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Java library for reading and writing Xbase (dBase/DBF) files.

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albfernandez/javadbf

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README.md

JavaDBF is a Java library for reading and writing XBase files. There are plenty of legacy applications around with .dbf as their primary storage format. JavaDBF was initially written for data transfer with such applications.

Till late 90s dBase and its cousins were the most preferred database platform for small and even medium enterprise applications. They required low hardware configurations and were cheaper to develop. Eventually more capable desktop databases like Microsoft Access came into picture, DBF file format still remains one of the simplest way to store and transfer data.

News and changes in version 1.0.0

Possible breaking changes

JavaDBF 1.0.0 is the first release considered stable. It has a lot of improvements and is almost compatible with old code. But there are some small changes that may break your code:

• Numeric and Double types (N and F) are now returned as BigDecimal instead of Double.
• DBFException is now a RuntimeException, not need to explictitly catch or rethrow, but yo can if you wish.
• Character data is now trimmed tailing white spaces. You can disable it calling reader.setTrimRightSpaces(false)

• Support for dbase Level 7 databases.
• Support for new field types.
  • Support for memo text and binary types (M, B, G, P) via external file (fpt or dbt)
  • Support for varchar (V) fields
  • Support for double (O) fields
  • Support for double (B) fields
  • Support for long character (up to 65534 bytes) fields

  Obtain the latest version of JavaDBF from release page at github. Download the jar file and put it in your $CLASSPATH variable. You are ready to go.

  If you are using Maven, you can add JavaDBF to your project using this dependency in your pom.xml

    com.github.albfernandez javadbf 1.13.1  

  JavaDBF has a simple API of its own and it does not implement the JDBC API. It is designed this way because JavaDBF is not intended to support full-blown RDBMS-style database interaction. And you are not supposed to use it like a back-end; it just doesn’t work that way. Also, JavaDBF is not designed to be thread-safe; keep that in mind when you design multithreaded applications.

  JavaDBF comes in the package com.linuxense.javadbf. Import that package in your Java code. Following examples will familiarise you with its APIs.

  JavaDBF supports almost all XBase data types. While reading, those types are interpretted as appropriate Java types. Following tables shows the mapping scheme.

  Read and write supported types

  XBase Type	XBase Symbol	Java Type used in JavaDBF
  Character	C	java.lang.String
  Numeric	N	java.math.BigDecimal
  Floating Point	F	java.math.BigDecimal
  Logical	L	java.lang.Boolean
  Date	D	java.util.Date

  FoxPro Type	Symbol	Java Type used in JavaDBF
  Currency	Y	java.math.BigDecimal
  Long	I	java.lang.Integer
  Date Type	T	java.util.Date
  Timestamp	@	java.util.Date
  AutoIncrement	+	java.lang.Integer
  Memo	M	java.lang.String or byte[]
  Binary	B	byte[] or java.lang.Double
  Blob	W	byte[]
  General	G	byte[]
  Picture	P	byte[]
  VarBinary	Q	byte[]
  Varchar	V	java.lang.String
  Double	O	java.lang.Double

  To read a DBF file, JavaDBF provides a DBFReader class. Following is a ready-to-compile, self-explanatory program describing almost all feature of the DBFReader class. Copy/paste this listing and compile it. Keep a .dbf file handy to pass to this program as its argument.

  import java.io.*; import com.linuxense.javadbf.*; public class JavaDBFReaderTest < public static void main(String args[]) < DBFReader reader = null; try < // create a DBFReader object reader = new DBFReader(new FileInputStream(args[0])); // get the field count if you want for some reasons like the following int numberOfFields = reader.getFieldCount(); // use this count to fetch all field information // if required for (int i = 0; i < numberOfFields; i++) < DBFField field = reader.getField(i); // do something with it if you want // refer the JavaDoc API reference for more details // System.out.println(field.getName()); > // Now, lets us start reading the rows Object[] rowObjects; while ((rowObjects = reader.nextRecord()) != null) < for (int i = 0; i < rowObjects.length; i++) < System.out.println(rowObjects[i]); > > // By now, we have iterated through all of the rows > catch (DBFException e) < e.printStackTrace(); > catch (IOException e) < e.printStackTrace(); > finally < DBFUtils.close(reader); > > >

  Reading a DBF File using field names

  From JavaDBF 1.7.0 you can use field names to access data. You must use nextRow instead nextRecord

   import java.io.*; import com.linuxense.javadbf.*; public class JavaDBFReaderWithFieldNamesTest < public static void main(String args[]) < DBFReader reader = null; try < // create a DBFReader object reader = new DBFReader(new FileInputStream(args[0])); // get the field count if you want for some reasons like the following int numberOfFields = reader.getFieldCount(); // use this count to fetch all field information // if required for (int i = 0; i < numberOfFields; i++) < DBFField field = reader.getField(i); // do something with it if you want // refer the JavaDoc API reference for more details // System.out.println(field.getName()); >// Now, lets us start reading the rows DBFRow row; while ((row = reader.nextRow()) != null) < System.out.println(row.getString("PHONE")); >// By now, we have iterated through all of the rows > catch (DBFException e) < e.printStackTrace(); >catch (IOException e) < e.printStackTrace(); >finally < DBFUtils.close(reader); >> > 

  Reading a DBF File with memo file

  You can specify memo file to read Memo fields from. If you don’t specify this file this fields will be filled with null

  import java.io.*; import com.linuxense.javadbf.*; public class JavaDBFReaderMemoTest < public static void main(String args[]) < DBFReader reader = null; try < // create a DBFReader object reader = new DBFReader(new FileInputStream(args[0])); reader.setMemoFile(new File("memo.dbt")); // do whatever you want with the data > catch (DBFException e) < e.printStackTrace(); > catch (IOException e) < e.printStackTrace(); > finally < DBFUtils.close(reader); > > >

  The class complementary to DBFReader is the DBFWriter. While creating a .dbf data file you will have to deal with two aspects:

  As mentioned above a dbf field is represented by the class DBFField. First, let us familiarise this class.

  Create an object of DBFField class:

  DBFField field = new DBFField(); field.setName("emp_name"); // give a name to the field field.setType(DBFDataType.CHARACTER); // and set its type field.setLength(25); // and length of the field

  This is, now, a complete DBFField Object ready to use. We have to create as many DBFField Objects as we want to be in the .dbf file. The DBFWriter class accept DBFField in an array. Now, let’s move on to the next step of populating data.

  Preparing DBFWriter Object

  A DBFWriter is used for creating a .dbf file. First lets create a DBFWriter object by calling its constructor and then set the fields created (as explained above) by calling the setFields method.

  OutputStream os = // wathever output you want to use DBFWriter writer = new DBFWriter(os); // fields is a non-empty array of DBFField objects writer.setFields(fields);

  Now, the DBFWriter Object is ready to be populated. The method for adding data to the DBFWriter is addRecord and it takes an Object array as its argument. This Object array is supposed contain values for the fields added with one-to-one correspondence with the fields set.

  Following is a complete program explaining all the steps described above:

  import com.linuxense.javadbf.*; import java.io.*; public class JavaDBFWriterTest < public static void main(String args[]) throws IOException < // let us create field definitions first // we will go for 3 fields DBFField[] fields = new DBFField[3]; fields[0] = new DBFField(); fields[0].setName("emp_code"); fields[0].setType(DBFDataType.CHARACTER); fields[0].setLength(10); fields[1] = new DBFField(); fields[1].setName("emp_name"); fields[1].setType(DBFDataType.CHARACTER); fields[1].setLength(20); fields[2] = new DBFField(); fields[2].setName("salary"); fields[2].setType(DBFDataType.NUMERIC); fields[2].setLength(12); fields[2].setDecimalCount(2); DBFWriter writer = new DBFWriter(new FileOutputStream(args[0])); writer.setFields(fields); // now populate DBFWriter Object rowData[] = new Object[3]; rowData[0] = "1000"; rowData[1] = "John"; rowData[2] = new Double(5000.00); writer.addRecord(rowData); rowData = new Object[3]; rowData[0] = "1001"; rowData[1] = "Lalit"; rowData[2] = new Double(3400.00); writer.addRecord(rowData); rowData = new Object[3]; rowData[0] = "1002"; rowData[1] = "Rohit"; rowData[2] = new Double(7350.00); writer.addRecord(rowData); // write to file writer.close(); > >

  Keep in mind that till the close method is called, all the added data will be kept in memory. So, if you are planning to write huge amount of data make sure that it will be safely held in memory till it is written to disk and the DBFWriter object is garbage-collected. Read the Sync Mode section to know how JavaDBF to use a special feature of JavaDBF to overcome this.

  Sync Mode: Writing Records to File as They are Added

  This is useful when JavaDBF is used to create a DBF with very large number of records. In this mode, instead of keeping records in memory for writing them once for all, records are written to file as addRecord() is called. Here is how to write in Sync Mode.

  Create DBFWriter instance by passing a File object which represents a new/non-existent or empty file. And you are done! But, as in the normal mode, remember to call close() when have added all the records. This will help JavaDBF to write the meta data with correct values. Here is a sample code:

  import com.linuxense.javadbf.*; import java.io.*; public class DBFWriterTest < public static void main(String args[]) throws IOException < // . DBFWriter writer = new DBFWriter(new File("/path/to/a/new/file")); // this DBFWriter object is now in Sync Mode // set fields writer.setFields(fields); // add the data writer.addRecord(rowData); // close writer.close(); // . > >

  From version 0.4.0 onwards JavaDBF supports appending of records to an existing DBF file. Use the same constructor used in Sync Mode to achieve this. But here the File object passed to the construction should represent the DBF file to which records are to be appended.

  It is illegal to call setFields in DBFWriter object created for appending. Here also it is required to call the close() method after adding all the records.

  import com.linuxense.javadbf.*; import java.io.*; public class DBFWriterTest < public static void main(String args[]) throws IOException < // . DBFWriter writer = new DBFWriter(new File("/path/to/an/existing/dbfile")); // this DBFWriter object is now in Syc Mode // add the data (no setFields, because it's an existing file) writer.addRecord(rowData); // close writer.close(); // . > >

  Clone the repository or download de tar file from releases page on github, then run the Maven command:

  git clone https://github.com/albfernandez/javadbf.git cd javadbf mvn clean package 

  The result file is target/javadbf-x.xx.x.jar

  Источник

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