Unsupported major.minor version 52.0

最近使用android studio （3.4.2）編譯一個工程竟然報錯了

FAILURE: Build failed with an exception.

* Where:
Build file 'F:\work201907\freen\build.gradle' line: 1

* What went wrong:
A problem occurred evaluating project ':freen'.
> java.lang.UnsupportedClassVersionError: com/android/build/gradle/LibraryPlugin : Unsupported major.minor version 52.0

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

顯然Unsupported major.minor version 52.0這個是說需要jdk 8,但是我默認配置的是jdk7。也就是說在控制檯輸入
java -version打印出來的版本是7，這個版本其實指向的是環境變量JAVA_HOME對應目錄下的jdk。我們的工程下面的gradlew.bat文件有段代碼這麼寫的

:findJavaFromJavaHome
set JAVA_HOME=%JAVA_HOME:"=%
set JAVA_EXE=%JAVA_HOME%/bin/java.exe

網上查詢說是要修改File—>project structure—>SDK Location---->JDK Location,但是我修改後發現沒用。我的電腦是同時安裝了jdk7和jdk8的。解決方法是直接將JAVA_HOME修改爲jdk8對應的目錄。