android 系统签名no conscrypt_openjdk_jni in java.library.path错误

1.获取系统签名

 把以下所有文件放入同一个文件夹

• 在Android系统源码中的\build\target\product\security目录下找到platform.x509.pem 和platform.pk8两个文件；

• 在out/host/Linux-x86/framework目录下找到signapk.jar文件

• 找到 libconscrypt_openjdk_jni库

  prebuilts/sdk/tools/linux/lib64/libconscrypt_openjdk_jni.so
  

• 需要进行系统签名的app_unsigned.apk 

2.在linux环境下，进入该文件夹目录执行以下命令即可完成签名即可

java -Djava.library.path=. -jar signapk.jar platform.x509.pem platform.pk8 app_unsigned.apk app_signed.apk

3.linux下可能出现问题，jdk环境不对，缺失jdk-8环境

java.lang.UnsupportedClassVersionError: *******: Unsupported major.minor version 52.0

4.编译安装jdk-8环境

$ sudo apt-get install openjdk-8-jdk
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package openjdk-8-jdk

    （1）解决办法：

         查看当前java环境

          $ update-java-alternatives -l

    java

    java-1.7.0-openjdk-amd64 1071 /usr/lib/jvm/java-1.7.0-openjdk-amd64

安装jdk-8

    $ sudo add-apt-repository ppa:openjdk-r/ppa

    $ sudo apt-get update

    $ sudo apt-get install openjdk-8-jdk

查看当前的jdk环境

    $ update-java-alternatives -l

    java-1.7.0-openjdk-amd64 1071 /usr/lib/jvm/java-1.7.0-openjdk-amd64
    java-1.8.0-openjdk-amd64 1069 /usr/lib/jvm/java-1.8.0-openjdk-amd64

         切换不同版本的jdk

$ sudo update-alternatives --config java
There are 2 choices for the alternative java (providing /usr/bin/java).

  Selection    Path                                            Priority   Status
------------------------------------------------------------
  0            /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java   1071      auto mode
  1            /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java   1071      manual mode
* 2            /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java   1069      manual mode

Press enter to keep the current choice[*], or type selection number:

$ sudo update-alternatives --config javac
$ sudo update-alternatives --config javap
$ sudo update-alternatives --config javadoc