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/*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import com.android.dx.gen.BinaryOp;
import com.android.dx.gen.Code;
import com.android.dx.gen.DexGenerator;
import com.android.dx.gen.FieldId;
import com.android.dx.gen.Local;
import com.android.dx.gen.MethodId;
import com.android.dx.gen.Type;
import com.android.dx.rop.code.AccessFlags;
import java.io.File;
import java.io.PrintStream;
public class HelloWorldMaker {
private static final Type<PrintStream> PRINT_STREAM = Type.get(PrintStream.class);
private static final FieldId<System, PrintStream> SYSTEM_OUT
= Type.get(System.class).getField(PRINT_STREAM, "out");
private static final MethodId<Integer, String> TO_HEX_STRING
= Type.get(Integer.class).getMethod(Type.STRING, "toHexString", Type.INT);
private static final MethodId<PrintStream, Void> PRINTLN
= PRINT_STREAM.getMethod(Type.VOID, "println", Type.STRING);
public static void main(String[] args) throws Exception {
/*
* This code generates Dalvik bytecode equivalent to the following
* program.
*
* public class HelloWorld {
* public static void hello() {
* int a = 0xabcd;
* int b = 0xaaaa;
* int c = a - b;
* String s = Integer.toHexString(c);
* System.out.println(s);
* }
* }
*/
DexGenerator generator = new DexGenerator();
// lookup the symbols of interest
Type<?> helloWorld = Type.get("LHelloWorld;");
MethodId hello = helloWorld.getMethod(Type.VOID, "hello");
// create some registers
// (I'd like a better syntax for this)
Code code = generator.declare(hello, AccessFlags.ACC_STATIC | AccessFlags.ACC_PUBLIC);
Local<Integer> a = code.newLocal(Type.INT);
Local<Integer> b = code.newLocal(Type.INT);
Local<Integer> c = code.newLocal(Type.INT);
Local<String> s = code.newLocal(Type.STRING);
Local<PrintStream> localSystemOut = code.newLocal(PRINT_STREAM);
// specify the code instruction-by-instruction (approximately)
code.loadConstant(a, 0xabcd);
code.loadConstant(b, 0xaaaa);
code.op(BinaryOp.SUBTRACT, c, a, b);
code.invokeStatic(TO_HEX_STRING, s, c);
code.sget(SYSTEM_OUT, localSystemOut);
code.invokeVirtual(PRINTLN, null, localSystemOut, s);
code.returnVoid();
// TODO: create the constructor
generator.declare(helloWorld, "Generated.java", AccessFlags.ACC_PUBLIC, Type.OBJECT);
// load the dex
File outputDir = new File(".");
ClassLoader loader = generator.load(HelloWorldMaker.class.getClassLoader(),
outputDir, outputDir);
Class<?> helloWorldClass = loader.loadClass("HelloWorld");
helloWorldClass.getMethod("hello").invoke(null);
}
}
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