======================= 第一节 ===========================
这儿简略的介绍了Android的java环境根底，在后面一节中会结合详细的实例来了解这一节的内容。
一、Dalvik虚拟机
Dalvik是Android的程序的java虚拟机，代码在dalvik/下，
./
|– Android.mk
|– CleanSpec.mk
|– MODULE_LICENSE_APACHE2
|– NOTICE
|– README.txt
|– dalvikvm 虚拟机的完成库
|– dexdump
|– dexlist
|– dexopt
|– docs
|– dvz
|– dx
|– hit
|– libcore
|– libcore-disabled
|– libdex
|– libnativehelper 运用JNI调用本地代码时用到这个库
|– run-core-tests.sh
|– tests
|– tools
`– vm
二、Android的java结构
Android层次中第3层是java结构，第四层便是java使用程序。
Android的java类代码，首要是在frameworks/base/core/java/下，
./
|– Android
|– com
|– jarjar-rules.txt
`– overview.html
咱们再看一下frameworks/base/目录
./
|– Android.mk
|– CleanSpec.mk
|– MODULE_LICENSE_APACHE2
|– NOTICE
|– api
|– awt
|– build
|– camera
|– cmds
|– common
|– core
|– data
|– docs
|– graphics
|– include
|– keystore
|– libs
|– location
|– media
|– native
|– obex
|– opengl
|– packages
|– preloaded-classes
|– sax
|– services
|– telephony
|– test-runner
|– tests
|– tools
|– vpn
`– wifi
这儿也有Android的java结构代码。
三、JNI
在Android中，经过JNI，java能够调用C写的代码，首要的完成是在frameworks/base/core/jni，经过检查Android.mk，咱们能够看到最终生成了libandroid_runtime.so，详细完成JNI功用需求上面咱们介绍的libnativehelper.so，
四、体系服务之java
1、binder，供给Android的IPC功用
2、servicemanager，服务办理的服务器端
3、体系进程zygote，担任孵化一切的新使用
======================= 第二节 ==========================
在我平常工作中首要是进行linux网络子体系的模块开发、linux使用程序(C/C++)开发。在学习和从事驱动模块开发的过程中，假如你对linux体系自身，包含使用程序开发都不了解，那么读内核代码就好像天书，毫无意义，所以我剖析结构也是从根本体系api开端的，当然也不会太多涉及到使用程序开发。
好，开端这节首要是讲一个简略的adnroid使用程序，从使用程序动身，到结构代码。
剖析的使用程序咱们也奉行拿来主义:froyo/development/samples/HelloActivity
./
|– Android.mk
|– AndroidManifest.xml
|– res
|– src
`– tests
其他的就多说了，看代码
/**
* Copyright (C) 2006 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.
*/
package Android.util;
import com.Android.internal.os.RuntimeInit;
import java.io.PrintWriter;
import java.io.StringWriter;
/**
* API for sending log output.
*
*
Generally, use the Log.v() Log.d() Log.i() Log.w() and Log.e()
* methods.
*
*
The order in terms of verbosity, from least to most is
* ERROR, WARN, INFO, DEBUG, VERBOSE. Verbose should never be compiled
* into an application except during development. Debug logs are compiled
* in but stripped at runtime. Error, warning and info logs are always kept.
*
*
Tip: A good convention is to declare a TAG constant
* in your class:
*
*
private static final String TAG = MyActivity;
*
* and use that in subsequent calls to the log methods.
*
*
*
Tip: Don’t forget that when you make a call like
*
Log.v(TAG, index= + i);
* that when you’re building the string to pass into Log.d, the compiler uses a
* StringBuilder and at least three allocations occur: the StringBuilder
* itself, the buffer, and the String object. Realistically, there is also
* another buffer allocation and copy, and even more pressure on the gc.
* That means that if your log message is filtered out, you might be doing
