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JavaBeans for Extended Types

This chapter describes JavaBeans provided with OC4J for use as extended types. For JSP pages, these types offer advantages over Java primitive types or standard java.lang types.

The chapter consists of the following:

Overview of JML Extended Types

JSP pages generally rely on core Java types in representing scalar values. However, neither of the following type categories is fully suitable for use in JSP pages:

primitive types such as int, float, and double

Values of these types cannot have a specified scope--they cannot be stored in a JSP scope object (for page, request, session, or application scope), because only objects can be stored in a scope object.
wrapper classes in the standard java.lang package, such as Integer, Float, and Double

Values of these types are objects, so they can theoretically be stored in a JSP scope object. However, they cannot be declared in a jsp:useBean action, because the wrapper classes do not follow the JavaBean model and do not provide zero-argument constructors.

Additionally, instances of the wrapper classes are immutable. To change a value, you must create a new instance and assign it appropriately.

To work around these limitations, OC4J provides the following JavaBean classes in the oracle.jsp.jml package to act as wrappers for the most common Java types:

JmlBoolean to represent a boolean value
JmlNumber to represent an int value
JmlFPNumber to represent a double value
JmlString to represent a String value

Each of these classes has a single attribute, value, and includes methods to get the value, set the value from input in various formats, test whether the value is equal to a value specified in any of several formats, and convert the value to a string.

Alternatively, instead of using the getValue() and setValue() methods, you can use the jsp:getProperty and jsp:setProperty tags, as with any other bean.

The following example creates a JmlNumber instance called count that has application scope:

<jsp:useBean id="count" class="oracle.jsp.jml.JmlNumber" scope="application" />

Later, assuming that the value has been set elsewhere, you can access it as follows:

<h3> The current count is <%=count.getValue() %> </h3>

The following example creates a JmlNumber instance called maxSize that has request scope, and sets it using setProperty:

<jsp:useBean id="maxSize" class="oracle.jsp.jml.JmlNumber" scope="request" >
    <jsp:setProperty name="maxSize" property="value" value="<%= 25 %>" />
</jsp:useBean>

JML Extended Type Descriptions

This section documents public methods of the four extended types--JmlBoolean, JmlNumber, JmlFPNumber, and JmlString--followed by an example.

Note:

To use the JML extended types, verify that the ojsputil.jar file is installed and in your classpath. This file is supplied with OC4J.

Type JmlBoolean

A JmlBoolean object represents a Java boolean value.

The getValue() and setValue() methods get or set the value property of the bean as a Java boolean value.

boolean getValue()
void setValue(boolean)

The setTypedValue() method has several signatures and can set the value property from a string (such as "true" or "false"), a java.lang.Boolean value, a Java boolean value, or a JmlBoolean value. For the string input, conversion of the string is performed according to the same rules as for the valueOf() method of the java.lang.Boolean class.

void setTypedValue(String)
void setTypedValue(Boolean)
void setTypedValue(boolean)
void setTypedValue(JmlBoolean)

The equals() method tests whether the value property is equal to the specified Java boolean value.

boolean equals(boolean)

The typedEquals() method has several signatures and tests whether the value property has a value equivalent to a specified string (such as "true" or "false"), java.lang.Boolean value, or JmlBoolean value.

boolean typedEquals(String)
boolean typedEquals(Boolean)
boolean typedEquals(JmlBoolean)

The toString() method returns the value property as a java.lang.String value, either "true" or "false".

String toString()

Type JmlNumber

A JmlNumber object represents a 32-bit number equivalent to a Java int value.

The getValue() and setValue() methods get or set the value property of the bean as a Java int value.

int getValue()
void setValue(int)

The setTypedValue() method has several signatures and can set the value property from a string, a java.lang.Integer value, a Java int value, or a JmlNumber value. For the string input, conversion of the string is performed according to the same rules as for the decode() method of the java.lang.Integer class.

void setTypedValue(String)
void setTypedValue(Integer)
void setTypedValue(int)
void setTypedValue(JmlNumber)

The equals() method tests whether the value property is equal to the specified Java int value.

boolean equals(int)

The typedEquals() method has several signatures and tests whether the value property has a value equivalent to a specified string (such as "1234"), java.lang.Integer value, or JmlNumber value.

boolean typedEquals(String)
boolean typedEquals(Integer)
boolean typedEquals(JmlNumber)

The toString() method returns the value property as an equivalent java.lang.String value (such as "1234"). This method has the same functionality as the toString() method of the java.lang.Integer class.

String toString()

Type JmlFPNumber

A JmlFPNumber object represents a 64-bit floating point number equivalent to a Java double value.

The getValue() and setValue() methods get or set the value property of the bean as a Java double value.

double getValue()
void setValue(double)

The setTypedValue() method has several signatures and can set the value property from a string (such as "3.57"), a java.lang.Integer value, a Java int value, a java.lang.Float value, a Java float value, a java.lang.Double value, a Java double value, or a JmlFPNumber value. For the string input, conversion of the string is according to the same rules as for the valueOf() method of the java.lang.Double class.

void setTypedValue(String)
void setTypedValue(Integer)
void setTypedValue(int)
void setTypedValue(Float)
void setTypedValue(float)
void setTypedValue(Double)
void setTypedValue(double)
void setTypedValue(JmlFPNumber)

The equals() method tests whether the value property is equal to the specified Java double value.

boolean equals(double)

The typedEquals() method has several signatures and tests whether the value property has a value equivalent to a specified string (such as "3.57"), java.lang.Integer value, Java int value, java.lang.Float value, Java float value, java.lang.Double value, Java double value, or JmlFPNumber value.

boolean typedEquals(String)
boolean typedEquals(Integer)
boolean typedEquals(int)
boolean typedEquals(Float)
boolean typedEquals(float)
boolean typedEquals(Double)
boolean typedEquals(JmlFPNumber)

The toString() method returns the value property as a java.lang.String value (such as "3.57"). This method has the same functionality as the toString() method of the java.lang.Double class.

String toString()

Type JmlString

A JmlString object represents a java.lang.String value.

The getValue() and setValue() methods get or set the value property of the bean as a java.lang.String value. If the input in a setValue() call is null, then the value property is set to an empty (zero-length) string.

String getValue()
void setValue(String)

The toString() method is functionally equivalent to the getValue() method.

String toString()

The setTypedValue() method sets the value property according to the specified JmlString value. If the JmlString value is null, then the value property is set to an empty (zero-length) string.

void setTypedValue(JmlString)

The isEmpty() method tests whether the value property is an empty (zero-length) string: ""

boolean isEmpty()

The equals() method has two signatures and tests whether the value property is equal to a specified java.lang.String value or JmlString value.

boolean equals(String)
boolean equals(JmlString)

JML Extended Types Example

This example illustrates the use of JML extended type JavaBeans for management of simple types at scope. The page declares four session objects--one for each JML type. The page presents a form that enables you to enter values for each of these types. Once new values are submitted, the form displays both the new values and the previously set values. In the process of generating this output, the page updates the session objects with the new form values.

<jsp:useBean id = "submitCount" class = "oracle.jsp.jml.JmlNumber" scope = "session" />

<jsp:useBean id = "bool" class = "oracle.jsp.jml.JmlBoolean" scope = "session" >
        <jsp:setProperty name = "bool" property = "value" param = "fBoolean" />
</jsp:useBean>

<jsp:useBean id = "num" class = "oracle.jsp.jml.JmlNumber" scope = "session" >
        <jsp:setProperty name = "num" property = "value" param = "fNumber" />
</jsp:useBean>

<jsp:useBean id = "fpnum" class = "oracle.jsp.jml.JmlFPNumber" scope = "session" >
        <jsp:setProperty name = "fpnum" property = "value" param = "fFPNumber" />
</jsp:useBean>

<jsp:useBean id = "str" class = "oracle.jsp.jml.JmlString" scope = "session" >
        <jsp:setProperty name = "str" property = "value" param = "fString" />
</jsp:useBean>


<HTML>

<HEAD>
        <META HTTP-EQUIV="Content-Type" CONTENT="text/html;CHARSET=iso-8859-1">
        <META NAME="GENERATOR" Content="Visual Page 1.1 for Windows">
        <TITLE>Extended Datatypes Sample</TITLE>
</HEAD>

<BODY BACKGROUND="images/bg.gif" BGCOLOR="#FFFFFF">

<% if (submitCount.getValue() > 1) { %>
        <h3> Last submitted values </h3>
        <ul>
                <li> bool: <%= bool.getValue() %>
                <li> num: <%= num.getValue() %>
                <li> fpnum: <%= fpnum.getValue() %>
                <li> string: <%= str.getValue() %>
        </ul>
<% }

   if (submitCount.getValue() > 0) { %>

        <jsp:setProperty name = "bool" property = "value" param = "fBoolean" />
        <jsp:setProperty name = "num" property = "value" param = "fNumber" />
        <jsp:setProperty name = "fpnum" property = "value" param = "fFPNumber" />
        <jsp:setProperty name = "str" property = "value" param = "fString" />

        <h3> New submitted values </h3>
        <ul>
                <li> bool: <jsp:getProperty name="bool" property="value" />
                <li> num: <jsp:getProperty name="num" property="value" />
                <li> fpnum: <jsp:getProperty name="fpnum" property="value" />
                <li> string: <jsp:getProperty name="str" property="value" />
        </ul>
<% } %>

<jsp:setProperty name = "submitCount" property = "value" value = "<%= submitCount.getValue() + 1 
%>" />

<FORM ACTION="index.jsp" METHOD="POST" ENCTYPE="application/x-www-form-urlencoded">
<P> <pre>
 boolean test: <INPUT TYPE="text" NAME="fBoolean" VALUE="<%= bool.getValue() %>" >
  number test: <INPUT TYPE="text" NAME="fNumber" VALUE="<%= num.getValue() %>" >
fpnumber test: <INPUT TYPE="text" NAME="fFPNumber" VALUE="<%= fpnum.getValue() %>" >
  string test: <INPUT TYPE="text" NAME="fString" VALUE= "<%= str.getValue() %>" >
</pre>

<P> <INPUT TYPE="submit">

</FORM>

</BODY>

</HTML>

2JavaBeans for Extended Types