code samples for BAEL-1789 Returning JSON object from a servlet

javax-servlets/pom.xml

@@ -3,6 +3,7 @@
 	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 	<modelVersion>4.0.0</modelVersion>
 	<artifactId>javax-servlets</artifactId>
+	<packaging>war</packaging>
 	<version>1.0-SNAPSHOT</version>
 
 	<parent>
@@ -29,18 +30,30 @@
 				</exclusion>
 			</exclusions>
 		</dependency>
+		<dependency>
+			<groupId>com.google.code.gson</groupId>
+			<artifactId>gson</artifactId>
+			<version>${gson.version}</version>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework</groupId>
 			<artifactId>spring-test</artifactId>
 			<version>${spring-test.version}</version>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.mockito</groupId>
+			<artifactId>mockito-core</artifactId>
+			<version>2.18.3</version>
+			<scope>test</scope>
+		</dependency>
 	</dependencies>
 
 	<properties>
 		<javax.servlet.version>3.1.0</javax.servlet.version>
 		<org.apache.httpcomponents.version>4.5.3</org.apache.httpcomponents.version>
 		<spring-test.version>5.0.5.RELEASE</spring-test.version>
+		<gson.version>2.8.4</gson.version>
 	</properties>
 
 </project>

javax-servlets/src/main/java/com/baeldung/model/Employee.java

@@ -0,0 +1,72 @@
+package com.baeldung.model;
+
+public class Employee {
+	
+	private int id;
+    private String name;
+    private String department;
+    private Double salary;
+	
+    public Employee(int id, String name, String department, Double salary) {
+		super();
+		this.id = id;
+		this.name = name;
+		this.department = department;
+		this.salary = salary;
+	}
+
+	@Override
+	public int hashCode() {
+		final int prime = 31;
+		int result = 1;
+		result = prime * result + id;
+		return result;
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj)
+			return true;
+		if (obj == null)
+			return false;
+		if (getClass() != obj.getClass())
+			return false;
+		Employee other = (Employee) obj;
+		if (id != other.id)
+			return false;
+		return true;
+	}
+
+	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 getDepartment() {
+		return department;
+	}
+	
+    public void setDepartment(String department) {
+		this.department = department;
+	}
+	
+    public Double getSalary() {
+		return salary;
+	}
+	
+    public void setSalary(Double salary) {
+		this.salary = salary;
+	}
+	
+}

javax-servlets/src/main/java/com/baeldung/servlets/EmployeeServlet.java

@@ -0,0 +1,37 @@
+package com.baeldung.servlets;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+
+import javax.servlet.annotation.WebServlet;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import com.baeldung.model.Employee;
+import com.google.gson.Gson;
+
+
+@WebServlet(name = "EmployeeServlet", urlPatterns = "/employeeServlet")
+public class EmployeeServlet extends HttpServlet {
+	
+	@Override
+    protected void doPost(HttpServletRequest request, HttpServletResponse response)
+      throws IOException {
+
+		int id = Integer.parseInt(request.getParameter("id"));
+        String name = request.getParameter("name");
+        String department = request.getParameter("department");
+        Double salary = Double.parseDouble(request.getParameter("salary"));
+        
+        Employee employee = new Employee(id, name, department, salary);
+        
+        PrintWriter out = response.getWriter();
+        String employeeJsonString = new Gson().toJson(employee);
+        response.setContentType("application/json");
+        response.setCharacterEncoding("UTF-8");
+        out.print(employeeJsonString);
+        out.flush();   
+	}
+
+}

javax-servlets/src/test/java/com/baeldung/servlets/EmployeeServletTest.java

@@ -0,0 +1,60 @@
+package com.baeldung.servlets;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Mockito.when;
+
+import java.io.PrintWriter;
+import java.io.StringWriter;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+
+import com.baeldung.model.Employee;
+import com.google.gson.Gson;
+
+
+@RunWith(MockitoJUnitRunner.class)
+public class EmployeeServletTest {
+	
+	@Mock
+	HttpServletRequest httpServletRequest;
+	
+	@Mock
+	HttpServletResponse httpServletResponse;
+	
+	Employee employee;
+	
+	@Test
+    public void whenPostRequestToEmployeeServlet_thenCorrect() throws Exception {
+
+		//Given
+		int id = 1;
+        String name = "Karan Khanna";
+        String department = "IT";
+        Double salary = 5000.0;
+        employee = new Employee(id, name, department, salary);
+        
+        //when
+		when(httpServletRequest.getParameter("id")).thenReturn(String.valueOf(id));
+        when(httpServletRequest.getParameter("name")).thenReturn(name);
+        when(httpServletRequest.getParameter("department")).thenReturn(department);
+        when(httpServletRequest.getParameter("salary")).thenReturn(String.valueOf(salary));
+        
+        StringWriter sw = new StringWriter();
+        PrintWriter pw = new PrintWriter(sw);
+        when(httpServletResponse.getWriter()).thenReturn(pw);
+
+        EmployeeServlet employeeServlet = new EmployeeServlet();
+        employeeServlet.doPost(httpServletRequest, httpServletResponse);
+        
+        String employeeJsonString = sw.getBuffer().toString().trim();
+        Employee fetchedEmployee = new Gson().fromJson(employeeJsonString, Employee.class);
+        assertEquals(fetchedEmployee, employee);
+    }
+
+}