96 lines
3.4 KiB
HTML
96 lines
3.4 KiB
HTML
<html>
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<head>
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<title>Basic Dalvik VM Invocation</title>
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</head>
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<body>
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<h1>Basic Dalvik VM Invocation</h1>
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<p>
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On an Android device, the Dalvik virtual machine usually executes embedded
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in the Android application framework. It's also possible to run it directly,
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just as you would a virtual machine on your desktop system.
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</p><p>
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After compiling your Java language sources, convert and combine the .class
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files into a DEX file, and push that to the device. Here's a simple example:
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</p><p><code>
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% <font color="green">echo 'class Foo {'\</font><br>
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> <font color="green">'public static void main(String[] args) {'\</font><br>
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> <font color="green">'System.out.println("Hello, world"); }}' > Foo.java</font><br>
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% <font color="green">javac Foo.java</font><br>
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% <font color="green">dx --dex --output=foo.jar Foo.class</font><br>
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% <font color="green">adb push foo.jar /sdcard</font><br>
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% <font color="green">adb shell dalvikvm -cp /sdcard/foo.jar Foo</font><br>
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Hello, world
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</code>
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</p><p>
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The <code>-cp</code> option sets the classpath. The initial directory
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for <code>adb shell</code> may not be what you expect it to be, so it's
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usually best to specify absolute pathnames.
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</p><p>
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The <code>dx</code> command accepts lists of individual class files,
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directories, or Jar archives. When the <code>--output</code> filename
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ends with <code>.jar</code>, <code>.zip</code>, or <code>.apk</code>,
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a file called <code>classes.dex</code> is created and stored inside the
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archive.
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</p><p>
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Run <code>adb shell dalvikvm -help</code> to see a list of command-line
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options.
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</p><p>
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<h2>Using a debugger</h2>
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<p>
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You can debug stand-alone applications with any JDWP-compliant debugger.
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There are two basic approaches.
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</p><p>
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The first way is to connect directly through TCP. Add, to the "dalvikvm"
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invocation line above, an argument like:
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</p><p>
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<code> -agentlib:jdwp=transport=dt_socket,address=8000,server=y,suspend=y</code>
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</p><p>
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This tells the VM to wait for a debugger to connect to it on TCP port 8000.
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You need to tell adb to forward local port 8000 to device port 8000:
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</p><p>
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<code>% <font color="green">adb forward tcp:8000 tcp:8000</font></code>
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</p><p>
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and then connect to it with your favorite debugger (using <code>jdb</code>
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as an example here):
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</p><p>
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<code>% <font color="green">jdb -attach localhost:8000</font></code>
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</p><p>
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When the debugger attaches, the VM will be in a suspended state. You can
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set breakpoints and then tell it to continue.
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</p><p>
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You can also connect through DDMS, like you would for an Android application.
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Add, to the "dalvikvm" command line:
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</p><p>
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<code> -agentlib:jdwp=transport=dt_android_adb,suspend=y,server=y</code>
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</p><p>
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Note the <code>transport</code> has changed, and you no longer need to
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specify a TCP port number. When your application starts, it will appear
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in DDMS, with "?" as the application name. Select it in DDMS, and connect
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to it as usual, e.g.:
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</p><p>
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<code>% <font color="green">jdb -attach localhost:8700</font></code>
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</p><p>
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Because command-line applications don't include the client-side
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DDM setup, features like thread monitoring and allocation tracking will not
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be available in DDMS. It's strictly a debugger pass-through in this mode.
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</p><p>
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See <a href="debugger.html">Dalvik Debugger Support</a> for more information
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about using debuggers with Dalvik.
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</p></p>
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<address>Copyright © 2009 The Android Open Source Project</address>
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</body>
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</html>
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