3072f56bf961a429c217869c03845d15fc90ca6b - platform/external/dexmaker

commit	3072f56bf961a429c217869c03845d15fc90ca6b	[log] [tgz]
author	Paul Duffin <paulduffin@google.com>	Wed Mar 15 16:08:40 2017 +0000
committer	android-build-merger <android-build-merger@google.com>	Wed Mar 15 16:08:40 2017 +0000
tree	5869af4d592f5e0e3b7b319008669f6ee9d68818
parent	db55101b385b9f5289697896df3f374620300b4a [diff]
parent	7d2fa18cfd9d254e73e31ca4674ee315d369f1a4 [diff]

tree: 5869af4d592f5e0e3b7b319008669f6ee9d68818

README.md

A Java-language API for doing compile time or runtime code generation targeting the Dalvik VM. Unlike cglib or ASM, this library creates Dalvik .dex files instead of Java .class files.

It has a small, close-to-the-metal API. This API mirrors the Dalvik bytecode specification giving you tight control over the bytecode emitted. Code is generated instruction-by-instruction; you bring your own abstract syntax tree if you need one. And since it uses Dalvik's dx tool as a backend, you get efficient register allocation and regular/wide instruction selection for free.

Class Proxies

Dexmaker includes a stock code generator for class proxies. If you just want to do AOP or class mocking, you don't need to mess around with bytecodes.

Mockito Mocks

Dexmaker includes class proxy support for Mockito. Add the mockito and the dexmaker .jar files to your Android test project's libs/ directory and you can use Mockito in your Android unit tests.

This requires Mockito 1.10.5 or newer.

Runtime Code Generation

This example generates a class and a method. It then loads that class into the current process and invokes its method.

public final class HelloWorldMaker {
    public static void main(String[] args) throws Exception {
        DexMaker dexMaker = new DexMaker();

        // Generate a HelloWorld class.
        TypeId<?> helloWorld = TypeId.get("LHelloWorld;");
        dexMaker.declare(helloWorld, "HelloWorld.generated", Modifier.PUBLIC, TypeId.OBJECT);
        generateHelloMethod(dexMaker, helloWorld);

        // Create the dex file and load it.
        File outputDir = new File(".");
        ClassLoader loader = dexMaker.generateAndLoad(HelloWorldMaker.class.getClassLoader(),
                outputDir, outputDir);
        Class<?> helloWorldClass = loader.loadClass("HelloWorld");

        // Execute our newly-generated code in-process.
        helloWorldClass.getMethod("hello").invoke(null);
    }

    /**
     * Generates Dalvik bytecode equivalent to the following method.
     *    public static void hello() {
     *        int a = 0xabcd;
     *        int b = 0xaaaa;
     *        int c = a - b;
     *        String s = Integer.toHexString(c);
     *        System.out.println(s);
     *        return;
     *    }
     */
    private static void generateHelloMethod(DexMaker dexMaker, TypeId<?> declaringType) {
        // Lookup some types we'll need along the way.
        TypeId<System> systemType = TypeId.get(System.class);
        TypeId<PrintStream> printStreamType = TypeId.get(PrintStream.class);

        // Identify the 'hello()' method on declaringType.
        MethodId hello = declaringType.getMethod(TypeId.VOID, "hello");

        // Declare that method on the dexMaker. Use the returned Code instance
        // as a builder that we can append instructions to.
        Code code = dexMaker.declare(hello, Modifier.STATIC | Modifier.PUBLIC);

        // Declare all the locals we'll need up front. The API requires this.
        Local<Integer> a = code.newLocal(TypeId.INT);
        Local<Integer> b = code.newLocal(TypeId.INT);
        Local<Integer> c = code.newLocal(TypeId.INT);
        Local<String> s = code.newLocal(TypeId.STRING);
        Local<PrintStream> localSystemOut = code.newLocal(printStreamType);

        // int a = 0xabcd;
        code.loadConstant(a, 0xabcd);

        // int b = 0xaaaa;
        code.loadConstant(b, 0xaaaa);

        // int c = a - b;
        code.op(BinaryOp.SUBTRACT, c, a, b);

        // String s = Integer.toHexString(c);
        MethodId<Integer, String> toHexString
                = TypeId.get(Integer.class).getMethod(TypeId.STRING, "toHexString", TypeId.INT);
        code.invokeStatic(toHexString, s, c);

        // System.out.println(s);
        FieldId<System, PrintStream> systemOutField = systemType.getField(printStreamType, "out");
        code.sget(systemOutField, localSystemOut);
        MethodId<PrintStream, Void> printlnMethod = printStreamType.getMethod(
                TypeId.VOID, "println", TypeId.STRING);
        code.invokeVirtual(printlnMethod, null, localSystemOut, s);

        // return;
        code.returnVoid();
    }
}

Use it in your app

Maven users can get dexmaker from Sonatype's central repository. The Mockito dependency is optional.

  <dependency>
    <groupId>com.google.dexmaker</groupId>
    <artifactId>dexmaker</artifactId>
    <version>1.2</version>
  </dependency>
  <dependency>
    <groupId>com.google.dexmaker</groupId>
    <artifactId>dexmaker-mockito</artifactId>
    <version>1.2</version>
  </dependency>

Download dexmaker-1.2.jar and dexmaker-mockito-1.2.jar.

Run the Unit Tests

The unit tests for dexmaker must be run on a dalvikvm. In order to do this, you can use Vogar in the following fashion:

$ java -jar vogar.jar --mode device --sourcepath /path/to/dexmaker/dexmaker/src/test/java --sourcepath /path/to/dexmaker/dexmaker/src/main/java --sourcepath /path/to/dexmaker/dx/src/main/java --device-dir /data/dexmaker /path/to/dexmaker/dexmaker/src/test/

Download vogar.jar.