0
Application.javaスプリングデータリポジトリは
package com.example;
import com.example.repository.AuthorRepository;
import com.example.entities.Author;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ApplicationContext;
import org.springframework.transaction.annotation.Transactional;
@SpringBootApplication
public class JpaHibernateApplication {
@Autowired
private static AuthorRepository authorRepository;
@Transactional
public static void main(String[] args) {
ApplicationContext ctx = SpringApplication.run(JpaHibernateApplication.class, args);
for(String name : ctx.getBeanDefinitionNames()){
System.out.println(name);
}
Author author = new Author();
author.setName("Vamsi");
authorRepository.save(author);
}
}
Author.javaが動作していない
package com.example.entities;
import javax.persistence.*;
@Entity
@Table(name="author")
public class Author {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String 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;
}
}
AuthorRepository
package com.example.repository;
import com.example.entities.Author;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
@Repository
public interface AuthorRepository extends CrudRepository<Author,Long> {
}
application.properties
spring.datasource.url = jdbc:mysql://localhost:3306/Learning?useSSL=false
spring.datasource.username = root
spring.datasource.password = root
# Show or not log for each sql query
spring.jpa.show-sql = true
# Hibernate ddl auto (create, create-drop, update)
spring.jpa.hibernate.ddl-auto = update
# Naming strategy
spring.jpa.hibernate.naming-strategy = org.hibernate.cfg.ImprovedNamingStrategy
# Use spring.jpa.properties.* for Hibernate native properties (the prefix is
# stripped before adding them to the entity manager)
# The SQL dialect makes Hibernate generate better SQL for the chosen database
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect
のGradleファイル
buildscript {
ext {
springBootVersion = '1.3.3.RELEASE'
}
repositories {
mavenCentral()
}
dependencies {
classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
}
}
apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'spring-boot'
jar {
baseName = 'demo'
version = '0.0.1-SNAPSHOT'
}
sourceCompatibility = 1.7
targetCompatibility = 1.7
repositories {
mavenCentral()
}
dependencies {
compile('org.springframework.boot:spring-boot-starter-data-jpa')
compile('org.springframework.boot:spring-boot-starter-web')
runtime('mysql:mysql-connector-java')
testCompile('org.springframework.boot:spring-boot-starter-test')
}
eclipse {
classpath {
containers.remove('org.eclipse.jdt.launching.JRE_CONTAINER')
containers 'org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.7'
}
}
task wrapper(type: Wrapper) {
gradleVersion = '2.12'
}
私は、アプリケーションの起動時に著者のオブジェクトを永続化しようとしています。しかし、それは以下のヌルポインタ例外を与えています。静的フィールドで
エラー
Exception in thread "main" java.lang.NullPointerException
at com.example.JpaHibernateApplication.main(JpaHibernateApplication.java:25)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)