JSONObject json = new JSONObject()错误

Java code

public class LoginAction extends ActionSupport {
    private String username;
    private String password;
    private UserService userService;
     private javax.servlet.http.HttpServletResponse response;
        // 获得HttpServletResponse对象
        public void setServletResponse(HttpServletResponse response){
        this.response = response;
    }   

    public UserService getUserService() {
        return userService;
    }

    public void setUserService(UserService userService) {
        this.userService = userService;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }    public String execute()throws JSONException, IOException,Exception {
        Users user=userService.find(username, password);
        if(user!=null){
            Map session =(Map)ActionContext.getContext().getSession();
            session.put("user",user);
            
            JSONObject json = new JSONObject();//这里错了,怎么解决?
            json.put("loginOK", true);
            json.put("success", true);
            response.getWriter().print(json);
            return null;            
        }else
            return "fail";
    }
}

抛出错误:2010-5-24 17:11:44 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet default threw exception
java.lang.NoClassDefFoundError: org/json/JSONException
at java.lang.Class.getDeclaredMethods0(Native Method)
at java.lang.Class.privateGetDeclaredMethods(Class.java:2427)
at java.lang.Class.getDeclaredMethods(Class.java:1791)
at com.zeroturnaround.javarebel.lR.makeClassDeclaredMethodCache(JRebel:229)
at com.zeroturnaround.javarebel.lR.getClassDeclaredMethodCache(JRebel:158)
at com.zeroturnaround.javarebel.lR.getDeclaredMethods(JRebel:456)
at java.lang.Class.getDeclaredMethods(Class.java:1791)
at ognl.OgnlRuntime.getDeclaredMethods(OgnlRuntime.java:1719)
at ognl.OgnlRuntime.getSetMethod(OgnlRuntime.java:1814)
at ognl.OgnlRuntime.hasSetMethod(OgnlRuntime.java:1836)
at ognl.OgnlRuntime.hasSetProperty(OgnlRuntime.java:1854)
at com.opensymphony.xwork2.ognl.accessor.CompoundRootAccessor.setProperty(CompoundRootAccessor.java:64)
at ognl.OgnlRuntime.setProperty(OgnlRuntime.java:2225)
at ognl.ASTProperty.setValueBody(ASTProperty.java:127)
at ognl.SimpleNode.evaluateSetValueBody(SimpleNode.java:220)
at ognl.SimpleNode.setValue(SimpleNode.java:301)
at ognl.Ognl.setValue(Ognl.java:737)
at com.opensymphony.xwork2.ognl.OgnlUtil.setValue(OgnlUtil.java:198)
at com.opensymphony.xwork2.ognl.OgnlValueStack.setValue(OgnlValueStack.java:161)
at com.opensymphony.xwork2.ognl.OgnlValueStack.setValue(OgnlValueStack.java:149)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.setParameters(ParametersInterceptor.java:276)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:187)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xw