CsvWriter.java

   1 /*
   2  * Copyright (C) 2007-2012 Mathieu Baudier
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *         http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 package org.argeo.util;
  17
  18 import java.io.IOException;
  19 import java.io.OutputStream;
  20 import java.io.OutputStreamWriter;
  21 import java.io.UnsupportedEncodingException;
  22 import java.io.Writer;
  23 import java.util.Iterator;
  24 import java.util.List;
  25
  26 import org.argeo.ArgeoException;
  27
  28 /** Write in CSV format. */
  29 public class CsvWriter {
  30         private final Writer out;
  31
  32         private char separator = ',';
  33         private char quote = '\"';
  34
  35         /**
  36          * Creates a CSV writer.
  37          *
  38          * @param out
  39          *            the stream to write to. Caller is responsible for closing it.
  40          */
  41         public CsvWriter(OutputStream out) {
  42                 this.out = new OutputStreamWriter(out);
  43         }
  44
  45         /**
  46          * Creates a CSV writer.
  47          *
  48          * @param out
  49          *            the stream to write to. Caller is responsible for closing it.
  50          */
  51         public CsvWriter(OutputStream out, String encoding) {
  52                 try {
  53                         this.out = new OutputStreamWriter(out, encoding);
  54                 } catch (UnsupportedEncodingException e) {
  55                         throw new ArgeoException("Cannot initialize CSV writer", e);
  56                 }
  57         }
  58
  59         /**
  60          * Write a CSV line. Also used to write a header if needed (this is
  61          * transparent for the CSV writer): simply call it first, before writing the
  62          * lines.
  63          */
  64         public void writeLine(List<?> tokens) {
  65                 try {
  66                         Iterator<?> it = tokens.iterator();
  67                         while (it.hasNext()) {
  68                                 writeToken(it.next().toString());
  69                                 if (it.hasNext())
  70                                         out.write(separator);
  71                         }
  72                         out.write('\n');
  73                         out.flush();
  74                 } catch (IOException e) {
  75                         throw new ArgeoException("Could not write " + tokens, e);
  76                 }
  77         }
  78
  79         /**
  80          * Write a CSV line. Also used to write a header if needed (this is
  81          * transparent for the CSV writer): simply call it first, before writing the
  82          * lines.
  83          */
  84         public void writeLine(Object[] tokens) {
  85                 try {
  86                         for (int i = 0; i < tokens.length; i++) {
  87                                 if (tokens[i] == null) {
  88                                         // TODO configure how to deal with null
  89                                         writeToken("");
  90                                 } else {
  91                                         writeToken(tokens[i].toString());
  92                                 }
  93                                 if (i != (tokens.length - 1))
  94                                         out.write(separator);
  95                         }
  96                         out.write('\n');
  97                         out.flush();
  98                 } catch (IOException e) {
  99                         throw new ArgeoException("Could not write " + tokens, e);
 100                 }
 101         }
 102
 103         protected void writeToken(String token) throws IOException {
 104                 // +2 for possible quotes, another +2 assuming there would be an already
 105                 // quoted string where quotes needs to be duplicated
 106                 // another +2 for safety
 107                 // we don't want to increase buffer size while writing
 108                 StringBuffer buf = new StringBuffer(token.length() + 6);
 109                 char[] arr = token.toCharArray();
 110                 boolean shouldQuote = false;
 111                 for (char c : arr) {
 112                         if (!shouldQuote) {
 113                                 if (c == separator)
 114                                         shouldQuote = true;
 115                                 if (c == '\n')
 116                                         shouldQuote = true;
 117                         }
 118
 119                         if (c == quote) {
 120                                 shouldQuote = true;
 121                                 // duplicate quote
 122                                 buf.append(quote);
 123                         }
 124
 125                         // generic case
 126                         buf.append(c);
 127                 }
 128
 129                 if (shouldQuote == true)
 130                         out.write(quote);
 131                 out.write(buf.toString());
 132                 if (shouldQuote == true)
 133                         out.write(quote);
 134         }
 135
 136         public void setSeparator(char separator) {
 137                 this.separator = separator;
 138         }
 139
 140         public void setQuote(char quote) {
 141                 this.quote = quote;
 142         }
 143
 144 }