csv.java

非常棒的java数据库

    private void pushBack(int ch) {
        back = ch;
    }

    private int readChar() throws IOException {
        int ch = back;
        if (ch != -1) {
            back = -1;
            return ch;
        } else if (endOfFile) {
            return -1;
        }
        ch = reader.read();
        if (ch < 0) {
            endOfFile = true;
            close();
        }
        return ch;
    }

    private String readValue() throws IOException {
        endOfLine = false;
        String value = null;
        outer:
        while (true) {
            int ch = readChar();
            if (ch < 0 || ch == '\r' || ch == '\n') {
                endOfLine = true;
                break;
            } else if (ch <= ' ') {
                // ignore spaces
                continue;
            } else if (ch == fieldSeparatorRead) {
                // null
                break;
            } else if (ch == fieldDelimiter) {
                // delimited value
                StringBuffer buff = new StringBuffer();
                boolean containsEscape = false;
                while (true) {
                    ch = readChar();
                    if (ch < 0) {
                        value = buff.toString();
                        break outer;
                    } else if (ch == fieldDelimiter) {
                        ch = readChar();
                        if (ch == fieldDelimiter) {
                            buff.append((char) ch);
                        } else {
                            pushBack(ch);
                            break;
                        }
                    } else if (ch == escapeCharacter) {
                        buff.append((char) ch);
                        ch = readChar();
                        if (ch < 0) {
                            break;
                        }
                        containsEscape = true;
                        buff.append((char) ch);
                    } else {
                        buff.append((char) ch);
                    }
                }
                value = buff.toString();
                if (containsEscape) {
                    value = unEscape(value);
                }
                while (true) {
                    ch = readChar();
                    if (ch < 0) {
                        break;
                    } else if (ch == ' ' || ch == '\t') {
                        // ignore
                    } else if (ch == fieldSeparatorRead) {
                        break;
                    } else if (ch == '\r' || ch == '\n') {
                        pushBack(ch);
                        endOfLine = true;
                        break;
                    } else {
                        pushBack(ch);
                        break;
                    }
                }
                break;
            } else if (ch == commentLineStart) {
                // comment until end of line
                while (true) {
                    ch = readChar();
                    if (ch < 0 || ch == '\r' || ch == '\n') {
                        break;
                    }
                }
                endOfLine = true;
                break;
            } else {
                // un-delimited value
                StringBuffer buff = new StringBuffer();
                buff.append((char) ch);
                while (true) {
                    ch = readChar();
                    if (ch == fieldSeparatorRead) {
                        break;
                    } else if (ch == '\r' || ch == '\n') {
                        pushBack(ch);
                        endOfLine = true;
                        break;
                    } else if (ch < 0) {
                        break;
                    }
                    buff.append((char) ch);
                }
                // check un-delimited value for nullString
                value = readNull(buff.toString().trim());
                break;
            }
        }
        // save memory
        return StringCache.get(value);
    }

    private String readNull(String s) {
        return s.equals(nullString) ? null : s;
    }

    private String unEscape(String s) {
        StringBuffer buff = new StringBuffer(s.length());
        int start = 0;
        char[] chars = null;
        while (true) {
            int idx = s.indexOf(escapeCharacter, start);
            if (idx < 0) {
                break;
            }
            if (chars == null) {
                chars = s.toCharArray();
            }
            buff.append(chars, start, idx - start);
            if (idx == s.length() - 1) {
                start = s.length();
                break;
            }
            buff.append(chars[idx + 1]);
            start = idx + 2;
        }
        buff.append(s.substring(start));
        return buff.toString();
    }

    /**
     * INTERNAL
     */
    public Object[] readRow() throws SQLException {
        if (reader == null) {
            return null;
        }
        String[] row = new String[columnNames.length];
        try {
            for (int i = 0;; i++) {
                String v = readValue();
                if (v == null) {
                    if (endOfFile && i == 0) {
                        return null;
                    }
                    if (endOfLine) {
                        if (i == 0) {
                            // empty line
                            i--;
                            continue;
                        }
                        break;
                    }
                }
                if (i < row.length) {
                    row[i] = v;
                }
            }
        } catch (IOException e) {
            throw convertException("IOException reading from " + fileName, e);
        }
        return row;
    }

    private SQLException convertException(String message, Exception e) {
        SQLException s = new SQLException(message, "CSV");
//#ifdef JDK14
        s.initCause(e);
//#endif
        return s;
    }

    /**
     * INTERNAL
     */
    public void close() {
        IOUtils.closeSilently(reader);
        reader = null;
        IOUtils.closeSilently(writer);
        writer = null;
    }

    /**
     * INTERNAL
     */
    public void reset() throws SQLException {
        throw new SQLException("Method is not supported", "CSV");
    }

    /**
     * Override the field separator for writing. The default is ",".
     *
     * @param fieldSeparatorWrite the field separator
     */
    public void setFieldSeparatorWrite(String fieldSeparatorWrite) {
        this.fieldSeparatorWrite = fieldSeparatorWrite;
    }

    /**
     * Get the current field separator for writing.
     *
     * @return the field separator
     */
    public String getFieldSeparatorWrite() {
        return fieldSeparatorWrite;
    }

    /**
     * Override the field separator for reading. The default is ','.
     *
     * @param fieldSeparatorRead the field separator
     */
    public void setFieldSeparatorRead(char fieldSeparatorRead) {
        this.fieldSeparatorRead = fieldSeparatorRead;
    }

    /**
     * Get the current field separator for reading.
     *
     * @return the field separator
     */
    public char getFieldSeparatorRead() {
        return fieldSeparatorRead;
    }

    /**
     * Get the current row separator for writing.
     *
     * @return the row separator
     */
    public String getRowSeparatorWrite() {
        return rowSeparatorWrite;
    }

    /**
     * Override the end-of-row marker for writing. The default is null. After
     * writing the end-of-row marker, a line feed is written (\n or \r\n
     * depending on the system settings).
     * 
     * @param rowSeparatorWrite the row separator
     */
    public void setRowSeparatorWrite(String rowSeparatorWrite) {
        this.rowSeparatorWrite = rowSeparatorWrite;
    }

    /**
     * Set the field delimiter. The default is " (a double quote).
     * 0 means no field delimiter is used.
     *
     * @param fieldDelimiter the field delimiter
     */
    public void setFieldDelimiter(char fieldDelimiter) {
        this.fieldDelimiter = fieldDelimiter;
    }

    /**
     * Get the current field delimiter.
     * 0 means no field delimiter is used.
     *
     * @return the field delimiter
     */
    public char getFieldDelimiter() {
        return fieldDelimiter;
    }

    /**
     * Set the escape character (used to escape the field delimiter). The
     * default is " (a double quote). 0 means no escape character is used.
     * 
     * @param escapeCharacter the escape character
     */
    public void setEscapeCharacter(char escapeCharacter) {
        this.escapeCharacter = escapeCharacter;
    }

    /**
     * Get the current escape character.
     * 0 means no escape character is used.
     *
     * @return the escape character
     */
    public char getEscapeCharacter() {
        return escapeCharacter;
    }

    /**
     * Set the line separator.
     *
     * @param lineSeparator the line separator
     */
    public void setLineSeparator(String lineSeparator) {
        this.lineSeparator = lineSeparator;
    }

    /**
     * Set the value that represents NULL.
     *
     * @param nullString the null
     */
    public void setNullString(String nullString) {
        this.nullString = nullString;
    }

}