JSON has been described in detail in the previous article, and JSON is straightforward and fast. And it blends well with JavaScript.
The JSP paging problem can be done well without the need to add a jar.
The following is a detailed description of the paging instance:
The effect is as shown in the picture, using Jsp+servlet technology
First: Write a JavaBean User.java
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Package Bean;
public class User {
private int id;
private String name;
private String password;
private int age;
Public User () {
Super ();
}
public User (int ID, string name, string password, int age) {
Super ();
This.id = ID;
THIS.name = name;
This.password = password;
This.age = age;
}
public int getId () {
return ID;
}
public void setId (int id) {
This.id = ID;
}
Public String GetName () {
return name;
}
public void SetName (String name) {
THIS.name = name;
}
Public String GetPassword () {
return password;
}
public void SetPassword (String password) {
This.password = password;
}
public int getage () {
return age;
}
public void Setage (int age) {
This.age = age;
}
@Override
Public String toString () {
{' id ': 1, ' name ': ' Zhangsan ', ' password ': ' 123 ', ' Age ': 1}
Return ' {' id ': ' +id+ ', ' name ': ' +name+ ', ' Password ': ' +password+ ', ' age ': ' +age+ '} ';
}
}
The thing to note here is how the ToString method changes.
Then: Let's write its control layer and DAO layer
To simplify the code and make it easier to value, the database is tentatively written as a collection
can see that
1.service receive request requests get the page to display the current page (as page page)
2. Create a string, add the user from database db in sequence, and encapsulate all data
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3. Return this string to the request page
Copy Code code as follows:
Package servlet;
Import java.io.IOException;
Import Java.io.PrintWriter;
Import java.util.LinkedList;
Import java.util.List;
Import javax.servlet.ServletException;
Import Javax.servlet.http.HttpServlet;
Import Javax.servlet.http.HttpServletRequest;
Import Javax.servlet.http.HttpServletResponse;
Import Bean. User;
public class Paging extends HttpServlet {
public static final int per_page = 3;
@Override
protected void Service (HttpServletRequest request, httpservletresponse response)
Throws Servletexception, IOException {
The paging data source currently gets the number of pages of the record how many pieces per page
int page = Integer.parseint (request.getparameter ("page"));
page = 1 i = 0
page = 2 3
int length = 0;//How many entries are currently taken
StringBuffer sb = new StringBuffer ();
Sb.append ("[");
//[{},{},{}]
String message = NULL;
if (page >= 1 && page <= 3) {
for (int i = (page-1) *per_page i < DB.list.size () &&length < per_page; i++) {
User u = DB.list.get (i);
Sb.append (u.tostring () + ",");
length++;
}
if (length > 0) {
message = sb.substring (0, Sb.length ()-1) + "]";
}else{
message = sb.tostring () + "]";
}
}else{
Response.setcontenttype ("Text/html;charset=utf-8");
Response.getwriter (). println ("disruptive");
Return
}
Response.setcontenttype ("Text/html;charset=utf-8");
Response.getwriter (). println (message);
}
}
Class db{
public static list<user> List = new linkedlist<user> ();
static{
List.add (New User (1, "Zhangsan", "Zs", 34));
List.add (New User (2, "Lisi", "LS", 34));
List.add (New User (3, "a", "H", 34));
List.add (New User (4, "B", "D", 34));
List.add (New User (5, "C", "G", 34));
List.add (New User (6, "D", "a", 34));
List.add (New User (7, "E", "D", 34));
List.add (New User (8, "F", "E", 34));
List.add (New User (9, "G", "a", 34));
}
}
After: JSP fill in, through the Ajax asynchronous submission page, and then get the corresponding string
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var mgs = Xmlhttprequest.responsetext;
var persons = Mgs.evaljson ();
Parse and add JSON data to the displayed area
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<%@ page language= "java" import= "java.util.*" pageencoding= "Utf-8"%>
<%
String path = Request.getcontextpath ();
String basepath = request.getscheme () + "://" +request.getservername () + ":" +request.getserverport () +path+ "/";
%>
<! DOCTYPE HTML PUBLIC "-//w3c//dtd HTML 4.01 transitional//en" >
<base href= "<%=basePath%>" >
<title>my JSP ' regist.jsp ' starting page</title>
<meta http-equiv= "Pragma" content= "No-cache" >
<meta http-equiv= "Cache-control" content= "No-cache" >
<meta http-equiv= "Expires" content= "0" >
<meta http-equiv= "keywords" content= "keyword1,keyword2,keyword3" >
<meta http-equiv= "description" content= "This are my page" >
<script type= "Text/javascript" src= "Js/prototype1.6.js" ></script>
<script type= "Text/javascript" src= "Js/jquery-1.4.4.js" ></script>
<script type= "Text/javascript" >
var paging = 0;
//
function page (p) {
/*if (p = = ' Next ' && paging < 3) {
paging + +;
}else if (p = = ' last ' && paging > 1) {
Paging--;
}else{
Alert (' Error ');
}*/
if (p = = ' Next ' && paging < 3) {
paging + +;
if (Paging > 1) {
$ (": Button:eq (0)"). Removeattr (' disabled ');
}
if (paging = = 3) {
$ (": Button:eq (1)"). attr (' disabled ', ' disabled ');
}
}else if (p = = ' last ' && paging > 1) {
Paging--;
$ (": Button:eq (1)"). Removeattr (' disabled ');
if (paging = = 1) {
$ (": Button:eq (0)"). attr (' disabled ', ' disabled ');
}
}
Createxmlhttprequest ();
Xmlhttprequest.onreadystatechange=back;
var url = encodeURI ("/json_page/paging?page=" +paging);
Xmlhttprequest.open ("Get", url,true);
Xmlhttprequest.send (NULL);
}
Let's say the name is XMLHttpRequest.
function Createxmlhttprequest () {
if (window. ActiveXObject) {
XMLHttpRequest = new ActiveXObject ("Microsoft.XMLHTTP");
}else{
XMLHttpRequest = new XMLHttpRequest ();
}
}
callback function
function back () {
if (xmlhttprequest.readystate = = 4 && xmlhttprequest.status = 200) {
var mgs = Xmlhttprequest.responsetext;
var persons = Mgs.evaljson ();
Alert (MGS);
$ ("table"). empty ();
$ ("table"). Append ($ ("<tr><td>id</td><td> username </td><td> password </TD><TD >age</td></tr> "));
for (var i = 0; i < persons.length;i++) {
var person = persons[i];
var $tr = $ ("<tr><td>" +person.id+ "</td><td>" +person.name+ "</td><td>" + Person.password+ "</td><td>" +person.age+ "</td></tr>");
$ ("table"). Append ($TR);
}
}
}
</script>
<body>
<input type= "button" disabled= "Disabled" value= "page" onclick= "page (' last '); /><input type= "button" value= "Next" onclick = "page (' Next ');" />
<table>
<tr><td>id</td><td> username </td><td> Password </td><td>age</td></ Tr>
</table>
</body>
In addition: To have these two JS OH
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<script type= "Text/javascript" src= "Js/prototype1.6.js" ></script>
<script type= "Text/javascript" src= "Js/jquery-1.4.4.js" ></script>
