java.lang.NullPointerException in My Spring Service with Rest Jax rs 如何解决？答案

【问题标题】：java.lang.NullPointerException in My Spring Service with Rest Jax rs How do fix it?java.lang.NullPointerException in My Spring Service with Rest Jax rs 如何解决？
【发布时间】：2015-05-05 19:03:32
【问题描述】：

我的用户服务为空如何解决？坦克 ;)

 java.lang.NullPointerException
    at com.what.now.rest.RestCreateUser.cretaeAccount(RestCreateUser.java:52)

REST 服务

浏览器服务

package com.what.now.rest;

import javax.ws.rs.Consumes;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

import org.apache.log4j.Logger;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import com.what.now.business.IUserBusiness;
import com.what.now.model.bean.User;
import com.what.now.model.dto.AccountRegisterDTO;
import com.what.now.tools.ConverterUserBeanDTO;
import com.what.now.tools.ValidateRestInput;

/**
 * Rest Service
 *
 */
@Component
@Path("/register")
public class RestCreateUser {
    @Autowired
    private IUserBusiness userService;
    @POST
    @Path("/createAccount")
    @Produces({ MediaType.APPLICATION_JSON, })
    @Consumes({ MediaType.APPLICATION_JSON, MediaType.APPLICATION_XHTML_XML })
    public Boolean cretaeAccount(final AccountRegisterDTO newAccount) {
        Boolean result = false;
            // create user
            User user = ConverterUserBeanDTO.userDtoToBean(newAccount);
            // add dto in bean
            // save user
            userService.create(user);
            // result to save
            if (user.getId() != 0) {
                result = true;
            }
        return result;   
}

服务

添加数据库的服务

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import com.what.now.business.IUserBusiness;
import com.what.now.dao.IUserDAO;
import com.what.now.model.bean.User;

@Service
public class UserBusinessImpl implements IUserBusiness {
    @Autowired
    IUserDAO userDAO;

    public void create(User user) {
         userDAO.create(user);
    }

    public User find(String id) {
        return userDAO.find(id);
    }

    public void update(User user) {
        userDAO.update(user);

    }

    public void delete(User user) {
        userDAO.delete(user);

    }

}

web.xml

用于 web 应用程序的配置 .. 这个配置用于加载 spring 上下文并初始化 Jersey servlet

<web-app 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_3_0.xsd"
            version="3.0">
// context application 
            <context-param>
                <param-name>contextConfigLocation</param-name>
                <param-value>classpath*:*/applicationContext.xml </param-value>
            </context-param>
                        <listener>
                <listener-class>
        org.springframework.web.context.ContextLoaderListener
                </listener-class>
            </listener>
            <servlet>
                <servlet-name>whatNow-rest-serlvet</servlet-name>
                <servlet-class>com.sun.jersey.spi.spring.container.servlet.SpringServlet</servlet-class>
                <init-param>
                    <param-name>com.sun.jersey.config.property.packages</param-name>
                    <param-value>com.what.now.rest</param-value>
                </init-param>
                <init-param>
                    <param-name>com.sun.jersey.api.json.POJOMappingFeature</param-name>
                    <param-value>true</param-value>
                </init-param>
                <load-on-startup>1</load-on-startup>
            </servlet>
            <servlet-mapping>
                <servlet-name>whatNow-rest-serlvet</servlet-name>
                <url-pattern>/rest/*</url-pattern>
            </servlet-mapping>
        </web-app>

applicationContext.xml

这是我的应用程序配置

 <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:aop="http://www.springframework.org/schema/aop" xmlns:context="http://www.springframework.org/schema/context"
    xmlns:jee="http://www.springframework.org/schema/jee" xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:task="http://www.springframework.org/schema/task"
    xsi:schemaLocation="http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.2.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.2.xsd">

  <context:component-scan base-package="com.what.now.*"
    annotation-config="true" />

  <tx:annotation-driven/>

</beans>

pom.xml

   <?xml version="1.0"?>
        <project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">      
          <modelVersion>4.0.0</modelVersion>       
           <groupId>com.what.now.project</groupId>
            <version>0.0.1-SNAPSHOT</version>
           <artifactId>whatNow-packaging</artifactId>
          <packaging>war</packaging>
          <url>http://maven.apache.org</url>
          <properties>
            <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
             <jdk.version>1.8</jdk.version>
              <spring.version>3.2.13.RELEASE</spring.version>
              <jersey.version>1.17.1</jersey.version>
                <jersey.client.version>1.17.1</jersey.client.version>
                <jersey.servlet.version>1.17.1</jersey.servlet.version>
                <jersey.json.version>1.17.1</jersey.json.version>
                <jersey.multipart>1.17.1</jersey.multipart>
                <javax.mail>1.4</javax.mail>
            <maven.compiler.target>1.8</maven.compiler.target>
            <maven.compiler.source>1.8</maven.compiler.source>
          </properties>
           <dependencies>
            <dependency>
              <groupId>junit</groupId>
              <artifactId>junit</artifactId>
              <version>3.8.1</version>
              <scope>test</scope>        
            </dependency>
             <!-- Spring  -->
                <dependency>
                    <groupId>org.springframework</groupId>
                    <artifactId>spring-core</artifactId>
                    <version>${spring.version}</version>
                </dependency>
                <dependency>
                    <groupId>org.springframework</groupId>
                    <artifactId>spring-context</artifactId>
                    <version>${spring.version}</version>
                </dependency>
                <dependency>
                    <groupId>org.springframework</groupId>
                    <artifactId>spring-orm</artifactId>
                    <version>${spring.version}</version>
                </dependency>
                <dependency>
                    <groupId>org.springframework</groupId>
                    <artifactId>spring-web</artifactId>
                    <version>${spring.version}</version>
                </dependency>
             <!-- Jersey   -->
            <dependency>
                    <groupId>com.sun.jersey</groupId>
                    <artifactId>jersey-json</artifactId>
                    <version>${jersey.json.version}</version>
            </dependency>       
            <dependency>
                     <groupId>com.sun.jersey</groupId>
                     <artifactId>jersey-servlet</artifactId>
                     <version>${jersey.servlet.version}</version>
            </dependency>
                 <!-- Spring + Jersey  -->
            <dependency>
                <groupId>com.sun.jersey.contribs</groupId>
                <artifactId>jersey-spring</artifactId>
                <version>${jersey.version}</version>
                <exclusions>
                        <exclusion>
                            <groupId>org.springframework</groupId>
                            <artifactId>spring</artifactId>
                        </exclusion>
                        <exclusion>
                            <groupId>org.springframework</groupId>
                            <artifactId>spring-core</artifactId>
                        </exclusion>
                        <exclusion>
                            <groupId>org.springframework</groupId>
                            <artifactId>spring-web</artifactId>
                        </exclusion>
                        <exclusion>
                            <groupId>org.springframework</groupId>
                            <artifactId>spring-beans</artifactId>
                        </exclusion>
                        <exclusion>
                            <groupId>org.springframework</groupId>
                            <artifactId>spring-context</artifactId>
                        </exclusion>
                    </exclusions>
            </dependency>
             <!-- hibernate  -->
</dependencies>
          </build>
        </project>

【问题讨论】：

您能否向我们展示您迄今为止为解决此问题所做的尝试？
我尝试在 RestCreateUser.java 中添加@Componont 注释。构建了 Spring servlet。但它没有工作
在 UserBusinessImpl 上尝试@Service("userService")？
我尝试@Service("userService") 不起作用:( ...

标签： spring rest maven jakarta-ee jax-rs

【解决方案1】：

这个例子适用于我的

应用程序上下文

 <beans xmlns="http://www.springframework.org/schema/beans"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
        xmlns:context="http://www.springframework.org/schema/context"
        xmlns:tx="http://www.springframework.org/schema/tx" 
        xsi:schemaLocation="
            http://www.springframework.org/schema/beans 
            http://www.springframework.org/schema/beans/spring-beans.xsd

            http://www.springframework.org/schema/tx 
            http://www.springframework.org/schema/tx/spring-tx.xsd

            http://www.springframework.org/schema/context
            http://www.springframework.org/schema/context/spring-context.xsd">

        <context:component-scan base-package="com.wu.wn.*" />
         <bean id="userService" class="com.wu.wn.services.impl.UserServiceImpl" />
         <bean id="noteService" class="com.wu.wn.services.impl.NoteServiceImpl" />
    </beans>

POM

这是我的依赖项

      <spring.version>4.1.4.RELEASE</spring.version>    
<spring.security.version>3.2.5.RELEASE</spring.security.version>
                <jersey.version>2.14</jersey.version>
                <jackson.version>1.9.13</jackson.version>
                <hibernate.version>4.2.7.Final</hibernate.version>
                <junit.version>4.11</junit.version>
                <log4j.version>1.2.17</log4j.version>
<dependencies>

        <!-- Jersey-Spring http://mvnrepository.com/artifact/org.glassfish.jersey.ext/jersey-spring3/2.4.1 -->
        <dependency>
            <groupId>org.glassfish.jersey.ext</groupId>
            <artifactId>jersey-spring3</artifactId>
            <version>${jersey.version}</version>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework</groupId>
                    <artifactId>spring-core</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>org.springframework</groupId>
                    <artifactId>spring-web</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>org.springframework</groupId>
                    <artifactId>spring-beans</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.media</groupId>
            <artifactId>jersey-media-json-jackson</artifactId>
            <version>${jersey.version}</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.media</groupId>
            <artifactId>jersey-media-multipart</artifactId>
            <version>${jersey.version}</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.ext</groupId>
            <artifactId>jersey-entity-filtering</artifactId>
            <version>${jersey.version}</version>
        </dependency>
        <!-- Spring 3 dependencies -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
            <exclusions>
                <exclusion>
                    <groupId>commons-logging</groupId>
                    <artifactId>commons-logging</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

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

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

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!-- JUnit for test -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${junit.version}</version>
            <scope>test</scope>
        </dependency>
            <!-- log  -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>${log4j.version}</version>
        </dependency>   
    </dependencies>

网络

<listener>
    <listener-class>
        org.springframework.web.context.ContextLoaderListener
    </listener-class>
</listener>

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>
        classpath:spring/applicationContext.xml
    </param-value>
</context-param>
<context-param>
    <param-name>logProperties</param-name>
    <param-value>classpath:log/log4j.properties</param-value>
</context-param>
<servlet>
    <servlet-name>jersey-servlet</servlet-name>
    <servlet-class>
        org.glassfish.jersey.servlet.ServletContainer
    </servlet-class>
    <init-param>
        <param-name>javax.ws.rs.Application</param-name>
        <param-value>com.wu.wn.rest.RestJaxRsApplication</param-value>          
    </init-param>       
    <load-on-startup>1</load-on-startup>
</servlet>

<servlet-mapping>
    <servlet-name>jersey-servlet</servlet-name>
    <url-pattern>/rest/*</url-pattern>
</servlet-mapping>

只是 @Autowired 为我的 not null 工作

【讨论】：

【解决方案2】：

你正在做一个包裹扫描

<context:component-scan base-package="com.what.now.*"

但您尚未在 Service 类中指定包名称。将其包更改为可扫描的包。

【讨论】：

那你换包了吗？