有关android工程的构建脚本（build.xml）的学习

学习【android-sdk-linux根目录】/tools/ant/build.xml，觉得如下几点很有用，记录之

1）ant脚本中属性值是于前置定义优化的原则，即属性发生重复定义时，前面定义的值不会被后面定义的覆盖；

2）需要注意javac的交叉编译参数（-bootclasspath <路径>        覆盖引导类文件的位置），注意到它可能很容易理解在J2SE平台下编译android平台的类文件是怎么做到的；

这里有介绍该参数的文章：http://docs.oracle.com/javase/6/docs/technotes/tools/solaris/javac.html#options

3）可利用ant -debug的参数来研究android的build.xml（这个强烈推荐使用），可以查看更多的日志输出，于便查看target运行时的参数；

使用事列：ant -debug release

如下为部份log

-compile:
Adding reference: project.javac.classpath
fileset: Setup scanner in dir /home/luogw/dev-tool/sdk/android-sdk-linux/tools/helloworld/src with patternSet{ includes: [] excludes: [] }
    [javac] com/luo/HelloWorldActivity.java added as com/luo/HelloWorldActivity.class doesn't exist.
fileset: Setup scanner in dir /home/luogw/dev-tool/sdk/android-sdk-linux/tools/helloworld/gen with patternSet{ includes: [] excludes: [] }
    [javac] /home/luogw/dev-tool/sdk/android-sdk-linux/tools/helloworld/gen/R.java.d skipped - don't know how to handle it
    [javac] com/luo/BuildConfig.java added as com/luo/BuildConfig.class doesn't exist.
    [javac] com/luo/R.java added as com/luo/R.class doesn't exist.
    [javac] Compiling 3 source files to /home/luogw/dev-tool/sdk/android-sdk-linux/tools/helloworld/bin/classes
    [javac] Using modern compiler
    [javac] Compilation arguments:
    [javac] '-d'
    [javac] '/home/luogw/dev-tool/sdk/android-sdk-linux/tools/helloworld/bin/classes'
    [javac] '-classpath'
    [javac] '/home/luogw/dev-tool/sdk/android-sdk-linux/tools/helloworld/bin/classes:/home/luogw/dev-tool/sdk/android-sdk-linux/tools/support/annotations.jar'
    [javac] '-sourcepath'
    [javac] '/home/luogw/dev-tool/sdk/android-sdk-linux/tools/helloworld/src:/home/luogw/dev-tool/sdk/android-sdk-linux/tools/helloworld/gen'
    [javac] '-target'
    [javac] '1.5'
    [javac] '-bootclasspath'
    [javac] '/home/luogw/dev-tool/sdk/android-sdk-linux/platforms/android-10/android.jar'
    [javac] '-encoding'
    [javac] 'UTF-8'
    [javac] '-g'
    [javac] '-source'
    [javac] '1.5'
    [javac] 
    [javac] The ' characters around the executable and arguments are
    [javac] not part of the command.
    [javac] Files to be compiled:
    [javac]     /home/luogw/dev-tool/sdk/android-sdk-linux/tools/helloworld/src/com/luo/HelloWorldActivity.java
    [javac]     /home/luogw/dev-tool/sdk/android-sdk-linux/tools/helloworld/gen/com/luo/BuildConfig.java
    [javac]     /home/luogw/dev-tool/sdk/android-sdk-linux/tools/helloworld/gen/com/luo/R.java

4）//TODO

注：目前我有个需求：想替换build.xml脚本中的-bootclasspath的值

但它不是一个属性值，不能通过前置定义的方式替换，暂时没有想到解决方案