limiteddocument.java

来自「输入框的字符与长度限制.调用方法源码里有说明.主要是覆盖setDocument方」· Java 代码 · 共 57 行

//文件名：LimitedDocument.java


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

public class LimitedDocument extends PlainDocument {

    private int maxLength = -1;
    private String allowCharAsString = null;

    public LimitedDocument() {
        super();
    }

    public LimitedDocument(int maxLength, String str) {
        super();
        this.maxLength = maxLength;
        allowCharAsString = str;
    }

    @Override
    public void insertString(int offset, String str, AttributeSet attrSet)
            throws BadLocationException {

        if (str == null) {
            return;
        }

        if (allowCharAsString != null && str.length() == 1) {
            if (allowCharAsString.indexOf(str) == -1) {
                return;
            }
        }

        char[] charVal = str.toCharArray();
        String strOldValue = getText(0, getLength());
        byte[] tmp = strOldValue.getBytes();

        if (maxLength != -1 && (tmp.length + charVal.length > maxLength)) {
            return;
        }

        super.insertString(offset, str, attrSet);
    }
}


//    用法：
//          LimitedDocument Input = new LimitedDocument(maxLength,allowCharAsString);   maxLength 为最大输入长度，allowCharAsString 为允许输入的字符
//          jTextField.setDocument(Input);      运用到文本框中
//    例如：
//          String AllowChar = "0123456789";
//          LimitedDocument Input = new LimitedDocument(11,AllowChar);