Created SetFieldRule which allows the XML Digester to set public fields on

objects with automatic conversion from a string to the appropriate field
type (currently supports int, Integer, String, int[] and String[]).


git-svn-id: https://samskivert.googlecode.com/svn/trunk@454 6335cc39-0255-0410-8fd6-9bcaacd3b74c

projects/samskivert/src/java/com/samskivert/xml/SetFieldRule.java

@@ -0,0 +1,139 @@
+//
+// $Id: SetFieldRule.java,v 1.1 2001/11/17 03:45:52 mdb Exp $
+//
+// samskivert library - useful routines for java programs
+// Copyright (C) 2001 Walter Korman
+// 
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.samskivert.xml;
+
+import java.lang.reflect.Field;
+import java.util.HashMap;
+
+import org.xml.sax.Attributes;
+import org.apache.commons.digester.Digester;
+import org.apache.commons.digester.Rule;
+
+import com.samskivert.util.StringUtil;
+
+/**
+ * Sets a field in the object on the top of the stack with a value parsed
+ * from the body of an element.
+ */
+public class SetFieldRule extends Rule
+{
+    /**
+     * Constructs a set field rule for the specified field.
+     */
+    public SetFieldRule (Digester digester, String fieldName)
+    {
+        super(digester);
+
+        // keep this for later
+        _fieldName = fieldName;
+    }
+
+    public void body (String bodyText)
+        throws Exception
+    {
+        _bodyText = bodyText.trim();
+    }
+
+    public void end ()
+        throws Exception
+    {
+        // make sure we've got something to set
+        if (StringUtil.blank(_bodyText)) {
+            if (digester.getDebug() >= 3) {
+                digester.log("  Skipping set field for lack of " +
+                             "body text [field=" + _fieldName + "].");
+            }
+            return;
+        }
+
+	Object top = digester.peek();
+	if (digester.getDebug() >= 1) {
+            digester.log("  Setting '" + _fieldName + "' to '" +
+                         _bodyText + "' on '" + top + "'.");
+        }
+
+        Field field = top.getClass().getField(_fieldName);
+
+        // look up an argument parser for the field type
+        Parser parser = (Parser)_parsers.get(field.getType());
+        if (parser == null) {
+            String errmsg = "Don't know how to convert strings into " +
+                "fields of type '" + field.getType() +
+                "' [field=" + _fieldName + ", target=" + top + "].";
+            throw new Exception(errmsg);
+        }
+
+        // parse the text and set the field
+        field.set(top, parser.parse(_bodyText));
+    }
+
+    protected static interface Parser
+    {
+        public Object parse (String source) throws Exception;
+    }
+
+    protected String _fieldName;
+    protected String _bodyText;
+
+    protected static HashMap _parsers;
+
+    protected static final int[] INT_ARRAY_PROTOTYPE = new int[0];
+    protected static final String[] STRING_ARRAY_PROTOTYPE = new String[0];
+
+    static {
+        _parsers = new HashMap();
+
+        // we can parse strings
+        _parsers.put(String.class, new Parser() {
+            public Object parse (String source) throws Exception {
+                return source;
+            }
+        });
+
+        // and ints
+        _parsers.put(Integer.TYPE, new Parser() {
+            public Object parse (String source) throws Exception {
+                return Integer.valueOf(source);
+            }
+        });
+
+        // and integers
+        _parsers.put(Integer.class, new Parser() {
+            public Object parse (String source) throws Exception {
+                return Integer.valueOf(source);
+            }
+        });
+
+        // and int arrays
+        _parsers.put(INT_ARRAY_PROTOTYPE.getClass(), new Parser() {
+            public Object parse (String source) throws Exception {
+                return StringUtil.parseIntArray(source);
+            }
+        });
+
+        // and string arrays, oh my!
+        _parsers.put(STRING_ARRAY_PROTOTYPE.getClass(), new Parser() {
+            public Object parse (String source) throws Exception {
+                return StringUtil.parseStringArray(source);
+            }
+        });
+    }
+}

projects/samskivert/tests/rsrc/xml/setfieldtest.xml

@@ -0,0 +1,7 @@
+<object>
+  <intField>5</intField>
+  <stringField>howdy partner!</stringField>
+  <integerField>15</integerField>
+  <intArrayField>1, 2, 3, 4, 5</intArrayField>
+  <stringArrayField>one, two, three, four, five</stringArrayField>
+</object>

projects/samskivert/tests/src/java/com/samskivert/xml/SetFieldRuleTest.java

@@ -0,0 +1,107 @@
+//
+// $Id: SetFieldRuleTest.java,v 1.1 2001/11/17 03:45:52 mdb Exp $
+//
+// samskivert library - useful routines for java programs
+// Copyright (C) 2001 Michael Bayne
+// 
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.samskivert.xml;
+
+import java.io.InputStream;
+import java.io.FileInputStream;
+
+import junit.framework.Test;
+import junit.framework.TestCase;
+
+import org.apache.commons.digester.Digester;
+
+import com.samskivert.Log;
+import com.samskivert.test.TestUtil;
+import com.samskivert.util.StringUtil;
+
+public class SetFieldRuleTest extends TestCase
+{
+    public SetFieldRuleTest ()
+    {
+        super(SetFieldRuleTest.class.getName());
+    }
+
+    public static class TestObject
+    {
+        public int intField;
+        public String stringField;
+        public Integer integerField;
+        public int[] intArrayField;
+        public String[] stringArrayField;
+
+        public String toString ()
+        {
+            return "[intField=" + intField + ", stringField=" + stringField +
+                ", integerField=" + integerField +
+                ", intArrayField=" + StringUtil.toString(intArrayField) +
+                ", stringArrayField=" + StringUtil.toString(stringArrayField) +
+                "]";
+        }
+    }
+
+    public void runTest ()
+    {
+        Digester digester = new Digester();
+
+        // create our object and push it onto the digester
+        TestObject object = new TestObject();
+        digester.push(object);
+
+        // set up some rules
+        digester.addRule("object/intField",
+                         new SetFieldRule(digester, "intField"));
+        digester.addRule("object/stringField",
+                         new SetFieldRule(digester, "stringField"));
+        digester.addRule("object/integerField",
+                         new SetFieldRule(digester, "integerField"));
+        digester.addRule("object/intArrayField",
+                         new SetFieldRule(digester, "intArrayField"));
+        digester.addRule("object/stringArrayField",
+                         new SetFieldRule(digester, "stringArrayField"));
+
+        try {
+            String xmlpath = TestUtil.getResourcePath("xml/setfieldtest.xml");
+            InputStream input = new FileInputStream(xmlpath);
+            digester.parse(input);
+            input.close();
+        } catch (Exception e) {
+            fail("Parsing failed: " + e);
+        }
+
+        assert(EXPECTED.equals(object.toString()));
+    }
+
+    public static Test suite ()
+    {
+        return new SetFieldRuleTest();
+    }
+
+    public static void main (String[] args)
+    {
+        SetFieldRuleTest test = new SetFieldRuleTest();
+        test.runTest();
+    }
+
+    protected static final String EXPECTED =
+        "[intField=5, stringField=howdy partner!, integerField=15, " +
+        "intArrayField=(1, 2, 3, 4, 5), " +
+        "stringArrayField=(one, two, three, four, five)]";
+}