1.首先去 这里 http://download.java.net/openjdk/jdk7/ 下载OpenJDK7的源码zip包。
2.安装编译工具包
如没安装aptitude，则先安装aptitude（sudo apt-get install aptitude）
sudo aptitude build-dep openjdk-6
3.注意：Ubuntu系统的语言必须切换到English（系统设置->语言支持）
4.修改hotspot/make/linux下的Makefile文件，注释掉以下内容，若不注释，会报错，然后exit 1退出编译：
check_os_version:
#ifeq ($(DISABLE_HOTSPOT_OS_VERSION_CHECK)$(EMPTY_IF_NOT_SUPPORTED),)
# $(QUIETLY) >&2 echo "*** This OS is not supported:" `uname -a`; exit 1;
#endif
5.修改jdk/make/javax/sound/jsoundalsa/下的Makefile文件，将
LDFLAGS += -lasound
改成
EXTRA_LIBS += -lasound
否则编译出错
6. 准备编译脚本：buildjdk.sh，放在解压对openjdk源码根目录下
#!/bin/bash
export LANG=C
export ALT_BOOTDIR=/usr/lib/jvm/java-6-openjdk
export ALLOW_DOWNLOADS=true
export USE_PRECOMPILED_HEADER=true
export SKIP_DEBUG_BUILD=false
export SKIP_FASTDEBUG_BUILD=true
export DEBUG_NAME=debug
unset CLASSPATH
unset JAVA_HOME
make sanity && make
7.执行编译脚本，./buildjdk.sh
8. 编译完成，检查结果
-- Build times ----------
Target debug_build
Start 2012-02-24 21:44:33
End 2012-02-24 22:40:32
00:00:52 corba
00:23:09 hotspot
00:09:25 jaxp
00:08:38 jaxws
00:13:01 jdk
00:00:54 langtools
00:55:59 TOTAL
-------------------------
make[1]: Leaving directory `/home/nathan/study/openjdk'
nathan@ubuntu:~/study/openjdk$ build/linux-i586-debug/j2sdk-image/bin/java -version
openjdk version "1.7.0-internal-debug"
OpenJDK Runtime Environment (build 1.7.0-internal-debug-nathan_2012_02_24_20_17-b00)
OpenJDK Server VM (build 21.0-b17-jvmg, mixed mode)