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public abstract class DbfReader implements Reader {
protected String encode = "GBK";
private FileChannel fileChannel;
protected Header header;
protected List<Field> fields;
private boolean recordRemoved;
int position = 0;
static Map<Integer, Class> readerMap = new HashMap<Integer, Class>();
static {
addReader(3, FoxproDBase3Reader.class);
}
public static void addReader(int type, Class clazz) {
readerMap.put(type, clazz);
}
public static void addReader(int type, String className) throws ClassNotFoundException {
readerMap.put(type, Class.forName(className));
}
public byte getType() {
return 3;
}
public String getEncode() {
return encode;
}
public Header getHeader() {
return header;
}
public List<Field> getFields() {
return fields;
}
public boolean isRecordRemoved() {
return recordRemoved;
}
public static Reader parse(String dbfFile, String encode) throws IOException, IllegalAccessException, InstantiationException {
return parse(new File(dbfFile), encode);
}
public static Reader parse(String dbfFile) throws IOException, IllegalAccessException, InstantiationException {
return parse(new File(dbfFile), "GBK");
}
public static Reader parse(File dbfFile) throws IOException, IllegalAccessException, InstantiationException {
return parse(dbfFile, "GBK");
}
public static Reader parse(File dbfFile, String encode) throws IOException, IllegalAccessException, InstantiationException {
RandomAccessFile aFile = new RandomAccessFile(dbfFile, "r");
FileChannel fileChannel = aFile.getChannel();
ByteBuffer byteBuffer = ByteBuffer.allocate(1);
fileChannel.read(byteBuffer);
byte type = byteBuffer.array()[0];
Class<Reader> readerClass = readerMap.get((int) type);
if (readerClass == null) {
fileChannel.close();
throw new IOException("不支持的文件类型[" + type + "]。");
}
DbfReader reader = (DbfReader) readerClass.newInstance();
reader.setFileChannel(fileChannel);
reader.readHeader();
reader.readFields();
return reader;
}
public void setFileChannel(FileChannel fileChannel) {
this.fileChannel = fileChannel;
}
protected abstract void readFields() throws IOException;
public void moveBeforeFirst() throws IOException {
position = 0;
fileChannel.position(header.getHeaderLength());
}
/**
* @param position 从1开始
* @throws java.io.IOException
*/
public void absolute(int position) throws IOException {
checkPosition(position);
this.position = position;
fileChannel.position(header.getHeaderLength() + (position - 1) * header.getRecordLength());
}
private void checkPosition(int position) throws IOException {
if (position >= header.getRecordCount()) {
throw new IOException("期望记录行数为" + (this.position + 1) + "，超过实际记录行数：" + header.getRecordCount() + "。");
}
}
protected abstract Field readField() throws IOException;
protected abstract void readHeader() throws IOException;
private void skipHeaderTerminator() throws IOException {
ByteBuffer byteBuffer = ByteBuffer.allocate(1);
readByteBuffer(byteBuffer);
}
public void close() throws IOException {
fileChannel.close();
}
public void next() throws IOException {
checkPosition(position);
ByteBuffer byteBuffer = ByteBuffer.allocate(1);
readByteBuffer(byteBuffer);
this.recordRemoved = (byteBuffer.array()[0] == '*');
for (Field field : fields) {
read(field);
}
position++;
}
public boolean hasNext() {
return position < header.getRecordCount();
}
private void read(Field field) throws IOException {
ByteBuffer buffer = ByteBuffer.allocate(field.getLength());
readByteBuffer(buffer);
field.setStringValue(new String(buffer.array(), encode).trim());
field.setBuffer(buffer);
}
protected void readByteBuffer(ByteBuffer byteBuffer) throws IOException {
fileChannel.read(byteBuffer);
}
}
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