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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1997, 2015 Oracle and/or its affiliates. All rights reserved.
*
* $Id$
*/
package db;
import com.sleepycat.db.*;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.InputStreamReader;
import java.io.IOException;
import java.io.PrintStream;
class AccessExample {
private static final int EXIT_SUCCESS = 0;
private static final int EXIT_FAILURE = 1;
public AccessExample() {
}
public static void usage() {
System.out.println("usage: java " +
"db.AccessExample [-r] [database]\n");
System.exit(EXIT_FAILURE);
}
public static void main(String[] argv) {
boolean removeExistingDatabase = false;
String databaseName = "access.db";
for (int i = 0; i < argv.length; i++) {
if (argv[i].equals("-r"))
removeExistingDatabase = true;
else if (argv[i].equals("-?"))
usage();
else if (argv[i].startsWith("-"))
usage();
else {
if ((argv.length - i) != 1)
usage();
databaseName = argv[i];
break;
}
}
try {
AccessExample app = new AccessExample();
app.run(removeExistingDatabase, databaseName);
} catch (DatabaseException dbe) {
System.err.println("AccessExample: " + dbe.toString());
System.exit(EXIT_FAILURE);
} catch (FileNotFoundException fnfe) {
System.err.println("AccessExample: " + fnfe.toString());
System.exit(EXIT_FAILURE);
}
System.exit(EXIT_SUCCESS);
}
// Prompts for a line, and keeps prompting until a non blank
// line is returned. Returns null on error.
//
public static String askForLine(InputStreamReader reader,
PrintStream out, String prompt) {
String result = "";
while (result != null && result.length() == 0) {
out.print(prompt);
out.flush();
result = getLine(reader);
}
return result;
}
// Not terribly efficient, but does the job.
// Works for reading a line from stdin or a file.
// Returns null on EOF. If EOF appears in the middle
// of a line, returns that line, then null on next call.
//
public static String getLine(InputStreamReader reader) {
StringBuffer b = new StringBuffer();
int c;
try {
while ((c = reader.read()) != -1 && c != '\n') {
if (c != '\r')
b.append((char)c);
}
} catch (IOException ioe) {
c = -1;
}
if (c == -1 && b.length() == 0)
return null;
else
return b.toString();
}
public void run(boolean removeExistingDatabase, String databaseName)
throws DatabaseException, FileNotFoundException {
// Remove the previous database.
if (removeExistingDatabase)
new File(databaseName).delete();
// Create the database object.
// There is no environment for this simple example.
DatabaseConfig dbConfig = new DatabaseConfig();
dbConfig.setErrorStream(System.err);
dbConfig.setErrorPrefix("AccessExample");
dbConfig.setType(DatabaseType.BTREE);
dbConfig.setAllowCreate(true);
Database table = new Database(databaseName, null, dbConfig);
//
// Insert records into the database, where the key is the user
// input and the data is the user input in reverse order.
//
InputStreamReader reader = new InputStreamReader(System.in);
for (;;) {
String line = askForLine(reader, System.out, "input> ");
if (line == null)
break;
String reversed = (new StringBuffer(line)).reverse().toString();
// See definition of StringDbt below
//
StringEntry key = new StringEntry(line);
StringEntry data = new StringEntry(reversed);
try {
if (table.putNoOverwrite(null, key, data) == OperationStatus.KEYEXIST)
System.out.println("Key " + line + " already exists.");
} catch (DatabaseException dbe) {
System.out.println(dbe.toString());
}
}
// Acquire an iterator for the table.
Cursor cursor;
cursor = table.openCursor(null, null);
// Walk through the table, printing the key/data pairs.
// See class StringDbt defined below.
//
StringEntry key = new StringEntry();
StringEntry data = new StringEntry();
while (cursor.getNext(key, data, null) == OperationStatus.SUCCESS)
System.out.println(key.getString() + " : " + data.getString());
cursor.close();
table.close();
}
// Here's an example of how you can extend DatabaseEntry in a
// straightforward way to allow easy storage/retrieval of strings,
// or whatever kind of data you wish. We've declared it as a static
// inner class, but it need not be.
//
static /*inner*/
class StringEntry extends DatabaseEntry {
StringEntry() {
}
StringEntry(String value) {
setString(value);
}
void setString(String value) {
byte[] data = value.getBytes();
setData(data);
setSize(data.length);
}
String getString() {
return new String(getData(), getOffset(), getSize());
}
}
}
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