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

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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
This commit is contained in:
mdb
2001-11-26 23:44:40 +00:00
parent f4c7631048
commit 0c3f04d9a5
3 changed files with 167 additions and 63 deletions
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projects/samskivert/src/java/com/samskivert/util/ValueMarshaller.java
+84
View File
@@ -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
+5 -63
View File
@@ -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);
// 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;
Object value = ValueMarshaller.unmarshal(field.getType(), _bodyText);
field.set(top, value);
}
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
+78
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@@ -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);
}
}
}