In previous chapters we have defined our ExtJs sample application that explains the use of Local and Remote query Methods. Also we saw how to define a custom template for a ComboBox display. In this chapter we are going to define the following
- Dynamic web application config file
- MySQL data resource for Tomcat
- Country Java Bean
- Web application utility methods that will process the ComboBox requests
- Web application Servlet to interact with the ExtJs application using JSON and Ajax Requests
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Java Web Application config file web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
<display-name>ExtJs4_ComboBox</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
<servlet>
<description>Country Servlet</description>
<display-name>CountryServlet</display-name>
<servlet-name>CountryServlet</servlet-name>
<servlet-class>com.as400samplecode.CountryServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>CountryServlet</servlet-name>
<url-pattern>/CountryServlet</url-pattern>
</servlet-mapping>
<resource-ref>
<description>MySQL Datasource</description>
<res-ref-name>jdbc/mysql</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
<res-sharing-scope>Shareable</res-sharing-scope>
</resource-ref>
</web-app>
Java Web Application MySQL data resource file context.xml
<?xml version="1.0" encoding="UTF-8"?> <Context reloadable="true"> <Resource auth="Container" name="jdbc/mysql" type="javax.sql.DataSource" driverClassName="com.mysql.jdbc.Driver" url="jdbc:mysql://localhost:3306/world" username="root" password="mysql" maxIdle="10" maxActive="200" maxWait="5" removeAbandoned="true" removeAbandonedTimeout="1200" /> </Context>
Java bean Country.java
package com.as400samplecode.util;
public class Country {
String code = null;
String name = null;
String continent = null;
String region = null;
Double lifeExpectancy = null;
Double gnp = null;
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getContinent() {
return continent;
}
public void setContinent(String continent) {
this.continent = continent;
}
public String getRegion() {
return region;
}
public void setRegion(String region) {
this.region = region;
}
public Double getLifeExpectancy() {
return lifeExpectancy;
}
public void setLifeExpectancy(Double lifeExpectancy) {
this.lifeExpectancy = lifeExpectancy;
}
public Double getGnp() {
return gnp;
}
public void setGnp(Double gnp) {
this.gnp = gnp;
}
}
Java Web Application utility functions to process the ComboBox requests CountryInformation.java
package com.as400samplecode.util;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.PreparedStatement;
import java.util.ArrayList;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.sql.DataSource;
public class CountryInformation {
Connection conn = null;
PreparedStatement stmt = null;
String sql = null;
public ArrayList<Country> getItems(String start, String limit, String query) {
ArrayList<Country> countryList = new ArrayList<Country>();
try {
Context ctx = (Context) new InitialContext().lookup("java:comp/env");
conn = ((DataSource) ctx.lookup("jdbc/mysql")).getConnection();
sql = "Select * from COUNTRY ";
if(query != null){
if(query.trim().equalsIgnoreCase("")){
sql = sql + "where code = '@@@' ";
}
else {
query = query.toUpperCase();
sql = sql + "where ucase(name) like '" + query + "%' ";
}
}
sql = sql + "order by name,code LIMIT ?,?";
stmt = conn.prepareStatement(sql);
stmt.setInt(1, Integer.parseInt(start));
stmt.setInt(2, Integer.parseInt(limit));
ResultSet rs = stmt.executeQuery();
while(rs.next()){
Country country = new Country();
country.setCode(rs.getString("code").trim());
country.setName(rs.getString("name").trim());
country.setContinent(rs.getString("continent").trim());
country.setRegion(rs.getString("region").trim());
country.setLifeExpectancy(rs.getString("lifeExpectancy") == null ? new Double(0) : Double.parseDouble(rs.getString("lifeExpectancy").trim()));
country.setGnp(rs.getString("gnp") == null ? new Double(0) : Double.parseDouble(rs.getString("gnp").trim()));
countryList.add(country);
}
rs.close();
stmt.close();
stmt = null;
conn.close();
conn = null;
}
catch(Exception e){System.out.println(e);}
finally {
if (stmt != null) {
try {
stmt.close();
} catch (SQLException sqlex) {
// ignore -- as we can't do anything about it here
}
stmt = null;
}
if (conn != null) {
try {
conn.close();
} catch (SQLException sqlex) {
// ignore -- as we can't do anything about it here
}
conn = null;
}
}
return countryList;
}
public int getTotalCount(String query) {
int totalCount = 0;
try {
Context ctx = (Context) new InitialContext().lookup("java:comp/env");
conn = ((DataSource) ctx.lookup("jdbc/mysql")).getConnection();
sql = "Select count(*) from COUNTRY ";
if(query != null){
if(query.trim().equalsIgnoreCase("")){
sql = sql + "where code = '@@@' ";
}
else {
query = query.toUpperCase();
sql = sql + "where ucase(name) like '" + query + "%' ";
}
}
sql = sql + "order by name,code";
stmt = conn.prepareStatement(sql);
ResultSet rs = stmt.executeQuery();
while(rs.next()){
totalCount = rs.getInt(1);
break;
}
rs.close();
stmt.close();
stmt = null;
conn.close();
conn = null;
}
catch(Exception e){System.out.println(e);}
finally {
if (stmt != null) {
try {
stmt.close();
} catch (SQLException sqlex) {
// ignore -- as we can't do anything about it here
}
stmt = null;
}
if (conn != null) {
try {
conn.close();
} catch (SQLException sqlex) {
// ignore -- as we can't do anything about it here
}
conn = null;
}
}
return totalCount;
}
}
Java Servlet to process Ajax Requests and send JSON object CountryServlet.java
package com.as400samplecode;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
import com.as400samplecode.util.Country;
import com.as400samplecode.util.CountryInformation;
public class CountryServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public CountryServlet() {
super();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request,response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String start = request.getParameter("start");
String limit = request.getParameter("limit");
String query = request.getParameter("query");
PrintWriter out = response.getWriter();
response.setContentType("text/html");
JSONArray arrayObj=new JSONArray();
CountryInformation countryInformation = new CountryInformation();
ArrayList<Country> countryList = countryInformation.getItems(start,limit,query);
for(int i=0;i<countryList.size();i++){
Country country = countryList.get(i);
JSONObject itemObj = JSONObject.fromObject(country);
arrayObj.add(itemObj);
}
JSONObject myObj = new JSONObject();
myObj.put("success", true);
myObj.put("countries", arrayObj);
myObj.put("totalCount", countryInformation.getTotalCount(query));
out.println(myObj.toString());
out.close();
}
}
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