[英]How can I prevent PrintWriter from printing a blank line at the beginning of each file?
[英]Java PrintWriter printing multiple blank lines at the beginning of each file
我使用 PrintWriter 很長時間了,從來沒有遇到過這個問題。 見下文
當我使用 excel 打開 csv 文件時,標題行的第一個元素消失了。
為了進一步調查,我發現在使用文本文件打開它時在開頭插入了幾個空行。
下面是我的代碼:
打印標題行:
public void printHubInboundHeader() {
try {
StringBuilder sb = new StringBuilder();
String headingPart1 = "Inbound_Hub, Date, Time,";
String headingPart2 = "Weight";
sb.append(headingPart1+headingPart2);
System.out.println(sb);
FileWriter.writeFile(sb.toString(),"filepath");
}
catch(Exception e) {
System.out.println("Something wrong when writting headerline");
e.printStackTrace();
}
}
打印實際數據:
public void printHubSummary(Hub hub, String filePath) {
try {
StringBuilder sb = new StringBuilder();
String h = hub.getHub_code();
String date = Integer.toString(hub.getGs().getDate());
String time = hub.getGs().getHHMMFromMinute(hub.getGs().getClock());
String wgt = Double.toString(hub.getIb_wgt());
sb.append(h+","+date+","+time+","+wgt);
// System.out.println("truck print line: " + sb);
FileWriter.writeFile(sb.toString(),filePath);
}
catch (Exception e) {
System.out.println("Something wrong when outputing truck summary file!");
e.printStackTrace();
}
}
文件編寫器代碼:
public class FileWriter {
private static String filenameTemp;
public static boolean creatFile(String name) throws IOException {
boolean flag = false;
filenameTemp = name + "";
System.out.println("write to file: "+filenameTemp);
File filename = new File(filenameTemp);
if (!filename.exists()) {
filename.createNewFile();
flag = true;
}
else {
filename.delete();
filename.createNewFile();
flag = true;
}
return flag;
}
public static boolean writeFile(String newStr, String filename) throws IOException {
boolean flag = false;
String filein = newStr + "\r\n";
String temp = "";
FileInputStream fis = null;
InputStreamReader isr = null;
BufferedReader br = null;
FileOutputStream fos = null;
PrintWriter pw = null;
try {
File file = new File(filename);
fis = new FileInputStream(file);
isr = new InputStreamReader(fis);
br = new BufferedReader(isr);
StringBuffer buf = new StringBuffer();
for (int j = 1; (temp = br.readLine()) != null; j++) {
buf = buf.append(temp);
buf = buf.append(System.getProperty("line.separator"));
}
buf.append(filein);
fos = new FileOutputStream(file);
byte[] unicode = {(byte)0xEF, (byte)0xBB, (byte)0xBF};
fos.write(unicode);
pw = new PrintWriter(fos);
pw.write(buf.toString().toCharArray());
pw.flush();
flag = true;
} catch (IOException e1) {
throw e1;
} finally {
if (pw != null) {
pw.close();
}
if (fos != null) {
fos.close();
}
if (br != null) {
br.close();
}
if (isr != null) {
isr.close();
}
if (fis != null) {
fis.close();
}
}
return flag;
}
public static void setFileName(String fileName){
filenameTemp = fileName;
}
}
我不知道這是否是您代碼的唯一問題,但每次調用FileWriter.writeFile
都會向文件添加一個新的字節順序標記。 這意味着您最終會在文件中使用多個標記,這可能會混淆某些工具。
要刪除FileWriter.writeFile
中的額外 BOM,您可以使用deleteCharAt
方法:
...
buf = buf.append(System.getProperty("line.separator"));
}
if (buf.length() > 0 && buf.charAt(0) == '\uFEFF') {
buf.deleteCharAt(0);
}
buf.append(filein);
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