CsvWriter.java

   1 package org.argeo.util;
   2
   3 import java.io.IOException;
   4 import java.io.OutputStream;
   5 import java.io.PrintWriter;
   6 import java.util.Iterator;
   7 import java.util.List;
   8
   9 import org.argeo.ArgeoException;
  10
  11 /** Write in CSV format. */
  12 public class CsvWriter {
  13         private final PrintWriter out;
  14
  15         private char separator = ',';
  16         private char quote = '\"';
  17
  18         /**
  19          * Creates a CSV writer. The header will be written immediately to the
  20          * stream.
  21          *
  22          * @param out
  23          *            the stream to write to. Caller is responsible for closing it.
  24          */
  25         public CsvWriter(OutputStream out) {
  26                 super();
  27                 this.out = new PrintWriter(out);
  28         }
  29
  30         /**
  31          * Write a CSV line. Also used to write a header if needed (this is
  32          * transparent for the CSV writer): simply call it first, before writing the
  33          * lines.
  34          */
  35         public void writeLine(List<?> tokens) {
  36                 try {
  37                         Iterator<?> it = tokens.iterator();
  38                         while (it.hasNext()) {
  39                                 writeToken(it.next().toString());
  40                                 if (it.hasNext())
  41                                         out.print(separator);
  42                         }
  43                         out.print('\n');
  44                         out.flush();
  45                 } catch (IOException e) {
  46                         throw new ArgeoException("Could not write " + tokens, e);
  47                 }
  48         }
  49
  50         protected void writeToken(String token) throws IOException {
  51                 // +2 for possible quotes, another +2 assuming there would be an already
  52                 // quoted string where quotes needs to be duplicated
  53                 // another +2 for safety
  54                 StringBuffer buf = new StringBuffer(token.length() + 6);
  55                 char[] arr = token.toCharArray();
  56                 boolean shouldQuote = false;
  57                 for (char c : arr) {
  58                         if (!shouldQuote) {
  59                                 if (c == separator)
  60                                         shouldQuote = true;
  61                                 if (c == '\n')
  62                                         shouldQuote = true;
  63                         }
  64
  65                         if (c == quote) {
  66                                 shouldQuote = true;
  67                                 // duplicate quote
  68                                 buf.append(quote);
  69                         }
  70
  71                         // generic case
  72                         buf.append(c);
  73                 }
  74
  75                 if (shouldQuote == true)
  76                         out.print(quote);
  77                 out.print(buf.toString());
  78                 if (shouldQuote == true)
  79                         out.print(quote);
  80         }
  81 }