IONIC：Dex无法解析版本52字节代码

Question

尝试在ionic中编译发布应用程序时出现此错误

Dex: Error converting bytecode to dex:
Cause: Dex cannot parse version 52 byte code.
This is caused by library dependencies that have been compiled using Java 8 or above.
If you are using the 'java' gradle plugin in a library submodule add
targetCompatibility = '1.7'
sourceCompatibility = '1.7'
to that submodule's build.gradle file.

离子信息：

@ionic/cli-utils  : 1.19.2
ionic (Ionic CLI) : 3.20.0

全局软件包：

cordova (Cordova CLI) : 8.0.0

本地套餐：

@ionic/app-scripts : 1.1.0
Cordova Platforms  : android 6.3.0 ios 4.5.4
Ionic Framework    : ionic-angular 2.0.1-201702132005

系统：

Node : v6.12.2
npm  : 5.8.0
OS   : Windows 10