属于《开发专家之 Sun ONE》系列丛书

//【代码7-3-4】
//ReadFromFile.java
import java.io.*;
class ReadFromFile
{
	public static void main(String args[])
	{
		System.out.println("Please enter a directory that the file located in:");
		//构造待读取文件的目录
		StringBuffer stfDir = new StringBuffer();
		//从键盘获取输入字符，存储进入字符缓冲区
		While((char ch = (char)System.in.read())!='\n')
		{
			stfDir.appendChar(ch);
		}
		//创建目录文件对象
		File dir = new File(stfDir.toString());

		System.out.println("Please enter a filename that want to read:");
		//获取待读取的文件名
		StringBuffer stfFilename = new StringBuffer();
		//从键盘获取输入字符，存储进入字符缓冲区
		While((char ch = (char)System.in.read())!='\n')
		{
			stfFilename.appendChar(ch);
		}
		//创建文件对象
		File readFrom = new File(dir,stfFilename.toString());

		//判断文件是否为目录、是否具有写权限、读权限
		if(readFrom.isFile() && reafFrom.canWrite() && reafFrom.canRead())
		{
			//创建RandomAccessFile对象
			RandomAccessFile rafFile = 
new RandomAccessFile(readFrom,"rw");
			//如果未读到文件尾，则继续读取
			while(rafFile.getFilePointer()<rafFile.length())
				System.out.println(file.readLine());
			//文件关闭
			rafFile.close();
		}
		else
			System.out.println("File cann't be read!");
	}
}