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??1 import ?java.awt.event.KeyEvent;
 ??2 import ?java.awt.event.KeyListener;
 ??3
??4 import ?javax.swing.JTextField;
 ??5 import ?javax.swing.event.CaretEvent;
 ??6 import ?javax.swing.event.CaretListener;
 ??7 import ?javax.swing.text.AttributeSet;
 ??8 import ?javax.swing.text.BadLocationException;
 ??9 import ?javax.swing.text.PlainDocument;
 ?10
?11 public ? class ?NumberTextFieldDocument? extends ?PlainDocument? implements ?KeyListener,?CaretListener {
 ?12 ????
 ?13 ???? int ?integerLength? = ? - 1 ;
 ?14 ???? int ?fractionLength? = ? - 1 ;
 ?15 ???? double ?MaxValue,?MinValue;
 ?16 ???? boolean ?useBound? = ? false ;
 ?17 ????String?correctValue? = ? "" ;
 ?18 ???? private ? int ?caretposold;
 ?19 ???? private ? int ?caretpos;
 ?20 ????
 ?21 ???? /**
?22 ?????*?
 ?23 ?????*
 ?24 ????? */
?25 ???? public ?NumberTextFieldDocument()? {
 ?26 ???????? super ();
 ?27 ????}
?28 ????
 ?29 ???? /**
?30 ?????*?
 ?31 ?????*? @param ?maxValue
 ?32 ?????*? @param ?minValue
 ?33 ????? */
?34 ???? public ?NumberTextFieldDocument( double ?maxValue,? double ?minValue)? {
 ?35 ???????? super ();
 ?36 ????????setBound(maxValue,?minValue);
 ?37 ????}
?38 ????
 ?39 ???? /**
?40 ?????*?
 ?41 ?????*? @param ?integerLength
 ?42 ?????*? @param ?fractionLength
 ?43 ????? */
?44 ???? public ?NumberTextFieldDocument( int ?integerLength,? int ?fractionLength)? {
 ?45 ???????? super ();
 ?46 ????????setLength(integerLength,?fractionLength);
 ?47 ????}
?48 ???? /**
?49 ?????*?
 ?50 ?????*? @param ?integerLength
 ?51 ?????*? @param ?fractionLength
 ?52 ????? */
?53 ???? public ? void ?setLength( int ?integerLength,? int ?fractionLength)? {
 ?54 ???????? if ?(integerLength? < ? 1 ? || ?fractionLength? < ? 0 )? {
 ?55 // ????????????Error
?56 ????????} ? else ? {
 ?57 ???????????? this .integerLength? = ?integerLength;
 ?58 ???????????? this .fractionLength? = ?fractionLength;
 ?59 ????????}
?60 ????}
?61 ????
 ?62 ???? /**
?63 ?????*?
 ?64 ?????*? @param ?maxValue
 ?65 ?????*? @param ?minValue
 ?66 ????? */
?67 ???? public ? void ?setBound( double ?maxValue,? double ?minValue)? {
 ?68 ???????? if ?(maxValue? < ?minValue)?
 ?69 ???????????? return ;
 ?70 ????????MaxValue? = ?maxValue;
 ?71 ????????MinValue? = ?minValue;
 ?72 ????????useBound? = ? true ;
 ?73 ????}
?74
?75 ????
 ?76 ???? public ? void ?insertString( int ?offs,?String?str,?AttributeSet?a)? throws ?BadLocationException? {
 ?77 ????????
 ?78 ????????String?oldtxt? = ?getText( 0 ,?getLength());
 ?79 ????????String?newtxt? = ?oldtxt.substring( 0 ,?offs)? + ?str? + ?oldtxt.substring(offs);
 ?80 ???????? boolean ?strRight? = ?testString(oldtxt);
 ?81 ???????? boolean ?newtxtRight? = ?testString(newtxt);
 ?82 ???????? if ?(strRight? && ? ! newtxtRight) {
 ?83 ???????????? return ;
 ?84 ????????} ? else ? if ?( ! strRight? && ? ! newtxtRight)? {
 ?85 ???????????? int ?rlen? = ?correctValue.length();
 ?86 ???????????? int ?flen? = ?oldtxt.length();
 ?87 ???????????? int ?sublen? = ?rlen? - ?flen;
 ?88 ???????????? for ?( int ?i? = ? 0 ;?i? < ?flen;?i ++ )? {
 ?89 ????????????????String?substr? = ?correctValue.substring( 0 ,?i)? + ?correctValue.substring(i? + ?sublen);
 ?90 ???????????????? if ?(substr.equals(oldtxt))? {
 ?91 ???????????????????? super .insertString(i,?correctValue.substring(i,?i? + ?sublen),?a);
 ?92 ????????????????????correctValue? = ?String.copyValueOf(getText( 0 ,?getLength()).toCharArray());
 ?93 ???????????????????? return ;
 ?94 ????????????????}
?95 ????????????}
?96 ???????????? return ;
 ?97 ????????}
?98 ????????
 ?99 ???????? super .insertString(offs,?str,?a);
 100 ????????correctValue? = ?String.copyValueOf(getText( 0 ,?getLength()).toCharArray());
 101 ????????
 102 ????}
103 ????
 104 ???? public ? void ?caretUpdate(CaretEvent?e)? {
 105 ????????caretposold? = ?caretpos;
 106 ????????caretpos? = ?e.getDot();
 107 // ????????System.out.print("?"?+?caretpos);
108 ????}
109 ????
 110 ???? public ? void ?keyTyped(KeyEvent?e)? {
 111 ????????
 112 ????}
113
114 ???? public ? void ?keyPressed(KeyEvent?e)? {
 115 ???????? if ?(e.getKeyCode()? == ?KeyEvent.VK_BACK_SPACE? || ?e.getKeyCode()? == ?KeyEvent.VK_DELETE)? {
 116 ????????????JTextField?field? = ?(JTextField)?e.getSource();
 117 ???????????? try ? {
 118 ????????????????String?nowtxt? = ?getText( 0 ,?getLength());
 119 ????????????????String?selecttxt? = ?field.getSelectedText();
 120 ???????????????? if ?(correctValue? == ? null ? || ?(selecttxt? != ? null ? && ?selecttxt.equals(correctValue)))? {
 121 ????????????????????correctValue? = ? null ;
 122 ???????????????????? return ;
 123 ????????????????}
124 ???????????????? if ?( ! testString(nowtxt))? {
 125 ???????????????????? int ?nowpos? = ?
 126 ????????????????????caretposold? - ?caretpos? == ?correctValue.length()? - ?nowtxt.length()? ? ?caretposold?:?caretpos;
 127 ????????????????????remove( 0 ,?getLength());
 128 ????????????????????insertString( 0 ,?correctValue,? null );
 129 ????????????????????field.setCaretPosition(nowpos);
 130 ????????????????} ? else ? {
 131 ????????????????????correctValue? = ?nowtxt;
 132 ????????????????}
133 ????????????} ? catch ?(BadLocationException?e1)? {
 134 ????????????????System.out.println(e1);
 135 ????????????}
136 ????????}
137 ????}
138
139 ???? public ? void ?keyReleased(KeyEvent?e)? {
 140 ???????? if ?(getLength()? == ? 0 )? {
 141 ???????????? return ;
 142 ????????}
143 ???????? if ?(e.getKeyCode()? == ?KeyEvent.VK_BACK_SPACE? || ?e.getKeyCode()? == ?KeyEvent.VK_DELETE)? {
 144 ????????????JTextField?field? = ?(JTextField)?e.getSource();
 145 ???????????? try ? {
 146 ????????????????String?nowtxt? = ?getText( 0 ,?getLength());
 147 ????????????????String?selecttxt? = ?field.getSelectedText();
 148 ???????????????? if ?(correctValue? == ? null ? || ?(selecttxt? != ? null ? && ?selecttxt.equals(correctValue)))? {
 149 ????????????????????correctValue? = ? null ;
 150 ???????????????????? return ;
 151 ????????????????}
152 ???????????????? if ?( ! testString(nowtxt))? {
 153 ???????????????????? int ?nowpos? = ?
 154 ????????????????????caretposold? - ?caretpos? == ?correctValue.length()? - ?nowtxt.length()? ? ?caretposold?:?caretpos;
 155 ????????????????????remove( 0 ,?getLength());
 156 ????????????????????insertString( 0 ,?correctValue,? null );
 157 ????????????????????field.setCaretPosition(nowpos);
 158 ????????????????} ? else ? {
 159 ????????????????????correctValue? = ?nowtxt;
 160 ????????????????}
161 ????????????} ? catch ?(BadLocationException?e1)? {
 162 ????????????????System.out.println(e1);
 163 ????????????}
164 ????????}
165 ????}
166 ????
 167 ???? private ? boolean ?testString(String?waitfortest)? {
 168 ???????? int ?dotindex? = ?waitfortest.indexOf( " . " );
 169 ???????? int ?strLength? = ?waitfortest.length();
 170 ???????? if ?(integerLength? != ? - 1 ? && ?fractionLength? != ? - 1 )? {
 171 ???????????? if ?(fractionLength? == ? 0 ? && ?dotindex? >= ? 0 )? {
 172 ???????????????? return ? false ;
 173 ????????????}
174 ???????????? if ?(dotindex? > ? 0 ? && ?dotindex? != ?strLength? - ? 1 )? {
 175 ????????????????String[]?splitstrs? = ?waitfortest.split( " \\. " );
 176 ???????????????? if ?(splitstrs.length? != ? 2 )? { // impossible
177 ???????????????????? return ? false ;
 178 ????????????????} ? else ? if ?(splitstrs[ 0 ].length()? > ?integerLength? || ?splitstrs[ 1 ].length()? > ?fractionLength)? {
 179 ???????????????????? return ? false ;
 180 ????????????????}
181 ????????????} ? else ? if ?((dotindex? == ? 0 ? && ?strLength? > ?fractionLength? + ? 1 )?
 182 ???????????????????? || ?(dotindex? == ?strLength? - ? 1 ? && ?strLength? > ?integerLength? + ? 1 )
 183 ???????????????????? || ?(dotindex? < ? 0 ? && ?strLength? > ?integerLength))? {
 184 ???????????????? return ? false ;
 185 ????????????}
186 ????????}
187
188 ????????waitfortest? = ?waitfortest.toLowerCase();
 189 ???????? if ?(waitfortest.indexOf( " ? " )? >= ? 0 ? || ?waitfortest.indexOf( " d " )? >= ? 0 ? || ?waitfortest.indexOf( " f " )? >= ? 0 ?)? {
 190 ???????????? return ? false ;
 191 ????????}
192 ???????? try ? {
 193 ???????????? if ?(dotindex? == ? 0 )? {
 194 ????????????????waitfortest? = ? " 0 " ? + ?waitfortest;
 195 ????????????}
196 ???????????? double ?num? = ?Double.parseDouble(waitfortest);
 197 ???????????? if ?(useBound? && ?(num? > ?MaxValue? || ?num? < ?MinValue))? {
 198 ???????????????? return ? false ;
 199 ????????????}
200 ????????} ? catch ?(Exception?e)? {
 201 ???????????? return ? false ;
 202 ????????}
203 ???????? return ? true ;
 204 ????}
205 ????
 206 }
207


下面是Test

?1import?javax.swing.*;
?2
?3public?class?NumberTextFieldDocumentTest?{
?4????public?static?void?main(String[]?args)?{
?5????????JFrame?f?=?new?JFrame("TextDocumentTest");
?6????????JPanel?panel?=?new?JPanel();
?7????????f.getContentPane().add(panel);
?8????????JTextField?txt?=?new?JTextField();
?9????????txt.setColumns(20);
10????????
11????????NumberTextFieldDocument?doc?=?new?NumberTextFieldDocument();
12????????doc.setBound(99999,?0.00001);
13????????doc.setLength(5,?5);
14????????txt.setDocument(doc);
15????????txt.addKeyListener(doc);
16????????txt.addCaretListener(doc);
17????????
18????????panel.add(txt);
19????????f.pack();
20????????f.setVisible(true);
21????????f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
22????????txt.setText("123.123");
23????????
24????}
25}
26