Build Restful web Service in Java

JAX-RS API is used to develop RestFul web services. in Java. Most commonly used implementation isJersey.JAX-RS specification provides annotations that are used by service programmer for annotating service methods and service class.

Implementation

Used Jersey implementation of JAX-RS API to build restful web service. The project need Eclipse IDE,Jersey jars and mysql-connector jar.
Download jars from below links.
https://dev.mysql.com/downloads/connector/j/3.1.html
https://jersey.java.net/download.html

Required Steps

  • Create a web application and add jars files of Jersey to the WEB-INF/lib.
  • Define entity classes which are to be exposed as resources and if XML representation is generated or consumed by the service then use JAXB annotation in the entity class and its jars.
  • Define service class and associate a URI to it using @Path annotation and define service methods.
  • In web.xml add a servlet entry for the org.glassfish.jersey.servlet.ServletContainer and provide service class location by initialization parameters to this servlet and define your service class package.

Following files of project

  1. Employee.java
  2. EmployeeController.java
  3. index.jsp
  4. web.xml
  5. Jersey jars
Employee.java
package com.expertwebindia.beans;
 
import javax.xml.bind.annotation.XmlAttribute;  
import javax.xml.bind.annotation.XmlElement;  
import javax.xml.bind.annotation.XmlRootElement;  
   
@XmlRootElement 
public class Employee {  
    private int id;  
    private String name;  
    private float salary;  
   
public Employee() {}  
public Employee(int id, String name, float salary) {  
    super();  
    this.id = id;  
    this.name = name;  
    this.salary = salary;  
}  
@XmlAttribute 
public int getId() {  
    return id;  
}  
public void setId(int id) {  
    this.id = id;  
}  
@XmlElement 
public String getName() {  
    return name;  
}  
public void setName(String name) {  
    this.name = name;  
}  
@XmlElement 
public float getSalary() {  
    return salary;  
}  
public void setSalary(float salary) {  
    this.salary = salary;  
}  
   
}

EmployeeController.java

package com.expertwebindia.rest;
 
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
 
import javax.ws.rs.Consumes;
import javax.ws.rs.DELETE;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
 
import com.expertwebindia.beans.Employee;
import com.expertwebindia.dao.GenericDao;
import com.google.gson.Gson;
@Path("/employee/")  
public class EmployeeController {  
 @GET 
 @Path("/all/")
 @Produces(MediaType.APPLICATION_JSON)
  public String getAllEmployees(){
     GenericDao dao = new GenericDao();
     Gson gson = new Gson();
     List<employee> list = new ArrayList<employee>();
     ResultSet rs = dao.get("employee", null);
     if(rs!=null){
          try {
            while(rs.next()){
                 Employee e = new Employee();
                 e.setId(rs.getInt("id")); 
                 e.setName(rs.getString("name")); 
                 e.setSalary(rs.getFloat("salary"));
                 list.add(e);
              }
        } catch (SQLException ex) {
            // TODO Auto-generated catch block
            ex.printStackTrace();
        }
      }
      return gson.toJson(list);
  } 
  @GET 
  @Path("/{id}")
  @Produces(MediaType.APPLICATION_JSON)
  public String getEmployeeById(@PathParam("id") int id) {  
      Gson gson = new Gson();
      GenericDao dao = new GenericDao();
      Employee e = new Employee();
      HashMap<string, object=""> map = new HashMap<string, object="">();
      map.put("id", id);
      ResultSet rs = dao.get("employee", map);
      if(rs!=null){
          try {
            while(rs.next()){
                 e.setId(rs.getInt("id")); 
                 e.setName(rs.getString("name")); 
                 e.setSalary(rs.getFloat("salary"));
              }
        } catch (SQLException ex) {
            // TODO Auto-generated catch block
            ex.printStackTrace();
        }
      }
      return gson.toJson(e);
      //return e;     
  }  
  @GET 
  @Path("/{id}")
  @Produces(MediaType.APPLICATION_XML)
  public Employee getEmployeeByIdInXML(@PathParam("id") int id) {  
      Gson gson = new Gson();
      GenericDao dao = new GenericDao();
      Employee e = new Employee();
      HashMap<string, object=""> map = new HashMap<string, object="">();
      map.put("id", id);
      ResultSet rs = dao.get("employee", map);
      if(rs!=null){
          try {
            while(rs.next()){
                 e.setId(rs.getInt("id")); 
                 e.setName(rs.getString("name")); 
                 e.setSalary(rs.getFloat("salary"));
              }
        } catch (SQLException ex) {
            // TODO Auto-generated catch block
            ex.printStackTrace();
        }
      }
      //return gson.toJson(e);
      return e;   
  }  
  @POST
  @Path("/add")
  @Consumes({MediaType.APPLICATION_JSON})
  @Produces({ MediaType.APPLICATION_JSON})
  public Response addEmployee(String empJson) {
     Gson gson = new Gson();
     Employee emp = gson.fromJson(empJson, Employee.class);
     GenericDao dao = new GenericDao(); 
     Response r = null;
     HashMap<string, object=""> map = new HashMap<string, object="">();
     map.put("id", emp.getId());
     map.put("name", emp.getName());
     map.put("salary",emp.getSalary());
     int status=0;
    try {
        dao.insert("employee", map);
        r =  Response.status(Response.Status.OK).entity("Successfully Created").build();
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        r= Response.status(Response.Status.BAD_REQUEST).entity("Unable to add new Employee").build();
    }
     return r;
  } 
  @DELETE
  @Path("/{id}")
  @Produces({ MediaType.APPLICATION_JSON})
  public Response deleteEmployee(@PathParam("id") int id){ 
    Response r = null;
     GenericDao dao = new GenericDao(); 
     if(id!=0){
         HashMap<string, object=""> map = new HashMap<string, object="">();
         map.put("id", id);
         int staus = dao.delete("employee", map);
         r =  Response.status(Response.Status.OK).entity("Successfully deleted").build();
          
     }else{
          
         r= Response.status(Response.Status.BAD_REQUEST).entity("Please provide employee id").build();
     }
     return r;
  }
  @POST
  @Path("/update")
  @Consumes({MediaType.APPLICATION_JSON})
  @Produces({ MediaType.APPLICATION_JSON})
  public Response updateEmployee(String empJson) {
      System.out.println("::::::::empJson="+empJson);
     Gson gson = new Gson();
     Employee emp = gson.fromJson(empJson, Employee.class);
     GenericDao dao = new GenericDao(); 
     Response r = null;
     HashMap<string, object=""> map = new HashMap<string, object="">();
     HashMap<string, object=""> cond = new HashMap<string, object="">();
     map.put("name", emp.getName());
     map.put("salary",emp.getSalary());
     cond.put("id", emp.getId());
     int status=0;
    try {
        dao.update("employee", map,cond);
        r =  Response.status(Response.Status.OK).entity("Successfully updated").build();
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        r= Response.status(Response.Status.BAD_REQUEST).entity("Unable to update Employee").build();
    }
     return r;
  }  
  
}     
</string,>

index.jsp

 
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>RestFul Web Sevices by Expertwebindia</title>
 
<style>
 
</style>
</head>
<body>
<h1>RestFul CRUD Application</h1>
<a href="javascript:void(0);" onclick="add();">Add Employee</a>
<br/><br/>
<table id="empData" width="750px" cellpadding="1" border="1">
</table>
<script>
jQuery(document).ready(function(){
    $.ajax({
        url: "http://localhost:9898/JAX-RS/rest/employee/all",
        type:"GET",
        success: function(data) {
             
        if(data!=null){
                var html = "<tr><td>ID</td><th>Name</td><td>Salary</td><td>Actions</td></tr>";
                $.each(data, function(i, employee) {
                  //use obj.id and obj.name here, for example:
                 // alert(employee.name);
                   html += "<tr id='row_"+employee.id+"'><td>"+employee.id+"</td><td>"+employee.name+"</td><td>"+employee.salary+"</td>";
                   html += "<td><a href='javascript:void(0);' onclick='editEmployee("+employee.id+")'>Edit</a>|";
                   html += "<a href='javascript:void(0);' onclick='deleteEmployee("+employee.id+")'>Delete</a></td>";
                  
                });
                $("#empData").append(html);
        }    
             
        },
        error: function(data) {}
    });
    $("#frmAdd").submit(function(){
        $.ajax({
            url: "http://localhost:9898/JAX-RS/rest/employee/add",
            type:"POST",
            contentType: "application/json; charset=utf-8",
            dataType: 'json',
            data:formToJSON(),
            statusCode : {
                200 : function(jqXHR) {
                     var html="";
                       html += "<tr><td>"+$('#id').val()+"</td><td>"+$('#name').val()+"</td><td>"+$('#salary').val()+"</td>";
                       html += "<td><a href='javascript:void(0);' onclick='editEmployee("+$('#id').val()+")'>Edit</a>|";
                       html += "<a href='javascript:void(0);' onclick='deleteEmployee("+$('#id').val()+")'>Delete</a></td>";
                      $("#empData").append(html);
                      $("#id").val("");
                      $("#name").val("");
                      $("#salary").val("");
 
                },
             400:function(jqXHR){
                  
                  alert("Please provide valid data");
             }
 
            },
        });
        return false;
    });    
    $("#frmEdit").submit(function(){
        $.ajax({
            url: "http://localhost:9898/JAX-RS/rest/employee/update",
            type:"POST",
            contentType: "application/json; charset=utf-8",
            dataType: 'json',
            data:formToJSON2(),
            statusCode : {
                200 : function(jqXHR) {
                     var html="";
                       html += "<tr id='row_"+$('#id2').val()+"'><td>"+$('#id2').val()+"</td><td>"+$('#name2').val()+"</td><td>"+$('#salary2').val()+"</td>";
                       html += "<td><a href='javascript:void(0);' onclick='editEmployee("+$('#id').val()+")'>Edit</a>|";
                       html += "<a href='javascript:void(0);' onclick='deleteEmployee("+$('#id').val()+")'>Delete</a></td>";
                       $("#row_"+$('#id2').val()).replaceWith(html);
                      // $("#empData").append(html);
                       alert("Profile Updated successfully");
                      $("#id").val("");
                      $("#name").val("");
                      $("#salary").val("");
                       $("#frmEdit").hide();
 
                },
             400:function(jqXHR){
                  
                  alert("Please provide valid data");
             }
 
            },
        });
        return false;
    });    
});
 function formToJSON() {
    var str= JSON.stringify({
        "id": $('#id').val(),
        "name": $('#name').val(),
        "salary": $('#salary').val()
        });
    return str;
}
 function formToJSON2() {
        var str= JSON.stringify({
            "id": $('#id2').val(),
            "name": $('#name2').val(),
            "salary": $('#salary2').val()
            });
        return str;
    }
 function deleteEmployee(id){
    $.ajax({
            url: "http://localhost:9898/JAX-RS/rest/employee/"+id,
            type:"DELETE",
            statusCode : {
                200 : function(jqXHR) {
                             $("#row_"+id).remove();    
                    },
                 400:function(jqXHR){
                      alert("Please provide valid data");
                 }
            }
    });
 }
 function editEmployee(id){
     $.ajax({
            url: "http://localhost:9898/JAX-RS/rest/employee/"+id,
            type:"GET",
            contentType: "application/json; charset=utf-8",
            dataType: 'json',
            success: function(data) {
            if(data){
                    $("#frmEdit #id2").val(data.id);
                    $("#frmEdit #name2").val(data.name);
                    $("#frmEdit #salary2").val(data.salary);
                    $("#frmAdd").hide();
                    $("#frmEdit").show();
            }    
                 
            },
            error: function(data) {}
        });
 }
 function add(){
     $("#frmAdd").show();
     $("#frmEdit").hide();
      
 }
</script>
<br/><br/><br/><br/>
<form action="" id="frmAdd" method="post">
<h2>Add Employee</h2>
<table width="750px">
<tr>
    <td>Id</td>
     <td><input type="text" name="id" id="id"></td>
</tr>
<tr>
    <td>Name</td>
     <td><input type="text" name="name" id="name"></td>
</tr>
<tr>
    <td>Salary</td>
     <td><input type="text" name="salary" id="salary"></td>
</tr>
<tr>
    <td></td>
     <td><input type="submit" name="add" value="Add Employee"></td>
</tr>
</table>
</form>
<form action="" id="frmEdit" method="post" style="display:none;">
<h2>Update Employee</h2>
<table width="750px">
<tr>
    <td>Id</td>
     <td><input type="text" name="id" id="id2"></td>
</tr>
<tr>
    <td>Name</td>
     <td><input type="text" name="name" id="name2"></td>
</tr>
<tr>
    <td>Salary</td>
     <td><input type="text" name="salary" id="salary2"></td>
</tr>
<tr>
    <td></td>
     <td><input type="submit" name="update" value="Update Employee"></td>
</tr>
</table>
</form>
</body>
</html>

web.xml

<!--?xml version="1.0" encoding="UTF-8"?-->  
 <?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" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">  
     <servlet>  
        <servlet-name>Jersey REST Service</servlet-name>  
        <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>  
        <init-param>  
            <param-name>jersey.config.server.provider.packages</param-name>  
            <param-value>com.expertwebindia.rest</param-value>  
        </init-param>  
        <load-on-startup>1</load-on-startup>  
      </servlet>  
      <servlet-mapping>  
        <servlet-name>Jersey REST Service</servlet-name>  
        <url-pattern>/rest/*</url-pattern>  
      </servlet-mapping>  
</web-app>    <web-app id="WebApp_ID" version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemalocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">  
     <servlet>  
</servlet></web-app>


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