java.lang.UnsupportedClassVersionError : com/mysite/folders/Folders : Unsupported major. 次要版本 51.0

Question

我创建了一个名为“Folders”的 java bean(暂时非常简单，因为我想让它主要工作)，我将其导出为 .jar 文件并将其放在/WEB-INF 中/lib/目录。但是，当我尝试在预期页面上使用它时，我收到此错误(如果需要，我可以添加长语句的 res):

Feb 22, 2013 12:02:31 PM org.apache.catalina.core.ApplicationDispatcher invoke
SEVERE: Servlet.service() for servlet jsp threw exception
java.lang.UnsupportedClassVersionError: com/mysite/folders/Folders : Unsupported major.minor     version 51.0 (unable to load class com.mysite.folders.Folders)

如果可能是导致问题的原因，那么这是 Bean:

package com.mysite.folders;

import java.io.Serializable;
import java.util.ArrayList;

public class Folders implements Serializable {

private String accountNumber;
private String folderName;
private String groupName;
private ArrayList<String> folderNames;
private ArrayList<String> groupNames;       

public String getAccountNumber() {
    return accountNumber;
}

public void setAccountNumber(String accountNumber) {
    this.accountNumber = accountNumber;
}

public String getFolderName() {
    return folderName;
}

public void setFolderName(String folderName) {
    this.folderName = folderName;
}

public String getGroupName() {
    return groupName;
}

public void setGroupName(String groupName) {
    this.groupName = groupName;
}

public ArrayList<String> getFolderNames() {
    return folderNames;
}

public void setFolderNames(ArrayList<String> folderNames) {
    this.folderNames = folderNames;
}

public ArrayList<String> getGroupNames() {
    return groupNames;
}

public void setGroupNames(ArrayList<String> groupNames) {
    this.groupNames = groupNames;
}

public Folders(String accountNumber, String folderName, String groupName,
        ArrayList<String> folderNames, ArrayList<String> groupNames) {
    super();
    this.accountNumber = accountNumber;
    this.folderName = folderName;
    this.groupName = groupName;
    this.folderNames = folderNames;
    this.groupNames = groupNames;
}
}

最后是我在页面上的声明:

<jsp:useBean id="Folders" scope="session" class="com.mysite.folders.Folders" />

我觉得我这样做是正确的，但不确定为什么这不起作用。任何建议或提示将不胜感激。

Answer 1

似乎您正在使用 JDK7 进行编译，并且在您使用它的地方降低版本

查看维基百科代码

正在使用的类文件格式的主版本号。

J2SE 7 = 51 (0x33 hex).

正如所有建议，也请参阅此 How to fix java.lang.UnsupportedClassVersionError: Unsupported major.minor version