BAEL-1649 Difference between @Controller and @RestController (#3885)

* Difference between @Controller and @RestController

* Difference between @Controller and @RestController - test fix

spring-mvc-java/src/main/java/com/baeldung/model/Book.java

@@ -0,0 +1,33 @@
+package com.baeldung.model;
+
+public class Book {
+
+    private int id;
+    private String author;
+    private String title;
+
+    public int getId() {
+        return id;
+    }
+    
+    public void setId(int id) {
+        this.id = id;
+    }
+    
+    public String getAuthor() {
+        return author;
+    }
+
+    public void setAuthor(String author) {
+        this.author = author;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public void setTitle(String title) {
+        this.title = title;
+    }
+    
+}

spring-mvc-java/src/main/java/com/baeldung/web/controller/SimpleBookController.java

@@ -0,0 +1,31 @@
+package com.baeldung.web.controller;
+
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+import org.springframework.web.bind.annotation.ResponseBody;
+
+import com.baeldung.model.Book;
+
+@Controller
+@RequestMapping("books")
+public class SimpleBookController {
+
+    @RequestMapping(value = "/{id}", method = RequestMethod.GET, produces = "application/json")
+    public @ResponseBody Book getBook(@PathVariable int id) {
+        return findBookById(id);
+    }
+
+    private Book findBookById(int id) {
+        Book book = null;
+        if (id == 42) {
+            book = new Book();
+            book.setId(id);
+            book.setAuthor("Douglas Adamas");
+            book.setTitle("Hitchhiker's guide to the galaxy");
+        }
+        return book;
+    }
+
+}

spring-mvc-java/src/main/java/com/baeldung/web/controller/SimpleBookRestController.java

@@ -0,0 +1,29 @@
+package com.baeldung.web.controller;
+
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.baeldung.model.Book;
+
+@RestController
+@RequestMapping("books-rest")
+public class SimpleBookRestController {
+    
+    @RequestMapping(value = "/{id}", method = RequestMethod.GET, produces = "application/json")
+    public Book getBook(@PathVariable int id) {
+        return findBookById(id);
+    }
+
+    private Book findBookById(int id) {
+        Book book = null;
+        if (id == 42) {
+            book = new Book();
+            book.setId(id);
+            book.setAuthor("Douglas Adamas");
+            book.setTitle("Hitchhiker's guide to the galaxy");
+        }
+        return book;
+    }
+}

spring-mvc-java/src/test/java/com/baeldung/web/controller/SimpleBookControllerTest.java

@@ -0,0 +1,35 @@
+package com.baeldung.web.controller;
+
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.test.web.servlet.setup.MockMvcBuilders;
+
+import com.baeldung.web.controller.SimpleBookController;
+
+public class SimpleBookControllerTest {
+
+    private MockMvc mockMvc;
+    private static final String CONTENT_TYPE = "application/json;charset=UTF-8";
+
+    @Before
+    public void setup() {
+        this.mockMvc = MockMvcBuilders.standaloneSetup(new SimpleBookController()).build();
+    }
+
+    @Test
+    public void givenBookId_whenMockMVC_thenVerifyResponse() throws Exception {
+        this.mockMvc
+            .perform(get("/books/42"))
+            .andExpect(status().isOk())
+            .andExpect(content().contentType(CONTENT_TYPE))
+            .andExpect(jsonPath("$.id").value(42));
+    }
+
+}
+

spring-mvc-java/src/test/java/com/baeldung/web/controller/SimpleBookRestControllerTest.java

@@ -0,0 +1,35 @@
+package com.baeldung.web.controller;
+
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.test.web.servlet.setup.MockMvcBuilders;
+
+import com.baeldung.web.controller.SimpleBookController;
+
+public class SimpleBookRestControllerTest {
+
+    private MockMvc mockMvc;
+    private static final String CONTENT_TYPE = "application/json;charset=UTF-8";
+
+    @Before
+    public void setup() {
+        this.mockMvc = MockMvcBuilders.standaloneSetup(new SimpleBookController()).build();
+    }
+
+    @Test
+    public void givenBookId_whenMockMVC_thenVerifyResponse() throws Exception {
+        this.mockMvc
+            .perform(get("/books/42"))
+            .andExpect(status().isOk())
+            .andExpect(content().contentType(CONTENT_TYPE))
+            .andExpect(jsonPath("$.id").value(42));
+    }
+
+}
+