Java读写文件通用格式

String path = "I:\";
		File file = new File(path + "user_id_pair.txt");
		FileReader reader = null;
		BufferedReader br = null;
		try {
			reader = new FileReader(file);
			br = new BufferedReader(reader);
			String str = null;
			int cnt=0;
			while ((str = br.readLine()) != null) {
				System.out.println(str);getClass();
				cnt++;
			}
			System.out.println("end!"+cnt);

		}
		catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		}
		finally {
			if (br != null) {
				try {
					br.close();
				}
				catch (Exception e2) {
					// TODO: handle exception
					e2.printStackTrace();
				}
			}
			if (reader != null) {
				try {
					reader.close();
				}
				catch (Exception e2) {
					// TODO: handle exception
					e2.printStackTrace();
				}
			}
		}

　　

FileWriter fw = null;
		BufferedWriter bw = null;
		PrintWriter pw = null;// "J:\user_id_pair.txt"
		try {
			fw = new FileWriter(new File(fileName), true);
			bw = new BufferedWriter(fw);
			pw = new PrintWriter(bw);
			pw.write(content);
		}
		catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		finally {
			if (pw != null) {
				pw.close();
			}
			if (bw != null) {
				try {
					bw.close();
				}
				catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			if (fw != null) {
				try {
					fw.close();
				}
				catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}