java將字符串寫入到文件中

將頁面上獲取的字符串內容寫入到指定目錄下新的csv文件中，並在行首添加id

		String sourceData = request.getParameter("generateData");
		String fileName = request.getParameter("fileName");
		fileName=fileName.replaceAll(".csv", "_add_id.csv");
		BufferedReader br = new BufferedReader(new InputStreamReader(new ByteArrayInputStream(sourceData.getBytes(Charset.forName("utf8"))), Charset.forName("utf8")));
		String line;
		File savePath = new File("F:/generateId");
		// 判斷上傳文件的保存目錄是否存在
        if (!savePath.exists() && !savePath.isDirectory())
        {
            System.out.println(savePath + "目錄不存在，需要創建");
            // 創建目錄
            savePath.mkdir();
        }
		BufferedWriter bw = new BufferedWriter(new FileWriter(savePath + "/" + fileName));// FileWriter(csv, true) 當參數爲true的時候寫入的數據會疊加不會覆蓋

		Set set = new HashSet();
		while (set.size() < 100000) {
			int val = (int) (Math.random() * 100000);
			set.add(val);
		}
		Iterator iterator = set.iterator();

		while ( (line = br.readLine()) != null && iterator.hasNext() ) {
			Integer id=(Integer) iterator.next();
		    bw.write(id+","+line);
		    bw.newLine();		    
		}
		bw.close();