Ant example source code file (ParserSupports.java)

This example Ant source code file (ParserSupports.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Ant tags/keywords

a, buildexception, buildexception, neither, not_recognized, not_recognized, not_supported, not_supported, property, sax, saxnotrecognizedexception, saxnotsupportedexception, string, string, xmlreader

The ParserSupports.java source code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 */
package org.apache.tools.ant.taskdefs.condition;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.ProjectComponent;
import org.apache.tools.ant.util.JAXPUtils;

import org.xml.sax.SAXNotRecognizedException;
import org.xml.sax.SAXNotSupportedException;
import org.xml.sax.XMLReader;

/**
 * Test for the XML parser supporting a particular feature
 * @since Ant 1.7
 */
public class ParserSupports extends ProjectComponent implements Condition {

    private String feature;
    private String property;
    private String value;
    // Error messages
    /** error - combined attributes not allowed */
    public static final String ERROR_BOTH_ATTRIBUTES =
            "Property and feature attributes are exclusive";
    /** feature */
    public static final String FEATURE = "feature";
    /** property */
    public static final String PROPERTY = "property";

    /** error - not recognized */
    public static final String NOT_RECOGNIZED =
            " not recognized: ";
    /** error - not supported */
    public static final String NOT_SUPPORTED =
            " not supported: ";
    /** error - missing attribute */
    public static final String ERROR_NO_ATTRIBUTES =
        "Neither feature or property are set";
    /** error - no value */
    public static final String ERROR_NO_VALUE =
        "A value is needed when testing for property support";

    /**
     * Feature to probe for.
     * @param feature the feature to probe for.
     */
    public void setFeature(String feature) {
        this.feature = feature;
    }

    /**
     * Property to probe for
     * @param property the property to probe for.
     */
    public void setProperty(String property) {
        this.property = property;
    }

    /**
     * Optional value to set.
     * Converted to a boolean value when setting a property
     * @param value the value to set.
     */
    public void setValue(String value) {
        this.value = value;
    }

    /** {@inheritDoc}. */
    public boolean eval() throws BuildException {
        if (feature != null && property != null) {
            throw new BuildException(ERROR_BOTH_ATTRIBUTES);
        }
        if (feature == null && property == null) {
            throw new BuildException(ERROR_NO_ATTRIBUTES);
        }
        //pick a value that is good for everything
        if (feature != null) {
            return evalFeature();
        }
        if (value == null) {
            throw new BuildException(ERROR_NO_VALUE);
        }
        return evalProperty();
    }

    /**
     * Get our reader
     * @return a reader
     */
    private XMLReader getReader() {
        JAXPUtils.getParser();
        return JAXPUtils.getXMLReader();
    }

    /**
     * Set a feature
     * @return true if the feature could be set
     */
    public boolean evalFeature() {
        XMLReader reader = getReader();
        if (value == null) {
            value = "true";
        }
        boolean v = Project.toBoolean(value);
        try {
            reader.setFeature(feature, v);
        } catch (SAXNotRecognizedException e) {
            log(FEATURE + NOT_RECOGNIZED + feature, Project.MSG_VERBOSE);
            return false;
        } catch (SAXNotSupportedException e) {
            log(FEATURE + NOT_SUPPORTED + feature, Project.MSG_VERBOSE);
            return false;
        }
        return true;
    }

    /**
     * Set a property
     * @return true if the feature could be set
     */
    public boolean evalProperty() {
        XMLReader reader = getReader();
        try {
            reader.setProperty(property, value);
        } catch (SAXNotRecognizedException e) {
            log(PROPERTY + NOT_RECOGNIZED + property, Project.MSG_VERBOSE);
            return false;
        } catch (SAXNotSupportedException e) {
            log(PROPERTY + NOT_SUPPORTED + property, Project.MSG_VERBOSE);
            return false;
        }
        return true;
    }
}