Android Source compiler does not sign apk

As stated , apk need source code under certain api, but current source compiler environment does not know the future will not change, so I want to re-sign their own , but now I do not know how to get unsigned apk, welcome to the great God pointing.
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teach you a way to / system / app / below you compiled apk copy it , and then extract the tool to open the META-INF files to delete the following two CERT is to get no signature APK the
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ah yesterday afternoon, just try to find a variety of Baidu one really quite fun
But jdk1.7 version jarsigner.jar signed apk problems need to use version 1.6 Results posted to the sub