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Add H2 read/write support for file formats such as ESRI shape file
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/**
* H2GIS is a library that brings spatial support to the H2 Database Engine
* .
*
* H2GIS is distributed under GPL 3 license. It is produced by CNRS
*
* DbaseFileHeader header = ...
* WritableFileChannel out = new FileOutputStream("thefile.dbf").getChannel();
* DbaseFileWriter w = new DbaseFileWriter(header,out);
* while ( moreRecords ) {
* w.write( getMyRecord() );
* }
* w.close();
* moreRecords and
* getMyRecord() logic...
*
* @author Ian Schneider
* @source $URL:
* http://svn.geotools.org/geotools/trunk/gt/modules/plugin/shapefile/src/main/java/org/geotools/data/shapefile/dbf/DbaseFileWriter.java $
*/
public class DbaseFileWriter {
private DbaseFileHeader header;
private DbaseFileWriter.FieldFormatter formatter;
WritableByteChannel channel;
private ByteBuffer buffer;
private static final Number NULL_NUMBER = Integer.valueOf(0);
private static final String NULL_STRING = "";
private Charset charset;
/**
* Create a DbaseFileWriter using the specified header and writing to the
* given channel.
*
* @param header
* The DbaseFileHeader to write.
* @param out
* The Channel to write to.
* @throws java.io.IOException
* If errors occur while initializing.
*/
public DbaseFileWriter(DbaseFileHeader header, WritableByteChannel out)
throws IOException {
this(header, out, Charset.forName(header.getFileEncoding()));
}
/**
* @return The DbaseFileHeader to write.
*/
public DbaseFileHeader getHeader() {
return header;
}
/**
* Create a DbaseFileWriter using the specified header and writing to the
* given channel.
*
* @param header
* The DbaseFileHeader to write.
* @param out
* The Channel to write to.
* @param charset
* The charset the dbf is (will be) encoded in
* @throws java.io.IOException
* If errors occur while initializing.
*/
public DbaseFileWriter(DbaseFileHeader header, WritableByteChannel out,
Charset charset) throws IOException {
header.writeHeader(out);
this.header = header;
this.channel = out;
// DBase does not support UTF-8
this.charset = charset == null ? Charset.forName(DbaseFileHeader.DEFAULT_ENCODING) : charset;
this.formatter = new DbaseFileWriter.FieldFormatter(this.charset);
init();
}
private void init() throws IOException {
buffer = ByteBuffer.allocateDirect(header.getRecordLength());
}
private void write() throws IOException {
buffer.position(0);
int r = buffer.remaining();
do {
r -= channel.write(buffer);
} while (r > 0);
}
/**
* Write a single dbase record.
*
* @param record
* The entries to write.
* @throws java.io.IOException
* If IO error occurs.
* @throws DbaseFileException
* If the entry doesn't comply to the header.
*/
public void write(Object[] record) throws IOException, DbaseFileException {
if (record.length != header.getNumFields()) {
throw new DbaseFileException("Wrong number of fields "
+ record.length + " expected " + header.getNumFields());
}
buffer.position(0);
// put the 'not-deleted' marker
buffer.put((byte) ' ');
for (int i = 0; i < header.getNumFields(); i++) {
String fieldString = fieldString(record[i], i);
if (header.getFieldLength(i) != fieldString
.getBytes(charset.name()).length) {
buffer.put(new byte[header.getFieldLength(i)]);
} else {
buffer.put(fieldString.getBytes(charset.name()));
}
}
write();
}
private String fieldString(Object obj, final int col) {
String o;
final int fieldLen = header.getFieldLength(col);
switch (header.getFieldType(col)) {
case 'C':
case 'M':
case 'G':
case 'c':
o = formatter.getFieldString(fieldLen, obj != null ? obj.toString() : NULL_STRING);
break;
case 'L':
case 'l':
o = (obj == null ? "F" : (Boolean)obj ? "T" : "F");
break;
case 'N':
case 'n':
// int?
if (header.getFieldDecimalCount(col) == 0) {
o = formatter.getFieldString(fieldLen, 0, (obj instanceof Number ? (Number)obj : NULL_NUMBER));
break;
}
case 'F':
case 'f':
o = formatter.getFieldString(fieldLen, header
.getFieldDecimalCount(col), (obj instanceof Number ? (Number)obj : NULL_NUMBER));
break;
case 'D':
case 'd':
o = formatter.getFieldString((obj instanceof Date ? (Date)obj : null));
break;
default:
throw new IllegalStateException("Unknown type "
+ header.getFieldType(col));
}
return o;
}
/**
* Release resources associated with this writer. Highly recommended
*
* @throws java.io.IOException
* If errors occur.
*/
public void close() throws IOException {
// IANS - GEOT 193, bogus 0x00 written. According to dbf spec, optional
// eof 0x1a marker is, well, optional. Since the original code wrote a
// 0x00 (which is wrong anyway) lets just do away with this :)
// - produced dbf works in OpenOffice and ArcExplorer java, so it must
// be okay.
// buffer.position(0);
// buffer.put((byte) 0).position(0).limit(1);
// write();
if (channel.isOpen()) {
channel.close();
}
buffer = null;
channel = null;
formatter = null;
}
/** Utility for formatting Dbase fields. */
public static class FieldFormatter {
private StringBuffer buffer = new StringBuffer(255);
private NumberFormat numFormat = NumberFormat
.getNumberInstance(Locale.US);
private Calendar calendar = Calendar.getInstance(Locale.US);
private String emptyString;
private static final int MAXCHARS = 255;
private Charset charset;
public FieldFormatter(Charset charset) {
// Avoid grouping on number format
numFormat.setGroupingUsed(false);
// build a 255 white spaces string
StringBuilder sb = new StringBuilder(MAXCHARS);
sb.setLength(MAXCHARS);
for (int i = 0; i < MAXCHARS; i++) {
sb.setCharAt(i, ' ');
}
this.charset = charset;
emptyString = sb.toString();
}
public String getFieldString(int size, String s) {
try {
buffer.replace(0, size, emptyString);
buffer.setLength(size);
// international characters must be accounted for so size !=
// length.
int maxSize = size;
if (s != null) {
buffer.replace(0, size, s);
int currentBytes = s.substring(0,
Math.min(size, s.length()))
.getBytes(charset.name()).length;
if (currentBytes > size) {
char[] c = new char[1];
for (int index = size - 1; currentBytes > size; index--) {
if (buffer.length() > index) {
c[0] = buffer.charAt(index);
String string = new String(c);
buffer.deleteCharAt(index);
currentBytes -= string.getBytes().length;
maxSize--;
}
}
} else {
if (s.length() < size) {
maxSize = size - (currentBytes - s.length());
for (int i = s.length(); i < size; i++) {
buffer.append(' ');
}
}
}
}
buffer.setLength(maxSize);
return buffer.toString();
} catch (UnsupportedEncodingException e) {
throw new IllegalStateException("This error should never happen...", e);
}
}
public String getFieldString(Date d) {
if (d != null) {
buffer.delete(0, buffer.length());
calendar.setTime(d);
int year = calendar.get(Calendar.YEAR);
int month = calendar.get(Calendar.MONTH) + 1; // returns 0
// based month?
int day = calendar.get(Calendar.DAY_OF_MONTH);
if (year < 1000) {
if (year >= 100) {
buffer.append('0');
} else if (year >= 10) {
buffer.append("00");
} else {
buffer.append("000");
}
}
buffer.append(year);
if (month < 10) {
buffer.append('0');
}
buffer.append(month);
if (day < 10) {
buffer.append('0');
}
buffer.append(day);
} else {
buffer.setLength(8);
buffer.replace(0, 8, emptyString);
}
buffer.setLength(8);
return buffer.toString();
}
public String getFieldString(int size, int decimalPlaces, Number n) {
buffer.delete(0, buffer.length());
if (n != null) {
numFormat.setMaximumFractionDigits(decimalPlaces);
numFormat.setMinimumFractionDigits(decimalPlaces);
numFormat.format(n, buffer, new FieldPosition(
NumberFormat.INTEGER_FIELD));
}
int diff = size - buffer.length();
if (diff >= 0) {
while (diff-- > 0) {
buffer.insert(0, ' ');
}
} else {
buffer.setLength(size);
}
return buffer.toString();
}
}
}
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