Display apex class code on click of Show button - salesforce

Question

I have a dynamic picklist field that contains all the apex classes name that are in my org. There is a "Show" button on the page as well. Now if a user selects a value from this picklist and clicks on Show button, the apex code of that class should get displayed below.
Pls suggest how can I implement it in my VF page.
Thanks!
<apex:form >
<apex:selectList value="{!selectedClass}" size="5">
<apex:selectOptions value="{!ClassList}" ></apex:selectOptions>
</apex:selectList>
<apex:pageBlock >
<apex:commandButton action="{!show}" value="Show" id="Button"/>
<apex:pageBlockSection title="My Current Class">

Answer 1

You could query the body field of the ApexClass object for what you're looking for:
public class SomeController {
private List<ApexClass> allApexClasses;
public String selectedClass {public get; public set;}
public String apexCodeOutput {public get; private set;}
public SomeController() {
// only select classes that aren't part of a managed package, since you won't be able to view the body
allApexClasses = [select id, name, body from ApexClass where lengthwithoutcomments <> -1 order by name asc];
}
public List<SelectOption> getClassList() {
List<SelectOption> opts = new List<SelectOption> opts;
for ( ApexClass ac : allApexClasses )
opts.add(new SelectOption(ac.Id, ac.Name));
return opts;
}
public PageReference show() {
if ( selectedClass != null ) {
Id classId = (Id) selectedClass;
for ( ApexClass ac : allApexClasses ) {
if ( classId == ac.Id ) {
apexCodeOutput = ac.body;
break;
}
}
}
return null;
}
}
And then in your VF page, just rerender the output code when clicking the button. You'll want to use a <pre> tag around the code to preserve spacing so the code is readable.
<apex:form>
<apex:selectList value="{!selectedClass}" size="5">
<apex:selectOptions value="{!ClassList}" ></apex:selectOptions>
</apex:selectList>
<apex:pageBlock >
<apex:commandButton action="{!show}" value="Show" rerender="apexoutput" id="Button"/>
<apex:pageBlockSection title="My Current Class">
<apex:outputPanel id="apexoutput">
<pre>{!apexcodeoutput}</pre>
</apex:outputPanel>
</apex:pageBlockSection>
</apex:pageBlock>
</apex:form>