Spring Boot-JPA

前文我们使用SPRING INITIALIZR快速构建了一个空的Spring Boot项目，并增加web模块实现了HTTP请求。

这一篇继续在该demo的基础上，增加JPA的功能。

JPA全称Java Persistence API.JPA通过JDK 5.0注解或XML描述对象关系表的映射关系，并将运行时的实体对象持久化到数据库中。

引入JPA模块

1.在POM文件中添加：

<!-- JPA模块 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

<!-- mysql -->

<dependency>
　　<groupId>mysql</groupId>
　　<artifactId>mysql-connector-java</artifactId>
　　<scope>runtime</scope>
</dependency>

2.在application.properties属性文件中定义好数据源（传统做法，这里不演示了）

2.(我们使用Spring推荐的yml来配置)新建application.yml文件，内容如下：

server:
  port: 8000
spring:
  application:
    name: demo
  jpa:
    properties:
      hibernate:
        cache:
          use_second_level_cache: false
          use_query_cache: false
        generate_statistics: true
        cache.region.factory_class: org.hibernate.cache.ehcache.EhCacheRegionFactory
    generate-ddl: false
    hibernate:
      ddl-auto: update
    show-sql: true
  datasource:
    platform: mysql
    url: jdbc:mysql://127.0.0.1:3306/demo?useUnicode=true&characterEncoding=utf8
    username: root
    password: 你的数据库密码
#    schema: classpath:schema.sql
#    data: classpath:data.sql
logging:
  level:
    root: info    

相应的，在本地创建一个叫demo的数据库，用于我们的测试。

定义2个实体

1.新建包com.v5ent.demo.domain

2.在这个包下新建两个实体类Tag和Note，代码如下

/*
 * Copyright 2012-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.v5ent.demo.domain;

import java.util.List;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.ManyToMany;
import javax.persistence.SequenceGenerator;

@Entity
public class Note {

    @Id
    @SequenceGenerator(name="note_generator", sequenceName="note_sequence", initialValue = 5)
    @GeneratedValue(generator = "note_generator")
    private long id;

    private String title;

    private String body;

    @ManyToMany
    private List<Tag> tags;

    protected Note() {};

    public Note(String title, String body) {
        this.title = title;
        this.body = body;
    }

    public long getId() {
        return this.id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getTitle() {
        return this.title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getBody() {
        return this.body;
    }

    public void setBody(String body) {
        this.body = body;
    }

    public List<Tag> getTags() {
        return this.tags;
    }

    public void setTags(List<Tag> tags) {
        this.tags = tags;
    }

}

Tag：

/*
 * Copyright 2012-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.v5ent.demo.domain;

import java.util.List;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.ManyToMany;
import javax.persistence.SequenceGenerator;

@Entity
public class Tag {

    @Id
    @SequenceGenerator(name="tag_generator", sequenceName="tag_sequence", initialValue = 4)
    @GeneratedValue(generator = "tag_generator")
    private long id;

    private String name;

    @ManyToMany(mappedBy = "tags")
    private List<Note> notes;

    public long getId() {
        return this.id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getName() {
        return this.name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public List<Note> getNotes() {
        return this.notes;
    }

    public void setNotes(List<Note> notes) {
        this.notes = notes;
    }

}

这里我们定义了两个多对多的实体，笔记和标签。

定义2个实体的Jpa

1.新建包com.v5ent.demo.repository

2.在这个包下新建两个Jpa类TagRepository和NoteRepository，代码如下

package com.v5ent.demo.repository;

import org.springframework.data.jpa.repository.JpaRepository;

import com.v5ent.demo.domain.Tag;

/**
 * Spring Data JPA repository for the Tag entity.
 */
public interface TagRepository extends JpaRepository<Tag,Long> {

}

package com.v5ent.demo.repository;

import java.util.List;

import org.springframework.data.jpa.repository.JpaRepository;

import com.v5ent.demo.domain.Note;

/**
 * Spring Data JPA repository for the Note entity.
 */
public interface NoteRepository extends JpaRepository<Note,Long> {

}

至此，所有的工作就完成了。

大家可以看一下仓库类的父类，常用的数据库访问操作都默认实现了。

JPA的查询方法

在JPA中有三种方式可以进行数据的查询（1,方法命名查询 2,@NamedQuery查询 3,@Query查询），

第一种：方法命名查询

1. Spring Data JPA支持通过定义在Repository接口的方法来定义查询，方法名字是根据实体类的属性名来确定的，示例如下：

/**
 * Spring Data JPA repository for the Note entity.
 */
public interface NoteRepository extends JpaRepository<Note,Long> {

    List<Note> findByBody(String body);

 　 List<Note> findByTitleAndBody(String title,String body);

}

从代码可以看出，使用findBy这样的关键字，就可以直接实现根据字段查询。（这里的findBy也可以用find,getBy,query,read代替）而And就相当于sql语句中的and。

2.用关键字限制结果数量，用top和first来实现，示例：

/*
*查询符合条件的前十条记录
*/
List<Note> findFirst10ByTitle(String title)
/*
*查询符合条件的前30条记录
*/
List<Note> findTop30ByTitle(String title);

第二种：@NamedQuery查询

Spring Data JPA 支持@NameQuery来定义查询方法，即一个名称映射一个查询语句(要在实体类上写，不是接口里写)，示例如下：

@Entity
@NamedQuery(name="Note.findByTitle",
query="select p from Note p where p.title=?1")
public class Note{

}

如果要将多个方法都进行重新定义，可以使用@NameQueries标签,示例如下：

@Entity
@NamedQueries({
@NamedQuery(name="Note.findByTitle",
query="select p from Note p where p.title=?1"),
@NamedQuery(name = "Note.withTitleAndBodyQuery",
query = "select p from Note p where p.title=?1 and body=?2")
})
public class Note{

}

这个时候，接口里定义的findByName方法就是上面的方法了，不再是方法命名查询的方法了。

第三种：@Query查询

Spring Data JPA 支持@Query来定义查询方法，使用方法是将@Query写在接口的方法上面，示例如下：

public interface NoteRepository extends JpaRepository<Note, Long> {
     @Query("select p from Note p where p.title like ?1 ")
    List<Note> anyQuery(String title);

}

这里的参数是根据索引号来进行查询的。

当然我们也是可以根据名称来进行匹配，然后进行查询的，示例如下：

public interface NoteRepository extends JpaRepository<Note, Long> {
     @Query("select p from Note p where p.title like :title")
    List<Note> anyQuery(@Param("title")String title); }

如果是模糊匹配呢，这么写：

@Query("select p from Note p where p.title like %:title%")
    List<Note> anyQuery(@Param("title")String title); 

我们再来看看更新是如何写的。

Spring Data JPA支持使用@Modifying和@Query注解组合来进行更新查询，示例如下：

@Modifying
@Transcational
@Query("update Note p set p.title=?1 ")
int setTitle(String title);

int表示的是更新语句所影响的行数。

来测试看看

1.我们不准使用之前的测试类，我准备直接在启动的时候测试。首先在DemoApplication中增加如下测试代码：

　　@Bean
    public CommandLineRunner demo(final NoteRepository repository) {
        return new CommandLineRunner() {

            @Override
            public void run(String... args) throws Exception {
                // save a couple of Notes
                repository.save(new Note("Have a nice Day", "Don’t let mental blocks control you. Set yourself free. Confront your fear and turn the mental blocks into building blocks."));
                repository.save(new Note("x-Notes", "Chloe O'Brian,Kim Bauer"));
                repository.save(new Note("Some Others", "No news is good news"));

                // fetch all Notes
                log.info("Notes found with findAll():");
                log.info("-------------------------------");
                for (Note note : repository.findAll()) {
                    log.info(note.toString());
                }

                // fetch an individual note by ID
                Note note = repository.findOne(1L);
                log.info("Note found with findOne(1L):");
                log.info("--------------------------------");
                log.info(note.toString());

                // fetch Notes by last name
                log.info("Note found with anyQuery(\"Some\"):");
                log.info("--------------------------------------------");
                for (Note bauer : repository.anyQuery("Some")) {
                    log.info(bauer.toString());
                }
            }
        };
    }

2.执行main方法跑起来，我们可以看到控制台输出了我们的操作日志。

-- ::07.820  INFO  --- [           main] com.v5ent.demo.DemoApplication           : Note found with findOne(1L):
-- ::07.820  INFO  --- [           main] com.v5ent.demo.DemoApplication           : --------------------------------
-- ::07.820  INFO  --- [           main] com.v5ent.demo.DemoApplication           : com.v5ent.demo.domain.Note@7893c715
-- ::07.820  INFO  --- [           main] com.v5ent.demo.DemoApplication           : Note found with anyQuery("Some"):
-- ::07.820  INFO  --- [           main] com.v5ent.demo.DemoApplication           : --------------------------------------------

补充

不得不提，在此基础上，实现Rest化API很简单。下面来展开实验：

在当前的情况下，我们看一下mvc方面的日志：

-- ::45.980  INFO  --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/hello]}" onto public java.lang.String com.v5ent.demo.web.HelloController.index()
-- ::45.985  INFO  --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
-- ::45.985  INFO  --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
-- ::46.024  INFO  --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-05-18 12:13:46.024  INFO 12664 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-05-18 12:13:46.078  INFO 12664 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
-- ::46.354  INFO  --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
-- ::46.421  INFO  --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s):  (http)

可以看到/hello这个我们之前实现的controller，如果我们要实现note和tag的对外api，当然也要自己写controller。但是Sring就是专门把这些固定的做法实现的机构，所以Spring已经封装了rest风格api所需要的controller实现。

简单来讲，我们只需要在pom文件中增加：

　　　　　<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-rest</artifactId>
        </dependency>

ok，现在启动看看日志：

-- ::36.876  INFO  --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@72a7c7e0: startup date [Thu May  :: CST ]; root of context hierarchy
-- ::36.954  INFO  --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/hello]}" onto public java.lang.String com.v5ent.demo.web.HelloController.index()
-- ::36.958  INFO  --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
-- ::36.959  INFO  --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
-- ::36.994  INFO  --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-05-18 12:55:36.995  INFO 7124 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-05-18 12:55:37.010  INFO 7124 --- [           main] .m.m.a.ExceptionHandlerExceptionResolver : Detected @ExceptionHandler methods in repositoryRestExceptionHandler
2017-05-18 12:55:37.102  INFO 7124 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
-- ::37.262  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerAdapter   : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@72a7c7e0: startup date [Thu May  :: CST ]; root of context hierarchy
-- ::37.275  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/ || ],methods=[OPTIONS],produces=[application/hal+json || application/json]}" onto public org.springframework.http.HttpEntity<?> org.springframework.data.rest.webmvc.RepositoryController.optionsForRepositories()
-- ::37.276  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/ || ],methods=[HEAD],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<?> org.springframework.data.rest.webmvc.RepositoryController.headForRepositories()
-- ::37.277  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/ || ],methods=[GET],produces=[application/hal+json || application/json]}" onto public org.springframework.http.HttpEntity<org.springframework.data.rest.webmvc.RepositoryLinksResource> org.springframework.data.rest.webmvc.RepositoryController.listRepositories()
-- ::37.280  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}],methods=[DELETE],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<?> org.springframework.data.rest.webmvc.RepositoryEntityController.deleteItemResource(org.springframework.data.rest.webmvc.RootResourceInformation,java.io.Serializable,org.springframework.data.rest.webmvc.support.ETag) throws org.springframework.data.rest.webmvc.ResourceNotFoundException,org.springframework.web.HttpRequestMethodNotSupportedException
-- ::37.280  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}],methods=[PATCH],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.RepositoryEntityController.patchItemResource(org.springframework.data.rest.webmvc.RootResourceInformation,org.springframework.data.rest.webmvc.PersistentEntityResource,java.io.Serializable,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler,org.springframework.data.rest.webmvc.support.ETag,java.lang.String) throws org.springframework.web.HttpRequestMethodNotSupportedException,org.springframework.data.rest.webmvc.ResourceNotFoundException
-- ::37.280  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}],methods=[OPTIONS],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<?> org.springframework.data.rest.webmvc.RepositoryEntityController.optionsForCollectionResource(org.springframework.data.rest.webmvc.RootResourceInformation)
-- ::37.281  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}],methods=[HEAD],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<?> org.springframework.data.rest.webmvc.RepositoryEntityController.headCollectionResource(org.springframework.data.rest.webmvc.RootResourceInformation,org.springframework.data.rest.webmvc.support.DefaultedPageable) throws org.springframework.web.HttpRequestMethodNotSupportedException
-- ::37.281  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}],methods=[GET],produces=[application/hal+json || application/json]}" onto public org.springframework.hateoas.Resources<?> org.springframework.data.rest.webmvc.RepositoryEntityController.getCollectionResource(org.springframework.data.rest.webmvc.RootResourceInformation,org.springframework.data.rest.webmvc.support.DefaultedPageable,org.springframework.data.domain.Sort,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler) throws org.springframework.data.rest.webmvc.ResourceNotFoundException,org.springframework.web.HttpRequestMethodNotSupportedException
-- ::37.281  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}],methods=[GET],produces=[application/x-spring-data-compact+json || text/uri-list]}" onto public org.springframework.hateoas.Resources<?> org.springframework.data.rest.webmvc.RepositoryEntityController.getCollectionResourceCompact(org.springframework.data.rest.webmvc.RootResourceInformation,org.springframework.data.rest.webmvc.support.DefaultedPageable,org.springframework.data.domain.Sort,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler) throws org.springframework.data.rest.webmvc.ResourceNotFoundException,org.springframework.web.HttpRequestMethodNotSupportedException
-- ::37.281  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}],methods=[POST],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.RepositoryEntityController.postCollectionResource(org.springframework.data.rest.webmvc.RootResourceInformation,org.springframework.data.rest.webmvc.PersistentEntityResource,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler,java.lang.String) throws org.springframework.web.HttpRequestMethodNotSupportedException
-- ::37.282  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}],methods=[OPTIONS],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<?> org.springframework.data.rest.webmvc.RepositoryEntityController.optionsForItemResource(org.springframework.data.rest.webmvc.RootResourceInformation)
-- ::37.282  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}],methods=[HEAD],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<?> org.springframework.data.rest.webmvc.RepositoryEntityController.headForItemResource(org.springframework.data.rest.webmvc.RootResourceInformation,java.io.Serializable,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler) throws org.springframework.web.HttpRequestMethodNotSupportedException
-- ::37.282  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}],methods=[GET],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<org.springframework.hateoas.Resource<?>> org.springframework.data.rest.webmvc.RepositoryEntityController.getItemResource(org.springframework.data.rest.webmvc.RootResourceInformation,java.io.Serializable,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler,org.springframework.http.HttpHeaders) throws org.springframework.web.HttpRequestMethodNotSupportedException
-- ::37.283  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}],methods=[PUT],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<? extends org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.RepositoryEntityController.putItemResource(org.springframework.data.rest.webmvc.RootResourceInformation,org.springframework.data.rest.webmvc.PersistentEntityResource,java.io.Serializable,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler,org.springframework.data.rest.webmvc.support.ETag,java.lang.String) throws org.springframework.web.HttpRequestMethodNotSupportedException
-- ::37.285  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}/{property}],methods=[DELETE],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<? extends org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.RepositoryPropertyReferenceController.deletePropertyReference(org.springframework.data.rest.webmvc.RootResourceInformation,java.io.Serializable,java.lang.String) throws java.lang.Exception
-- ::37.286  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}/{property}],methods=[GET],produces=[application/x-spring-data-compact+json || text/uri-list]}" onto public org.springframework.http.ResponseEntity<org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.RepositoryPropertyReferenceController.followPropertyReferenceCompact(org.springframework.data.rest.webmvc.RootResourceInformation,java.io.Serializable,java.lang.String,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler) throws java.lang.Exception
-- ::37.286  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}/{property}],methods=[GET],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.RepositoryPropertyReferenceController.followPropertyReference(org.springframework.data.rest.webmvc.RootResourceInformation,java.io.Serializable,java.lang.String,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler) throws java.lang.Exception
-- ::37.286  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}/{property}/{propertyId}],methods=[GET],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.RepositoryPropertyReferenceController.followPropertyReference(org.springframework.data.rest.webmvc.RootResourceInformation,java.io.Serializable,java.lang.String,java.lang.String,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler) throws java.lang.Exception
-- ::37.286  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}/{property}/{propertyId}],methods=[DELETE],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.RepositoryPropertyReferenceController.deletePropertyReferenceId(org.springframework.data.rest.webmvc.RootResourceInformation,java.io.Serializable,java.lang.String,java.lang.String) throws java.lang.Exception
-- ::37.287  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}/{property}],methods=[PATCH || PUT || POST],consumes=[application/json || application/x-spring-data-compact+json || text/uri-list],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<? extends org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.RepositoryPropertyReferenceController.createPropertyReference(org.springframework.data.rest.webmvc.RootResourceInformation,org.springframework.http.HttpMethod,org.springframework.hateoas.Resources<java.lang.Object>,java.io.Serializable,java.lang.String) throws java.lang.Exception
-- ::37.288  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/search],methods=[GET],produces=[application/hal+json || application/json]}" onto public org.springframework.data.rest.webmvc.RepositorySearchesResource org.springframework.data.rest.webmvc.RepositorySearchController.listSearches(org.springframework.data.rest.webmvc.RootResourceInformation)
-- ::37.288  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/search/{search}],methods=[HEAD],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<java.lang.Object> org.springframework.data.rest.webmvc.RepositorySearchController.headForSearch(org.springframework.data.rest.webmvc.RootResourceInformation,java.lang.String)
-- ::37.289  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/search/{search}],methods=[GET],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<?> org.springframework.data.rest.webmvc.RepositorySearchController.executeSearch(org.springframework.data.rest.webmvc.RootResourceInformation,org.springframework.util.MultiValueMap<java.lang.String, java.lang.Object>,java.lang.String,org.springframework.data.rest.webmvc.support.DefaultedPageable,org.springframework.data.domain.Sort,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler,org.springframework.http.HttpHeaders)
-- ::37.289  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/search],methods=[HEAD],produces=[application/hal+json || application/json]}" onto public org.springframework.http.HttpEntity<?> org.springframework.data.rest.webmvc.RepositorySearchController.headForSearches(org.springframework.data.rest.webmvc.RootResourceInformation)
-- ::37.290  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/search/{search}],methods=[OPTIONS],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<java.lang.Object> org.springframework.data.rest.webmvc.RepositorySearchController.optionsForSearch(org.springframework.data.rest.webmvc.RootResourceInformation,java.lang.String)
-- ::37.291  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/search/{search}],methods=[GET],produces=[application/x-spring-data-compact+json]}" onto public org.springframework.hateoas.ResourceSupport org.springframework.data.rest.webmvc.RepositorySearchController.executeSearchCompact(org.springframework.data.rest.webmvc.RootResourceInformation,org.springframework.http.HttpHeaders,org.springframework.util.MultiValueMap<java.lang.String, java.lang.Object>,java.lang.String,java.lang.String,org.springframework.data.rest.webmvc.support.DefaultedPageable,org.springframework.data.domain.Sort,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler)
-- ::37.291  INFO  --- [           main] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/search],methods=[OPTIONS],produces=[application/hal+json || application/json]}" onto public org.springframework.http.HttpEntity<?> org.springframework.data.rest.webmvc.RepositorySearchController.optionsForSearches(org.springframework.data.rest.webmvc.RootResourceInformation)
-- ::37.294  INFO  --- [           main] o.s.d.r.w.BasePathAwareHandlerMapping    : Mapped "{[/profile],methods=[GET]}" onto org.springframework.http.HttpEntity<org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.ProfileController.listAllFormsOfMetadata()
-- ::37.295  INFO  --- [           main] o.s.d.r.w.BasePathAwareHandlerMapping    : Mapped "{[/profile],methods=[OPTIONS]}" onto public org.springframework.http.HttpEntity<?> org.springframework.data.rest.webmvc.ProfileController.profileOptions()
-- ::37.295  INFO  --- [           main] o.s.d.r.w.BasePathAwareHandlerMapping    : Mapped "{[/profile/{repository}],methods=[GET],produces=[application/alps+json || */*]}" onto org.springframework.http.HttpEntity<org.springframework.data.rest.webmvc.RootResourceInformation> org.springframework.data.rest.webmvc.alps.AlpsController.descriptor(org.springframework.data.rest.webmvc.RootResourceInformation)
-- ::37.295  INFO  --- [           main] o.s.d.r.w.BasePathAwareHandlerMapping    : Mapped "{[/profile/{repository}],methods=[OPTIONS],produces=[application/alps+json]}" onto org.springframework.http.HttpEntity<?> org.springframework.data.rest.webmvc.alps.AlpsController.alpsOptions()
-- ::37.296  INFO  --- [           main] o.s.d.r.w.BasePathAwareHandlerMapping    : Mapped "{[/profile/{repository}],methods=[GET],produces=[application/schema+json]}" onto public org.springframework.http.HttpEntity<org.springframework.data.rest.webmvc.json.JsonSchema> org.springframework.data.rest.webmvc.RepositorySchemaController.schema(org.springframework.data.rest.webmvc.RootResourceInformation)
-- ::37.465  INFO  --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
-- ::37.602  INFO  --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s):  (http)

发现多了很多rest api的映射，这表示成功了。

访问http://localhost:8000/notes/1，可以看到rest api已经直接可用了。hal+json 的格式，如果有疑问可留言。