myeclipse修改代码运行无效的解决方法
解决方法:
问题出现在项目的.project中，复制一个好的项目的.project文件替换掉它，我就是这个方法解决的。
我的.project文件内容如下（可以对比一下缺少啥，或者可以替换掉）：
<?xml version="1.0" encoding="UTF-8"?>
<projectDescription>
<name>police_px_qyb</name>
<comment></comment>
<projects>
</projects>
<buildSpec>
<buildCommand>
<name>org.eclipse.wst.common.project.facet.core.builder</name>
<arguments>
</arguments>
</buildCommand>
<buildCommand>
<name>org.eclipse.ui.externaltools.ExternalToolBuilder</name>
<triggers>full,incremental,</triggers>
<arguments>
<dictionary>
<key>LaunchConfigHandle</key>
<value><project>/.externalToolBuilders/org.eclipse.wst.jsdt.core.javascriptValidator (9).launch</value>
</dictionary>
</arguments>
</buildCommand>
<buildCommand>
<name>com.genuitec.eclipse.j2eedt.core.WebClasspathBuilder</name>
<arguments>
</arguments>
</buildCommand>
<buildCommand>
<name>org.eclipse.jdt.core.javabuilder</name>
<arguments>
</arguments>
</buildCommand>
<buildCommand>
<name>com.genuitec.eclipse.j2eedt.core.J2EEProjectValidator</name>
<arguments>
</arguments>
</buildCommand>
<buildCommand>
<name>com.genuitec.eclipse.j2eedt.core.DeploymentDescriptorValidator</name>
<arguments>
</arguments>
</buildCommand>
<buildCommand>
<name>org.eclipse.ui.externaltools.ExternalToolBuilder</name>
<triggers>full,incremental,</triggers>
<arguments>
<dictionary>
<key>LaunchConfigHandle</key>
<value><project>/.externalToolBuilders/org.eclipse.wst.validation.validationbuilder (1).launch</value>
</dictionary>
</arguments>
</buildCommand>
<buildCommand>
<name>com.genuitec.eclipse.ast.deploy.core.DeploymentBuilder</name>
<arguments>
</arguments>
</buildCommand>
<buildCommand>
<name>org.eclipse.wst.validation.validationbuilder</name>
<arguments>
</arguments>
</buildCommand>
</buildSpec>
<natures>
<nature>org.eclipse.jem.workbench.JavaEMFNature</nature>
<nature>com.genuitec.eclipse.ast.deploy.core.deploymentnature</nature>
<nature>com.genuitec.eclipse.j2eedt.core.webnature</nature>
<nature>org.eclipse.jdt.core.javanature</nature>
<nature>org.eclipse.wst.jsdt.core.jsNature</nature>
<nature>org.eclipse.wst.common.project.facet.core.nature</nature>
<nature>org.eclipse.wst.common.modulecore.ModuleCoreNature</nature>
</natures>
</projectDescription>