我在struts1.3.8中使用Netbeans 6.9和java脚本，点击提交按钮后出现错误 这是netbeans输出：
[WARNING: Unhandled Exception thrown: class java.lang.NullPointerException].
错误消息：
javax.servlet.ServletException: java.lang.NullPointerException
org.apache.struts.action.RequestProcessor.processException(RequestProcessor.java:520)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:427)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:228)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
这是我的代码
jsp页面：
<html:form action="/adminTask" onsubmit="return checkCheckBoxes(this);" >
<table>
<tr>
<td align="left">Select your task:</td></tr>
<tr>
<td align="left">
<input type="checkbox" id="taskElement1" name="task" value="add" onchange="toggleStatus()"/>Add<br/>
<input type="checkbox" id="taskElement2" name="task" value="edit" onchange="toggleStatus()"/>Edit<br/>
<input type="checkbox" id="taskElement3" name="task" value="delete" onchange="toggleStatus()"/>Delete<br/>
</td>
</tr>
<tr>
<td align="left"><br/>Select what you want to do the task on:</td>
</tr>
<tr>
<td>
<input type="checkbox" id="objectElement4" name="object" value="customer" onchange="objectStatus()"/>Customer<br/>
<input type="checkbox" id="objectElement5" name="object" value="supplier" onchange="objectStatus()"/>Supplier<br/>
<input type="checkbox" id="objectElement6" name="object" value="category" onchange="objectStatus()"/>Category<br/>
<input type="checkbox" id="objectElement7" name="object" value="brand" onchange="objectStatus()"/>Brand<br/>
<input type="checkbox" id="objectElement8" name="object" value="product" onchange="objectStatus()"/>Product<br/>
</td>
</tr>
<tr>
<td><br/><html:submit value="Go" /></td>
</tr>
</table>
</html:form>
豆子：
public class adminTaskForm extends org.apache.struts.action.ActionForm {
private String task;
private String object;
public String getTask() {
return task;
}
public String getObject() {
return object;
}
public void setObject(String object) {
this.object = object;
}
/**
* @param string
*/
public void setTask(String task) {
this.task = task;
}
public adminTaskForm() {
super();
// TODO Auto-generated constructor stub
}
动作类：
公共类checkadminTaskAction扩展org.apache.struts.action.Action {
private static final String FAILURE = "failure";
public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)
throws Exception {
//Initilized Action error
ActionErrors errors = new ActionErrors();
// set the session on in the page
HttpSession session = request.getSession(true);
//Call LoginForm Instance here
adminTaskForm formBean = (adminTaskForm) form;
// extract user data
String task = formBean.getTask();
String object = formBean.getObject();
System.out.println(task);
System.out.println(object);
//Set up flag message
boolean adminFlag = false;
String taskFlag;
String objectFlag;
//set up address & adminTask
String address = null;
String adminTask = null;
// perform validation
if (task == null || // task parameter does not exist
task.length() < 1) // task parameter is empty
{
errors.add("task", new ActionMessage("errors.task.required"));
}
if (object == null || // object parameter does not exist
object.length() < 1) // object parameter is empty
{
errors.add("object", new ActionMessage("errors.object.required"));
}
//Save error messages keys into the appropriate HTTP request attribute for use by the <html:errors> tag
saveErrors(request, errors);
//Check- is errors empty
if (errors.isEmpty()) {
adminFlag = true;
} else {
adminFlag = false;
}
if (adminFlag == true) {
// start admin tasks
System.out.println("////////////////////////// start checkadminTasksAction /////////////////////////");
/// if the admin selected add task
if (task.equals("add")) {
taskFlag = "add";
/// if the admin selected add customer
if (object.equals("customer")) {
objectFlag = "customer";
} /// if the admin selected add supplier
else if (object.equals("supplier")) {
objectFlag = "supplier";
} /// if the admin selected add category
else if (object.equals("category")) {
objectFlag = "category";
} /// if the admin selected add brand
else if (object.equals("brand")) {
objectFlag = "brand";
} /// if the admin selected add product
else {
objectFlag = "product";
}
/// set the session to pass values
session.setAttribute("task", task);
session.setAttribute("object", object);
System.out.println(task + "ing " + object);
}/// if the admin selected edit task
else if (task.equals("edit")) {
taskFlag = "edit";
/// if the admin selected edit customer
if (object.equals("customer")) {
objectFlag = "customer";
} /// if the admin selected edit supplier
else if (object.equals("supplier")) {
objectFlag = "supplier";
} /// if the admin selected edit category
else if (object.equals("category")) {
objectFlag = "category";
} /// if the admin selected edit brand
else if (object.equals("brand")) {
objectFlag = "brand";
} /// if the admin selected edit product
else {
objectFlag = "product";
}
/// set the session to pass values
session.setAttribute("task", task);
session.setAttribute("object", objectFlag);
}/// if the admin selected delete task
else if (task.equals("delete")) {
taskFlag = "delete";
/// if the admin selected delete customer
if (object.equals("customer")) {
objectFlag = "customer";
} /// if the admin selected delete supplier
else if (object.equals("supplier")) {
objectFlag = "supplier";
} /// if the admin selected delete category
else if (object.equals("category")) {
objectFlag = "category";
} /// if the admin selected delete brand
else if (object.equals("brand")) {
objectFlag = "brand";
} /// if the admin selected delete product
else {
objectFlag = "product";
} /// if the admin selected nothing
/// set the session to pass values
session.setAttribute("adminTask", taskFlag);
session.setAttribute("taskObject", objectFlag);
}
if(adminTask.equals("add")){
request.getRequestDispatcher("/insert" + object + ".jsp").forward(request, response);
}
else if(adminTask.equals("edit") ||
adminTask.equals("delete")){
request.getRequestDispatcher("/updateObjects.jsp").forward(request, response);
}
else {
errors.add("forward", new ActionMessage("errors.forward"));
System.out.println("error forwarding");
}
}
return mapping.findForward(FAILURE);
}
}