关于异常positioned update are not supported总结

今天项目中遇到了positioned update are not supported这个异常

先看源代码吧

UserAction.java

public class UserAction extends ActionSupport{
 private String password;
 private User user;
 private String validateCode;
 private Boolean success;
 private String msg;
 
 public void setUser(User user) {
  this.user = user;
 }
 public User getUser() {
  return user;
 }

 public String getPassword() {
  return password;
 }
 public void setPassword(String password) {
  this.password = password;
 }
 public String getValidateCode() {
  return validateCode;
 }
 public void setValidateCode(String validateCode) {
  this.validateCode = validateCode;
 }
 public Boolean getSuccess() {
  return success;
 }
 public void setSuccess(Boolean success) {
  this.success = success;
 }
 public String getMsg() {
  return msg;
 }
 public void setMsg(String msg) {
  this.msg = msg;
 }

 @Resource private UserService userService;
 @SuppressWarnings("static-access")
 public String list(){
  String start =  ServletActionContext.getRequest().getParameter("start");
  String limit =  ServletActionContext.getRequest().getParameter("limit");
  Integer index = Integer.parseInt(start);
  Integer pageSize = Integer.parseInt(limit);
  String json = userService.convertAllUser(index,pageSize);
  //输出json对象
  HttpServletResponse response = ServletActionContext.getResponse();
  response.setContentType("Application/json;charset=GBK");
  response.setHeader("Cache-Control","no-cache");
  PrintWriter out = null;
  try {
   out = response.getWriter();
   out.print(json);
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }finally{
   if(out!=null){
    out.flush();
    out.close();
   }
  }
  return this.SUCCESS;
 }
 @SuppressWarnings("static-access")
 public String update(){
  HttpServletRequest request = ServletActionContext.getRequest();
  String jsonArray = request.getParameter("data");
  userService.saveAllUsers(jsonArray);
  return this.SUCCESS;
 }
 @SuppressWarnings("static-access")
 public String delete(){
  HttpServletRequest request = ServletActionContext.getRequest();
  String jsonArray = request.getParameter("data");
  userService.deleteAllUser(jsonArray);
  return this.SUCCESS;
 }
 @SuppressWarnings("static-access")
 public String checkUser(){
  String name = ServletActionContext.getRequest().getParameter("name");
  System.out.println(name);
  if(name!=null){
   List<User> users = userService.getUserByName(name);
   System.out.println("--------------------");
   System.out.println(users.size());
   System.out.println("--------------------");
   if(users.size()!=0){
    success = true;
    msg = "用户名已存在";
   }else{
    success = false;
    msg = "用户名可以注册";
   }
  }
  System.err.println(msg);
  System.out.println(success);
  return this.SUCCESS;
 }
 @SuppressWarnings("static-access")
 public String save(){
  String roleId = ServletActionContext.getRequest().getParameter("role_id");
  System.out.println(roleId);
  Integer role_id = Integer.parseInt(roleId);
  System.out.println(user);
  System.out.println(password);
  System.out.println(role_id);
  if(user!=null){
   userService.saveUser(user,role_id);
   success = true;
   msg = "保存成功";
  }
  return this.SUCCESS;
 }
 @SuppressWarnings("static-access")
 public String checkLogin(){
  String validate = (String) ActionContext.getContext().getSession().get("validateCode");
  if(validate.equals(validateCode.trim())){
   String userName = user.getUserName().trim();
   String psd = user.getPassword().trim();
   List<User> users = userService.getUserByName(userName);
   if(users.size()!=0){
    User user = users.get(0);
    if(user.getPassword().equals(psd)){
     success = true;
     msg = "登录成功";
     Role role = user.getRole();
     List<ACL> acls = role.getAcls();
     List<UserAllInfo> userInfos = new ArrayList<UserAllInfo>();
     ArrayList<Module> modules = new ArrayList<Module>();
     HttpSession session = ServletActionContext.getRequest().getSession();
     for(ACL acl :acls){
      Module module = acl.getModule();
      UserAllInfo userInfo = new UserAllInfo(module.getId(),acl.getPermission(),user.getUserName(),module.getText());
      userInfos.add(userInfo);
      modules.add(module);
     }
     session.setAttribute("user", user);
     session.setAttribute("acl", acls);
     session.setAttribute("role", role);
     session.setAttribute("modules", modules);
     session.setAttribute("userInfo", userInfos);
    }
   }else{
    success = false;
    msg = "用户名不存在";
   }
  }else{
   success = false;
   msg = "验证码错误";
  }
  return this.SUCCESS;
 }
}

UserService.java

@Service
public class UserService {
 @Resource private UserDAO  userDAO;
 @Resource private RoleDAO roleDAO;
 public List<User> getUsers(){
  return userDAO.getUsers();
 }
 @SuppressWarnings({ "unchecked", "deprecation" })
 public void saveAllUsers(String jsonUser){
  JSONArray jsonArray = JSONArray.fromObject(jsonUser);
  List<User> users = JSONArray.toList(jsonArray, User.class);
  for(User user :users){
    if(user!=null){
     userDAO.update(user);
    }
  }
 }
 public String convertAllUser(Integer index,Integer pageSize){
  List<User> users = userDAO.getUsers();
  List<User> subUsers = null;
  int count = users.size();
  if((count%pageSize)<=0){
   subUsers = users.subList(0,count);
  }else if((count/pageSize)>index){
   subUsers = users.subList(index, pageSize);
  }else{
   subUsers = users.subList(((count/pageSize)*pageSize),count);
  }
  String json="";
  PropertyFilter filter = new PropertyFilter() {
   public boolean apply(Object source, String name, Object value) {
    // TODO Auto-generated method stub
    if(name.equals("role"))return true;
    return false;
   }
  };
  JsonConfig config = new JsonConfig();
  config.setJsonPropertyFilter(filter);
  if(users!=null){
   json+="{root:";
   json += JSONArray.fromObject(subUsers, config).toString();
   json+=",totalProperty:"+count+"}";
  }
  return json;
 }
 @SuppressWarnings({ "unchecked", "deprecation" })
 public void deleteAllUser(String jsonUser){
  JSONArray jsonArray = JSONArray.fromObject(jsonUser);
  List<User> users = JSONArray.toList(jsonArray, User.class);
  for(User user :users){
   int id = user.getId();
   if((user!=null)&&(id!=0)){
    userDAO.delete(id);
   }
  }
 }
 public void saveUser(User user,Integer role_id){
  Role role = roleDAO.getRoleById(role_id);
  user.setRole(role);
  userDAO.save(user);
 }
 public List<User> getUserByName(String userName){
  return userDAO.getUserByName(userName);
 }
}
加红的地方是我下面要讲的地方

先说下出现这个异常的原因吧 由于Role role = roleDAO.getRoleById(role_id);在获取role对象时对象里的个别属性是延迟加载的 当中有一些对象是延迟加载的，这些对象并不是原role类中的属性，而是由cglib这个字节码生成器动态生成的对象。Hibernate在这个子类中添加了hibernateLazyInitializer等等的附加属性。由于jsonplugin并不区分类和动态生成的类，所以也会试图序列化hibernateLazyInitializer属性，从而导致出现上述的异常。

思路如下：

1、判断这个对象是否由cglib生成的。代码如下：

boolean isCreateByCGLIB = clazz.getName().indexOf("$$EnhancerByCGLIB$$") > -1 ? true : false;

如果此对象确实是由cglib生成的，那么我们取此对象的基类，这一步很关键，因为通过取得此对象的基类，我们就忽略了所有由cglib生成的跟hibernate相关的属性。

2、通过反射，取得此对象的所有继续于基类的属性。

3、通过反射，取得此对象的所有get方法器（这一步不能省，不然出来的属性就少了）。

4、输出json。
可是我们需要user的getter 和setter方法 那不能去掉这两个方法怎么办呢  那只有这样 在struts的配置文件中加一下配置

action name="user_*" class="userAction" method="{1}">
    <result name="success" type="json">
     <param name="excludeProperties">user</param>
    </result>
   </action>

在序列化action里属性时不序列化user这个属性 就可以了