I'm creating a simple rest controller with Spring Boot and the Web dependency. I'm trying to deserialize a JSON body to a test POJO with only 3 fields, but when I attempt to make a POST request, the server responds with a 500 error and the error I get in the console is:
.w.s.m.s.DefaultHandlerExceptionResolver : Failed to write HTTP message: org.springframework.http.converter.HttpMessageNotWritableException: No converter found for return value of type: class java.util.LinkedHashMap
All of the code I have written is as follows:
EmailApplication.java:
package com.test.email.app;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
#SpringBootApplication
#ComponentScan(basePackages = { "com.test.email" })
public class EmailApplication {
public static void main(String[] args) {
SpringApplication.run(EmailApplication.class, args);
}
#Bean
public CommandLineRunner commandLineRunner(ApplicationContext ctx) {
return args -> {
System.out.println("----- You're up and running with test-email-app! -----");
};
}
}
EmailController.java:
package com.test.email.controller;
import com.test.email.entity.TestEntity;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.bind.annotation.RequestMapping;
import java.net.URI;
#RestController
public class EmailController {
#RequestMapping(value = "/", method = RequestMethod.GET)
public String index() {
TestEntity entity = new TestEntity();
return "test-email-app index";
}
#RequestMapping(value = "/poster", method = RequestMethod.POST)
public ResponseEntity<String> poster(#RequestBody TestEntity testEntity) {
URI location = URI.create("/poster");
return ResponseEntity.created(location).body(testEntity.getUrl());
}
}
TestEntity.java
package com.test.email.entity;
/**
* An entity for serialization/deserialization testing
*/
public class TestEntity {
public String url;
public int count;
public double height;
public TestEntity() {}
public TestEntity(String url, int count, double height) {
this.url = url;
this.count = count;
this.height = height;
}
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
public int getCount() {
return count;
}
public void setCount(int count) {
this.count = count;
}
public double getHeight() {
return height;
}
public void setHeight(double height) {
this.height = height;
}
}
I'm making a POST request with Postman using only the header Content-Type: application/json and with the body:
{ "url": "http://google.com", "count": 3, "height": 2.4 }
I don't know why Spring can't convert from a LinkedHashMap to my POJO. Any help would be appreciated.
Edit:
My pom.xml is as follows:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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>
<groupId>com.test.email</groupId>
<artifactId>test-email-app</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>test-email-app</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.3.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
After Analyzing your problem, I found some cases where this issue can arise.
Those are given bellow:
Inner Class:
If your class TestEntity is Inner class of your endpoint.
Just transfer your TestEntity from Inner class to a separate class and run your code, it will work.
Support Inner Class:
If you want to support inner class a RequestBody then make TestEntity class as static, this will solve your problem.
Spring dependency configuration:
If still not solved your problem, check your dependency on pom.xml. May be you are not adding dependency on proper way. For this you can view this answer . Or you can add jackson explicitly in your pom.xml file.
Dependencies are:
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>2.4.3</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.4.3</version>
</dependency>
Hope this will solve your problem :)
If still not solved your problem, check some youtube video or some blog site or download some open-source project from github.
Thanks :)
Related links:
Spring #Requestbody not mapping to inner class
Try to specify that your method consumes JSON. Change your annotation:
#RequestMapping(value = "/poster", method = RequestMethod.POST)
to
#PostMapping(value = "/poster",
consumes = MediaType.APPLICATION_JSON_UTF8_VALUE,
produces = MediaType.TEXT_HTML)
The main part here that you specify that you accept your input to be JSON. Not sure what type you return but you can specify the appropriate type or remove the "produces" part. The main part is to specify what your input is
Ideally this code should work but give a try by adding below dependency in pom.xml
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.5.0</version>
</dependency>
Related
I have just started a Spring tutorial. I do everything the same as the lecturer, but if I make a getRequest nothing changes. I also do not have any grey globe icons next to the #RequestMapping and #GetMapping annotations ss of grey globe icon. Would be happy to have any suggestions. Here is the erorr I get when I call the controller endpoint error page
package Controller;
import model.Il;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.Arrays;
import java.util.List;
#RestController
#RequestMapping("/iller")
public class ILController {
#GetMapping
public ResponseEntity<List<Il>> getIller(){
Il il1 = new Il("34", "Istanbul");
Il il2 = new Il("06", "Ankara");
List<Il> iller = Arrays.asList(il1, il2);
return new ResponseEntity<>(iller, HttpStatus.OK);
}
}
Il class:
package model;
import lombok.Data;
#Data
public class Il {
private String id;
private String name;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Il(){
this.id = "defaultId";
this.name = "defaultName";
}
public Il(String id, String name){
this.id = id;
this.name = name;
}
}
I built your example from scratch with Intellij. Could you try re-editing your code as in the screenshot? If you need help with Spring, please write.
you need to fill the annotation #GetMapping with a path that defines your GET method.
For example, try something like this:
#GetMapping(value = "/GetIller")
public ResponseEntity<List<Il>> getIller(){
Il il1 = new Il("34", "Istanbul");
Il il2 = new Il("06", "Ankara");
List<Il> iller = Arrays.asList(il1, il2);
return new ResponseEntity<>(iller, HttpStatus.OK);
}
Same for other HTTP methods (POST, PUT, PATCH, DELETE ...)
Please check the pom also:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.7.3</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.example</groupId>
<artifactId>demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>demo</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>17</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
application.yml
server:
port: 9090
Application.java
#SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
Regarding the Glob Icon feature, I think that feature is only available in the IntelliJ Enterprise version.
By clicking that grey globe icon it gives 3 options -
Go to declaration or usage
Generate request in HTTP Client
Show all endpoints of module
I'm trying to implement custom method in Spring Data repository using Spring Boot 1.5.9.RELEASE.
I created the repository:
package com.example.springdatademo;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
#Repository
interface MyEntityRepository extends JpaRepository<MyEntity, String>, CustomMyEntityRepository {
}
Provided the custom repository:
package com.example.springdatademo;
interface CustomMyEntityRepository {
MyEntity myCustomFindQuery();
}
And the implementation:
package com.example.springdatademo;
import org.springframework.stereotype.Component;
#Component
class CustomMyEntityRepositoryImpl implements CustomMyEntityRepository {
#Override
public MyEntity myCustomFindQuery() {
System.out.println("hello from custom query implementation");
return null;
}
}
Plus, I provided an invocation:
package com.example.springdatademo;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.context.annotation.Bean;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
#EntityScan
#EnableJpaRepositories
#SpringBootApplication
public class SpringDataDemoApplication {
public static void main(String[] args) {
SpringApplication.run(SpringDataDemoApplication.class, args);
}
#Bean
public CommandLineRunner run(MyEntityRepository repository) {
return (args) -> {
final MyEntity myEntity1 = repository.myCustomFindQuery();
repository.save(new MyEntity(1, "fieldTwo"));
for (MyEntity myEntity : repository.findAll()) {
System.out.println(myEntity);
}
};
}
}
pom.xml is just plain one generated from spring initializer:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.9.RELEASE</version>
<!-- <version>2.1.9.RELEASE</version>-->
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.example</groupId>
<artifactId>spring-data-demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>spring-data-demo</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
When running the project on Spring Boot 1.5.9.RELEASE I'm getting a problem on container creation:
Caused by: java.lang.IllegalArgumentException: Failed to create query method public abstract com.example.springdatademo.MyEntity com.example.springdatademo.CustomMyEntityRepository.myCustomFindQuery()! No property myCustomFindQuery found for type MyEntity!
Changing the Spring Boot version to 2.1.9.RELEASE works fine and gives me the expected result.
I can't find any tips in spring-data-jpa-1.11.9.RELEASE documentation
I just checked out your code and was able to fix it. This is what I did
Rename MyEntityRepositoryCustomImpl to MyEntityRepositoryImpl and
As I told you in my comment, cutom repository should be named MyEntityRepositoryCustom(I guess you already did this)
Naming convention is the key here. Impl class should be named <BaseRepository>Impl. And not <CustomRepository>Impl
If you want your current code to run then you need a #NamedQuery if you want to run hql
or if you want to run native query #NamedNativeQuery with a name MyEntity.myCustomFindQuery in your Entity class
#NamedQuery(name="MyEntity.myCustomFindQuery",
query="SELECT 1 as a, 'a' as b from MyEntity")
or
#NamedNativeQuery(name="MyEntity.myCustomFindQuery",
query="SELECT 1 as a, 'a' as b", resultSetMapping="mapmyCustomFindQuery")
#SqlResultSetMapping(name = "mapmyCustomFindQuery", classes = {
#ConstructorResult(targetClass = MyEntity.class, columns = {
#ColumnResult(name = "a"), #ColumnResult(name = "b")
})
})
Alternatively you can keep both repository separate (means MyEntityRepository shouldn't extend MyEntityRepositoryCustom
in that case your Application class will look like below
#Autowired
MyEntityRepository repository;
#Autowired
MyEntityRepositoryCustom entityRepositoryCustom;
public static void main(String[] args) {
SpringApplication.run(SpringDataDemoApplication.class, args);
}
#Bean
public CommandLineRunner run() {
return (args) -> {
final MyEntity myEntity1 = entityRepositoryCustom.myCustomFindQuery();
repository.save(new MyEntity(1, "fieldTwo"));
for (MyEntity myEntity : repository.findAll()) {
System.out.println(myEntity);
}
};
}
I have an error that I can't track down. I'm new so sorry if I missed this in the searches, but I tried several things and no luck.
UserApi.java:
package com.jsp.jsp;
import com.jsp.models.User;
import com.jsp.services.UserService;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
#RestController
class UserApi {
private final UserService userService;
public UserApi(UserService userService) {
this.userService = userService;
}
#RequestMapping(value="/api/user", method=RequestMethod.POST)
public User createUser(
#RequestParam(value="name", required=true) String name,
#RequestParam(value="email", required=true) String email,
#RequestParam(value="password", required=true) String password,
#RequestParam(value="confirm", required=true) String confirm)
{
User u = this.userService.createUser(new User(name, email, password));
return u;
}
}
UserRepository.java:
package com.jsp.repositories;
import org.springframework.stereotype.Repository;
import java.util.List;
import java.util.Optional;
import com.jsp.models.User;
import org.springframework.data.repository.CrudRepository;
#Repository
public interface UserRepository extends CrudRepository<User, Long> {
List<User> findByEmail(String email);
Optional<User> findById(Long id);
List<User> findAll();
}
Server.java
package com.jsp.jsp;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
// import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
#SpringBootApplication(scanBasePackages={"com.jsp.models","com.jsp.repositories","com.jsp.services"})
#RestController
public class Server {
public static void main(String[] args) {
SpringApplication.run(Server.class, args);
}
}
UserService.java
package com.jsp.services;
import java.util.List;
import com.jsp.models.User;
import com.jsp.repositories.UserRepository;
import org.springframework.stereotype.Service;
#Service
public class UserService {
private final UserRepository userRepository;
public UserService(UserRepository userRepository) {
this.userRepository = userRepository;
}
public List<User> allUsers() {
return this.userRepository.findAll();
}
public User createUser(User u) {
return this.userRepository.save(u);
}
}
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 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>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.2.RELEASE</version>
<relativePath /> <!-- lookup parent from repository -->
</parent>
<groupId>com.jsp</groupId>
<artifactId>jsp</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>demo</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.apache.tomcat.embed</groupId>
<artifactId>tomcat-embed-jasper</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jstl</artifactId>
</dependency>
<dependency>
<groupId>org.postgresql</groupId>
<artifactId>postgresql</artifactId>
<version>42.2.5</version>
</dependency>
<dependency>
<groupId>org.mindrot</groupId>
<artifactId>jbcrypt</artifactId>
<version>0.4</version>
</dependency>
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-jpa</artifactId>
<version>1.11.7.RELEASE</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
So in short, when I run the above project in VSCode, it errors out with the following:
2019-02-23 19:07:52.744 WARN 25412 --- [ restartedMain]
ConfigServletWebServerApplicationContext : Exception encountered
during context initialization - cancelling refresh attempt:
org.springframework.beans.factory.UnsatisfiedDependencyException:
Error creating bean with name 'userService' defined in file
[C:\Users\Alex\Documents\dojo\javatown\everything\target\classes\com\jsp\services\UserService.class]:
Unsatisfied dependency expressed through constructor parameter 0;
nested exception is
org.springframework.beans.factory.NoSuchBeanDefinitionException: No
qualifying bean of type 'com.jsp.repositories.UserRepository'
available: expected at least 1 bean which qualifies as autowire
candidate. Dependency annotations: {}
My understanding is that the repository I made should be automatically turned into a bean and then wire itself up to the service I made. However, that seems to be not happening. My example videos are using MySQL -- will that make a difference? Am I using the right driver for Postgres 11? I'm super lost.
Some remarks and suggestions:
1.add autowired annotation on your constructor, it is clearer what you need spring to do.
#Autowired
public UserService(UserRepository userRepository) {
this.userRepository = userRepository;
}
2. I don't understand #RestController annotation on your main class.
#SpringBootApplication(scanBasePackages {"com.jsp.models","com.jsp.repositories","com.jsp.services"})
#RestController --> THIS CAN BE REMOVED
public class Server {
public static void main(String[] args) {
SpringApplication.run(Server.class, args);
}
}
3.You should add #EnableJpaRepositories("com.jsp.repositories") on your spring boot application => it will scan the repositories in that package.
#SpringBootApplication(scanBasePackages {"com.jsp.models","com.jsp.repositories","com.jsp.services"})
#EnableJpaRepositories("com.jsp.repositories")
public class Server {
public static void main(String[] args) {
SpringApplication.run(Server.class, args);
}
}
My sample spring boot REST web service gives 404 error, and I am not sure what went wrong
package com.in28minutes.springboot.studentservices;
#SpringBootApplication
public class StudentServicesApplication {
public static void main(String[] args) {
SpringApplication.run(StudentServicesApplication.class, args);
}
}
package com.in28minutes.springboot.controller;
#RestController
public class StudentController {
#Autowired
private StudentService studentService;
#GetMapping("/students/{studentId}/courses")
public List<Course> retrieveCoursesForStudent(#PathVariable String
studentId) {
return studentService.retrieveCourses(studentId);
}
#GetMapping("/students/{studentId}/courses/{courseId}")
public Course retrieveDetailsForCourse(#PathVariable String studentId,
#PathVariable String courseId) {
return studentService.retrieveCourse(studentId, courseId);
}
}
My Request from POSTMan REST request sender:
http://localhost:8080/students/stu1/courses/course1
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.1.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.in28minutes.springboot</groupId>
<artifactId>student-services</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>student-services</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
Response:
{
"timestamp": "2018-12-28T02:48:00.185+0000",
"status": 404,
"error": "Not Found",
"message": "No message available",
"path": "/students/stu1/courses/course1"
}
As assumed, you have Controller classes in different package com.in28minutes.springboot.controller; and Spring boot main class in different package com.in28minutes.springboot.studentservices;
#SpringBootApplication
By default #SpringBootApplication will only scan from the package of the class that declares this annotation.
This is a convenience annotation that is equivalent to declaring #Configuration, #EnableAutoConfiguration and #ComponentScan.
If specific packages are not defined, scanning will occur from the package of the class that declares this annotation.
use #ComponentScan to scan controller package
#ComponentScan(basePackages = {"com.in28minutes.springboot.controller"})
#SpringBootApplication
public class StudentServicesApplication {
public static void main(String[] args) {
SpringApplication.run(StudentServicesApplication.class, args);
}
}
More Info : ref
The issue is resolved, #Component needed to be added to Service class, along with #ComponentScan in the main application class:
package com.in28minutes.springboot.service;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
import org.springframework.stereotype.Component;
import com.in28minutes.springboot.model.Course;
import com.in28minutes.springboot.model.Student;
#Component
public class StudentService {
public List<Course> retrieveCourses(String studentId) {
Map<String, Course> courses = Student.getStudentObj(studentId).getCourses();
List<Course> courseList =
courses.values().parallelStream().collect(Collectors.toList());
return courseList;
}
public Course retrieveCourse(String studentId, String courseId) {
return Student.getStudentObj(studentId).getCourses().get(courseId);
}
}
package com.in28minutes.springboot;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;
#SpringBootApplication
#ComponentScan("com.in28minutes.springboot")
public class StudentServicesApplication {
public static void main(String[] args) {
SpringApplication.run(StudentServicesApplication.class, args);
}
}
I'm pretty new to Java, but I wanted to try to build a simple project with SpringMVC. It's just a simple CRUD app that should allow people to post notes.
When attempting to submit the form or query for notes, I get a null pointer exception when I attempt to call methods on JdbcTemplate. Here is the code for my application class:
package mvc;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.jdbc.core.JdbcTemplate;
#SpringBootApplication
public class SpringMvcApplication implements CommandLineRunner {
public static void main(String[] args) {
SpringApplication.run(SpringMvcApplication.class, args);
}
#Autowired
JdbcTemplate jdbcTemplate;
public JdbcTemplate getJdbcTemplate() {
return jdbcTemplate;
}
public void run(String... string) throws Exception {
System.out.println("Creating tables");
jdbcTemplate.execute("drop table notes if exists");
jdbcTemplate.execute(("create table notes(" +
"id serial, content varchar(255), author varchar(255))"));
}
public static SpringMvcApplication instance = new SpringMvcApplication();
public static SpringMvcApplication getInstance() { return instance; }
}
Here is my NoteController.java:
package mvc;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
#Controller
public class NoteController {
#RequestMapping("/notes")
public String index() {
return "index";
}
#RequestMapping("/notes/new")
public String newNote(Model model) {
model.addAttribute("note",new Note());
return "new";
}
#RequestMapping(value="/notes", method= RequestMethod.POST)
public String create(Note note, Model model) {
model.addAttribute("note", note);
Note.create(note.getContent(), note.getAuthor());
return "show";
}
#RequestMapping(value = "/notes/{noteId}", method=RequestMethod.GET)
public String show(#PathVariable String noteId) {
long id = Long.parseLong(noteId);
Note note = Note.find(id);
return "show";
}
}
My Note model:
package mvc;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
public class Note {
private Long id;
private String content;
private String author;
public Note() {}
public Note(Long id, String content, String author) {
this.id = id;
this.content = content;
this.author = author;
}
public Long getId() {
return id;
}
public String getContent() {
return content;
}
public String getAuthor() {
return author;
}
public String toString() {
return content + "by " + author;
}
public static void create(String content, String author) {
JdbcTemplate jdbcTemplate = SpringMvcApplication.getInstance().getJdbcTemplate();
jdbcTemplate.update("INSERT INTO notes(content, author) values (?,?)", content, author);
}
public static Note find(Long id) {
JdbcTemplate jdbcTemplate = SpringMvcApplication.getInstance().getJdbcTemplate();
List<Note> notes = jdbcTemplate.query("SELECT id, content, author FROM notes WHERE id = ?", new Object[]{id},
new RowMapper<Note>() {
#Override
public Note mapRow(ResultSet rs, int rowNum) throws SQLException {
return new Note(rs.getLong("id"), rs.getString("content"),
rs.getString("author"));
}
});
return notes.get(0);
}
}
Here's my pom.xml:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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>
<groupId>org.test</groupId>
<artifactId>mvc</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>Spring MVC</name>
<description>MVC Project for Ship It Saturday</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.2.3.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<start-class>mvc.SpringMvcApplication</start-class>
<java.version>1.7</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.2.4</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>1.2.2</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.postgresql</groupId>
<artifactId>postgresql</artifactId>
<version>9.3-1100-jdbc41</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
</dependency>
</dependencies>
I'm not really sure what the issue is with my code here. I was following a few different guides but most of them weren't too clear on what code was doing what. I'm sure there are probably some really obvious issues here, but I'm totally new to Spring and Java so I'm not seeing it.
EDIT:
Here is what I think are the relevant lines of the trace:
2015-04-11 19:01:35.125 ERROR 24895 --- [nio-8080-exec-2] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause
java.lang.NullPointerException: null
at mvc.Note.create(Note.java:44)
at mvc.NoteController.create(NoteController.java:30)
I should also mention that the run() method in the SpringMVCApplication class works just fine at creating the table, and if I move the insert and query statements into that method with static data the also work. It's only when I move them into their own methods so that I can use them dynamically that everything falls apart.
As already mentioned in the comments your SpringMvcApplication.getInstance() will not work as expected. You need something to connect the "spring-world" with the "not-spring-world". A possible solution would be to save the ApplicationContext as singleton.
#SpringBootApplication
public class SpringMvcApplication {
private static ApplicationContext context;
public static void main(String[] args) {
context = SpringApplication.run(SpringMvcApplication.class, args);
}
public static JdbcTemplate getJdbcTemplate() {
return context.getBean(JdbcTemplate.class);
}
}
Maybe you have to adapt it to your needs.