我如何知道我的代码库是否有Java8方法

我遇到了一些问题，AppEngine抱怨我的代码有Java1.8方法，而AppEngine需要Java1.7。这是错误跟踪。我不知道如何修理它

Failed startup of context com.google.apphosting.utils.jetty.RuntimeAppEngineWebAppContext@6c5c4442{/,/base/data/home/apps/s~myapi-mobile/1.123456789034567}
org.mortbay.util.MultiException[java.lang.UnsupportedClassVersionError: org/apache/jsp/editor_005fform_jsp : Unsupported major.minor version 52.0, java.lang.UnsupportedClassVersionError: org/apache/jsp/editor_005fform_jsp : Unsupported major.minor version 52.0]
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:656)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.createHandler(AppVersionHandlerMap.java:203)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.getHandler(AppVersionHandlerMap.java:176)
    at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:133)
    at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:501)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:446)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:453)
    at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:276)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:312)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:304)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:450)
    at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:235)
    at java.lang.Thread.run(Thread.java:745)
java.lang.UnsupportedClassVersionError: org/apache/jsp/editor_005fform_jsp : Unsupported major.minor version 52.0
    at com.google.appengine.runtime.Request.process-9f0a91645afbfd1f(Request.java)
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:820)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
    at sun.reflect.GeneratedMethodAccessor5.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:375)
    at org.mortbay.util.Loader.loadClass(Loader.java:91)
    at org.mortbay.util.Loader.loadClass(Loader.java:71)
    at org.mortbay.jetty.servlet.Holder.doStart(Holder.java:73)
    at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:242)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:446)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:453)
    at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:276)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:312)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:304)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:450)
    at java.lang.Thread.run(Thread.java:745)
java.lang.UnsupportedClassVersionError: org/apache/jsp/editor_005fform_jsp : Unsupported major.minor version 52.0
    at com.google.appengine.runtime.Request.process-9f0a91645afbfd1f(Request.java)
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:820)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
    at sun.reflect.GeneratedMethodAccessor5.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:375)
    at org.mortbay.util.Loader.loadClass(Loader.java:91)
    at org.mortbay.util.Loader.loadClass(Loader.java:71)
    at org.mortbay.jetty.servlet.Holder.doStart(Holder.java:73)
    at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:242)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:446)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:453)
    at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:276)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:312)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:304)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:450)
    at java.lang.Thread.run(Thread.java:745)

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消息并不告诉您有Java8方法，它告诉您的Java文件是使用Java8编译器编译的，而执行环境是早期的Java版本。

要回答实际问题，您可以尝试使用Java 7（或更低版本）编译器编译代码，看看会发生什么

如果代码编译时没有问题，那么很可能没有使用Java8方法（虽然这不是必须的，但是可能有使用反射调用Java8方法的情况）

如果存在异常，则必须检查异常以查看其根本原因

---

如果错误报告明显不存在的方法（例如新的collections/streams API），或者报告无法识别的语法（例如使用lambdas，

（）->{}

），那么您很可能使用Java 8。

QUOTE：：一般来说，Java编译器从未强制执行API遵从性，因此作为示例，您可以使用JDK 7编译程序，使用-source 1.6和-target 1.6，并且仍然引用JDK 7中JDK 6中不可用的API，那么一切都将顺利编译（只要您引用新的API而不使用任何Java 7语言语法）。显然，由于缺少API，它不会在Java6上运行。简而言之，编译器不强制执行这一点；它只强制语言遵从性，使用任何API…这篇关于谷歌代码的文章是关于一些不同的东西。它是关于Java8的libs中可用方法的运行时依赖性。如果您想避免这种情况，您需要将IDE配置为针对目标Java版本的JRE进行编译。如果您试图使用一个不可用的方法，则会收到另一条错误消息。可能是重复的