ジャーナルのPOSTメソッドのヌルポインター例外

Question

ジャージーとハイバネーションを使用してWebプロジェクトを構築しています。私は郵便配達員の厳しい作業をテストしています。 POSTメソッドの場合、私はNULLポインタの例外を取得し、私は解決する方法を知らない。私を助けてください。私はジャージーで新しいです。

以下は私のコードと完全なスタックトレースです。

BookRepository.com

package com.bookstrore.repository; 

import java.util.ArrayList; 

import java.util.List; 

import org.hibernate.Transaction; 
import org.hibernate.Session; 
import org.hibernate.Query; 

import com.bookstrore.model.Book; 
import com.bookstrore.model.SessionUtil; 
//import com.pluralsight.model.User; 

public class BookRepositoryStub { 

    public void createBook(Book book) { 
     Session session = SessionUtil.getSession();   
      Transaction tx = session.beginTransaction(); 
      createBook(session,book);   
      tx.commit(); 
      session.close(); 

    } 

    private void createBook(Session session, Book bo){ 
     Book book=new Book(); 

     book.setBook_id(bo.getBook_id()); 
     book.setBook_title(bo.getBook_title()); 
     book.setBook_author(bo.getBook_author()); 
     book.setBook_description(bo.getBook_description()); 
     book.setBook_price(bo.getBook_price()); 


     session.save(book); 
    } 

    public List<Book> getBooks(){ 
     Session session = SessionUtil.getSession();  
     Query query = session.createQuery("from Book"); 
     List<Book> books = query.list(); 
     session.close(); 
     return books; 
    } 
    public int delete(int book_id){ 
     Session session = SessionUtil.getSession(); 
     Transaction tx = session.beginTransaction(); 
     String hql = "delete from Book where book_id = :book_id"; 
     Query query = session.createQuery(hql); 
     query.setInteger("book_id",book_id); 
     int rowCount = query.executeUpdate(); 
     System.out.println("Rows affected: " + rowCount); 
     tx.commit(); 
     session.close(); 
     return rowCount; 
    } 

    public int update(int book_id, Book bo){ 
     if(book_id <=0) 
       return 0; 
     Session session = SessionUtil.getSession(); 
      Transaction tx = session.beginTransaction(); 
      String hql = "update Book set book_title = :book_title, book_author = :book_author, book_description = :book_description, book_price = :book_price, where book_id = :book_id"; 
      Query query = session.createQuery(hql); 
      query.setInteger("book_id", book_id); 
      query.setString("book_title",bo.getBook_title()); 
      query.setString("book_author",bo.getBook_author()); 
      query.setString("book_description",bo.getBook_description()); 
      query.setInteger("book_price",bo.getBook_price()); 

      int rowCount = query.executeUpdate(); 
      System.out.println("Rows affected: " + rowCount); 
      tx.commit(); 
      session.close(); 
      return rowCount; 
    } 

} 

BookResource.java

package com.bookstrore; 

    import java.util.List; 



    import javax.ws.rs.Consumes; 
    import javax.ws.rs.DELETE; 
    import javax.ws.rs.GET; 
    import javax.ws.rs.POST; 
    import javax.ws.rs.PUT; 
    import javax.ws.rs.Path; 
    import javax.ws.rs.PathParam; 
    import javax.ws.rs.Produces; 
    import javax.ws.rs.core.MediaType; 
    import javax.ws.rs.core.MultivaluedMap; 
    import javax.ws.rs.core.Response; 
    import javax.ws.rs.core.Response.Status; 

    import com.bookstrore.model.Book; 
    //import com.ebook.model.User; 
    //import com.ebook.repository.BookRepository; 
    import com.bookstrore.repository.BookRepositoryStub; 


    @Path("books") 
    public class BookResource { 
     //private BookRepository bookRepository=new BookRepositoryStub(); 

     @GET 
     @Produces("application/json") 

     public List<Book> getBook() { 
      BookRepositoryStub book = new BookRepositoryStub(); 
      List books = book.getBooks(); 
      return books; 
     } 

     @DELETE 
     @Path("{bookId}") 
     @Consumes("application/json") 
     public Response delete(@PathParam("bookId") int book_id){ 
      BookRepositoryStub book = new BookRepositoryStub(); 
       int count = book.delete(book_id); 
       if(count==0){ 
        return Response.status(Response.Status.BAD_REQUEST).build(); 
       } 


      return Response.ok().build(); 
     } 

     @PUT 
     @Path("{bookId}") 
     //@Consumes(MediaType.APPLICATION_JSON) 
     @Consumes("application/json") 
     public Response update(@PathParam("bookId") int book_id, Book bo){ 
      BookRepositoryStub book = new BookRepositoryStub(); 
      int count = book.update(book_id, bo); 
      if(count==0){ 
       return Response.status(Response.Status.BAD_REQUEST).build(); 

     } 
      return Response.ok().build(); 
     } 

     @POST 
     @Path("book") 
     @Consumes("application/json") 
     //@Produces({MediaType.APPLICATION_JSON, MediaType.APPLICATION_XML}) 
     public Response createBook(Book bo){ 
      bo.setBook_title(bo.getBook_title()); 
      bo.setBook_author(bo.getBook_author()); 
      bo.setBook_description(bo.getBook_description()); 
      bo.setBook_price(bo.getBook_price()); 

      BookRepositoryStub book = new BookRepositoryStub(); 
      book.createBook(bo); 

      return Response.ok().build(); 
     } 

    } 

Book.java 

package com.bookstrore.model; 

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="book") 
public class Book { 

    @Id 
    @GeneratedValue(strategy=GenerationType.IDENTITY) 

    private int book_id; 
    @Column 
    private String book_title; 
    @Column 
    private String book_author; 
    @Column 
    private String book_description; 
    @Column 
    private int book_price; 
    public int getBook_id() { 
     return book_id; 
    } 
    public void setBook_id(int book_id) { 
     this.book_id = book_id; 
    } 
    public String getBook_title() { 
     return book_title; 
    } 
    public void setBook_title(String book_title) { 
     this.book_title = book_title; 
    } 
    public String getBook_author() { 
     return book_author; 
    } 
    public void setBook_author(String book_author) { 
     this.book_author = book_author; 
    } 
    public String getBook_description() { 
     return book_description; 
    } 
    public void setBook_description(String book_description) { 
     this.book_description = book_description; 
    } 
    public int getBook_price() { 
     return book_price; 
    } 
    public void setBook_price(int book_price) { 
     this.book_price = book_price; 
    } 


} 

のpom.xml

<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/maven-v4_0_0.xsd"> 

    <modelVersion>4.0.0</modelVersion> 

    <groupId>com.bookstore</groupId> 
    <artifactId>BookStore</artifactId> 
    <packaging>war</packaging> 
    <version>1.0-SNAPSHOT</version> 
    <name>BookStore</name> 

    <build> 
     <finalName>BookStore</finalName> 
     <plugins> 
      <plugin> 
       <groupId>org.apache.maven.plugins</groupId> 
       <artifactId>maven-compiler-plugin</artifactId> 
       <version>2.5.1</version> 
       <inherited>true</inherited> 
       <configuration> 
        <source>1.7</source> 
        <target>1.7</target> 
       </configuration> 
      </plugin> 
     </plugins> 
    </build> 

    <dependencyManagement> 
     <dependencies> 

     <dependency> 
     <groupId>com.fasterxml.jackson.core</groupId> 
     <artifactId>jackson-databind</artifactId> 
     <version>2.2.3</version> 
      </dependency> 
      <dependency> 
       <groupId>org.glassfish.jersey</groupId> 
       <artifactId>jersey-bom</artifactId> 
       <version>${jersey.version}</version> 
       <type>pom</type> 
       <scope>import</scope> 
      </dependency> 
     </dependencies> 
    </dependencyManagement> 

    <dependencies> 
     <dependency> 
      <groupId>org.glassfish.jersey.containers</groupId> 
      <artifactId>jersey-container-servlet-core</artifactId> 
      <!-- use the following artifactId if you don't need servlet 2.x compatibility --> 
      <!-- artifactId>jersey-container-servlet</artifactId --> 
      <version>2.22.1</version> 
     </dependency> 
     <dependency> 
      <groupId>org.hibernate</groupId> 
      <artifactId>hibernate-core</artifactId> 
      <version>4.3.10.Final</version> 
     </dependency> 

     <dependency> 
      <groupId>mysql</groupId> 
      <artifactId>mysql-connector-java</artifactId> 
      <version>5.1.34</version> 
     </dependency> 

     <dependency> 
      <groupId>org.glassfish.jersey.media</groupId> 
      <artifactId>jersey-media-moxy</artifactId> 
     </dependency> 


</dependencies> 
<properties> 
    <jersey.version>2.22.1</jersey.version> 
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> 
</properties> 

web.xmlの

<?xml version="1.0" encoding="UTF-8"?> 
<!-- This web.xml file is not required when using Servlet 3.0 container, 
    see implementation details http://jersey.java.net/nonav/documentation/latest/jax-rs.html --> 
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> 
    <servlet> 
     <servlet-name>Jersey Web Application</servlet-name> 
     <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class> 
     <init-param> 
      <param-name>jersey.config.server.provider.packages</param-name> 
      <param-value>com.bookstrore</param-value> 
     </init-param> 
     <load-on-startup>1</load-on-startup> 
    </servlet> 
    <servlet-mapping> 
     <servlet-name>Jersey Web Application</servlet-name> 
     <url-pattern>/webapi/*</url-pattern> 
    </servlet-mapping> 
</web-app> 

スタックトレース：

<pre>java.lang.NullPointerException 
    com.bookstrore.BookResource.createBook(BookResource.java:72) 
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) 
    sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) 
    java.lang.reflect.Method.invoke(Unknown Source) 
    org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory$1.invoke(ResourceMethodInvocationHandlerFactory.java:81) 
    org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:144) 
    org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:161) 
    org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$ResponseOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:160) 
    org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:99) 
    org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:389) 
    org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:347) 
    org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:102) 
    org.glassfish.jersey.server.ServerRuntime$2.run(ServerRuntime.java:326) 
    org.glassfish.jersey.internal.Errors$1.call(Errors.java:271) 
    org.glassfish.jersey.internal.Errors$1.call(Errors.java:267) 
    org.glassfish.jersey.internal.Errors.process(Errors.java:315) 
    org.glassfish.jersey.internal.Errors.process(Errors.java:297) 
    org.glassfish.jersey.internal.Errors.process(Errors.java:267) 
    org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317) 
    org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:305) 
    org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1154) 
    org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:471) 
    org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:425) 
    org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:383) 
    org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:336) 
    org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:223) 
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) 
</pre> 

私はあなたの助けのために楽しみにしています！お願いします！ありがとうございました！

Answer 1

あなたのコードには2つの問題があると思いますが、それらを変更することで問題は解決します。

まず、クラス "Book"では、id（hibernateによって自動生成される）以外のすべてのパラメータとともにコンストラクタを記述し、引数のないコンストラクタも必要とします。したがって、これを追加してください：

そして、あなたは@Entityと@Tableで行ったように、クラス "Book"を@XmlRootElementとして宣言しなければなりません。

このビデオは、なぜこのすべてのを説明し、それはまた、Webサービスとジャージーと初心者のための素晴らしいチュートリアルです：

https://www.youtube.com/watch?v=BaZdlJSts5A&list=PLqq-6Pq4lTTZh5U8RbdXq0WaYvZBz2rbn&index=14

は、この情報がお役に立てば幸い！あなたのブッククラスは次のようになります：

@Entity 
@Table(name="book") 
@XmlRootElement 
public class Book { 

@Id 
@GeneratedValue(strategy=GenerationType.IDENTITY) 
private int book_id; 
@Column 
private String book_title; 
@Column 
private String book_author; 
@Column 
private String book_description; 
@Column 
private int book_price; 

public Book(){ } 

public Book(String title, String author, String description, int price){ 
    book_title = title; 
    book_author = author; 
    book_description = description; 
    book_price = price; 
} 
public int getBook_id() { 
    return book_id; 
} 
public void setBook_id(int book_id) { 
    this.book_id = book_id; 
} 
public String getBook_title() { 
    return book_title; 
} 
public void setBook_title(String book_title) { 
    this.book_title = book_title; 
} 
public String getBook_author() { 
    return book_author; 
} 
public void setBook_author(String book_author) { 
    this.book_author = book_author; 
} 
public String getBook_description() { 
    return book_description; 
} 
public void setBook_description(String book_description) { 
    this.book_description = book_description; 
} 
public int getBook_price() { 
    return book_price; 
} 
public void setBook_price(int book_price) { 
    this.book_price = book_price; 
} 


}