Package org.h2.tools

Class Csv

  • All Implemented Interfaces:
    SimpleRowSource

    public class Csv
    extends java.lang.Object
    implements SimpleRowSource
    A facility to read from and write to CSV (comma separated values) files. When reading, the BOM (the byte-order-mark) character 0xfeff at the beginning of the file is ignored.
    • Constructor Summary

      Constructors 
      Constructor Description
      Csv()  
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void close()
      INTERNAL
      boolean getCaseSensitiveColumnNames()
      Get the current case sensitive column names setting.
      char getEscapeCharacter()
      Get the current escape character.
      char getFieldDelimiter()
      Get the current field delimiter.
      char getFieldSeparatorRead()
      Get the current field separator for reading.
      java.lang.String getFieldSeparatorWrite()
      Get the current field separator for writing.
      char getLineCommentCharacter()
      Get the line comment character.
      java.lang.String getLineSeparator()
      Get the line separator used for writing.
      java.lang.String getNullString()
      Get the current null string.
      boolean getPreserveWhitespace()
      Whether whitespace in unquoted text is preserved.
      boolean getWriteColumnHeader()
      Whether the column header is written.
      java.sql.ResultSet read​(java.io.Reader reader, java.lang.String[] colNames)
      Reads CSV data from a reader and returns a result set.
      java.sql.ResultSet read​(java.lang.String inputFileName, java.lang.String[] colNames, java.lang.String charset)
      Reads from the CSV file and returns a result set.
      java.lang.Object[] readRow()
      INTERNAL
      void reset()
      INTERNAL
      void setCaseSensitiveColumnNames​(boolean caseSensitiveColumnNames)
      Override the case sensitive column names setting.
      void setEscapeCharacter​(char escapeCharacter)
      Set the escape character.
      void setFieldDelimiter​(char fieldDelimiter)
      Set the field delimiter.
      void setFieldSeparatorRead​(char fieldSeparatorRead)
      Override the field separator for reading.
      void setFieldSeparatorWrite​(java.lang.String fieldSeparatorWrite)
      Override the field separator for writing.
      void setLineCommentCharacter​(char lineCommentCharacter)
      Set the line comment character.
      void setLineSeparator​(java.lang.String lineSeparator)
      Set the line separator used for writing.
      void setNullString​(java.lang.String nullString)
      Set the value that represents NULL.
      java.lang.String setOptions​(java.lang.String options)
      INTERNAL.
      void setPreserveWhitespace​(boolean value)
      Enable or disable preserving whitespace in unquoted text.
      void setWriteColumnHeader​(boolean value)
      Enable or disable writing the column header.
      int write​(java.io.Writer writer, java.sql.ResultSet rs)
      Writes the result set to a file in the CSV format.
      int write​(java.lang.String outputFileName, java.sql.ResultSet rs, java.lang.String charset)
      Writes the result set to a file in the CSV format.
      int write​(java.sql.Connection conn, java.lang.String outputFileName, java.lang.String sql, java.lang.String charset)
      Writes the result set of a query to a file in the CSV format.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Constructor Detail

      • Csv

        public Csv()
    • Method Detail

      • write

        public int write​(java.io.Writer writer,
                         java.sql.ResultSet rs)
                  throws java.sql.SQLException
        Writes the result set to a file in the CSV format.
        Parameters:
        writer - the writer
        rs - the result set
        Returns:
        the number of rows written
        Throws:
        java.sql.SQLException - on failure
      • write

        public int write​(java.lang.String outputFileName,
                         java.sql.ResultSet rs,
                         java.lang.String charset)
                  throws java.sql.SQLException
        Writes the result set to a file in the CSV format. The result set is read using the following loop:
         while (rs.next()) {
             writeRow(row);
         }
         
        Parameters:
        outputFileName - the name of the csv file
        rs - the result set - the result set must be positioned before the first row.
        charset - the charset or null to use the system default charset
        Returns:
        the number of rows written
        Throws:
        java.sql.SQLException - on failure
      • write

        public int write​(java.sql.Connection conn,
                         java.lang.String outputFileName,
                         java.lang.String sql,
                         java.lang.String charset)
                  throws java.sql.SQLException
        Writes the result set of a query to a file in the CSV format.
        Parameters:
        conn - the connection
        outputFileName - the file name
        sql - the query
        charset - the charset or null to use the system default charset (see system property file.encoding)
        Returns:
        the number of rows written
        Throws:
        java.sql.SQLException - on failure
      • read

        public java.sql.ResultSet read​(java.lang.String inputFileName,
                                       java.lang.String[] colNames,
                                       java.lang.String charset)
                                throws java.sql.SQLException
        Reads from the CSV file and returns a result set. The rows in the result set are created on demand, that means the file is kept open until all rows are read or the result set is closed. If the columns are read from the CSV file, then the following rules are used: columns names that start with a letter or '_', and only contain letters, '_', and digits, are considered case insensitive and are converted to uppercase. Other column names are considered case sensitive (that means they need to be quoted when accessed).
        Parameters:
        inputFileName - the file name
        colNames - or null if the column names should be read from the CSV file
        charset - the charset or null to use the system default charset
        Returns:
        the result set
        Throws:
        java.sql.SQLException - on failure
      • read

        public java.sql.ResultSet read​(java.io.Reader reader,
                                       java.lang.String[] colNames)
                                throws java.io.IOException
        Reads CSV data from a reader and returns a result set. The rows in the result set are created on demand, that means the reader is kept open until all rows are read or the result set is closed.
        Parameters:
        reader - the reader
        colNames - or null if the column names should be read from the CSV file
        Returns:
        the result set
        Throws:
        java.io.IOException - on failure
      • readRow

        public java.lang.Object[] readRow()
                                   throws java.sql.SQLException
        INTERNAL
        Specified by:
        readRow in interface SimpleRowSource
        Returns:
        the row or null
        Throws:
        java.sql.SQLException - on failure
      • reset

        public void reset()
                   throws java.sql.SQLException
        INTERNAL
        Specified by:
        reset in interface SimpleRowSource
        Throws:
        java.sql.SQLException - if this operation is not supported
      • setFieldSeparatorWrite

        public void setFieldSeparatorWrite​(java.lang.String fieldSeparatorWrite)
        Override the field separator for writing. The default is ",".
        Parameters:
        fieldSeparatorWrite - the field separator
      • getFieldSeparatorWrite

        public java.lang.String getFieldSeparatorWrite()
        Get the current field separator for writing.
        Returns:
        the field separator
      • setCaseSensitiveColumnNames

        public void setCaseSensitiveColumnNames​(boolean caseSensitiveColumnNames)
        Override the case sensitive column names setting. The default is false. If enabled, the case of all column names is always preserved.
        Parameters:
        caseSensitiveColumnNames - whether column names are case sensitive
      • getCaseSensitiveColumnNames

        public boolean getCaseSensitiveColumnNames()
        Get the current case sensitive column names setting.
        Returns:
        whether column names are case sensitive
      • setFieldSeparatorRead

        public void setFieldSeparatorRead​(char fieldSeparatorRead)
        Override the field separator for reading. The default is ','.
        Parameters:
        fieldSeparatorRead - the field separator
      • getFieldSeparatorRead

        public char getFieldSeparatorRead()
        Get the current field separator for reading.
        Returns:
        the field separator
      • setLineCommentCharacter

        public void setLineCommentCharacter​(char lineCommentCharacter)
        Set the line comment character. The default is character code 0 (line comments are disabled).
        Parameters:
        lineCommentCharacter - the line comment character
      • getLineCommentCharacter

        public char getLineCommentCharacter()
        Get the line comment character.
        Returns:
        the line comment character, or 0 if disabled
      • setFieldDelimiter

        public void setFieldDelimiter​(char fieldDelimiter)
        Set the field delimiter. The default is " (a double quote). The value 0 means no field delimiter is used.
        Parameters:
        fieldDelimiter - the field delimiter
      • getFieldDelimiter

        public char getFieldDelimiter()
        Get the current field delimiter.
        Returns:
        the field delimiter
      • setEscapeCharacter

        public void setEscapeCharacter​(char escapeCharacter)
        Set the escape character. The escape character is used to escape the field delimiter. This is needed if the data contains the field delimiter. The default escape character is " (a double quote), which is the same as the field delimiter. If the field delimiter and the escape character are both " (double quote), and the data contains a double quote, then an additional double quote is added. Example:
         Data: He said "Hello".
         Escape character: "
         Field delimiter: "
         CSV file: "He said ""Hello""."
         
        If the field delimiter is a double quote and the escape character is a backslash, then escaping is done similar to Java (however, only the field delimiter is escaped). Example:
         Data: He said "Hello".
         Escape character: \
         Field delimiter: "
         CSV file: "He said \"Hello\"."
         
        The value 0 means no escape character is used.
        Parameters:
        escapeCharacter - the escape character
      • getEscapeCharacter

        public char getEscapeCharacter()
        Get the current escape character.
        Returns:
        the escape character
      • setLineSeparator

        public void setLineSeparator​(java.lang.String lineSeparator)
        Set the line separator used for writing. This is usually a line feed (\n or \r\n depending on the system settings). The line separator is written after each row (including the last row), so this option can include an end-of-row marker if needed.
        Parameters:
        lineSeparator - the line separator
      • getLineSeparator

        public java.lang.String getLineSeparator()
        Get the line separator used for writing.
        Returns:
        the line separator
      • setNullString

        public void setNullString​(java.lang.String nullString)
        Set the value that represents NULL. It is only used for non-delimited values.
        Parameters:
        nullString - the null
      • getNullString

        public java.lang.String getNullString()
        Get the current null string.
        Returns:
        the null string.
      • setPreserveWhitespace

        public void setPreserveWhitespace​(boolean value)
        Enable or disable preserving whitespace in unquoted text.
        Parameters:
        value - the new value for the setting
      • getPreserveWhitespace

        public boolean getPreserveWhitespace()
        Whether whitespace in unquoted text is preserved.
        Returns:
        the current value for the setting
      • setWriteColumnHeader

        public void setWriteColumnHeader​(boolean value)
        Enable or disable writing the column header.
        Parameters:
        value - the new value for the setting
      • getWriteColumnHeader

        public boolean getWriteColumnHeader()
        Whether the column header is written.
        Returns:
        the current value for the setting
      • setOptions

        public java.lang.String setOptions​(java.lang.String options)
        INTERNAL. Parse and set the CSV options.
        Parameters:
        options - the options
        Returns:
        the character set