Source Code Cross Referenced for FileUtil.java in  » Database-Client » SQL-Workbench » workbench » util » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Database Client » SQL Workbench » workbench.util 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /*
002:         * FileUtil.java
003:         *
004:         * This file is part of SQL Workbench/J, http://www.sql-workbench.net
005:         *
006:         * Copyright 2002-2008, Thomas Kellerer
007:         * No part of this code maybe reused without the permission of the author
008:         *
009:         * To contact the author please send an email to: support@sql-workbench.net
010:         *
011:         */
012:        package workbench.util;
013:
014:        import java.io.BufferedReader;
015:        import java.io.Closeable;
016:        import java.io.File;
017:        import java.io.FileReader;
018:        import java.io.IOException;
019:        import java.io.InputStream;
020:        import java.io.OutputStream;
021:        import java.io.Reader;
022:        import java.util.Collection;
023:        import java.util.HashSet;
024:        import java.util.List;
025:        import java.util.Set;
026:        import workbench.log.LogMgr;
027:
028:        /**
029:         * @author  support@sql-workbench.net
030:         */
031:        public class FileUtil {
032:            private static final int BUFF_SIZE = 16 * 1024;
033:
034:            /*
035:             * Closes all streams in the list.
036:             * @param a list of streams to close
037:             * @see #closeQuitely(Closeable)
038:             */
039:            public static void closeStreams(List<Closeable> streams) {
040:                if (streams == null)
041:                    return;
042:
043:                for (Closeable str : streams) {
044:                    closeQuitely(str);
045:                }
046:            }
047:
048:            /**
049:             * Read the lines of the given Reader into a Collection.
050:             * The Reader will be closed after all lines have been read.
051:             * 
052:             * @param in the "file" to read
053:             * @return a Collection with all the lines in the file
054:             */
055:            public static Collection<String> getLines(BufferedReader in) {
056:                Set result = new HashSet<String>();
057:
058:                try {
059:                    String line;
060:                    while ((line = in.readLine()) != null) {
061:                        if (!StringUtil.isEmptyString(line))
062:                            result.add(line);
063:                    }
064:                } catch (Exception e) {
065:                    LogMgr.logError("FileUtil.getLines", "Error reading lines",
066:                            e);
067:                } finally {
068:                    closeQuitely(in);
069:                }
070:                return result;
071:            }
072:
073:            /**
074:             * Read the contents of the Reader into the provided StringBuilder.
075:             * Max. numLines lines are read.
076:             * 
077:             * The Reader will not be closed
078:             * 
079:             * @param in the Reader to be used 
080:             * @param buffer the StringBuilder to received the lines
081:             * @param numLines the max. number of lines to be read
082:             * @param lineEnd the lineEnding to be used
083:             * @return the number of lines read
084:             */
085:            public static final int readLines(BufferedReader in,
086:                    StringBuilder buffer, int numLines, String lineEnd)
087:                    throws IOException {
088:                int lines = 0;
089:                String line = in.readLine();
090:                while (line != null && lines < numLines) {
091:                    buffer.append(line);
092:                    buffer.append(lineEnd);
093:                    lines++;
094:                    line = in.readLine();
095:                }
096:                if (line != null) {
097:                    // loop was ended due to numLines reached, so append the 
098:                    // last line retrieved
099:                    buffer.append(line);
100:                    buffer.append(lineEnd);
101:                }
102:                return lines;
103:            }
104:
105:            /**
106:             * Try to detect the line ending used by the passed Reader.
107:             * This will advance the reader until a line ending is found.
108:             * The reader will not be closed
109:             * 
110:             * @param in the "file" to test
111:             * @return the sequence of characters used as the line ending (e.g. \n or \r\n)
112:             * @throws java.io.IOException
113:             */
114:            public static final String getLineEnding(Reader in)
115:                    throws IOException {
116:                String ending = null;
117:                char c = (char) in.read();
118:                while (c != -1) {
119:                    if (c == '\r') {
120:                        char n = (char) in.read();
121:                        if (n == '\n') {
122:                            ending = "\r\n";
123:                            break;
124:                        }
125:                    } else if (c == '\n') {
126:                        ending = "\n";
127:                        break;
128:                    }
129:                    c = (char) in.read();
130:                }
131:                return ending;
132:            }
133:
134:            public static final long estimateRecords(File f) throws IOException {
135:                return estimateRecords(f, 5);
136:            }
137:
138:            /**
139:             * Tries to estimate the number of records in the given file.
140:             * This is done by reading the first <tt>sampleLines</tt> records
141:             * of the file and assuming the average size of an row in the first
142:             * lines is close to the average row in the complete file.
143:             */
144:            public static final long estimateRecords(File f, long sampleLines)
145:                    throws IOException {
146:                if (sampleLines <= 0)
147:                    throw new IllegalArgumentException(
148:                            "Sample size must be greater then zero");
149:                if (!f.exists())
150:                    return -1;
151:                if (!f.isFile())
152:                    return -1;
153:                long size = f.length();
154:                if (size == 0)
155:                    return 0;
156:
157:                long lineSize = 0;
158:
159:                BufferedReader in = null;
160:                try {
161:                    in = new BufferedReader(new FileReader(f), 8192);
162:                    in.readLine(); // skip the first line
163:                    int lfSize = StringUtil.LINE_TERMINATOR.length();
164:                    for (int i = 0; i < sampleLines; i++) {
165:                        String line = in.readLine();
166:                        if (line == null)
167:                            return i + 1;
168:                        lineSize += (line.length() + lfSize);
169:                    }
170:                } finally {
171:                    closeQuitely(in);
172:                }
173:                return (size / (lineSize / sampleLines));
174:
175:            }
176:
177:            /**
178:             * Copies the content of the InputStream to the OutputStream.
179:             * Both streams are closed automatically.
180:             */
181:            public static long copy(InputStream in, OutputStream out)
182:                    throws IOException {
183:                long filesize = 0;
184:                try {
185:                    byte[] buffer = new byte[BUFF_SIZE];
186:                    int bytesRead = in.read(buffer);
187:                    while (bytesRead != -1) {
188:                        filesize += bytesRead;
189:                        out.write(buffer, 0, bytesRead);
190:                        bytesRead = in.read(buffer);
191:                    }
192:                } finally {
193:                    closeQuitely(out);
194:                    closeQuitely(in);
195:                }
196:                return filesize;
197:            }
198:
199:            /**
200:             * Read the content of the Reader into a String.
201:             * The Reader is closed automatically.
202:             */
203:            public static String readCharacters(Reader in) throws IOException {
204:                if (in == null)
205:                    return null;
206:                StringBuilder result = new StringBuilder(1024);
207:                char[] buff = new char[BUFF_SIZE];
208:                int bytesRead = in.read(buff);
209:                try {
210:                    while (bytesRead > -1) {
211:                        result.append(buff, 0, bytesRead);
212:                        bytesRead = in.read(buff);
213:                    }
214:                } finally {
215:                    closeQuitely(in);
216:                }
217:                return result.toString();
218:            }
219:
220:            /**
221:             * Read the content of the InputStream into a ByteArray.
222:             * The InputStream is closed automatically.
223:             */
224:            public static byte[] readBytes(InputStream in) throws IOException {
225:                if (in == null)
226:                    return null;
227:                ByteBuffer result = new ByteBuffer();
228:                byte[] buff = new byte[BUFF_SIZE];
229:
230:                try {
231:                    int bytesRead = in.read(buff);
232:                    while (bytesRead > -1) {
233:                        result.append(buff, 0, bytesRead);
234:                        bytesRead = in.read(buff);
235:                    }
236:                } finally {
237:                    closeQuitely(in);
238:                }
239:                return result.getBuffer();
240:            }
241:
242:            /**
243:             * Returns the number of characters according to the 
244:             * encoding in the specified file. For single-byte 
245:             * encodings this should be identical to source.length()
246:             * 
247:             * For large files this might take some time!
248:             * 
249:             * @param source the (text) file to check
250:             * @param encoding the encoding of the text file
251:             * @return the number of characters (not bytes) in the file
252:             */
253:            public static long getCharacterLength(File source, String encoding)
254:                    throws IOException {
255:                BufferedReader r = null;
256:                long result = 0;
257:                try {
258:                    r = EncodingUtil.createBufferedReader(source, encoding,
259:                            32 * 1024);
260:                    // Not very efficient, but I can't think of a different solution
261:                    // to retrieve the number of characters
262:                    result = r.skip(Long.MAX_VALUE);
263:                } finally {
264:                    closeQuitely(r);
265:                }
266:
267:                return result;
268:            }
269:
270:            /**
271:             * Closes a Closeable without throwing any errors
272:             * 
273:             * @param c the Closeable to close
274:             */
275:            public static void closeQuitely(Closeable c) {
276:                if (c == null)
277:                    return;
278:
279:                try {
280:                    c.close();
281:                } catch (IOException e) {
282:                    // ignore
283:                }
284:            }
285:        }
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