用 jdb 追踪 Android

You may have debug Android in eclipse, Have you ever used jdb  tracing Android. Since Dalvikvm support jdwp, we can use jdb to debug the program.  there are 2 ways

Android as debug host

Steps

1) update libandroid_runtime

change below

frameworks/base/core/jni/AndroidRuntime.cpp
    620     opt.optionString =
    621         "-agentlib:jdwp=transport=dt_android_adb,suspend=n,server=y";

as

opt.optionString = "-agentlib:jdwp=transport=dt_socket,address=8011,server=y,suspend=y";

use "mmm frameworks/base/core/jni" to re-generate  system/lib/libandroid_runtime.so, then copy to your runing env (system/lib)

 

2) change system/root/default.prop on your running env

change "ro.debuggable=0" to "ro.debuggable=1"

if you won not do it,  you can specify  AndroidManifest.xml

<application android:label="@string/app_name" android:icon="@drawable/plasma" android:debuggable="true">

Or the App can not be debugged

3) start the app

check stop you will see below

I/Zygote  ( 6843/6843): Accepting command socket connections

I/jdwp    ( 7385/7385): JDWP will wait for debugger on port 8011

4) use jdb to attach the port

jdb -attach localhost:8011

--- you will see ---

Initializing jdb ...
>
VM Started: "thread=<1> main", dalvik.system.Zygote.nativeForkSystemServer(), line=-1 bci=-1

<1> main[1]

 

5)  include source dirs by "use" command, you will see source code

<1> main[1]  use  /home/user/jb/frameworks/base/core/java:/home/user/jb/frameworks/base/packages/SettingsProvider/src/:/home/user/jb/frameworks/base/services/java

 
6) set break and trace

Use commands: stop in, cont, list, next, you will able to trace your code

<1> main[1] stop in com.android.server.InputMethodManagerService.getEnabledInputMethodSubtypeList

Deferring breakpoint com.android.server.InputMethodManagerService.getEnabledInputMethodSubtypeList.

<1> main[1] cont

> Ignoring cmd 268435570/199/1 from the VM

Set deferred breakpoint com.android.server.InputMethodManagerService.getEnabledInputMethodSubtypeList

Breakpoint hit: "thread=<12> android.server.ServerThread", com.android.server.InputMethodManagerService.getEnabledInputMethodSubtypeList(), line=845 bci=0

845            synchronized (mMethodMap) {

 

<12> android.server.ServerThread[1] list

841    

842        @Override

843        public List<InputMethodSubtype> getEnabledInputMethodSubtypeList(InputMethodInfo imi,

844                boolean allowsImplicitlySelectedSubtypes) {

845 =>         synchronized (mMethodMap) {

846                return getEnabledInputMethodSubtypeListLocked(imi, allowsImplicitlySelectedSubtypes);

847            }

848        }

849    

850        @Override

<12> android.server.ServerThread[1] next

Step completed: "thread=<12> android.server.ServerThread", com.android.server.InputMethodManagerService.getEnabledInputMethodSubtypeList(), line=846 bci=3

846                return getEnabledInputMethodSubtypeListLocked(imi, allowsImplicitlySelectedSubtypes);

<12> android.server.ServerThread[1]

Jdb as debug host

There are shortcomings in "Android as host", because every time the JavaVM starts up,  it will move to listen status, So the SystemServer will listen, even we don't want to. so "Jdb as debug host" is a better idea.

1) update libandroid_runtime