Annulla la registrazione dei caratteri con GraphicsEnvironment?

Question

di recente ho scoperto come registrare un font TTF con la GraphicsEnvironment locali, st, per il mio caso d'uso (SVG-to-PNG transcodifica), Apache Batik può riconoscere il tipo di carattere:

import java.awt.Font; 
import java.awt.FontFormatException; 
import java.awt.GraphicsEnvironment; 

// [...] 

GraphicsEnvironment lge = GraphicsEnvironment.getLocalGraphicsEnvironment(); 
try { 
    Font font = Font.createFont(Font.TRUETYPE_FONT, fontFile); 
    lge.registerFont(font); 
} catch (FontFormatException e) { 
    logger.warn(e.getMessage(), e); 
} catch (IOException e) { 
    logger.warn(e.getMessage(), e); 
} 

Tuttavia, ero chiedendo se potessi annullare la registrazione di tutti i font preesistenti per garantire che solo i caratteri che registro vengano utilizzati nella transcodifica.

Non c'è GraphicsEnvironment # unregisterFont (...), come è possibile ottenere questo risultato?

PS: Non voglio creare una sottoclasse di GraphicsEnvironment, dato che non posso assumere la presenza di sottoclassi specifiche, come sun.awt.Win32GraphicsEnvironment.

EDIT: Alcune Ulteriori informazioni:

• Come sun.font.FontManager cambia con Java7 (dalla classe di interfacciarsi, e quant'altro), preferisco non usare qualsiasi soluzione affidamento su di esso.
• My JVM è Oracle JVM.

Answer 1

Questo non può essere fatto senza riflettere su variabili statiche private e così ... sei sicuro di aver bisogno di fare questo?

Controlla il codice sorgente su sun.font.FontManager.registerFont, potrebbe già avere la sicurezza che desideri. (Questo è il metodo che fa il vero lavoro quando si chiama GraphicsEnvironment.registerFont)

public boolean registerFont(Font font) { 
    /* This method should not be called with "null". 
    * It is the caller's responsibility to ensure that. 
    */ 
    if (font == null) { 
     return false; 
    } 

    /* Initialise these objects only once we start to use this API */ 
    synchronized (regFamilyKey) { 
     if (createdByFamilyName == null) { 
      createdByFamilyName = new Hashtable<String,FontFamily>(); 
      createdByFullName = new Hashtable<String,Font2D>(); 
     } 
    } 

    if (! FontAccess.getFontAccess().isCreatedFont(font)) { 
     return false; 
    } 
    /* We want to ensure that this font cannot override existing 
    * installed fonts. Check these conditions : 
    * - family name is not that of an installed font 
    * - full name is not that of an installed font 
    * - family name is not the same as the full name of an installed font 
    * - full name is not the same as the family name of an installed font 
    * The last two of these may initially look odd but the reason is 
    * that (unfortunately) Font constructors do not distinuguish these. 
    * An extreme example of such a problem would be a font which has 
    * family name "Dialog.Plain" and full name of "Dialog". 
    * The one arguably overly stringent restriction here is that if an 
    * application wants to supply a new member of an existing family 
    * It will get rejected. But since the JRE can perform synthetic 
    * styling in many cases its not necessary. 
    * We don't apply the same logic to registered fonts. If apps want 
    * to do this lets assume they have a reason. It won't cause problems 
    * except for themselves. 
    */ 
    HashSet<String> names = getInstalledNames(); 
    Locale l = getSystemStartupLocale(); 
    String familyName = font.getFamily(l).toLowerCase(); 
    String fullName = font.getFontName(l).toLowerCase(); 
    if (names.contains(familyName) || names.contains(fullName)) { 
     return false; 
    } 

    /* Checks passed, now register the font */ 
    Hashtable<String,FontFamily> familyTable; 
    Hashtable<String,Font2D> fullNameTable; 
    if (!maybeMultiAppContext()) { 
     familyTable = createdByFamilyName; 
     fullNameTable = createdByFullName; 
     fontsAreRegistered = true; 
    } else { 
     AppContext appContext = AppContext.getAppContext(); 
     familyTable = 
      (Hashtable<String,FontFamily>)appContext.get(regFamilyKey); 
     fullNameTable = 
      (Hashtable<String,Font2D>)appContext.get(regFullNameKey); 
     if (familyTable == null) { 
      familyTable = new Hashtable<String,FontFamily>(); 
      fullNameTable = new Hashtable<String,Font2D>(); 
      appContext.put(regFamilyKey, familyTable); 
      appContext.put(regFullNameKey, fullNameTable); 
     } 
     fontsAreRegisteredPerAppContext = true; 
    } 
    /* Create the FontFamily and add font to the tables */ 
    Font2D font2D = FontUtilities.getFont2D(font); 
    int style = font2D.getStyle(); 
    FontFamily family = familyTable.get(familyName); 
    if (family == null) { 
     family = new FontFamily(font.getFamily(l)); 
     familyTable.put(familyName, family); 
    } 
    /* Remove name cache entries if not using app contexts. 
    * To accommodate a case where code may have registered first a plain 
    * family member and then used it and is now registering a bold family 
    * member, we need to remove all members of the family, so that the 
    * new style can get picked up rather than continuing to synthesise. 
    */ 
    if (fontsAreRegistered) { 
     removeFromCache(family.getFont(Font.PLAIN)); 
     removeFromCache(family.getFont(Font.BOLD)); 
     removeFromCache(family.getFont(Font.ITALIC)); 
     removeFromCache(family.getFont(Font.BOLD|Font.ITALIC)); 
     removeFromCache(fullNameTable.get(fullName)); 
    } 
    family.setFont(font2D, style); 
    fullNameTable.put(fullName, font2D); 
    return true; 
}