import java.io.*;
public class sample { 
    public static void main(String[] args) {
        try{
            int rs;
            File file=new File("C:\\","test.txt");
            FileInputStream fis =new FileInputStream(file);
            InputStreamReader isr=new InputStreamReader(fis);
            while((rs=isr.read())!=-1)
             /*顺序读取文件里的内容并赋值给整型变量b，直到文件结束为止(False)*/
                System.out.print((char)rs);
            isr.close();        
        }catch(IOException e){
            e.printStackTrace();
        }
    }
}

运行结果