问题解决:
在eclipse中，window-->preferences-->Java-->Installed JREs
选中JRE 点击Edit
写入这句话:
-Xms800m -Xmx800m -XX:MaxNewSize=256m -XX:MaxPermSize=256m
并设置当前使用的tomcat的运行jdk为当前刚刚设置过的jdk即可
当加入tomcat7的时候有时候启动不起来报错误为
严重: Error waiting for multi-thread deployment of directories to completehostConfig.deployWar=Deploying web application archive {0}
java.util.concurrent.ExecutionException: java.lang.OutOfMemoryError: Java heap space
at java.util.concurrent.FutureTask$Sync.innerGet(FutureTask.java:222)
at java.util.concurrent.FutureTask.get(FutureTask.java:83)
at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:1023)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:474)
at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1413)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:313)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
at org.apache.catalina.util.LifecycleBase.setStateInternal(LifecycleBase.java:401)
at org.apache.catalina.util.LifecycleBase.setState(LifecycleBase.java:346)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1140)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:785)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.OutOfMemoryError: Java heap space
at java.io.BufferedInputStream.<init>(BufferedInputStream.java:178)
at org.apache.tomcat.util.bcel.classfile.ClassParser.<init>(ClassParser.java:77)
at org.apache.catalina.startup.ContextConfig.processAnnotationsStream(ContextConfig.java:2065)
at org.apache.catalina.startup.ContextConfig.processAnnotationsJar(ContextConfig.java:1942)
at org.apache.catalina.startup.ContextConfig.processAnnotationsUrl(ContextConfig.java:1908)
at org.apache.catalina.startup.ContextConfig.processAnnotations(ContextConfig.java:1893)
at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1296)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:855)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:346)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5173)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:618)
at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1100)
at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1618)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
... 5 more
2012-10-25 8:47:41 org.apache.coyote.AbstractProtocol start
信息: Starting ProtocolHandler ["http-apr-8080"]
Exception in thread "main"
java.lang.OutOfMemoryError: Java heap space
at org.apache.tomcat.util.net.AprEndpoint$Poller.init(AprEndpoint.java:1110)
at org.apache.tomcat.util.net.AprEndpoint.startInternal(AprEndpoint.java:576)
at org.apache.tomcat.util.net.AbstractEndpoint.start(AbstractEndpoint.java:620)
at org.apache.coyote.AbstractProtocol.start(AbstractProtocol.java:444)
at org.apache.catalina.connector.Connector.startInternal(Connector.java:1010)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:459)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:732)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.startup.Catalina.start(Catalina.java:675)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:322)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:451)