TerminalMonitorpublic class TerminalMonitor extends Object | Examples 4.4 through 4.6. |
(Omit source code)
| Fields Summary |
|---|
| static Connection | connection | | static BufferedReader | input |
| Methods Summary |
|---|
| public static void | executeStatement(java.lang.StringBuffer buff)
String sql = buff.toString();
Statement statement = null;
try {
statement = connection.createStatement();
if( statement.execute(sql) ) { // true means the SQL was a SELECT
processResults(statement.getResultSet());
}
else { // no result sets, see how many rows were affected
int num;
switch(num = statement.getUpdateCount()) {
case 0:
System.out.println("No rows affected.");
break;
case 1:
System.out.println(num + " row affected.");
break;
default:
System.out.println(num + " rows affected.");
}
}
}
catch( SQLException e ) {
throw e;
}
finally { // close out the statement
if( statement != null ) {
try { statement.close(); }
catch( SQLException e ) { }
}
}
| | public static void | main(java.lang.String[] args)
DriverPropertyInfo[] required;
StringBuffer buffer = new StringBuffer();
Properties props = new Properties();
boolean connected = false;
Driver driver;
String url;
int line = 1; // Mark current input line
if( args.length < 1 ) {
System.out.println("Syntax: <java -Djdbc.drivers=DRIVER_NAME " +
"TerminalMonitor JDBC_URL>");
return;
}
url = args[0];
// We have to get a reference to the driver so we can
// find out what values to prompt the user for in order
// to make a connection.
try {
driver = DriverManager.getDriver(url);
}
catch( SQLException e ) {
e.printStackTrace();
System.err.println("Unable to find a driver for the specified " +
"URL.");
System.err.println("Make sure you passed the jdbc.drivers " +
"property on the command line to specify " +
"the driver to be used.");
return;
}
try {
required = driver.getPropertyInfo(url, props);
}
catch( SQLException e ) {
e.printStackTrace();
System.err.println("Unable to get driver property information.");
return;
}
input = new BufferedReader(new InputStreamReader(System.in));
// some drivers do not implement this properly
// if that is the case, prompt for user name and password
try {
if( required.length < 1 ) {
props.put("user", prompt("user: "));
props.put("password", prompt("password: "));
}
else {
// for each required attribute in the driver property info
// prompt the user for the value
for(int i=0; i<required.length; i++) {
if( !required[i].required ) {
continue;
}
props.put(required[i].name,
prompt(required[i].name + ": "));
}
}
}
catch( IOException e ) {
e.printStackTrace();
System.err.println("Unable to read property info.");
return;
}
// Make the connection.
try {
connection = DriverManager.getConnection(url, props);
}
catch( SQLException e ) {
e.printStackTrace();
System.err.println("Unable to connect to the database.");
}
connected = true;
System.out.println("Connected to " + url);
// Enter into a user input loop
while( connected ) {
String tmp, cmd;
// Print a prompt
if( line == 1 ) {
System.out.print("TM > ");
}
else {
System.out.print(line + " -> ");
}
System.out.flush();
// Get the next line of input
try {
tmp = input.readLine();
}
catch( java.io.IOException e ) {
e.printStackTrace();
return;
}
// Get rid of extra space in the command
cmd = tmp.trim();
// The user wants to commit pending transactions
if( cmd.equals("commit") ) {
try {
connection.commit();
System.out.println("Commit successful.");
}
catch( SQLException e ) {
System.out.println("Error in commit: " + e.getMessage());
}
buffer = new StringBuffer();
line = 1;
}
// The user wants to execute the current buffer
else if( cmd.equals("go") ) {
if( !buffer.equals("") ) {
try {
executeStatement(buffer);
}
catch( SQLException e ) {
System.out.println(e.getMessage());
}
}
buffer = new StringBuffer();
line = 1;
continue;
}
// The user wants to quit
else if( cmd.equals("quit") ) {
connected = false;
continue;
}
// The user wants to clear the current buffer
else if( cmd.equals("reset") ) {
buffer = new StringBuffer();
line = 1;
continue;
}
// The user wants to abort a pending transaction
else if( cmd.equals("rollback") ) {
try {
connection.rollback();
System.out.println("Rollback successful.");
}
catch( SQLException e ) {
System.out.println("An error occurred during rollback: " +
e.getMessage());
}
buffer = new StringBuffer();
line = 1;
}
// The user wants version info
else if( cmd.startsWith("show") ) {
DatabaseMetaData meta;
try {
meta = connection.getMetaData();
cmd = cmd.substring(5, cmd.length()).trim();
if( cmd.equals("version") ) {
showVersion(meta);
}
else {
System.out.println("show version"); // Bad arg
}
}
catch( SQLException e ) {
System.out.println("Failed to load meta data: " +
e.getMessage());
}
buffer = new StringBuffer();
line = 1;
}
// The input that is not a keyword should appended be to the buffer
else {
buffer.append(" " + tmp);
line++;
continue;
}
}
try {
connection.close();
}
catch( SQLException e ) {
System.out.println("Error closing connection: " + e.getMessage());
}
System.out.println("Connection closed.");
| | public static void | processResults(java.sql.ResultSet results)
try {
ResultSetMetaData meta = results.getMetaData();
StringBuffer bar = new StringBuffer();
StringBuffer buffer = new StringBuffer();
int cols = meta.getColumnCount();
int row_count = 0;
int i, width = 0;
// Prepare headers for each of the columns
// The display should look like:
// --------------------------------------
// | Column One | Column Two |
// --------------------------------------
// | Row 1 Value | Row 1 Value |
// --------------------------------------
// create the bar that is as long as the total of all columns
for(i=1; i<=cols; i++) {
width += meta.getColumnDisplaySize(i);
}
width += 1 + cols;
for(i=0; i<width; i++) {
bar.append('-");
}
bar.append('\n");
buffer.append(bar.toString() + "|");
// After the first bar goes the column labels
for(i=1; i<=cols; i++) {
StringBuffer filler = new StringBuffer();
String label = meta.getColumnLabel(i);
int size = meta.getColumnDisplaySize(i);
int x;
// If the label is longer than the column is wide,
// then we truncate the column label
if( label.length() > size ) {
label = label.substring(0, size);
}
// If the label is shorter than the column, pad it with spaces
if( label.length() < size ) {
int j;
x = (size-label.length())/2;
for(j=0; j<x; j++) {
filler.append(' ");
}
label = filler + label + filler;
if( label.length() > size ) {
label = label.substring(0, size);
}
else {
while( label.length() < size ) {
label += " ";
}
}
}
// Add the column header to the buffer
buffer.append(label + "|");
}
// Add the lower bar
buffer.append("\n" + bar.toString());
// Format each row in the result set and add it on
while( results.next() ) {
row_count++;
buffer.append('|");
// Format each column of the row
for(i=1; i<=cols; i++) {
StringBuffer filler = new StringBuffer();
Object value = results.getObject(i);
int size = meta.getColumnDisplaySize(i);
String str;
if( results.wasNull() ) {
str = "NULL";
}
else {
str = value.toString();
}
if( str.length() > size ) {
str = str.substring(0, size);
}
if( str.length() < size ) {
int j, x;
x = (size-str.length())/2;
for(j=0; j<x; j++) {
filler.append(' ");
}
str = filler + str + filler;
if( str.length() > size ) {
str = str.substring(0, size);
}
else {
while( str.length() < size ) {
str += " ";
}
}
}
buffer.append(str + "|");
}
buffer.append("\n");
}
// Stick a row count up at the top
if( row_count == 0 ) {
buffer = new StringBuffer("No rows selected.\n");
}
else if( row_count == 1 ) {
buffer = new StringBuffer("1 row selected.\n" +
buffer.toString() + bar.toString());
}
else {
buffer = new StringBuffer(row_count + " rows selected.\n" +
buffer.toString() + bar.toString());
}
System.out.print(buffer.toString());
System.out.flush();
}
catch( SQLException e ) {
throw e;
}
finally {
try { results.close(); }
catch( SQLException e ) { }
}
| | public static java.lang.String | prompt(java.lang.String prop)
String tmp = "";
while( tmp.length() < 1 ) {
System.out.print(prop);
tmp = input.readLine().trim();
}
return tmp;
| | public static void | showVersion(java.sql.DatabaseMetaData meta)
try {
System.out.println("TerminalMonitor v2.0");
System.out.println("DBMS: " + meta.getDatabaseProductName() +
" " + meta.getDatabaseProductVersion());
System.out.println("JDBC Driver: " + meta.getDriverName() +
" " + meta.getDriverVersion());
}
catch( SQLException e ) {
System.out.println("Failed to get version info: " +
e.getMessage());
}
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