下载地址
http://jdk.java.net/java-se-ri/8
找到
The source code of the RI binaries is available under the GPLv2 in a single zip file (md5) 121 MB.
点击zip进行下载，下载地址为
https://download.java.net/openjdk/jdk8u40/ri/openjdk-8u40-src-b25-10_feb_2015.zip
编译环境centos7（minimal纯净环境）
打开包内的README和内附的连接http://hg.openjdk.java.net/jdk8/jdk8/raw-file/tip/README-builds.html阅读使用方式
首先安装系统依赖
安装unzip
yum install -y unzip zip
下载JDK7
从这里下载http://jdk.java.net/java-se-ri/7
https://download.java.net/openjdk/jdk7u75/ri/openjdk-7u75-b13-linux-x64-18_dec_2014.tar.gz
tar xzvf openjdk-7u75-b13-linux-x64-18_dec_2014.tar.gz
#解包
unzip openjdk*
cd openjdk#配置编译
chmod 777 configure
#指定--with-boot-jdk到jdk7目录
./configure --with-boot-jdk=../java-se-7u75-ri/
#此时提示安装开发工具、依赖包，执行如下命令
yum groupinstall "Development Tools"
yum install -y libXtst-devel libXt-devel libXrender-devel cups-devel freetype-devel alsa-lib-devel
再次执行./configure --with-boot-jdk=../java-se-7u75-ri/
出现如下提示表示成功
====================================================
A new configuration has been successfully created in
/root/openjdk/build/linux-x86_64-normal-server-release
using configure arguments '--with-boot-jdk=../java-se-7u75-ri/'.
Configuration summary:
* Debug level: release
* JDK variant: normal
* JVM variants: server
* OpenJDK target: OS: linux, CPU architecture: x86, address length: 64#接下来进行编译
make all
#等待一段时间后，会在目录中生成build/*/images/j2sdk-image，比如我这里就是build/linux-x86_64-normal-server-release/images/j2sdk-image
cd build/linux-x86_64-normal-server-release/images/j2sdk-image/
ls
bin/java -version
查看编译后的java版本信息
