srcAdd.jsp用于解决java.lang.NoSuchMethodError_综合

在实际开发中，经常会遇到jar包冲突而抛出的：java.lang.NoSuchMethodError
,排查起来非常的麻烦。本JSP页面的功能就是用于java类路径定位，使用时将srcAdd.jsp放置在项目的根路径下，项目运行起来之后，在地址栏输入URL，如 .../srcAdd.jsp?className=java.net.URL即可查看类所在的路径

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>  
<%@ page import="java.security.*,java.net.*,java.io.*"%>  
<%!  public static URL getClassLocation(final Class cls)   {  if(cls==null)  {  throw new IllegalArgumentException("null input: cls");  }  URL result=null;  final String clsAsResource=cls.getName().replace('.', '/').concat(".class");  final ProtectionDomain pd=cls.getProtectionDomain();  // java.lang.Class contract does not specify if 'pd' can ever be null;  // it is not the case for Sun's implementations, but guard against null  // just in case:  if(pd != null)   {  final CodeSource cs=pd.getCodeSource();  // 'cs' can be null depending on the classloader behavior:  if(cs != null)   {  result=cs.getLocation();  }  if(result != null)   {  // Convert a code source location into a full class file location  // for some common cases:  if("file".equals(result.getProtocol()))   {  try   {  if(result.toExternalForm().endsWith(".jar") || result.toExternalForm().endsWith(".zip"))  {  result=new URL("jar:".concat(result.toExternalForm()).concat("!/").concat(clsAsResource));  }  else if(new File(result.getFile()).isDirectory())  {  result=new URL(result, clsAsResource);  }  }  catch(MalformedURLException ignore)   {  }  }  }  }  if(result == null)   {  // Try to find 'cls' definition as a resource; this is not  // document．d to be legal, but Sun's implementations seem to         //allow this:  final ClassLoader clsLoader=cls.getClassLoader();  result=clsLoader != null ? clsLoader.getResource(clsAsResource) : ClassLoader.getSystemResource(clsAsResource);  }  return result;  }  
%>  
<html>  
<head>  
<title>srcAdd.jar</title>  
</head>  
<body bgcolor="#ffffff">  使用方法，className参数为类的全名，不需要.class后缀，如  srcAdd.jsp?className=java.net.URL  
<%  try  {  String classLocation=null;  String error=null;  String className=request.getParameter("className");  classLocation=""+getClassLocation(Class.forName(className));  if(error == null)   {  out.print("类" + className + "实例的物理文件位于：");  out.print("<hr>");  out.print(classLocation);  }  else   {  out.print("类" + className + "没有对应的物理文件。<br>");  out.print("错误：" + error);  }  }  catch(Exception e)  {  out.print("异常。"+e.getMessage());  }  
%>  
</body>  
</html>