java 只能输入数字的文本框

//只能输入数字的文本框,继承了JTextField,所以可以当做工具直接来用

import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.io.Serializable;

import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;

/**
 * <p>
 * Title: OpenSwing
 * </p>
 * <p>
 * Description: JNumberField 数字格式输入框
 * </p>
 * 履历:<BR>
 * 2005/04/17 1.将最大长度,小数位长度修正成符合数据库定义的规范,如:NUMBER(10,2)<BR>
 * 即:最大长度10,小数位长度2,其中整数最大可能长度只能为8;<BR>
 * 2005/04/21 修正了不能输入负数的BUG<BR>
 * <p>
 * Copyright: Copyright (c) 2004
 * </p>
 * <p>
 * Company:
 * </p>
 */
public class JNumberField extends JTextField implements ActionListener,
  FocusListener, Serializable {

 public JNumberField() {
  this(true);
 }

 public JNumberField(boolean addAction) {
  this(16, 0, addAction);
 }

 public JNumberField(int intPartLen) {
  this(intPartLen, true);
 }

 public JNumberField(int intPartLen, boolean addAction) {
  this(intPartLen, 0, addAction);
 }

 /**
  * 控制文本框的长度
  *
  * @param maxLen
  * @param decLen
  */
 public JNumberField(int maxLen, int decLen) {
  this(maxLen, decLen, true);
 }

 public JNumberField(int maxLen, int decLen, boolean addAction) {
//  setPreferredSize(new Dimension(150, 25));// 设置组件的首选大小
  // this.setSize(150, 25);
  setDocument(new NumberDocument(maxLen, decLen));// 设置文本框关联一个文本
  super.setHorizontalAlignment(JTextField.LEFT);// 设置从左边开始输入
  if (addAction)
   addActionListener(this);
  addFocusListener(this);
 }

 public JNumberField(int maxLen, int decLen, double minRange,
   double maxRange, boolean addAction) {
  setPreferredSize(new Dimension(150, 25));
  setDocument(new NumberDocument(maxLen, decLen, minRange, maxRange));
  super.setHorizontalAlignment(JTextField.RIGHT);
  if (addAction)
   addActionListener(this);
  addFocusListener(this);
 }

 public void actionPerformed(ActionEvent e) {
  transferFocus();
 }

 public void focusGained(FocusEvent e) {
  selectAll();
 }

 public void focusLost(FocusEvent e) {
 }

  public static void main(String[] args) {
  // JFrame frame = OpenSwingUtil.createDemoFrame("JNumberField Demo");
  // frame.getContentPane().setLayout(new GridLayout(10, 2));
  // frame.getContentPane().add(new JLabel("New JNumberField()"));
  // frame.getContentPane().add(new JNumberField());
  // frame.getContentPane().add(new JLabel("New JNumberField(2)"));
  // frame.getContentPane().add(new JNumberField(2));
  // frame.getContentPane().add(new JLabel("New JNumberField(8,2)"));
  // frame.getContentPane().add(new JNumberField(8, 2));
  // frame.getContentPane().add(new
//  JLabel("New JNumberField(5,2,-10,100)"));
  // frame.getContentPane().add(new JNumberField(5, 2, -10, 100, false));
  // frame.setVisible(true);
  JFrame frame = new JFrame();
  final JTextField field = new JNumberField();
  frame.add(field);
  field.addActionListener(new ActionListener(){
 
  public void actionPerformed(ActionEvent e) {
  System.out.println(field.getText().trim());
  }});
  frame.pack();
  frame.setVisible(true);
  }
}

class NumberDocument extends PlainDocument {// 不包含字符的类

 int maxLength = 16;// 默认的是十六

 int decLength = 0;

 double minRange = -Double.MAX_VALUE;

 double maxRange = Double.MAX_VALUE;

 public NumberDocument(int maxLen, int decLen) {
  maxLength = maxLen;
  decLength = decLen;
 }

 /**
  * @param decLen
  *            int 小数位长度
  * @param maxLen
  *            int 最大长度(含小数位)
  * @param minRange
  *            double 最小值
  * @param maxRange
  *            double 最大值
  */
 public NumberDocument(int maxLen, int decLen, double minRange,
   double maxRange) {
  this(maxLen, decLen);
  this.minRange = minRange;
  this.maxRange = maxRange;
 }

 public NumberDocument(int decLen) {
  decLength = decLen;
 }

 public NumberDocument() {
 }

 public void insertString(int offset, String s, AttributeSet a)
   throws BadLocationException {
  String str = getText(0, getLength());

  if (
  // 不能为f,F,d,D
  s.equals("F")
    || s.equals("f")
    || s.equals("D")
    || s.equals("d")
    // 第一位是0时,第二位只能为小数点
    || (str.trim().equals("0") && !s.substring(0, 1).equals(".") && offset != 0)
    // 整数模式不能输入小数点
    || (s.equals(".") && decLength == 0)) {
   Toolkit.getDefaultToolkit().beep();
   return;
  }
  String strIntPart = "";
  String strDecPart = "";
  String strNew = str.substring(0, offset) + s
    + str.substring(offset, getLength());
  strNew = strNew.replaceFirst("-", ""); // 控制能输入负数
  int decPos = strNew.indexOf(".");
  if (decPos > -1) {
   strIntPart = strNew.substring(0, decPos);
   strDecPart = strNew.substring(decPos + 1);
  } else {
   strIntPart = strNew;
  }
  if (strIntPart.length() > (maxLength - decLength)
    || strDecPart.length() > decLength
    || (strNew.length() > 1 && strNew.substring(0, 1).equals("0") && !strNew
      .substring(1, 2).equals("."))) {
   Toolkit.getDefaultToolkit().beep();
   return;
  }

  try {
   if (!strNew.equals("") && !strNew.equals("-")) {// 控制能输入负数
    double d = Double.parseDouble(strNew);
    if (d < minRange || d > maxRange) {
     throw new Exception();
    }
   }
  } catch (Exception e) {
   Toolkit.getDefaultToolkit().beep();
   return;
  }
  super.insertString(offset, s, a);
 }

}