写一个Iterator标签

 前段时间参与项目,觉得用的分页有些繁琐,  工作之余,自己写了一个
IteratorTag.java(标签类)

/** */ /**
 * 
 * collection :  需要迭代的List
 * dataNum    :  总共有多少页
 * nowPage    :  当前页
 * name       :  每次迭代保存对象的名称
 * actionUrl  :  分页的请求路径
 */
public   class  IteratorTag  extends  TagSupport  ... {
    private static final long serialVersionUID = 1311335738605478571L;
    
    
    private String collection;
    private String dataNum;
    private String nowPage;
    private int dataNumint;
    private int nowPageint;
    private int i;
    private String name;
    private Iterator it;
    private JspWriter out;
    private String actionUrl;
    private String posturl;

    @Override
    public int doAfterBody() throws JspException ...{
        // TODO Auto-generated method stub
        return doNext(it);
    }

    @Override
    public int doEndTag() throws JspException ...{
        // TODO Auto-generated method stub
        writePagination();
        return EVAL_PAGE;
    }

    @Override
    public int doStartTag() throws JspException ...{
        out = pageContext.getOut();
        Collection coll = (Collection) loadObject(pageContext,
                collection);
        if(coll == null) return SKIP_BODY;
        dataNumint = (Integer) loadObject(pageContext, dataNum);
        nowPageint = (Integer) loadObject(pageContext, nowPage);
        it = coll.iterator();
        
        if (it != null) ...{
            writePagination();
            return doNext(it);
        } else ...{
            return SKIP_BODY;
        }
    }

    protected int doNext(Iterator it) ...{
        if (it.hasNext()) ...{
            pageContext.setAttribute(name, it.next(), PageContext.PAGE_SCOPE);
            return EVAL_BODY_AGAIN;
        } else ...{
            return SKIP_BODY;
        }
    }
    
    //打印分页 
    protected void writePagination()...{
        try ...{
            out.print("<div class='turnPage'>");
            actionUrl = actionUrl + (actionUrl.indexOf("?")!=-1?"&":"?");
            if (nowPageint > 1) ...{
                posturl = actionUrl + "dataNum=" + dataNumint + "&nowPage="
                        + (nowPageint - 1);
                out.print("<a href='" + posturl + "'>上一页</a>");
            }
            if(dataNumint <= 7)...{
                for (int i = 1; i <= dataNumint; i++) ...{
                    posturl = actionUrl + "dataNum=" + dataNumint + "&nowPage="
                            + i;
                    if (i == nowPageint) ...{
                        if(this.dataNumint!=1)
                        ...{
                            out.print("<a href='javascript:void(0);'>");
                            out.print("<font color='red'>" + i + "</font>");
                            out.print("</a>");
                        }
                    } else ...{
                        out.print("<a href='" + posturl + "'>");
                        out.print(i);
                        out.print("</a>");
                    }
                }
            }else ...{
                if(nowPageint <= 4)...{
                    for (int i = 1; i <= 7; i++) ...{
                        posturl = actionUrl + "dataNum=" + dataNumint + "&nowPage="
                                + i;
                        if (i == nowPageint) ...{
                            if(this.dataNumint!=1)
                            ...{
                                out.print("<a href='javascript:void(0);'>");
                                out.print("<font color='red'>" + i + "</font>");
                                out.print("</a>");
                            }
                        }else
                        ...{
                            out.print("<a href='" + posturl + "'>");
                            out.print(i);
                            out.print("</a>");
                        }
                    }
                    out.print("...");
                }else if (nowPageint > 4 && dataNumint - nowPageint < 4) ...{
                    out.print("...");
                    for (int i = nowPageint - 3; i <= dataNumint; i++) ...{
                        posturl = actionUrl + "dataNum=" + dataNumint + "&nowPage="
                                + i;
                        if (i == nowPageint) ...{
                            if(this.dataNumint!=1)
                            ...{
                                out.print("<a href='javascript:void(0);'>");
                                out.print("<font color='red'>" + i + "</font>");
                                out.print("</a>");
                            }
                        }else
                        ...{
                            out.print("<a href='" + posturl + "'>");
                            out.print(i);
                            out.print("</a>");
                        }
                    }
                }else ...{
                    out.print("...");
                    for (int i = nowPageint - 3; i <= nowPageint + 3; i++) ...{
                        posturl = actionUrl + "dataNum=" + dataNumint + "&nowPage="
                                + i;
                        if (i == nowPageint) ...{
                            if(this.dataNumint!=1)
                            ...{
                                out.print("<a href='javascript:void(0);'>");
                                out.print("<font color='red'>" + i + "</font>");
                                out.print("</a>");
                            }
                        }else
                        ...{
                            out.print("<a href='" + posturl + "'>");
                            out.print(i);
                            out.print("</a>");
                        }
                    }
                    out.print("...");
                }
            }
            if (nowPageint < dataNumint) ...{
                posturl = actionUrl + "dataNum=" + dataNumint + "&nowPage="
                        + (nowPageint + 1);
                out.print("<a href='" + posturl + "'>下一页</a>");
            }
            out.print("</div>");

        } catch (IOException e) ...{
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

      //在四个范围内查询对象
      public static Object loadObject(PageContext context, String name) ...{
        if (null != context.getAttribute(name)) ...{
            return context.getAttribute(name);
        }
        if (null != context.getRequest().getAttribute(name)) ...{
            return context.getRequest().getAttribute(name);
        }
        if (null != context.getSession().getAttribute(name)) ...{
            return context.getSession().getAttribute(name);
        }
        if (null != context.getServletContext().getAttribute(name)) ...{
            return context.getServletContext().getAttribute(name);
        }
        return null;
    }

    public void setCollection(String collection) ...{
        this.collection = collection;
    }

    public void setName(String name) ...{
        this.name = name;
    }

    public void setDataNum(String dataNum) ...{
        this.dataNum = dataNum;
    }

    public void setNowPage(String nowPage) ...{
        this.nowPage = nowPage;
    }

    public void setActionUrl(String actionUrl) ...{
        this.actionUrl = actionUrl;
    }

}

一个iterator.tld与web.xml放在同一目录

<? xml version="1.0" encoding="UTF-8" ?>
<! DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN" "web-jsptaglibrary_1_2.dtd"  >
< taglib >
     < tlib-version > tlib-version </ tlib-version >
     < jsp-version > jsp-version </ jsp-version >
     < short-name > short-name </ short-name >
     < tag >
         < name > iterator </ name >
         < tag-class > com.web.util.IteratorTag </ tag-class >
         < attribute >
             < name > collection </ name >
             < required > true </ required >
             < rtexprvalue > true </ rtexprvalue >
         </ attribute >
         < attribute >
             < name > name </ name >
             < required > true </ required >
         </ attribute >
        
         < attribute >
             < name > dataNum </ name >
             < required > true </ required >
             < rtexprvalue > true </ rtexprvalue >
         </ attribute >
         < attribute >
             < name > nowPage </ name >
             < required > true </ required >
             < rtexprvalue > true </ rtexprvalue >
         </ attribute >
         < attribute >
             < name > actionUrl </ name >
             < required > true </ required >
             < rtexprvalue > true </ rtexprvalue >
         </ attribute >
     </ tag >
</ taglib >

最后在jsp中声明就可以使用了

<% @ taglib prefix = " iterator "  uri = " /WEB-INF/iterator.tld " %>

< iterator:iterator name = " Photo "  actionUrl = " EditPhoto_find.action?albumId=${albumId} "  nowPage = " nowPage "  dataNum = " dataNum "  collection = " photoList " >
  $ ... {Photo}
</ iterator:iterator >

效果如下