uk.ac.starlink.util.CgiQuery Maven / Gradle / Ivy
package uk.ac.starlink.util;
import java.net.MalformedURLException;
import java.net.URL;
import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;
import java.util.Locale;
/**
* Utility class for constructing CGI query strings.
*
* @author Mark Taylor (Starlink)
* @since 1 Oct 2004
*/
public class CgiQuery {
private final StringBuffer sbuf_;
private int narg;
/** Legal characters for query part of a URI - see RFC 2396. */
private final static String QUERY_CHARS =
"abcdefghijklmnopqrstuvwxyz" +
"ABCDEFGHIJKLMNOPQRSTUVWXYZ" +
"0123456789" +
"-_.!~*'()";
/**
* Constructs a CGI query.
* The submitted base argument may optionally be a
* partially-formed CGI-query, that is, one ending in a '?'
* and zero or more '&name=value' pairs.
*
* @param base base part of the CGI URL
* @throws IllegalArgumentException if base is not a legal
* base URL
*/
public CgiQuery( String base ) {
base = base.trim();
try {
new URL( base );
}
catch ( MalformedURLException e ) {
throw (IllegalArgumentException)
new IllegalArgumentException( "Not a url: " + base )
.initCause( e );
}
sbuf_ = new StringBuffer( base );
}
/**
* Adds an integer argument to this query.
* For convenience the return value is this query.
*
* @param name argument name
* @param value value for the argument
* @return this query
*/
public CgiQuery addArgument( String name, long value ) {
return addArgument( name, Long.toString( value ) );
}
/**
* Adds a floating point argument to this query.
* For convenience the return value is this query.
*
* @param name argument name
* @param value value for the argument
* @return this query
*/
public CgiQuery addArgument( String name, double value ) {
return addArgument( name, formatDouble( value ) );
}
/**
* Adds a single-precision floating point argument to this query.
* For convenience the return value is this query.
*
* @param name argument name
* @param value value for the argument
* @return this query
*/
public CgiQuery addArgument( String name, float value ) {
return addArgument( name, formatFloat( value ) );
}
/**
* Adds a string argument to this query.
* For convenience the return value is this query.
*
* @param name argument name
* @param value unescaped value for the argument
* @return this query
*/
public CgiQuery addArgument( String name, String value ) {
if ( narg++ == 0 ) {
char lastChar = sbuf_.charAt( sbuf_.length() - 1 );
if ( lastChar != '?' && lastChar != '&' ) {
sbuf_.append( sbuf_.indexOf( "?" ) >= 0 ? '&' : '?' );
}
}
else {
sbuf_.append( '&' );
}
sbuf_.append( name )
.append( '=' );
if ( value != null ) {
for ( int i = 0; i < value.length(); i++ ) {
char c = value.charAt( i );
if ( QUERY_CHARS.indexOf( c ) >= 0 ) {
sbuf_.append( c );
}
else if ( c >= 0x10 && c <= 0x7f ) {
sbuf_.append( '%' )
.append( Integer.toHexString( (int) c ) );
}
else {
throw new IllegalArgumentException( "Bad character in \"" +
value + "\"" );
}
}
}
return this;
}
/**
* Returns this query as a URL.
*
* @return query URL
*/
public URL toURL() {
try {
return new URL( sbuf_.toString() );
}
catch ( MalformedURLException e ) {
throw new AssertionError(); // I think, since base is a URL
}
}
public boolean equals( Object o ) {
return o instanceof CgiQuery
&& o.toString().equals( toString() );
}
public int hashCode() {
return toString().hashCode();
}
/**
* Returns this query as a string.
*
* @return query string
*/
public String toString() {
return sbuf_.toString();
}
/**
* Formats a double precision value.
*
* @param value value
* @return string representation
*/
public static String formatDouble( double value ) {
return formatDouble( value, 16, 32 );
}
/**
* Formats a single precision value.
*
* @param value value
* @return string representation
*/
public static String formatFloat( float value ) {
return formatDouble( (double) value, 7, 32 );
}
/**
* Formats a floating point value.
* It will be done in fixed point format if it can be done within the
* given number of characters, else exponential notation.
*
* @param value value
* @param nsf number of significant figures
* @param maxleng maximum length of string - if longer than this,
* will return to exponential notation
* @return fixed format string representation
*/
public static String formatDouble( double value, int nsf, int maxleng ) {
String sval = Double.toString( value );
if ( sval.indexOf( 'E' ) < 0 ) {
return sval;
}
else {
int log10 = log10( value );
StringBuffer fbuf = new StringBuffer( "0." );
for ( int i = 0; i < nsf - log10; i++ ) {
fbuf.append( '0' );
}
DecimalFormat format = new DecimalFormat( fbuf.toString() );
format.setDecimalFormatSymbols( new DecimalFormatSymbols( Locale
.US ) );
String fval = format.format( value );
fval = fval.replaceFirst( "0+$", "" );
if ( fval.length() <= maxleng ) {
return fval;
}
else {
return sval;
}
}
}
/**
* Returns approximate logarithm to base 10 of the value.
*
* @param value value
* @return approximate log to base 10
*/
private static int log10( double value ) {
return (int)
Math.round( Math.log( Math.abs( value ) ) / Math.log( 10 ) );
}
}