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apache / felix-site-pub / ce5028da261c6ed2e1928e6338c81e1f24559823 / . / ipojo / api / 1.11.0 / src-html / org / apache / felix / ipojo / handlers / dependency / ProxyGenerator.html
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<pre><span class="sourceLineNo">001</span>/*<a name="line.1"></a>
<span class="sourceLineNo">002</span> * Licensed to the Apache Software Foundation (ASF) under one<a name="line.2"></a>
<span class="sourceLineNo">003</span> * or more contributor license agreements. See the NOTICE file<a name="line.3"></a>
<span class="sourceLineNo">004</span> * distributed with this work for additional information<a name="line.4"></a>
<span class="sourceLineNo">005</span> * regarding copyright ownership. The ASF licenses this file<a name="line.5"></a>
<span class="sourceLineNo">006</span> * to you under the Apache License, Version 2.0 (the<a name="line.6"></a>
<span class="sourceLineNo">007</span> * "License"); you may not use this file except in compliance<a name="line.7"></a>
<span class="sourceLineNo">008</span> * with the License. You may obtain a copy of the License at<a name="line.8"></a>
<span class="sourceLineNo">009</span> *<a name="line.9"></a>
<span class="sourceLineNo">010</span> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.10"></a>
<span class="sourceLineNo">011</span> *<a name="line.11"></a>
<span class="sourceLineNo">012</span> * Unless required by applicable law or agreed to in writing,<a name="line.12"></a>
<span class="sourceLineNo">013</span> * software distributed under the License is distributed on an<a name="line.13"></a>
<span class="sourceLineNo">014</span> * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY<a name="line.14"></a>
<span class="sourceLineNo">015</span> * KIND, either express or implied. See the License for the<a name="line.15"></a>
<span class="sourceLineNo">016</span> * specific language governing permissions and limitations<a name="line.16"></a>
<span class="sourceLineNo">017</span> * under the License.<a name="line.17"></a>
<span class="sourceLineNo">018</span> */<a name="line.18"></a>
<span class="sourceLineNo">019</span><a name="line.19"></a>
<span class="sourceLineNo">020</span>package org.apache.felix.ipojo.handlers.dependency;<a name="line.20"></a>
<span class="sourceLineNo">021</span><a name="line.21"></a>
<span class="sourceLineNo">022</span><a name="line.22"></a>
<span class="sourceLineNo">023</span>import java.lang.reflect.Method;<a name="line.23"></a>
<span class="sourceLineNo">024</span>import java.lang.reflect.Modifier;<a name="line.24"></a>
<span class="sourceLineNo">025</span><a name="line.25"></a>
<span class="sourceLineNo">026</span>import org.objectweb.asm.ClassWriter;<a name="line.26"></a>
<span class="sourceLineNo">027</span>import org.objectweb.asm.Label;<a name="line.27"></a>
<span class="sourceLineNo">028</span>import org.objectweb.asm.MethodVisitor;<a name="line.28"></a>
<span class="sourceLineNo">029</span>import org.objectweb.asm.Opcodes;<a name="line.29"></a>
<span class="sourceLineNo">030</span>import org.objectweb.asm.Type;<a name="line.30"></a>
<span class="sourceLineNo">031</span><a name="line.31"></a>
<span class="sourceLineNo">032</span>/**<a name="line.32"></a>
<span class="sourceLineNo">033</span> * Generates proxy class delegating operation invocations thanks to a<a name="line.33"></a>
<span class="sourceLineNo">034</span> * a dependency.<a name="line.34"></a>
<span class="sourceLineNo">035</span> * @author &lt;a href="mailto:dev@felix.apache.org"&gt;Felix Project Team&lt;/a&gt;<a name="line.35"></a>
<span class="sourceLineNo">036</span> */<a name="line.36"></a>
<span class="sourceLineNo">037</span>public class ProxyGenerator implements Opcodes {<a name="line.37"></a>
<span class="sourceLineNo">038</span><a name="line.38"></a>
<span class="sourceLineNo">039</span> /**<a name="line.39"></a>
<span class="sourceLineNo">040</span> * The dependency name.<a name="line.40"></a>
<span class="sourceLineNo">041</span> */<a name="line.41"></a>
<span class="sourceLineNo">042</span> private static final String DEPENDENCY = "m_dependency";<a name="line.42"></a>
<span class="sourceLineNo">043</span><a name="line.43"></a>
<span class="sourceLineNo">044</span> /**<a name="line.44"></a>
<span class="sourceLineNo">045</span> * The dependency descriptor.<a name="line.45"></a>
<span class="sourceLineNo">046</span> */<a name="line.46"></a>
<span class="sourceLineNo">047</span> private static final String DEPENDENCY_DESC = Type.getDescriptor(Dependency.class);<a name="line.47"></a>
<span class="sourceLineNo">048</span><a name="line.48"></a>
<span class="sourceLineNo">049</span> /**<a name="line.49"></a>
<span class="sourceLineNo">050</span> * Dependency internal class name.<a name="line.50"></a>
<span class="sourceLineNo">051</span> */<a name="line.51"></a>
<span class="sourceLineNo">052</span> private static final String DEPENDENCY_INTERNAL_NAME = "org/apache/felix/ipojo/handlers/dependency/Dependency";<a name="line.52"></a>
<span class="sourceLineNo">053</span><a name="line.53"></a>
<span class="sourceLineNo">054</span> /**<a name="line.54"></a>
<span class="sourceLineNo">055</span> * Gets the internal names of the given class objects.<a name="line.55"></a>
<span class="sourceLineNo">056</span> * @param classes the classes<a name="line.56"></a>
<span class="sourceLineNo">057</span> * @return the array containing internal names of the given class array.<a name="line.57"></a>
<span class="sourceLineNo">058</span> */<a name="line.58"></a>
<span class="sourceLineNo">059</span> private static String[] getInternalClassNames(Class[] classes) {<a name="line.59"></a>
<span class="sourceLineNo">060</span> final String[] names = new String[classes.length];<a name="line.60"></a>
<span class="sourceLineNo">061</span> for (int i = 0; i &lt; names.length; i++) {<a name="line.61"></a>
<span class="sourceLineNo">062</span> names[i] = Type.getInternalName(classes[i]);<a name="line.62"></a>
<span class="sourceLineNo">063</span> }<a name="line.63"></a>
<span class="sourceLineNo">064</span> return names;<a name="line.64"></a>
<span class="sourceLineNo">065</span> }<a name="line.65"></a>
<span class="sourceLineNo">066</span><a name="line.66"></a>
<span class="sourceLineNo">067</span> /**<a name="line.67"></a>
<span class="sourceLineNo">068</span> * Generates a proxy class.<a name="line.68"></a>
<span class="sourceLineNo">069</span> * @param spec the proxied service specification<a name="line.69"></a>
<span class="sourceLineNo">070</span> * @return the byte[] for the generated proxy class.<a name="line.70"></a>
<span class="sourceLineNo">071</span> */<a name="line.71"></a>
<span class="sourceLineNo">072</span> public static byte[] dumpProxy(Class spec) {<a name="line.72"></a>
<span class="sourceLineNo">073</span> ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS);<a name="line.73"></a>
<span class="sourceLineNo">074</span> String internalClassName = Type.getInternalName(spec); // Specification class internal name.<a name="line.74"></a>
<span class="sourceLineNo">075</span> String[] itfs = new String[0];<a name="line.75"></a>
<span class="sourceLineNo">076</span> String parent = "java/lang/Object";<a name="line.76"></a>
<span class="sourceLineNo">077</span> if (spec.isInterface()) {<a name="line.77"></a>
<span class="sourceLineNo">078</span> itfs = new String[] {internalClassName}; // Implemented interface.<a name="line.78"></a>
<span class="sourceLineNo">079</span> } else {<a name="line.79"></a>
<span class="sourceLineNo">080</span> parent = internalClassName;<a name="line.80"></a>
<span class="sourceLineNo">081</span> }<a name="line.81"></a>
<span class="sourceLineNo">082</span> String className = internalClassName + "$$Proxy"; // Unique name.<a name="line.82"></a>
<span class="sourceLineNo">083</span><a name="line.83"></a>
<span class="sourceLineNo">084</span> // Turn around the VM changes (FELIX-2716) about java.* classes.<a name="line.84"></a>
<span class="sourceLineNo">085</span> if (className.startsWith("java/")) {<a name="line.85"></a>
<span class="sourceLineNo">086</span> className = "$" + className;<a name="line.86"></a>
<span class="sourceLineNo">087</span> }<a name="line.87"></a>
<span class="sourceLineNo">088</span><a name="line.88"></a>
<span class="sourceLineNo">089</span> Method[] methods = spec.getMethods(); // Method to delegate<a name="line.89"></a>
<span class="sourceLineNo">090</span><a name="line.90"></a>
<span class="sourceLineNo">091</span> cw.visit(Opcodes.V1_3, Opcodes.ACC_PUBLIC | Opcodes.ACC_FINAL, className, null, parent, itfs);<a name="line.91"></a>
<span class="sourceLineNo">092</span> addDependencyField(cw);<a name="line.92"></a>
<span class="sourceLineNo">093</span><a name="line.93"></a>
<span class="sourceLineNo">094</span> // We try to call super() on the parent, however this should not be used as proxing does work only for interface.<a name="line.94"></a>
<span class="sourceLineNo">095</span> generateConstructor(cw, className, parent);<a name="line.95"></a>
<span class="sourceLineNo">096</span><a name="line.96"></a>
<span class="sourceLineNo">097</span> // For each method, create the delegator code.<a name="line.97"></a>
<span class="sourceLineNo">098</span> for (int i = 0; i &lt; methods.length; i++) {<a name="line.98"></a>
<span class="sourceLineNo">099</span> if ((methods[i].getModifiers() &amp; (Modifier.STATIC | Modifier.FINAL)) == 0) {<a name="line.99"></a>
<span class="sourceLineNo">100</span> generateDelegator(cw, methods[i], className, internalClassName);<a name="line.100"></a>
<span class="sourceLineNo">101</span> }<a name="line.101"></a>
<span class="sourceLineNo">102</span> }<a name="line.102"></a>
<span class="sourceLineNo">103</span><a name="line.103"></a>
<span class="sourceLineNo">104</span> cw.visitEnd();<a name="line.104"></a>
<span class="sourceLineNo">105</span><a name="line.105"></a>
<span class="sourceLineNo">106</span> return cw.toByteArray();<a name="line.106"></a>
<span class="sourceLineNo">107</span><a name="line.107"></a>
<span class="sourceLineNo">108</span> }<a name="line.108"></a>
<span class="sourceLineNo">109</span><a name="line.109"></a>
<span class="sourceLineNo">110</span> /**<a name="line.110"></a>
<span class="sourceLineNo">111</span> * Generates a delegated method.<a name="line.111"></a>
<span class="sourceLineNo">112</span> * @param cw the class writer<a name="line.112"></a>
<span class="sourceLineNo">113</span> * @param method the method object to delegate<a name="line.113"></a>
<span class="sourceLineNo">114</span> * @param className the generated class name<a name="line.114"></a>
<span class="sourceLineNo">115</span> * @param itfName the internal specification class name<a name="line.115"></a>
<span class="sourceLineNo">116</span> */<a name="line.116"></a>
<span class="sourceLineNo">117</span> private static void generateDelegator(ClassWriter cw, Method method,<a name="line.117"></a>
<span class="sourceLineNo">118</span> String className, String itfName) {<a name="line.118"></a>
<span class="sourceLineNo">119</span> String methodName = method.getName();<a name="line.119"></a>
<span class="sourceLineNo">120</span> String desc = Type.getMethodDescriptor(method);<a name="line.120"></a>
<span class="sourceLineNo">121</span> String[] exceptions = getInternalClassNames(method.getExceptionTypes());<a name="line.121"></a>
<span class="sourceLineNo">122</span> int modifiers = method.getModifiers()<a name="line.122"></a>
<span class="sourceLineNo">123</span> &amp; ~(Modifier.ABSTRACT | Modifier.NATIVE | Modifier.SYNCHRONIZED);<a name="line.123"></a>
<span class="sourceLineNo">124</span> Type[] types = Type.getArgumentTypes(method);<a name="line.124"></a>
<span class="sourceLineNo">125</span><a name="line.125"></a>
<span class="sourceLineNo">126</span> int freeRoom = 1;<a name="line.126"></a>
<span class="sourceLineNo">127</span> for (int t = 0; t &lt; types.length; t++) {<a name="line.127"></a>
<span class="sourceLineNo">128</span> freeRoom = freeRoom + types[t].getSize();<a name="line.128"></a>
<span class="sourceLineNo">129</span> }<a name="line.129"></a>
<span class="sourceLineNo">130</span><a name="line.130"></a>
<span class="sourceLineNo">131</span> MethodVisitor mv = cw.visitMethod(modifiers, methodName, desc, null,<a name="line.131"></a>
<span class="sourceLineNo">132</span> exceptions);<a name="line.132"></a>
<span class="sourceLineNo">133</span> mv.visitCode();<a name="line.133"></a>
<span class="sourceLineNo">134</span><a name="line.134"></a>
<span class="sourceLineNo">135</span> mv.visitVarInsn(ALOAD, 0);<a name="line.135"></a>
<span class="sourceLineNo">136</span> mv.visitFieldInsn(GETFIELD, className, DEPENDENCY, DEPENDENCY_DESC); // The dependency is on the stack.<a name="line.136"></a>
<span class="sourceLineNo">137</span> mv.visitMethodInsn(INVOKEVIRTUAL, DEPENDENCY_INTERNAL_NAME, "getService", // Call getService<a name="line.137"></a>
<span class="sourceLineNo">138</span> "()Ljava/lang/Object;"); // The service object is on the stack.<a name="line.138"></a>
<span class="sourceLineNo">139</span> int varSvc = freeRoom;<a name="line.139"></a>
<span class="sourceLineNo">140</span> freeRoom = freeRoom + 1; // Object Reference.<a name="line.140"></a>
<span class="sourceLineNo">141</span> mv.visitVarInsn(ASTORE, varSvc); // Store the service object.<a name="line.141"></a>
<span class="sourceLineNo">142</span><a name="line.142"></a>
<span class="sourceLineNo">143</span> Label notNull = new Label();<a name="line.143"></a>
<span class="sourceLineNo">144</span> Label isNull = new Label();<a name="line.144"></a>
<span class="sourceLineNo">145</span> mv.visitVarInsn(ALOAD, varSvc); // Load the service<a name="line.145"></a>
<span class="sourceLineNo">146</span> mv.visitJumpInsn(IFNONNULL, notNull); // If not null go to not null<a name="line.146"></a>
<span class="sourceLineNo">147</span> // Null branch - throw the exception<a name="line.147"></a>
<span class="sourceLineNo">148</span> mv.visitLabel(isNull);<a name="line.148"></a>
<span class="sourceLineNo">149</span> mv.visitTypeInsn(NEW, "java/lang/RuntimeException");<a name="line.149"></a>
<span class="sourceLineNo">150</span> mv.visitInsn(DUP);<a name="line.150"></a>
<span class="sourceLineNo">151</span> mv.visitLdcInsn("No service available");<a name="line.151"></a>
<span class="sourceLineNo">152</span> mv.visitMethodInsn(INVOKESPECIAL, "java/lang/RuntimeException", "&lt;init&gt;", "(Ljava/lang/String;)V");<a name="line.152"></a>
<span class="sourceLineNo">153</span> mv.visitInsn(ATHROW);<a name="line.153"></a>
<span class="sourceLineNo">154</span> // End of the null branch<a name="line.154"></a>
<span class="sourceLineNo">155</span><a name="line.155"></a>
<span class="sourceLineNo">156</span> // Not null, go one the execution<a name="line.156"></a>
<span class="sourceLineNo">157</span> mv.visitLabel(notNull);<a name="line.157"></a>
<span class="sourceLineNo">158</span><a name="line.158"></a>
<span class="sourceLineNo">159</span> // Invoke the method on the service object.<a name="line.159"></a>
<span class="sourceLineNo">160</span> mv.visitVarInsn(ALOAD, varSvc);<a name="line.160"></a>
<span class="sourceLineNo">161</span> // Push argument on the stack.<a name="line.161"></a>
<span class="sourceLineNo">162</span> int i = 1; // Arguments. (non static method)<a name="line.162"></a>
<span class="sourceLineNo">163</span> for (int t = 0; t &lt; types.length; t++) {<a name="line.163"></a>
<span class="sourceLineNo">164</span> mv.visitVarInsn(types[t].getOpcode(ILOAD), i);<a name="line.164"></a>
<span class="sourceLineNo">165</span> i = i + types[t].getSize();<a name="line.165"></a>
<span class="sourceLineNo">166</span> }<a name="line.166"></a>
<span class="sourceLineNo">167</span> // Invocation<a name="line.167"></a>
<span class="sourceLineNo">168</span> mv.visitMethodInsn(INVOKEINTERFACE, itfName, methodName, desc);<a name="line.168"></a>
<span class="sourceLineNo">169</span><a name="line.169"></a>
<span class="sourceLineNo">170</span> // Return the result<a name="line.170"></a>
<span class="sourceLineNo">171</span> Type returnType = Type.getReturnType(desc);<a name="line.171"></a>
<span class="sourceLineNo">172</span> if (returnType.getSort() != Type.VOID) {<a name="line.172"></a>
<span class="sourceLineNo">173</span> mv.visitInsn(returnType.getOpcode(IRETURN));<a name="line.173"></a>
<span class="sourceLineNo">174</span> } else {<a name="line.174"></a>
<span class="sourceLineNo">175</span> mv.visitInsn(RETURN);<a name="line.175"></a>
<span class="sourceLineNo">176</span> }<a name="line.176"></a>
<span class="sourceLineNo">177</span><a name="line.177"></a>
<span class="sourceLineNo">178</span> // End of the method.<a name="line.178"></a>
<span class="sourceLineNo">179</span> mv.visitMaxs(0, 0);<a name="line.179"></a>
<span class="sourceLineNo">180</span> mv.visitEnd();<a name="line.180"></a>
<span class="sourceLineNo">181</span> }<a name="line.181"></a>
<span class="sourceLineNo">182</span><a name="line.182"></a>
<span class="sourceLineNo">183</span> /**<a name="line.183"></a>
<span class="sourceLineNo">184</span> * Generates the constructors. The constructor receives a dependency<a name="line.184"></a>
<span class="sourceLineNo">185</span> * and set the {@link ProxyGenerator#DEPENDENCY} field.<a name="line.185"></a>
<span class="sourceLineNo">186</span> * @param cw the class writer<a name="line.186"></a>
<span class="sourceLineNo">187</span> * @param className the generated class name.<a name="line.187"></a>
<span class="sourceLineNo">188</span> */<a name="line.188"></a>
<span class="sourceLineNo">189</span> private static void generateConstructor(ClassWriter cw, String className, String parent) {<a name="line.189"></a>
<span class="sourceLineNo">190</span> MethodVisitor mv = cw.visitMethod(Opcodes.ACC_PUBLIC, "&lt;init&gt;", '(' + DEPENDENCY_DESC + ")V", null, null);<a name="line.190"></a>
<span class="sourceLineNo">191</span> mv.visitCode();<a name="line.191"></a>
<span class="sourceLineNo">192</span><a name="line.192"></a>
<span class="sourceLineNo">193</span> mv.visitVarInsn(ALOAD, 0); // Load this<a name="line.193"></a>
<span class="sourceLineNo">194</span> mv.visitInsn(DUP); // Dup<a name="line.194"></a>
<span class="sourceLineNo">195</span> mv.visitMethodInsn(INVOKESPECIAL, parent, "&lt;init&gt;", "()V"); // Call super<a name="line.195"></a>
<span class="sourceLineNo">196</span> mv.visitVarInsn(ALOAD, 1); // Load the argument<a name="line.196"></a>
<span class="sourceLineNo">197</span> mv.visitFieldInsn(PUTFIELD, className, DEPENDENCY, DEPENDENCY_DESC); // Assign the dependency field<a name="line.197"></a>
<span class="sourceLineNo">198</span> mv.visitInsn(RETURN); // Return void<a name="line.198"></a>
<span class="sourceLineNo">199</span><a name="line.199"></a>
<span class="sourceLineNo">200</span> mv.visitMaxs(0, 0);<a name="line.200"></a>
<span class="sourceLineNo">201</span> mv.visitEnd();<a name="line.201"></a>
<span class="sourceLineNo">202</span> }<a name="line.202"></a>
<span class="sourceLineNo">203</span><a name="line.203"></a>
<span class="sourceLineNo">204</span> /**<a name="line.204"></a>
<span class="sourceLineNo">205</span> * Adds the dependency field {@link ProxyGenerator#DEPENDENCY}.<a name="line.205"></a>
<span class="sourceLineNo">206</span> * @param cw the class writer<a name="line.206"></a>
<span class="sourceLineNo">207</span> */<a name="line.207"></a>
<span class="sourceLineNo">208</span> private static void addDependencyField(ClassWriter cw) {<a name="line.208"></a>
<span class="sourceLineNo">209</span> cw.visitField(Opcodes.ACC_FINAL, DEPENDENCY, DEPENDENCY_DESC, null, null);<a name="line.209"></a>
<span class="sourceLineNo">210</span> cw.visitEnd();<a name="line.210"></a>
<span class="sourceLineNo">211</span> }<a name="line.211"></a>
<span class="sourceLineNo">212</span><a name="line.212"></a>
<span class="sourceLineNo">213</span>}<a name="line.213"></a>
</pre>
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