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<a href="https://community.jboss.org/index.jspa" style="text-decoration: none; color: #E1E1E1">JBoss Community</a></h1>
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Using Javassist on Eclipse
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created by <a href="https://community.jboss.org/people/diego.adrada">Diego Adrada</a> in <i>Javassist Development</i> - <a href="https://community.jboss.org/message/817875#817875">View the full discussion</a>
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<div class="jive-rendered-content"><p><span id="result_box" lang="en"><span class="hps">Greetings</span>, I'm starting <span class="hps">with</span> <span class="hps">Javassist</span>, I have implemented <span class="hps atn">an example of </span>Hello <span class="hps">World</span> <span class="hps">with</span> <span class="hps">following code:</span></span></p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p><span lang="en"><span class="hps"><br/></span><pre class="jive-pre"><code class="jive-code jive-java"><font color="navy"><b>public</b></font> <font color="navy"><b>class</b></font> HelloWorld <font color="navy">{</font>
 
 
   <font color="navy"><b>public</b></font> <font color="navy"><b>static</b></font> <font color="navy"><b>void</b></font> main(String[] args) <font color="navy">{</font>
       <font color="navy"><b>new</b></font> HelloWorld().sayHello();
   <font color="navy">}</font>
 
   <font color="navy"><b>public</b></font> <font color="navy"><b>void</b></font> sayHello()<font color="navy">{</font>
       System.out.println(<font color="red">"Hello!!! This is the original version!!!"</font>);
   <font color="navy">}</font>
<font color="navy">}</font>
</code></pre></span></p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><pre class="jive-pre"><code class="jive-code jive-java"><font color="navy"><b>import</b></font> javassist.CannotCompileException;
<font color="navy"><b>import</b></font> javassist.CtClass;
<font color="navy"><b>import</b></font> javassist.CtMethod;
<font color="navy"><b>import</b></font> javassist.NotFoundException;
 
<font color="navy"><b>import</b></font> java.io.IOException;
 
<font color="navy"><b>import</b></font> <font color="navy"><b>static</b></font> javassist.ClassPool.getDefault;
 
 
<font color="navy"><b>public</b></font> <font color="navy"><b>class</b></font> ByteCodeInjector <font color="navy">{</font>
 
   <font color="navy"><b>public</b></font> <font color="navy"><b>static</b></font> <font color="navy"><b>final</b></font> String CLASS_NAME = <font color="red">"HelloWorld"</font>;
   <font color="navy"><b>public</b></font> <font color="navy"><b>static</b></font> <font color="navy"><b>final</b></font> String METHOD = <font color="red">"sayHello"</font>;
 
   <font color="navy"><b>public</b></font> <font color="navy"><b>static</b></font> <font color="navy"><b>void</b></font> main(String[] argos) <font color="navy"><b>throws</b></font> Exception<font color="navy">{</font>
       modifyByteCode(CLASS_NAME,METHOD);
   <font color="navy">}</font>
 
   <font color="navy"><b>public</b></font> <font color="navy"><b>static</b></font> <font color="navy"><b>void</b></font> modifyByteCode(String className ,String methodName)
           <font color="navy"><b>throws</b></font> NotFoundException, CannotCompileException, IOException <font color="navy">{</font>
       <font color="darkgreen">//Get the Class implementation byte code</font>
       CtClass ctClass = getDefault().get(className);
 
       <font color="darkgreen">//Get the method from the Class byte code</font>
       CtMethod method= ctClass.getDeclaredMethod(methodName);
 
       <font color="darkgreen">/**
        * Creating the new Method implementation
        */</font>
       StringBuffer content = <font color="navy"><b>new</b></font> StringBuffer();
       content.append(<font color="red">"{\n System.out.println(\"Hello!!! This is the Modified version!!!\");\n } "</font>);
 
       <font color="darkgreen">/**
        * Inserting the content
        */</font>
       method.setBody(content.toString());
       System.out.println(<font color="red">"Replacing Method \' sayHello\' s body with new implementation : "</font> + content);
        <font color="darkgreen">//modify the actual class File</font>
       ctClass.writeFile();
   <font color="navy">}</font>
<font color="navy">}</font>
</code></pre><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p><span id="result_box" lang="en"><span class="hps">This example</span> <span class="hps">has already</span> <span class="hps">worked well</span> <span class="hps">compiling</span> <span class="hps">classes</span> <span class="hps">from</span> <span class="hps">console.</span> <span class="hps">My question is</span> <span class="hps">about what</span> <span class="hps">I need</span> <span class="hps">to implement</span> <span class="hps">this example</span> <span class="hps">in</span> <span class="hps">Eclipse</span>? <span class="hps">It</span> <span class="hps">must have some sort</span> <span class="hps">of</span> <span class="hps">special</span> <span class="hps">consideration</span>?<br/><span class="hps">Thank you for your help.</span></span></p></div>
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<p style="margin: 0;">Reply to this message by <a href="https://community.jboss.org/message/817875#817875">going to Community</a></p>
<p style="margin: 0;">Start a new discussion in Javassist Development at <a href="https://community.jboss.org/choose-container!input.jspa?contentType=1&containerType=14&container=2063">Community</a></p>
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