Spring Data JPA without Spring Boot

Question

Spring Boot doesn\'t work with Google App Engine (at least not for me).

However much of the examples written or available in the GitHub or other repositorie

Answer 1

Just created this example for you:

src/main/webapp/WEB-INF/spring/context.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
    xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:jpa="http://www.springframework.org/schema/data/jpa"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
        http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa.xsd">

    <context:property-placeholder location="/WEB-INF/spring/jdbc.properties" />

    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
        p:driverClassName="${jdbc.driverClassName}" p:url="${jdbc.url}"
        p:username="${jdbc.username}" p:password="${jdbc.password}" />

    <bean id="hibernateJpaVendorAdapter"
        class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" />

    <!-- Configure the entity manager factory bean -->
    <bean id="entityManagerFactory"
        class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="jpaVendorAdapter" ref="hibernateJpaVendorAdapter" />
        <!-- Set JPA properties -->
        <property name="jpaProperties">
            <props>
                <prop key="hibernate.dialect">${hibernate.dialect}</prop>
            </props>
        </property>
        <property name="packagesToScan" value="com.demo.data" />
    </bean>

    <!-- Configure the transaction manager bean -->
    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory" />
    </bean>

    <tx:annotation-driven />

    <jpa:repositories base-package="com.demo.data" />
    <context:component-scan base-package="com.demo.svc" />
</beans>

/src/main/webapp/WEB-INF/spring/jdbc.properties

# JDBC Connection
jdbc.driverClassName=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://host:3306/db
jdbc.username=user
jdbc.password=password
hibernate.dialect=org.hibernate.dialect.MySQLDialect

/src/main/webapp/WEB-INF/spring/servlet-context.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:beans="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

    <context:component-scan base-package="com.demo.web" />
</beans:beans>

web.xml

<?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" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    version="2.5">
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/spring/context.xml</param-value>
    </context-param>
    <context-param>
        <param-name>webAppRootKey</param-name>
        <param-value>demo_jpa</param-value>
    </context-param>

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <servlet>
        <servlet-name>appServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/spring/servlet-context.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>appServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

pom.xml

<properties>
    <org.springframework-version>4.1.7.RELEASE</org.springframework-version>
    <org.hibernate-em-version>4.3.8.Final</org.hibernate-em-version>
    <org.springframework.data-version>1.9.0.RELEASE</org.springframework.data-version>
    <dbcp-version>1.4</dbcp-version>
    <mysql-connector-version>5.1.28</mysql-connector-version>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context-support</artifactId>
        <version>${org.springframework-version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>${org.springframework-version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework.data</groupId>
        <artifactId>spring-data-jpa</artifactId>
        <version>${org.springframework.data-version}</version>
    </dependency>

    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>${org.hibernate-em-version}</version>
    </dependency>

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>${mysql-connector-version}</version>
    </dependency>

    <dependency>
        <groupId>commons-dbcp</groupId>
        <artifactId>commons-dbcp</artifactId>
        <version>${dbcp-version}</version>
    </dependency>
</dependencies>

Data Entity: com.demo.data.User

package com.demo.data;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "SYS_USERS")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "USER_ID")
    private int id;

    @Column(name = "USER_NAME")
    private String name;

    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;
    }
}

Spring Data JPA Repository: com.demo.data.UserRepository

package com.demo.data;

import org.springframework.data.repository.CrudRepository;

public interface UserRepository extends CrudRepository<User, Integer> {
}

Service

Interface:

package com.demo.svc;

import com.demo.data.User;

public interface UserService {
    User findUserById(Integer id);
}

Implementation:

package com.demo.svc;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.demo.data.User;
import com.demo.data.UserRepository;

@Service
public class UserServiceImpl implements UserService {
    @Autowired
    UserRepository userRepository;

    public User findUserById(Integer id) {
        return userRepository.findOne(id);
    }
}

Web Controller: com.demo.web.UserController

package com.demo.web;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import com.demo.svc.UserService;

@Controller
public class UserController {
    @Autowired
    UserService svc;

    @RequestMapping("/")
    @ResponseBody
    public String test() {
        return svc.findUserById(1).getName();
    }
}

Answer 2

This is happening because you haven't created the bean of UserRepository in context. There are a number of ways you can do this since you're not using a spring boot project so it won't make an object in the container at startup due to which @Autowired is not injecting the object in the UserRepository class. For this project, you can update the following in your project:

 package com.demo.svc;

 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Service;

 import com.demo.data.User;
 import com.demo.data.UserRepository;

 @Service
 public class UserServiceImpl implements UserService {

 UserRepository userRepository;

 public User findUserById(Integer id) {
     return userRepository.findOne(id);
 }

  public UserRepository setRepo(UserRepository repo)
  {
    userRepository=repo;
  }

}

Also, you'll need to inject the object from the container. In src/main/webapp/WEB-INF/spring/context.xml

<bean id="repo" class="com.demo.data.UserRepository"></bean>

<!--Setting the object ref in com.demo.svc.UserServiceImpl-->

<bean id="userserviceImpl" class="com.demo.svc.UserServiceImpl">
 <property name="userRepository" ref="repo"></property>
 </bean>

Hope it helps