XmlParseableValidator.java

package be.selckin.swu.util.xml;

import com.google.common.base.Supplier;
import nu.xom.Builder;
import nu.xom.ParsingException;
import org.apache.wicket.validation.IValidatable;
import org.apache.wicket.validation.IValidator;
import org.apache.wicket.validation.ValidationError;

import java.io.IOException;
import java.io.StringReader;

public class XmlParseableValidator implements IValidator<String> {
    private Supplier<Builder> builderSupplier;

    public XmlParseableValidator(Supplier<Builder> builderSupplier) {
        this.builderSupplier = builderSupplier;
    }

    @Override
    public void validate(IValidatable<String> validatable) {
        try {
            builderSupplier.get().build(new StringReader(validatable.getValue()));
        } catch (ParsingException ex) {
            error(validatable, toErrorMessage(ex));
        } catch (IOException ex) {
            error(validatable, ex.getMessage());
        }
    }

    private void error(IValidatable<String> validatable, String msg) {
        ValidationError error = new ValidationError();
        error.setMessage("Not a valid xml document: " + msg);
        validatable.error(error);
    }

    private String toErrorMessage(ParsingException ex) {
        if (ex.getLineNumber() > 0)
            return ex.getMessage() + " at line " + ex.getLineNumber() + ", column " + ex.getColumnNumber();
        else
            return ex.getMessage();

    }
}