# 软件环境丨Software Environment

OS：CentOS 6.5
JDK: OpenJDK-7u40

# 准备工作丨Preparation

下载源码包 | Download source code package
OpenJDK Source Releases
解压源码包 | Decompress the package
```
# unzip openjdk-7u40-fcs-src-b43-26_aug_2013.zip
```
- hotspot 虚拟机实现，大部分是C/C++代码
- jdk Java核心类库目录，位于 jdk/src/share/classes
- langtools 一些编译工具
安装依赖 | Install dependence
```
# yum -y install gcc gcc-c++ alsa-lib alsa-lib-devel libXrender libXrender-devel libXi-devel libXt-devel libXtst-devel cups cups-devel
```
安装freetype | install freetype
```
# ./configure && make && make install
```
安装ant | install ant

# ln -s /usr/local/apache-ant-1.9.4/bin/ant /usr/bin/ant

安装JDK（如果已有则不必重新安装） | install JDK(optional if already installed)
Sun JDK或Open JDK均可，过程略.

# 环境配置丨Environment Configuration

编辑文件vim ~/.bash_profile加入以下变量 | Modify the .bash_profile and set the variables below

export LANG="C"
export ALT_BOOTDIR="/usr/java/jdk1.7.0_67/"
export ANT_HOME="/usr/local/apache-ant-1.9.4"
export ALT_FREETYPE_HEADERS_PATH="/usr/local/include/freetype2"
export ALT_FREETYPE_LIB_PATH="/usr/local/lib"
export ALLOW_DOWNLOADS=true
export SKIP_DEBUG_BUILD=false
export SKIP_FASTDEBUG_BUILD=true
export DEBUG_NAME=debug
unset JAVA_HOME
unset CLASSPATH

使变量生效 | make the variables take effect

# source ~/.bash_profile

# 编译源码丨Compile Source Code

测试环境是否健全 | Check environment if sane.

# make sanity

如果输出以下内容则表示通过，可以进行编译。| if the environment is OK, it can be compiled.

Sanity check passed.

开始编译 | start to compile use 'make' command

# make ARCH_DATA_MODEL=64

看到如下输出则为编译成功 | It indicates that OpenJDK has been compiled successfully

>>>Finished making images @ Sat Nov  8 00:45:16 EST 2014 ...
make[2]: Leaving directory `/usr/local/openjdk/jdk/make'
########################################################################
##### Leaving jdk for target(s) sanity all docs images             #####
########################################################################
##### Build time 00:10:15 jdk for target(s) sanity all docs images #####
########################################################################

#-- Build times ----------
Target debug_build
Start 2014-11-08 00:26:41
End   2014-11-08 00:45:16
00:02:11 corba
00:04:36 hotspot
00:00:24 jaxp
00:00:30 jaxws
00:10:15 jdk
00:00:39 langtools
00:18:35 TOTAL
-------------------------
make[1]: Leaving directory `/usr/local/openjdk'
[root@BobServerStation openjdk]#

# 测试验证丨Testing & Verification

一个测试类Test.java

/**
* Author: Bob.Z
* Date: 2014-11-08
*/
public class Test{
  public static void main(String[] args){
       System.out.println("Hello OpenJDK~");
  }
}

使用刚生成的JDK编译：

# ./build/linux-amd64/bin/javac Test.java

在当前目录下会生成Test.class文件，然后运行便会看到输出。

# ./build/linux-amd64/bin/java Test
Hello OpenJDK~

另一个测试修改JDK源码
进入目录jdk/src/share/classes/java/io，然后修改PrintStream.java

/**
   * Prints a string.  If the argument is <code>null</code> then the string
   * <code>"null"</code> is printed.  Otherwise, the string's characters are
   * converted into bytes according to the platform's default character
   * encoding, and these bytes are written in exactly the manner of the
   * <code>{@link #write(int)}</code> method.
   *
   * @param      s   The <code>String</code> to be printed
   */
  public void print(String s) {
      if (s == null) {
          s = "null";
      }
      s = s + " This is OpenJdk7 compiled by Bob.Z!!!";  // 重新赋值
      write(s);
  }

接下来重新编译JDK，重新编译刚才的Test.java文件并运行会看到如下输出：

在CentOS 6.5上编译OpenJDK7源码 | Compile OpenJDK7 source code on CentOS 6.5 - Bob.Z - 断尘居