public class ReadFile {

	/**

	 * 按行读取文件操作

	 * @throws IOException

	 */

	public void readFile(String fileName) throws IOException{

		//(1)File 类

		File file = new File(fileName);

		//

		BufferedReader reader = null;

		try {

			//(2) 将文件放入到BufferedReader中

			reader  = new BufferedReader(new FileReader(file));

			String temp = null;

			int line = 0;

			while( (temp = reader.readLine()) != null){

				System.out.println(temp + (++line));

			}

		} catch (FileNotFoundException e) {

			// TODO Auto-generated catch block

			e.printStackTrace();

		}finally{

			reader.close();

		}

	}

	/**

	 * 文件的写入操作

	 */

	public void writeFile(String fileName, String str) throws IOException{

		File file = new File(fileName);

		//true实现对文件的追加操作

		FileWriter ws = new FileWriter(file,true);

		ws.write(str);

		ws.close();

	}

	/**

	 * 对于一个大文本文件，我们仅仅读取最后的N行

	 * @throws IOException

	 */

	public String[] getLastNFromFile(String fileName) throws IOException{

		String []temp = new String[5];

		File f = new File(fileName);

		BufferedReader reader = new BufferedReader(new FileReader(f));

		String temp1 = null;

		int line = 0;

		while((temp1 = reader.readLine()) != null){

			temp[line++]= temp1;

			if(line >= 5 ){

				line = 0;

			}

		}

		return temp;

	}

	/**

	 * 通过索引进行操作

	 * @throws IOException

	 */

	public String[] getLastNFromFileByIndex(String fileName) throws IOException{

		String []temp = new String[5];

		File f = new File(fileName);

		BufferedReader reader = new BufferedReader(new FileReader(f));

		String temp1 = null;

		int line = 0;

		while((temp1 = reader.readLine()) != null){

			line++;

		}

		return temp;

	}

}