java.bean.Introspector does not conform to the specs and is inconsistent

Name: boT120536 Date: 01/22/2001


java version "1.2.2"
Classic VM (build JDK-1.2.2-W, native threads, symcjit)

java version "1.3.0_01"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.0_01)
Java HotSpot(TM) Client VM (build 1.3.0_01, mixed mode)

Same thing on Solaris j2se1_3_0

The JDK 1.3.0 version of java.beans.Introspector is broken, and behavior is not
consistent across JVM version (1.2.2). This is a problem when using java beans
from a JSP engine that would report not finding properties for a given bean.
Following is a detailed description of the problems as they were observed during
our debug phase. Other problems might be lying in the Introspector
when using the low-level introspection though.

1) depending on the order of the method declaration it would fail to list some
available properties, when types are mixed between boolean and simple return
value:

If I define:
    public boolean isQueryTranslated()
    {
            return false;
    }

    public void setQueryTranslated(String s1)
    {
    }

    public String getQueryTranslated()
    {
            return "";
    }

Then the JDK 1.3.0 would *not* find the write method of the property
'queryTranslated'

However, if I change the order of the method declaration to the following:
    public void setQueryTranslated(String s1)
    {
    }

    public String getQueryTranslated()
    {
            return "";
    }

    public boolean isQueryTranslated()
    {
            return false;
    }

Then the JDK 1.3.0 *would* find the write method of the property
'queryTranslated'
In addition, for this example JDK 1.2.2 and JDK 1.3.0 does not behave
consistently!


2) under some [undiagnosed] circumstances, it would fail to list all available
properties

In the attached ConfigBean example, under the JDK 1.2.2, my assumption reading
the specs is that I should obtain 4 properties:
'queryTranslatable' (boolean read), 'loginPassword' (string read), 'loginName'
(string read) and 'queryTranslated' (string Read Write)
 I would obtain a list of 4 properties, whereas the JDK 1.3.0 would only find
two: 'loginPassword' and 'queryTranslated'
It seems to me that there is a logic bug in the java Beans introspection, where
not only the presence of a property in methods is checked for instead of full
pattern matching (ie using string.indexOf() >0 instead of String.equals())


For reference, here is what the specs version 1.0.1 say:
"8.3.1 Simple properties
By default, we use design patterns to locate properties by looking for methods
of the form:
public < PropertyType> get< PropertyName>();
public void set< PropertyName>(< PropertyType> a);
If we discover a matching pair of "get<PropertyName>" and "set<PropertyName>"
methods
that take and return the same type, then we regard these methods as defining a
read-write prop-erty
whose name will be "<propertyName>". We will use the "get<PropertyName>" method
to get the property value and the "set<PropertyName>" method to set the property
value. The
pair of methods may be located either in the same class or one may be in a base
class and the
other may be in a derived class.
If we find only one of these methods, then we regard it as defining either a
read-only or a write-only
property called "<propertyName>"
By default we assume that properties are neither bound nor constrained (see
Section 7).
So a simple read-write property "foo" might be represented by a pair of methods:
public Wombat getFoo();
public void setFoo(Wombat w);

8.3.2 Boolean properties
In addition, for boolean properties, we allow a getter method to match the
pattern:
public boolean is< PropertyName>();
This "is<PropertyName>" method may be provided instead of a "get<PropertyName>"
meth-od,
or it may be provided in addition to a "get<PropertyName>" method.
In either case, if the "is<PropertyName>" method is present for a boolean
property then we will
use the "is<PropertyName>" method to read the property value.
An example boolean property might be:
public boolean isMarsupial();
public void setMarsupial(boolean m);
"





Here is the test driver that I used for performing by tests:


package custom.client.jsp;

import custom.client.jsp.ConfigBean;

public class TestObfuscation {
    public TestObfuscation (){

    }

    public static void main (String[] args) {
try {

Class myClass = ConfigBean.class;
String prop = "queryTranslated";

java.beans.BeanInfo info
= java.beans.Introspector.getBeanInfo(myClass);
if ( info != null ) {
java.beans.PropertyDescriptor pd[]
= info.getPropertyDescriptors();
for (int i = 0 ; i < pd.length ; i++) {
System.out.println("\n\ni=" + i + "\n");
System.out.println("pd[i]:" + pd[i]);
System.out.println("pd[i].getReadMethod():" +
pd[i].getReadMethod());
System.out.println("pd[i].getName(): [" + pd[i].getName() + "]");
System.out.println("pd[i].getName().equals(prop) :" +
pd[i].getName().equals(prop));
System.out.println("pd[i].getWriteMethod():" +
pd[i].getWriteMethod());

if ( pd[i].getName().equals(prop) ) {
System.out.println("method:" + pd[i].getWriteMethod());
System.out.println("type:" + pd[i].getPropertyType());
break;
}
}
}
} catch(Exception e) {
e.printStackTrace();
}
    } // end of main ()
    
}// TestObfuscation


Here is the simplified version of the ConfigBean class that is the introspected
bean:

package custom.client.jsp;

import java.util.Enumeration;
import java.util.Vector;


public class ConfigBean
{

    private String a;
    private String b;
    private boolean g;
    private boolean h;
    private String m;
    private Enumeration p;

    private Enumeration c;
    private Enumeration f;
    private Enumeration e;
    private Enumeration k;
    private Enumeration i;
    private String d[];
    private String q[];
    private String l[];


    public boolean isQueryTranslatable()
    {
            return false;
    }


    public String getLoginPassword()
    {
            return "";
    }

    public String getLoginName()
    {
            return "";
    }


// public boolean isQueryTranslated()
// {
// return false;
// }

    public void setQueryTranslated(String s1)
    {
    }

    public String getQueryTranslated()
    {
            return "";
    }


// public String getQueryLanguage()
// {
// return "";
// }

// public void setQueryLanguage(String s1)
// {
// }


}
(Review ID: 115521)
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