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 blocke.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;}}