自界说分页标签
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自界说分页标签

2019-06-14

自界说分页标签

自界说分页标签

副标题#e#

近期在做的S2SH项目，因为多处用到分页，BOSS要求小弟将其抽象出来。小弟鄙人，实际参加开拓的履历也就1年。

于是花了点时间将其做成自界说标签供所有需要分页的业务挪用。小结一下，供新手参考

自界说标签利用如下：

JSP页面引入：

<%@ taglib uri="/htdz-tag" prefix="htdz-tag"%>

在需要摆放翻页的相关按钮处利用：

<htdz-tag:PagerTag pagesize="${pagesize}" rowcount="${rowcount}" currpagenum="${currpagenum}" action="${action}"/>

以下先容如何自界说标签：

1.首先是针对自界说标签的描写：

建设WEB-INF/tags/htdz-tag.tld标签描写文件：

<?xml version="1.0" encoding="UTF-8" ?>
<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
version="2.0">
<description>htdz tag</description>
<display-name>htdz tag</display-name>
<tlib-version>1.0</tlib-version>
<short-name>htdz-tag</short-name>
<uri>/htdz-tag</uri>

<tag>
<!--分页控件利用说明：
1.最全参数用法：<htdz-tag:PagerTag pagesize="${pagesize}" rowcount="${rowcount}" currpagenum="${currpagenum}" action="${action}" className="button_small"/>
1.最简参数用法：<htdz-tag:PagerTag pagesize="${pagesize}" rowcount="${rowcount}" currpagenum="${currpagenum}" action="${action}"/>
参数说明：
1. pagesize为每页记录数(必写)
2. rowcount为总记录数(必写)
3. currpagenum为当前页数(必写)
4. className为分页按钮样式，假如不写，则为默认样式
5. action为URL请求路径(必写)
-->
<description>分页控件</description>
<!--JSP里利用时的标签名-->
<name>PagerTag</name>
<!--用以将自界说标签理会成控件的Java类-->
<tag-class>com.htdz.util.tag.PagerTag</tag-class>
<body-content>JSP</body-content>
<!--每个attribute代表标签的一个属性-->
<attribute>
<description>pagesize:每页条数</description>
<!--属性名-->
<name>pagesize</name>
<!--是否必填属性-->
<required>true</required>
<!--此属性值是否接管EL,<%= 之类的形式-->
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<description>rowcount:总记录数</description>
<name>rowcount</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<description>currpagenum:当前页数</description>
<name>currpagenum</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<description>action:URL请求路径</description>
<name>action</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<description>className:用于客户端确定分页按钮的样式</description>
<name>className</name>
<required>false</required>
</attribute>
</tag>

</taglib>


#p#副标题#e#

2.建设用于将标签理会为页面翻页控件的类

PagerTag.java

public class PagerTag extends TagSupport {
    public static final int USER_PAGESIZE = 5;// 礼物搜索--每页记录数
    private static final String DEFAULT_BUTTON_CLASS= "button_small"; //翻页按钮默认样式
    private static final String DISABLE_BUTTON_CLASS= "button_small_disable"; //失效按钮默认样式
    private int pagesize;
    private int rowcount;
    private int currpagenum;
    private String action;
    private String className; 
    public PagerTag() {
    }
    public void setPagesize(int pagesize) {
        this.pagesize = pagesize;
    }
    public void setRowcount(int rowcount) {
        this.rowcount = rowcount;
    }
   public void setCurrpagenum(int currpagenum) {
        this.currpagenum = currpagenum;
    }
    public void setClassName(String className) {
        this.className = className;
    }
    public void setAction(String action) {
        this.action = action;
    }
    public int doStartTag() throws JspException {
        if (new Integer(pagesize) == null) {
            throw new JspException("PagerTag标签中缺乏pagesize属性！");
        }else if(pagesize==0){
            throw new JspException("PagerTag标签中的pagesize属性无值！");
        }
        if (new Integer(rowcount) == null) {
            throw new JspException("PagerTag标签中缺乏rowcount属性！");
        }
        if (new Integer(currpagenum) == null) {
            throw new JspException("PagerTag标签中缺乏currpagenum属性！");
        }
        if (action == null) {
            throw new JspException("PagerTag标签中缺乏action属性！");
        }else if(action.length()==0){
            throw new JspException("PagerTag标签中的action属性无值！");
        }
        //假如页面标签中没写className属性，则让翻页按钮应用默认的按钮样式
        if(className==null||className.length()==0){
            className = DEFAULT_BUTTON_CLASS;
        }
        //获取总页数
        int totalpagesize = getTotalpagesize(rowcount);
        //用以符号是否能上翻
        boolean noUp = false;
        //用以符号是否能下翻
        boolean noDown = false;
        //声明应用于'首页'，'上一页'按钮的样式(因为此俩按钮要么同时失效，要么同时可用)
        String buttonClass1 = className;
        //声明应用于'下一页'，'尾页'按钮的样式(同上)
        String buttonClass2 = className;
        //假如无记录，则配置总页数与当前页数都为1
        if(rowcount==0){
            currpagenum = 1;
            totalpagesize = 1;
        }
        //假如当前页是第一页
        if(currpagenum==1){
            noUp = true;
            //配置'首页'，'上一页'按钮失效样式
            buttonClass1 = DISABLE_BUTTON_CLASS;
        }
        //假如当前页是最大页
        if(currpagenum==totalpagesize){
            noDown = true;
            //配置'下一页'，'尾页'按钮失效样式
            buttonClass2 = DISABLE_BUTTON_CLASS;
        }
        try {
            StringBuffer html = new StringBuffer();
            html.append(currpagenum+"/"+totalpagesize+"页");
            html.append("<input class="+buttonClass1+" type=\"button\" value=\"首页\" onclick=\"turnPage('first','"+currpagenum+"','"+totalpagesize+"','"+action+"')\" ");
            if(noUp){
                html.append("disabled=\"true\"");
            }
            html.append("/>");
            html.append("<input class="+buttonClass1+" type=\"button\" value=\"上一页\" onclick=\"turnPage('up','"+currpagenum+"','"+totalpagesize+"','"+action+"')\" ");
            if(noUp){
                html.append("disabled=\"true\"");
            }
            html.append("/>");
            html.append("<input class="+buttonClass2+" type=\"button\" value=\"下一页\" onclick=\"turnPage('down','"+currpagenum+"','"+totalpagesize+"','"+action+"')\"");
            if(noDown){
                html.append("disabled=\"true\"");
            }
            html.append("/>");
            html.append("<input class="+buttonClass2+" type=\"button\" value=\"尾页\" onclick=\"turnPage('last','"+currpagenum+"','"+totalpagesize+"','"+action+"')\" ");
            if(noDown){
                html.append("disabled=\"true\"");
            }
            html.append("/>");
            html.append(currpagenum+"/"+totalpagesize+"页&nbsp;&nbsp;");
            html.append("<input type=\"text\" maxlength=\"3\" id=\"text\" size=\"3\" onkeypress=\"return checkInput(event);\" />页");
            html.append("<input class="+className+" type=\"button\" value=\"GO\" onclick=\"turnPage('to','"+currpagenum+"','"+totalpagesize+"','"+action+"')\" />");
            pageContext.getOut().println(html.toString());
        } catch (Exception e) {
            throw new JspException(e.getMessage());
        }
         return this.SKIP_BODY;
    }
     /**
      * 按照总记录数获得总页数
      * 
      * @param rowcount
      *            总记录数
      * @return 总页数
      */
    public int getTotalpagesize(int rowcount) {
        int totalpagesize = 0;
        if (rowcount % pagesize == 0) {
            totalpagesize = rowcount / pagesize;
        } else {
            totalpagesize = rowcount / pagesize + 1;
        }
        return totalpagesize;
    }
}

#p#副标题#e#

到此为止，自界说标签书已完成。可应用于项目遍地，只要页面上遵循标签描写法则，靠山该给标签属性传值的时候记得传就行了。

以下用一个简朴的例子来说明一下，赤色字体显示的部别离健忘写就行了。

UserAction.java:

#p#分页标题#e#

public class UserAction extends ActionSupport {

private UserService userService;
private List<User> users;

public String findUser(){
String str = null;
HttpServletRequest request = ServletActionContext.getRequest();
Map sessionMap = ActionContext.getContext().getSession();

String currpagenum= "1";
try {
String pagenum = request.getParameter("pagenum ");
if(pagenum != null && pagenum .length()!=0){
currpagenum= pagenum ;
}
} catch (Exception e) {

}

//查询用户记录
users= userService.findUser(pageNum);
if(users.size!=0){
request.setAttribute("users", users);

int rowcount = userService.getCount();

request.setAttribute("rowcount ",rowcount );
request.setAttribute("currpagenum",currpagenum);

str = "success";//乐成视图
}else{
message = "无记录!"
str = "failure";//失败视图
}

request.setAttribute("pagesize", PagerTag.USER_PAGESIZE);
request.setAttribute("action", "findUser.action);

//返回视图
return str;
}

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

public List<User> getUsers(){
return users;
}
public void setUsers(List<User> users){
this.users = users;
}

}

UserService.java:

#p#分页标题#e#

public class UserService {

private UserDao userDao;

public List<User> findUser(String pageNum){
List<User> userList = userDao.findUser(pageNum);
return userList;
}

public int getCount(){
int count = userDao.getCount();
return count;
}

public UserDao getUserDao() {
return userDao;
}
public void setUserDao(UserDao userDao) {
this.userDao = userDao;
}
}

UserDao.java:

public class UserDao extends HibernateDaoSupport {

/**
* 查询用户
* @return User工具荟萃
*/
public List<User> findUser(String pagenum) {
List<User> users = null;
Session session = null;
try {
int myPagenum= Integer.parseInt(pagenum);
String hql = "from User";
session = this.getSession();
Query query = session.createQuery(hql);
query.setFirstResult(Pager.USER_PAGESIZE * (myPagenum - 1));
query.setMaxResults(Pager.USER_PAGESIZE);
users = query.list();
session.flush();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (session != null) {
session.close();
}
}
return users;
}

/**
* 获取用户总记录数
* @return 用户总记录数
*/
public int getCount(){
String hql ="select count(id) from User";
Session session = null;
int count =0;
try {
session = this.getSession();
Query query = session.createQuery(hql);
List list = query.list();
session.flush();
count = Integer.parseInt(list.get(0).toString());
} catch (Exception e) {
e.printStackTrace();
} finally{
session.close();
}
return count;
}

}

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