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ExtJs 4 MVC Architecture tutorial using Java Servlets - Part 5

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In the previous chapters we have completed everything from defining all ExtJs object and Java objects needed for the application except for our final step, create the servlet.

Tip: Make sure you download the json-lib-2.4-jdk15.jar in addition to your JDBC jar for this project. The jsob-lib helps in creating and parsing JSON objects.

Step 12: Define the Servlet - ItemMaintenance.java

package com.as400samplecode;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
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 net.sf.json.JSONSerializer;

import com.as400samplecode.util.Item;
import com.as400samplecode.util.ItemInformation;

public class ItemMaintenance extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public ItemMaintenance() {
        super();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //get the company from the request
        String company = request.getParameter("company");
       
        //get out Grid paging toolbar parameters
        String start = request.getParameter("start");
        String limit = request.getParameter("limit");

        //printwriter to send the JSON response back
        PrintWriter out = response.getWriter();
        //set content type
        response.setContentType("text/html");

        //create a new JSON array to send the list of items
        JSONArray arrayObj=new JSONArray();
       
        //get arraylist of items based on the request 
        ItemInformation itemInformation = new ItemInformation(company);
        ArrayList<Item> itemList = itemInformation.getItems(start,limit);
       
        //loop thru the array list to populate the JSON array
        for(int i=0;i<itemList.size();i++){
           
            //get item Object
            Item item = itemList.get(i);
            //this creates a JSON object from bean object
            JSONObject itemObj = JSONObject.fromObject(item);
            //add to array list
            arrayObj.add(itemObj);
        }

        //Create a JSON object to wrap your JSOn array and provide the root element items
        JSONObject myObj = new JSONObject();
        //sets success to true
        myObj.put("success", true);
        //set the JSON root to items
        myObj.put("items", arrayObj);
        //set the total number of Items
        myObj.put("totalCount", itemInformation.getTotalCount());

        //convert the JSON object to string and send the response back
        out.println(myObj.toString());
        out.close();
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       
        //get the company from the request
        String company = request.getParameter("company");
       
        //the addData has item information during add otherwise null
        String addData = request.getParameter("addData");
        boolean add = false;
       
        //get payload from request body
        String payLoad = getBody(request);
        //in case of a ADD use the addData information instead of payLoad
        if(addData != null){
            add = true;
            payLoad = addData;
        }
        System.out.println("Payload:" + payLoad);
       
        ArrayList<Item> itemList = new ArrayList<Item>();   
       
        //If the payload is not a single JSON object then parse the array 
        //and create the the item arraylist
        if(payLoad.startsWith("[")){
            JSONArray arrayObj = JSONArray.fromObject(payLoad);
            for (int i = 0; i < arrayObj.size(); ++i) {
                JSONObject itemObj = arrayObj.getJSONObject(i);
                //parse JSON populate the Item bean 
                Item item = (Item) JSONObject.toBean(itemObj, Item.class);
                itemList.add(item);
            }
        }
        //parse the single JSON object and put that in the item arraylist
        else {
            JSONObject itemObj = (JSONObject) JSONSerializer.toJSON(payLoad); 
            //parse JSON populate the Item bean
            Item item = (Item) JSONObject.toBean(itemObj, Item.class);
            itemList.add(item);
        }

        ItemInformation itemInformation = new ItemInformation(company);
        boolean success = false;
        if(add){
            //add the item information
            success = itemInformation.addItems(itemList);
        }
        else {
            //update the item information
            success = itemInformation.updateItems(itemList);
        }
       
        PrintWriter out = response.getWriter();
        response.setContentType("text/html");

        //send response whether the request to add or update was successful
        JSONObject myObj = new JSONObject();
        myObj.put("success", success);
        out.println(myObj.toString());
        out.close();
    }

    //Get JSON payLoad from the request body
    private String getBody(HttpServletRequest request) throws IOException{

        String body = null;
        StringBuilder stringBuilder = new StringBuilder();
        BufferedReader bufferedReader = null;

        try {
            InputStream inputStream = request.getInputStream();
            if (inputStream != null) {
                bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
                char[] charBuffer = new char[128];
                int bytesRead = -1;
                while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {
                    stringBuilder.append(charBuffer, 0, bytesRead);
                }
            } else {
                stringBuilder.append("");
            }
        } catch (IOException ex) {
            throw ex;
        } finally {
            if (bufferedReader != null) {
                try {
                    bufferedReader.close();
                } catch (IOException ex) {
                    throw ex;
                }
            }
        }
       
        body = stringBuilder.toString();
        return body;
    }

}

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