CSVWriter


1   /*------------------------------------------------------------------------------
2   Name:      CSVWriter.java
3   Project:   jutils.org
4   Comment:   writes CSV (Comma Separated Value) files
5   Version:   $Id: CSVWriter.java,v 1.2 2004/04/07 08:04:24 laurent Exp $
6   Author:    Roedy Green roedy@mindprod.com, Heinrich Goetzger goetzger@gmx.net
7   ------------------------------------------------------------------------------*/
8   package org.jutils.csv;
9   
10  import java.io.EOFException  ;
11  import java.io.FileWriter  ;
12  import java.io.IOException  ;
13  import java.io.PrintWriter  ;
14  import java.io.Writer  ;
15  
16  /**
17   * Writes CSV (Comma Separated Value) files.
18   *
19   * This format is mainly used my Microsoft Word and Excel.
20   * Fields are separated by commas, and enclosed in
21   * quotes if they contain commas or quotes.
22   * Embedded quotes are doubled.
23   * Embedded spaces do not normally require surrounding quotes.
24   * The last field on the line is not followed by a comma.
25   * Null fields are represented by two commas in a row.
26   *
27   * @author copyright (c) 2002 Roedy Green  Canadian Mind Products
28   * Roedy posted this code on Newsgroups:comp.lang.java.programmer on 27th March 2002.
29   *
30   * Heinrich added some stuff like comment ability and linewise working.
31   *
32   */
33  public class CSVWriter {
34  
35     /**
36      * Constructor
37      *
38      * @param pw     PrintWriter where fields will be written.
39      * @param forceQuotes
40      *               true if you want all fields surrounded in quotes,
41      *               whether or not they contain commas, quotes or spaces.
42      * @param separator
43      *               field separator character, usually ',' in North America,
44      *               ';' in Europe and sometimes '\t' for tab.
45      * @param lineSeparator
46      *               gives the delimiter for the line; is per default set to
47      *               the system property 'line.separator'
48      */
49     public CSVWriter(PrintWriter   pw, boolean forceQuotes, char separator, String   lineSeparator) {
50        this.pw = pw;
51        this.forceQuotes = forceQuotes;
52        this.separator = separator;
53        this.comment = "# ";
54        this.lineSeparator = lineSeparator;
55     } // end of CSVWriter
56  
57     public CSVWriter(Writer   w, boolean forceQuotes, char separator, String   lineSeparator) {
58         this(new PrintWriter  (w),forceQuotes,separator,lineSeparator);
59     }
60  
61     /**
62      * Constructor with default field separator ','.
63      *
64      * @param pw     PrintWriter where fields will be written.
65      */
66     public CSVWriter(PrintWriter   pw) {
67        this.pw = pw;
68        this.forceQuotes = false;
69        this.separator = ',';
70        this.comment = "# ";
71        this.lineSeparator = System.getProperty("line.separator");
72     } // end of CSVWriter
73  
74      
75     public CSVWriter(Writer   w) {
76         this(new PrintWriter  (w));
77     }
78  
79     /**
80      * Constructor with default field separator ','.
81      *
82      * @param pw     PrintWriter where fields will be written.
83      * @param comment Character used to start a comment line
84      */
85     public CSVWriter(PrintWriter   pw, char comment) {
86        this.pw = pw;
87        this.forceQuotes = false;
88        this.separator = ',';
89        this.comment = String.valueOf(comment) + " ";
90        this.lineSeparator = System.getProperty("line.separator");
91     } // end of CSVWriter
92  
93     public CSVWriter(Writer   w, char comment) {
94         this(new PrintWriter  (w),comment);
95     }
96  
97     /**
98      * PrintWriter where CSV fields will be written.
99      */
100    PrintWriter   pw;
101 
102    /**
103     * true if you want all fields surrounded in quotes,
104     * whether or not they contain commas, quotes or spaces.
105     */
106    boolean forceQuotes;
107 
108    /*
109     * field separator character, usually ',' in North America,
110     * ';' in Europe and sometimes '\t' for tab.
111     */
112    char separator;
113 
114    /**
115     * true if there has was a field previously written to
116     * this line, meaning there is a comma pending to
117     * be written.
118     */
119    boolean wasPreviousField = false;
120 
121    /**
122     * Character to start a comment line with. May be '#' for example.
123     */
124    String   comment;
125 
126    /**
127     * Line separator.
128     */
129    String   lineSeparator;
130 
131    /**
132     * Writes a single coment line to the file given by the <code>text</code>.
133     * This is the text leaded by the <code>comment char + " "</code>, given in the constructor.
134     * @param text contains the comment text.
135     */
136    public void writeCommentln(String   text) {
137       if (wasPreviousField) writeln(); // close open line since we need to start a new one for comment
138       pw.print(comment);
139       //wasPreviousField = false; // to prevent a comma after the comment sign
140       write(text);
141       writeln();
142    } // end of writeComentln
143 
144    /**
145     * Writes a single value in a line suited by a newline to the file given by the <code>token</code>.
146     * @param token contains the value.
147     */
148    public void writeln(String   token) {
149       write(token);
150       writeln();
151    } // end of writeln
152 
153    /**
154     * Writes a new line in the CVS output file to demark the end of record.
155     */
156    public void writeln() {
157       /* don't bother to write last pending comma on the line */
158       wasPreviousField = false;
159       pw.print(lineSeparator);
160    } // end of writeln
161 
162    /**
163     * Writes a single line of comma separated values from the array given by <code>line</code>.
164     * @param line containig an array of tokens.
165     */
166    public void writeln(String  [] line) {
167       for(int ii=0; ii < line.length; ii++) {
168          write(line[ii]);
169       } // end of for
170 
171       writeln(); // write newLine
172 
173    } // end of writeln
174 
175    /**
176      * Write one csv field to the file, followed by a separator
177      * unless it is the last field on the line. Lead and trailing
178      * blanks will be removed.
179      *
180      * @param s      The string to write.  Any additional quotes or
181      *               embedded quotes will be provided by write.
182      */
183    public void write(String   s) {
184       if ( wasPreviousField ) {
185          pw.print(separator);
186       }
187 
188       if ( s == null ) {
189          pw.print("");
190          return;
191       } // end of if s == null
192 
193       s = s.trim();
194       if ( s.indexOf('\"') >= 0 ) {
195          /* worst case, needs surrounding quotes and internal quotes doubled */
196          pw.print ('\"');
197          for ( int i=0; i<s.length(); i++ ) {
198             char c = s.charAt(i);
199             if ( c == '\"' ) {
200                pw.print("\"\"");
201             } else {
202                pw.print(c);
203             }
204          }
205          pw.print ('\"');
206          // end of if \"
207       } else if ( s.indexOf('\n') >=0 ) {
208          // bad case as well: having a new line in the token: \n
209          pw.print ('\"');
210          for ( int i=0; i<s.length(); i++ ) {
211             char c = s.charAt(i);
212             if ( c == '\n' ) {
213                pw.print("\\n");
214             } else {
215                pw.print(c);
216             }
217          }
218          pw.print ('\"');
219          // end of if \n
220       } else if ( forceQuotes || s.indexOf(separator) >= 0 ) {
221          /* need surrounding quotes */
222          pw.print ('\"');
223          pw.print(s);
224          pw.print ('\"');
225       } else {
226          /* ordinary case, no surrounding quotes needed */
227          pw.print(s);
228       }
229       /* make a note to print trailing comma later */
230       wasPreviousField = true;
231    } // end of write
232 
233    /**
234     * Close the PrintWriter.
235     */
236    public void close() {
237       if ( pw != null ) {
238          pw.close();
239          pw = null;
240       } // end of if
241    } // end of close
242 
243    /**
244     * Test driver
245     *
246     * @param args  [0]: The name of the file.
247     */
248    static public void main(String  [] args) {
249       try {
250          // write out a test file
251          PrintWriter   pw = new PrintWriter  ( new FileWriter  (args[0]));
252          CSVWriter csv = new CSVWriter(pw, false, ',', System.getProperty("line.separator") );
253          csv.writeCommentln("This is a test csv-file: '" + args[0] + "'");
254          csv.write("abc");
255          csv.write("def");
256          csv.write("g h i");
257          csv.write("jk,l");
258          csv.write("m\"n\'o ");
259          csv.writeln();
260          csv.write("m\"n\'o ");
261          csv.write("    ");
262          csv.write("a");
263          csv.write("x,y,z");
264          csv.write("x;y;z");
265          csv.writeln();
266          csv.writeln(new String  [] {"This", "is", "an", "array."});
267          csv.close();
268       } catch ( IOException    e ) {
269          e.printStackTrace();
270          System.out.println(e.getMessage());
271       }
272    } // end main
273 
274 } // end CSVWriter
275 
276 // end of file
277
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