We already know how to create simple projects with netbeans see project creating with maven and creating simple web project in netbeans.
Here we want to send json data response from servlet.
Here a link is available in jsp page on link click it is calling /jsonResponse url where JsonResponse’s doGet() method is get called.
How to set HttpServletResponse set body json is as below
To generate json response we are setting response.setContentType("application/json"); that is used to set response as application/json.
Here response is reference variable of HttpServletResponse.
In servlet student object is created with name gender mobile number and three subjects marks. After creating object we are converting objects to json using gson library.
Project Explorer
index.jsp
This file contains a link on click that will goto /jsonResponse url
<%@page contentType=”text/html” pageEncoding=”UTF-8″%>
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<a href="jsonResponse" data-abc="true">Get Json response from server</a> |
JsonResponse.java
Getting request from index.jsp page following code is executed.
response.setContentType(“application/json”); is used to send response as json.
response.setCharacterEncoding(“utf-8”); is character encoding method.
We have created student object which contains students id,name,gender,address, mobileNo and set of subjects and address.
We send this data to jsp using Gson Object.
The method gson.toJson(student); is converting objet to json string
then we are passing json data to PrintWriter object to write in browser
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package ebhor.servlet; import com.google.gson.Gson; import java.io.IOException; import java.io.PrintWriter; import java.util.HashSet; import java.util.Set; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; @WebServlet(urlPatterns = {"/jsonResponse"}) public class JsonResponse extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("application/json"); response.setCharacterEncoding("utf-8"); Student student = new Student(12, "Ram Kumar", "Male", "1234565678"); Subject subject1 = new Subject(1, "Computer Fundamentals"); Subject subject2 = new Subject(2, "Computer Graphics"); Subject subject3 = new Subject(3, "Data Structures"); Set subjects = new HashSet(); subjects.add(subject1); subjects.add(subject2); subjects.add(subject3); student.setSubjects(subjects); Address address = new Address(1, "Street 23 NN West ", "Bhilai", "Chhattisgarh", "India"); student.setAddress(address); Gson gson = new Gson(); String jsonData = gson.toJson(student); PrintWriter out = response.getWriter(); try { out.println(jsonData); } finally { out.close(); } } } |
Student.java
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package ebhor.servlet; import java.io.Serializable; import java.util.Set; import java.util.HashSet; public class Student implements Serializable { private long id; private String name; private String gender; private Address address; private Set subjects = new HashSet(0); private String mobileNo; public Student() { } public Student(long id, String name, String gender, String mobileNo) { this.id = id; this.name = name; this.gender = gender; this.mobileNo = mobileNo; } public long getId() { return id; } public void setId(long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getGender() { return gender; } public void setGender(String gender) { this.gender = gender; } public Address getAddress() { return address; } public void setAddress(Address address) { this.address = address; } public Set getSubjects() { return subjects; } public void setSubjects(Set subjects) { this.subjects = subjects; } public String getMobileNo() { return mobileNo; } public void setMobileNo(String mobileNo) { this.mobileNo = mobileNo; } } |
Subject.java
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package ebhor.servlet; import java.io.Serializable; public class Subject implements Serializable { private long id; private String name; public Subject() { } public Subject(long id, String name) { this.id = id; this.name = name; } public long getId() { return id; } public void setId(long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } } |
Address
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package ebhor.servlet; import java.io.Serializable; public class Address implements Serializable{ private long id; private String street; private String city; private String state; private String country; public Address() { } public Address(long id, String street, String city, String state, String country) { this.id = id; this.street = street; this.city = city; this.state = state; this.country = country; } public long getId() { return id; } public void setId(long id) { this.id = id; } public String getStreet() { return street; } public void setStreet(String street) { this.street = street; } public String getCity() { return city; } public void setCity(String city) { this.city = city; } public String getState() { return state; } public void setState(String state) { this.state = state; } public String getCountry() { return country; } public void setCountry(String country) { this.country = country; } } |
Result
This is index.jsp page after running the project on click on link it will show json data in browser
Downlaod above program from here