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Diffstat (limited to 'src/interfaces/jdbc/example/psql.java')
| -rw-r--r-- | src/interfaces/jdbc/example/psql.java | 210 |
1 files changed, 210 insertions, 0 deletions
diff --git a/src/interfaces/jdbc/example/psql.java b/src/interfaces/jdbc/example/psql.java new file mode 100644 index 00000000000..adad24f4d08 --- /dev/null +++ b/src/interfaces/jdbc/example/psql.java @@ -0,0 +1,210 @@ +package example; + +import java.io.*; +import java.sql.*; +import java.text.*; + +/** + * This example application demonstrates some of the drivers other features + * by implementing a simple psql replacement in Java. + * + */ + +public class psql +{ + Connection db; // The connection to the database + Statement st; // Our statement to run queries with + DatabaseMetaData dbmd; // This defines the structure of the database + + public psql(String args[]) throws ClassNotFoundException, FileNotFoundException, IOException, SQLException + { + String url = args[0]; + String usr = args[1]; + String pwd = args[2]; + + // Load the driver + Class.forName("postgresql.Driver"); + + // Connect to database + System.out.println("Connecting to Database URL = " + url); + db = DriverManager.getConnection(url, usr, pwd); + + dbmd = db.getMetaData(); + st = db.createStatement(); + + // This prints the backend's version + System.out.println("Connected to "+dbmd.getDatabaseProductName()+" "+dbmd.getDatabaseProductVersion()); + + System.out.println(); + + // This provides us the means of reading from stdin + StreamTokenizer input = new StreamTokenizer(new InputStreamReader(System.in)); + input.resetSyntax(); + input.slashSlashComments(true); // allow // as a comment delimiter + input.eolIsSignificant(false); // treat eol's as spaces + input.wordChars(32,126); + input.whitespaceChars(59,59); + input.quoteChar(39); + + // Now the main loop. + int tt=0,lineno=1; + while(tt!=StreamTokenizer.TT_EOF) { + System.out.print("["+lineno+"] "); + System.out.flush(); + + // Here, we trap SQLException so they don't terminate the application + try { + if((tt=input.nextToken())==StreamTokenizer.TT_WORD) { + processLine(input.sval); + lineno++; + } + } catch(SQLException ex) { + System.out.println(ex.getMessage()); + } + } + + System.out.println("Now closing the connection"); + st.close(); + db.close(); + + } + + /** + * This processes a statement + */ + public void processLine(String line) throws SQLException + { + if(line.startsWith("\\")) { + processSlashCommand(line); + return; + } + + boolean type = st.execute(line); + boolean loop=true; + while(loop) { + if(type) { + // A ResultSet was returned + ResultSet rs=st.getResultSet(); + displayResult(rs); + } else { + int count = st.getUpdateCount(); + + if(count==-1) { + // This indicates nothing left + loop=false; + } else { + // An update count was returned + System.out.println("Updated "+st.getUpdateCount()+" rows"); + } + } + + if(loop) + type = st.getMoreResults(); + } + } + + /** + * This displays a result set. + * Note: it closes the result once complete. + */ + public void displayResult(ResultSet rs) throws SQLException + { + ResultSetMetaData rsmd = rs.getMetaData(); + + // Print the result column names + int cols = rsmd.getColumnCount(); + for(int i=1;i<=cols;i++) + System.out.print(rsmd.getColumnLabel(i)+(i<cols?"\t":"\n")); + + // now the results + while(rs.next()) { + for(int i=1;i<=cols;i++) { + Object o = rs.getObject(i); + if(rs.wasNull()) + System.out.print("{null}"+(i<cols?"\t":"\n")); + else + System.out.print(rs.getObject(i).toString()+(i<cols?"\t":"\n")); + } + } + + // finally close the result set + rs.close(); + } + + /** + * This process / commands (for now just /d) + */ + public void processSlashCommand(String line) throws SQLException + { + if(line.startsWith("\\d")) { + + if(line.startsWith("\\d ")) { + // Display details about a table + String table=line.substring(3); + displayResult(dbmd.getColumns(null,null,table,"%")); + } else { + String types[] = null; + if(line.equals("\\d")) + types=allUserTables; + else if(line.equals("\\di")) + types=usrIndices; + else if(line.equals("\\dt")) + types=usrTables; + else if(line.equals("\\ds")) + types=usrSequences; + else if(line.equals("\\dS")) + types=sysTables; + else + throw new SQLException("Unsupported \\d command: "+line); + + // Display details about all system tables + // + // Note: the first two arguments are ignored. To keep to the spec, + // you must put null here + // + displayResult(dbmd.getTables(null,null,"%",types)); + } + } else + throw new SQLException("Unsupported \\ command: "+line); + } + + private static final String allUserTables[] = {"TABLE","INDEX","SEQUENCE"}; + private static final String usrIndices[] = {"INDEX"}; + private static final String usrTables[] = {"TABLE"}; + private static final String usrSequences[] = {"SEQUENCE"}; + private static final String sysTables[] = {"SYSTEM TABLE","SYSTEM INDEX"}; + + /** + * Display some instructions on how to run the example + */ + public static void instructions() + { + System.out.println("\nThis example shows how some of the other JDBC features work within the\ndriver. It does this by implementing a very simple psql equivalent in java.\nNot everything that psql does is implemented.\n"); + System.out.println("Useage:\n java example.psql jdbc:postgresql:database user password [debug]\n\nThe debug field can be anything. It's presence will enable DriverManager's\ndebug trace. Unless you want to see screens of items, don't put anything in\nhere."); + System.exit(1); + } + + /** + * This little lot starts the test + */ + public static void main(String args[]) + { + System.out.println("PostgreSQL psql example v6.3 rev 1\n"); + + if(args.length<3) + instructions(); + + // This line outputs debug information to stderr. To enable this, simply + // add an extra parameter to the command line + if(args.length>3) + DriverManager.setLogStream(System.err); + + // Now run the tests + try { + psql test = new psql(args); + } catch(Exception ex) { + System.err.println("Exception caught.\n"+ex); + ex.printStackTrace(); + } + } +} |