我使用了JSP代码并在tomcat5.5服务器下执行了相同的操作。它工作被罚款。现在我已经将相同的代码复制到其他系统的tomcat服务器下。但是在提交该 jsp 文件时，收到以下错误。导致错误的原因可能是什么？请指教。
root cause:
javax.servlet.ServletException: Bad version number in .class file (unable to load class myfirst.SearchLink)
org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:841)
org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:774)
org.apache.jsp.Test_jsp._jspService(Test_jsp.java:70)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:369)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:308)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:259)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
java.lang.UnsupportedClassVersionError: Bad version number in .class file (unable to load class myfirst.SearchLink)
org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:1962)
org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:931)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1403)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1282)
org.apache.jasper.servlet.JasperLoader.loadClass(JasperLoader.java:125)
org.apache.jasper.servlet.JasperLoader.loadClass(JasperLoader.java:63)
java.lang.ClassLoader.loadClassInternal(Unknown Source)
org.apache.jsp.Test_jsp._jspService(Test_jsp.java:51)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:369)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:308)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:259)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
更新
即使编译了我拥有的所有 java 代码，在当前版本的 java 中，我也会遇到相同的错误..
最近更新
@Pangea 是的，我在 JSP 代码中使用 myfirst.SearchLink，如下所示，
myfirst.SearchLink o=new myfirst.SearchLink();
String result=o.checkURL(url);
我的 SearchLink 的 java 代码如下，
package myfirst;
import java.net.URL;
import java.net.URLConnection;
import java.sql.*;
public class SearchLink{
public static void main(String args[]) throws Exception {
}
public String checkURL(String link)throws SQLException{
Connection con=null;
Statement stmt=null;
Statement stmtR=null;
String mem;
if(con==null){
SQLConnection.setURL("jdbc:sqlserver://192.168.2.53\\SQL2005;user=sa;password=365media;DatabaseName=LN_ADWEEK");
con=SQLConnection.getNewConnection();
stmt=con.createStatement();
stmtR=con.createStatement();
}
try{
ResultSet rs;
boolean hasRows=false;
rs=stmt.executeQuery("select url from urls_linkins where url='"+link+"'");
while(rs.next()){
hasRows=true;
//String mem=rs.getString(1);
rs.close();
return "This URL already exists in DB";
}
rs.close();
if (!hasRows)
{
URL url = new URL(link);
String domain=url.getHost();
String Str="This URL does not exist in DB<br><br><br>";
rs=stmtR.executeQuery("select url from urls_linkins where url like '%"+domain+"%'");
boolean flag=false;
while(rs.next()){
if(!flag){
Str=Str+"<Br>"+"Similar Domains in DB are";
}
flag=true;
mem=rs.getString(1);
//System.out.println("Similar Domains already in DB"+mem);
Str=Str+"<Br>"+mem;
}
return Str;
}
return "This URL does not exist in DB";
}catch(Exception e){
e.printStackTrace();
return e.getMessage();
}finally{
if(stmtR!=null){
stmtR.close();
}
if(stmt!=null){
stmt.close();
}
if(con!= null){
con.close();
}
}
}
public String addURL(String link,String source)throws SQLException{
Connection con=null;
Statement stmt=null;
Statement stmtR=null;
final String rssvar="Rss";
if(con==null){
SQLConnection.setURL("jdbc:sqlserver://192.168.2.53\\SQL2005;user=sa;password=365media;DatabaseName=LN_ADWEEK");
con=SQLConnection.getNewConnection();
stmt=con.createStatement();
stmtR=con.createStatement();
}
try{
PreparedStatement insertUrlStatement = con.prepareStatement("INSERT INTO urls_linkins(url, source_name, is_active, is_periodic, Link_Type, New_Entry) VALUES(?, ?, ?, ?, ?, ?)");
//insertUrlStatement.setInt(1, 21211);
insertUrlStatement.setString(1, link);
insertUrlStatement.setString(2, source);
insertUrlStatement.setInt(3, 1);
insertUrlStatement.setInt(4, 0);
insertUrlStatement.setString(5, rssvar);
insertUrlStatement.setInt(6, 1);
insertUrlStatement.executeUpdate();
insertUrlStatement.close();
return "The URL has been added to the Database";}
catch(Exception e){
e.printStackTrace();
return e.getMessage();
}finally{
if(stmtR!=null){
stmtR.close();
}
if(stmt!=null){
stmt.close();
}
if(con!= null){
con.close();
}
}
}
public String addURL1(String link,String source)throws SQLException{
Connection con=null;
Statement stmt=null;
Statement stmtR=null;
final String other="Other";
if(con==null){
SQLConnection.setURL("jdbc:sqlserver://192.168.2.53\\SQL2005;user=sa;password=365media;DatabaseName=LN_ADWEEK");
con=SQLConnection.getNewConnection();
stmt=con.createStatement();
stmtR=con.createStatement();
}
try{
PreparedStatement insertUrlStatement = con.prepareStatement("INSERT INTO urls_linkins(url, source_name, is_active, is_periodic, Link_Type, New_Entry) VALUES(?, ?, ?, ?, ?, ?)");
//insertUrlStatement.setInt(1, 21211);
insertUrlStatement.setString(1, link);
insertUrlStatement.setString(2, source);
insertUrlStatement.setInt(3, 1);
insertUrlStatement.setInt(4, 0);
insertUrlStatement.setString(5, other);
insertUrlStatement.setInt(6, 1);
insertUrlStatement.executeUpdate();
insertUrlStatement.close();
return "The URL has been added to the Database";}
catch(Exception e){
e.printStackTrace();
return e.getMessage();
}finally{
if(stmtR!=null){
stmtR.close();
}
if(stmt!=null){
stmt.close();
}
if(con!= null){
con.close();
}
}
}
public String addmultiple(String file)throws SQLException{
return file;
}
}
最佳答案
这意味着您的代码是针对运行该代码的 tomcat 服务器不支持的 java 版本进行编译的。可能您将代码移至使用旧版本 java 的 5.5 之前的旧版 tomcat
关于java - 错误提示 "Bad version in .class file"，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/4070443/