Date: 2004-09-21T07:59:48
Editor: KrisSchneider <[EMAIL PROTECTED]>
Wiki: Apache Struts Wiki
Page: ExposedBeanProperties
URL: http://wiki.apache.org/struts/ExposedBeanProperties
no comment
New Page:
##language:en
#pragma section-numbers off
Here's a utility class that will dump information about a bean's exposed properties:
{{{
import java.beans.*;
import java.io.*;
import java.util.*;
public class SimpleBeanDumper {
public static void dump(Class beanClass) throws IntrospectionException {
dump(beanClass, new PrintWriter(System.out, true));
}
public static void dump(Class beanClass, PrintWriter out) throws
IntrospectionException {
if (beanClass == null) {
throw new NullPointerException("No bean class specified");
}
if (out == null) {
out = new PrintWriter(System.out, true);
}
out.println("Dumping Properties for: " + beanClass.getName());
out.println();
BeanInfo beanInfo = Introspector.getBeanInfo(beanClass);
PropertyDescriptor[] descriptors = beanInfo.getPropertyDescriptors();
for (int i = 0, n = descriptors.length; i < n; i++) {
PropertyDescriptor descriptor = descriptors[i];
String propName = descriptor.getName();
out.println(propName);
out.println(" propertyType: " + descriptor.getPropertyType());
out.println(" readMethod: " + descriptor.getReadMethod());
out.println(" writeMethod: " + descriptor.getWriteMethod());
if (descriptor instanceof IndexedPropertyDescriptor) {
IndexedPropertyDescriptor indexedDescriptor =
(IndexedPropertyDescriptor)descriptor;
out.println(" indexedPropertyType: " +
indexedDescriptor.getIndexedPropertyType());
out.println(" indexedReadMethod: " +
indexedDescriptor.getIndexedReadMethod());
out.println(" indexedWriteMethod: " +
indexedDescriptor.getIndexedWriteMethod());
}
}
}
public static void main(String[] args) throws Exception {
Class clazz = MyBean.class;
if (args.length > 0) {
clazz = Class.forName(args[0]);
}
dump(clazz);
}
public static class MyBean implements Serializable {
public int getID() { return 0; }
public void setID(int id) {}
public String getId() { return null; }
public void setId(String id) {}
public String[] getFriends() { return null; }
public String getFriends(int i) { return null; }
public void setFriends(String[] friends) {}
public void setFriends(int i, String friend) {}
public Map getMap() { return null; }
public void setMap(Map map) {}
}
}
}}}
If the class is run as:
{{{
java SimpleBeanDumper
}}}
Then the output should look something like:
{{{
Dumping Properties for: SimpleBeanDumper$MyBean
ID
propertyType: int
readMethod: public int SimpleBeanDumper$MyBean.getID()
writeMethod: public void SimpleBeanDumper$MyBean.setID(int)
class
propertyType: class java.lang.Class
readMethod: public final native java.lang.Class java.lang.Object.getClass()
writeMethod: null
friends
propertyType: class [Ljava.lang.String;
readMethod: public java.lang.String[] SimpleBeanDumper$MyBean.getFriends()
writeMethod: public void
SimpleBeanDumper$MyBean.setFriends(java.lang.String[])
indexedPropertyType: class java.lang.String
indexedReadMethod: public java.lang.String SimpleBeanDumper$MyBean.getFriends(int)
indexedWriteMethod: public void
SimpleBeanDumper$MyBean.setFriends(int,java.lang.String)
id
propertyType: class java.lang.String
readMethod: public java.lang.String SimpleBeanDumper$MyBean.getId()
writeMethod: public void SimpleBeanDumper$MyBean.setId(java.lang.String)
map
propertyType: interface java.util.Map
readMethod: public java.util.Map SimpleBeanDumper$MyBean.getMap()
writeMethod: public void SimpleBeanDumper$MyBean.setMap(java.util.Map)
}}}
In other words, a {{{SimpleBeanDumper.MyBean}}} instance exposes five properties:
'''ID''', '''class''', '''friends''', '''id''', and '''map'''. Note that while most of
the properties can be both read and written, the '''class''' property is read-only.
Also note that the '''class''' property is actually inherited from
{{{java.lang.Object}}}.
Here's another dump example, this time using {{{java.util.HashMap}}}:
{{{
java SimpleBeanDumper java.util.HashMap
}}}
The output should look something like:
{{{
Dumping Properties for: java.util.HashMap
class
propertyType: class java.lang.Class
readMethod: public final native java.lang.Class java.lang.Object.getClass()
writeMethod: null
empty
propertyType: boolean
readMethod: public boolean java.util.AbstractMap.isEmpty()
writeMethod: null
}}}
In other words, a {{{HashMap}}} instance exposes two simple read-only properties
called '''class''' and '''empty'''.
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
