public class AddToCart extends ActionSupport {
/**
*
*/
private static final long serialVersionUID = 1L;
public BookBean book;
public BookBean getBook() {
return book;
}
public void setBook(BookBean book) {
this.book = book;
}
@SuppressWarnings("unchecked")
public String add() throws Exception
{ ActionContext ctx=ActionContext.getContext();
Map session=ctx.getSession();
HttpServletRequest request=ServletActionContext.getRequest();
ArrayList booklist=(ArrayList) session.get("booklist");
String id= request.getParameter("bookid");
BookDAO dao=new BookDAO();
book=dao.lookupByid(Integer.parseInt(id));
if(booklist==null){
booklist=new ArrayList();
booklist.add(book);
}
else
{
booklist.add(book);
}
session.put("booklist", booklist);
return SUCCESS;
}
@SuppressWarnings("unchecked")
public String del() throws Exception
{ HttpServletRequest request=ServletActionContext.getRequest();
String id=request.getParameter("bookid");
ActionContext ctx=ActionContext.getContext();
Map session=ctx.getSession();
ArrayList booklist=new ArrayList();
booklist= (ArrayList) session.get("booklist");
try{
BookDAO dao=new BookDAO();
book=dao.lookupByid(Integer.parseInt(id)); booklist.remove(book);
session.put("booklist", booklist);
return SUCCESS;
}catch(Exception e){
e.printStackTrace();
}
return INPUT;
}
public String clear() throws Exception
{
ActionContext ctx=ActionContext.getContext();
Map session=ctx.getSession();
ArrayList booklist=new ArrayList();
booklist=(ArrayList) session.get("booklist");
if(booklist!=null)
{
booklist.clear();
}
return SUCCESS;
}
} 这是一个购物车的例子 del方法中有问题 求教高手
/**
*
*/
private static final long serialVersionUID = 1L;
public BookBean book;
public BookBean getBook() {
return book;
}
public void setBook(BookBean book) {
this.book = book;
}
@SuppressWarnings("unchecked")
public String add() throws Exception
{ ActionContext ctx=ActionContext.getContext();
Map session=ctx.getSession();
HttpServletRequest request=ServletActionContext.getRequest();
ArrayList booklist=(ArrayList) session.get("booklist");
String id= request.getParameter("bookid");
BookDAO dao=new BookDAO();
book=dao.lookupByid(Integer.parseInt(id));
if(booklist==null){
booklist=new ArrayList();
booklist.add(book);
}
else
{
booklist.add(book);
}
session.put("booklist", booklist);
return SUCCESS;
}
@SuppressWarnings("unchecked")
public String del() throws Exception
{ HttpServletRequest request=ServletActionContext.getRequest();
String id=request.getParameter("bookid");
ActionContext ctx=ActionContext.getContext();
Map session=ctx.getSession();
ArrayList booklist=new ArrayList();
booklist= (ArrayList) session.get("booklist");
try{
BookDAO dao=new BookDAO();
book=dao.lookupByid(Integer.parseInt(id)); booklist.remove(book);
session.put("booklist", booklist);
return SUCCESS;
}catch(Exception e){
e.printStackTrace();
}
return INPUT;
}
public String clear() throws Exception
{
ActionContext ctx=ActionContext.getContext();
Map session=ctx.getSession();
ArrayList booklist=new ArrayList();
booklist=(ArrayList) session.get("booklist");
if(booklist!=null)
{
booklist.clear();
}
return SUCCESS;
}
} 这是一个购物车的例子 del方法中有问题 求教高手
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public String del() throws Exception
里面
booklist.remove(book);
session.put("booklist", booklist);
return SUCCESS;加个判断(因为你没发现你那样写无论booklist.remove(book)成功不成功都会 return SUCCESS;)改下: boolean suc = booklist.remove(book);
if(suc){
session.put("booklist", booklist);
return SUCCESS;
}
这样得到的book跟session中的book尽管值一样,但地址不一样,是不相等的。如果你硬要删除这个对象,那你去重写equals方法与hashCode这两个方法在Book类里。