Moved the value marshalling code out of SetFieldRule and into a separate

class. Created a digester rule that sets public fields of objects based on
element attributes.


git-svn-id: https://samskivert.googlecode.com/svn/trunk@477 6335cc39-0255-0410-8fd6-9bcaacd3b74c

projects/samskivert/src/java/com/samskivert/util/ValueMarshaller.java

@@ -0,0 +1,84 @@
+//
+// $Id: ValueMarshaller.java,v 1.1 2001/11/26 23:44:40 mdb Exp $
+
+package com.samskivert.util;
+
+import java.util.HashMap;
+
+/**
+ * Provides a mechanism for converting a string representation of a value
+ * into a Java object when provided with the type of the target object.
+ * This is used to do things like populate object fields with values
+ * parsed from an XML file and the like.
+ */
+public class ValueMarshaller
+{
+    /**
+     * Attempts to convert the specified value to an instance of the
+     * specified object type.
+     *
+     * @exception Exception thrown if no field parser exists for the
+     * target type or if an error occurs while parsing the value.
+     */
+    public static Object unmarshal (Class type, String source)
+        throws Exception
+    {
+        // look up an argument parser for the field type
+        Parser parser = (Parser)_parsers.get(type);
+        if (parser == null) {
+            String errmsg = "Don't know how to convert strings into " +
+                "values of type '" + type + "].";
+            throw new Exception(errmsg);
+        }
+        return parser.parse(source);
+    }
+
+    protected static interface Parser
+    {
+        public Object parse (String source) throws Exception;
+    }
+
+    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/src/java/com/samskivert/xml/SetFieldRule.java

@@ -1,5 +1,5 @@
 //
-// $Id: SetFieldRule.java,v 1.1 2001/11/17 03:45:52 mdb Exp $
+// $Id: SetFieldRule.java,v 1.2 2001/11/26 23:44:40 mdb Exp $
 //
 // samskivert library - useful routines for java programs
 // Copyright (C) 2001 Walter Korman
@@ -21,13 +21,13 @@
 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;
+import com.samskivert.util.ValueMarshaller;
 
 /**
  * Sets a field in the object on the top of the stack with a value parsed
@@ -70,70 +70,12 @@ public class SetFieldRule extends Rule
                          _bodyText + "' on '" + top + "'.");
         }
 
+        // convert the source string into an object and set the field
         Field field = top.getClass().getField(_fieldName);
-
+        Object value = ValueMarshaller.unmarshal(field.getType(), _bodyText);
-        // look up an argument parser for the field type
+        field.set(top, value);
-        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/src/java/com/samskivert/xml/SetPropertyFieldsRule.java

@@ -0,0 +1,78 @@
+//
+// $Id: SetPropertyFieldsRule.java,v 1.1 2001/11/26 23:44:40 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 org.xml.sax.Attributes;
+import org.apache.commons.digester.Digester;
+import org.apache.commons.digester.Rule;
+
+import com.samskivert.util.StringUtil;
+import com.samskivert.util.ValueMarshaller;
+
+/**
+ * Sets the fields in the object on the top of the stack from the
+ * attributes available in the matched element.
+ */
+public class SetPropertyFieldsRule extends Rule
+{
+    /**
+     * Constructs a set property fields rule.
+     */
+    public SetPropertyFieldsRule (Digester digester)
+    {
+        super(digester);
+    }
+
+    public void begin (Attributes attrs)
+        throws Exception
+    {
+        Object top = digester.peek();
+        Class topclass = top.getClass();
+
+        // iterate over the attributes, setting public fields where
+        // applicable
+	for (int i = 0; i < attrs.getLength(); i++) {
+	    String name = attrs.getLocalName(i);
+            if (StringUtil.blank(name)) {
+                name = attrs.getQName(i);
+            }
+
+            // look for a public field with this name
+            Field field = topclass.getField(name);
+            if (field == null) {
+                continue;
+            }
+
+            // convert the value into the appropriate object type
+	    String valstr = attrs.getValue(i);
+            Object value = ValueMarshaller.unmarshal(field.getType(), valstr);
+            if (digester.getDebug() >= 9) {
+                digester.log("  Setting property '" + name + "' to '" +
+                             valstr + "'");
+            }
+
+            // and finally set the field
+            field.set(top, value);
+	}
+    }
+}