Java IO Hello World

/**
 * 
 */
package test;
import java.io.*;

/**
 * @author Administrator
 *
 */
public class IoStudy {
    public static String read(String fileName) throws IOException{
        BufferedReader br=new BufferedReader(new FileReader(fileName));
        String s;
        StringBuilder sb=new StringBuilder();
        while((s=br.readLine())!=null)
            sb.append(s+"\n");
        br.close();
        return sb.toString();
    }

    /**
     * @param args
     */
    public static void main(String[] args) throws IOException {
        // TODO 自动生成方法存根
        System.out.print(read("IoStudy.txt"));
    }

}

在根目录下新建一个文件IoStudy.txt