package com.godwin.news.util
import java.io.UnsupportedEncodingException
import java.net.URLDecoder
import java.util.ArrayList
/**
* 分页类,用于封闭分页显示信息
*
* @author javabs
*
*/
public class Pager {
// 当前页
private int currentPage
// 总页数
private int totalPage
// 总记录数
private int totalRecord
// 每页条数
private int pageSize
// 是否有下一页
private int hasNext
private ArrayList keys
private ArrayList values
// 查询串
private String queryString
// 首页
private String firstLink
// 上一页
private String previousLink
// 下一页
private String nextLink
// 尾页
private String lastLink
// 链接
private String forScriptLink
public Pager(int pageSize, String queryString) {
keys = new ArrayList()
values = new ArrayList()
setQueryString(queryString)
setPageSize(pageSize)
}
public String getForScriptLink() {
if (keys.contains("toPage"))
removeKey("toPage")
String tmp = getQueryString()
if (tmp.length() == 0)
return "?"
else
return "?" + tmp + "&"
}
public int getCurrentPage() {
return currentPage
}
public void setCurrentPage(String toPage) {
int tmpage = 1
try {
tmpage = Integer.parseInt(toPage)
} catch (NumberFormatException e) {
tmpage = 1
}
if (tmpage <1)
tmpage = 1
else if (tmpage >getTotalPage())
tmpage = getTotalPage()
currentPage = tmpage
}
public String getFirstLink() {
return getQueryStr(1)
}
public int getHasNext() {
int i = 1
if (getCurrentPage() >= getTotalPage())
i = 0
return i
}
public String getLastLink() {
return getQueryStr(getTotalPage())
}
public String getNextLink() {
return getQueryStr(currentPage == totalPage ? currentPage : (currentPage + 1))
}
public int getPageSize() {
return pageSize
}
public void setPageSize(int pageSize) {
this.pageSize = pageSize
}
public String getPreviousLink() {
return getQueryStr(currentPage == 1 ? currentPage : currentPage - 1)
}
public void setPreviousLink(String previousLink) {
this.previousLink = previousLink
}
public String getQueryString() {
StringBuffer sb = new StringBuffer()
for (int i = 0i <keys.size()i++) {
String key = (String) keys.get(i)
String value = (String) values.get(i)
sb.append("&")
sb.append(key)
sb.append("=")
sb.append(value)
}
return sb.delete(0, 1).toString()
}
public void setQueryString(String queryString) {
if (queryString != null) {
String s[] = queryString.split("&")
for (int i = 0i <s.lengthi++) {
String s1[] = s[i].split("=")
if (s1.length == 2) {
keys.add(s1[0])
values.add(s1[1])
} else {
keys.add(s1[0])
values.add("")
}
}
}
}
public int getTotalPage() {
return totalPage
}
public void setTotalPage() {
if (totalRecord % pageSize == 0) {
totalPage = totalRecord / pageSize
totalPage = totalPage == 0 ? 1 : totalPage
}
else
totalPage = totalRecord / pageSize + 1
}
public int getTotalRecord() {
return totalRecord
}
public void setTotalRecord(int totalRecord) {
this.totalRecord = totalRecord
setTotalPage()
}
public String[] getQueryParameterValues(String key) {
return getQueryParameterValues(key, "UTF-8")
}
public String[] getQueryParameterValues(String key, String decode) {
ArrayList ret = new ArrayList()
for (int i = 0i <keys.size()i++)
if (((String) keys.get(i)).equals(key))
try {
ret.add(URLDecoder.decode((String) values.get(i), decode))
} catch (UnsupportedEncodingException e) {
ret.add((String) values.get(i))
}
if (ret.size() == 0)
return null
String strArr[] = new String[ret.size()]
for (int i = 0i <ret.size()i++)
strArr[i] = (String) ret.get(i)
return strArr
}
public String getQueryParameter(String key) {
return getQueryParameter(key, "UTF-8")
}
public String getQueryParameter(String key, String decode) {
String value = ""
if (key != "toPage") {
try {
value = URLDecoder.decode(getValue(key), decode)
} catch (UnsupportedEncodingException e) {
value = getValue(key)
}
} else {
int tmpage = 1
try {
value = getValue(key)
tmpage = Integer.parseInt(value)
} catch (NumberFormatException e) {
tmpage = 1
} catch (NullPointerException e1) {
tmpage = 1
}
if (tmpage <1)
tmpage = 1
else if (tmpage >getTotalPage())
tmpage = getTotalPage()
value = (new StringBuffer(String.valueOf(tmpage))).toString()
}
return value
}
public void setQueryParameter(String key, String value) {
if (key.equals("toPage"))
removeKey(key)
keys.add(key)
values.add(value)
}
public String getQueryStr(int toPage) {
setQueryParameter("toPage", (new StringBuffer(String.valueOf(toPage))).toString())
return "?" + getQueryString()
}
private String getValue(String key) {
String ret = ""
for (int i = 0i <keys.size()i++) {
if (!((String) keys.get(i)).equals(key))
continue
ret = (String) values.get(i)
break
}
return ret
}
private void removeKey(String key) {
for (int i = 0i <keys.size()i++) {
if (!((String) keys.get(i)).equals(key))
continue
keys.remove(i)
values.remove(i)
break
}
}
public static void main(String args[]) {
String str = "a=中文aa&b=2&c=3&c=4&c=5"
Pager page = new Pager(2, str)
page.setTotalRecord(10)
page.setCurrentPage("1")
System.out.println(page.getFirstLink())
System.out.println(page.getPreviousLink())
System.out.println(page.getNextLink())
System.out.println(page.getLastLink())
String s = page.getQueryParameter("a")
System.out.println("s: " + s)
}
}
建议还是使用带条件查询的sql，这样返回的结果集不会太大。实现分页通常有两种方式，根据具体情况而选择：1. 把读取的结果集存放在集合中，然后进行分页算法实现分布，这种方式会将内容读取到内存，所以建议带条件查询的结果集使用；
2. 使用数据库的特性，根据传入分页数据（起始位置、读取数目等）来读取数据库。
