我有与升级Eclipse Java编译器相反的问题：我使用的是 可以 支持JDK 1.7的Eclipse 3.7.1 ，但是现在我正在为JDK
1.6进行开发…一直运行良好，但是突然之间我变得越来越难受我执行蚂蚁构建时出现的类似错误（见下文）。

我想使用JDK 1.6；我在哪里设置？Eclipse设置正确（每个项目的Java Build
Path指向JRE系统库[jdk1.6.0_16]），但是ant似乎无视它。

[javac] warning: java\nio\ByteBuffer.class(java\nio:ByteBuffer.class): major version 51 is newer than 50, the highest major version supported by this compiler.
[javac] It is recommended that the compiler be upgraded.
[javac] warning: java\lang\Object.class(java\lang:Object.class): major version 51 is newer than 50, the highest major version supported by this compiler.
[javac] It is recommended that the compiler be upgraded.
[javac] warning: java\util\Collections.class(java\util:Collections.class): major version 51 is newer than 50, the highest major version supported by this compiler.
[javac] It is recommended that the compiler be upgraded.
[javac] warning: java\util\EnumMap.class(java\util:EnumMap.class): major version 51 is newer than 50, the highest major version supported by this compiler.
[javac] It is recommended that the compiler be upgraded.

更新：更多线索-
这是我第一次在单独的Eclipse工作区中构建此特定项目，该工作区从先前的工作区导入该项目。我切换回旧的工作区并构建了相同的项目，并且构建良好。

差异似乎是ant在新工作区中的1.7 JRE中运行，而ant在我的旧工作区中的1.6
JRE中运行。是什么赋予了？我在哪里设置？我似乎无法弄清楚哪个设置不同。