jersey中的webservice接口里如何注入spring管理的bean

桃扇骨 2021-09-28 18:42 176阅读 0赞

一、问题说明

jersey版本：1.19

spring版本：3.0.4

我先把配置以及代码相关信息加以说明，然后再对问题进行说明

需要调用的业务service（StudentService）以及实现类（StudentServiceImpl）

package com.kittycoder.studentmgmt.service;
    
    public interface StudentService {
    	void selectAllStudents();
    }

package com.kittycoder.studentmgmt.service.impl;
    
    public interface StudentServiceImpl implements StudentService {
    	public void selectAllStudents() {
    		System.out.println("查询所有学生");
    	}
    }

applicationContext.xml对业务service的配置

web.xml中Jersey的配置

<servlet>
    	<servlet-name>Jersey REST Service</servlet-name>
    	<servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class>
    	<init-param>
    		<param-name>com.sun.jersey.config.property.packages</param-name>
    		<param-value>com.kittycoder.webservice</param-value>
    	</init-param>
    	<load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
    	<servlet-name>Jersey REST Service</servlet-name>
    	<url-pattern>/webservice/*</url-pattern>
    </servlet-mapping>

webservice接口对应的类StudentWebService

package com.kittycoder.webservice.service;
    
    @WebService("studentWebService")
    public class StudentWebService {
    	
    	@Autowired
    	public StudentService studentService;
    	
    	// 调用路径http://localhost:8080/MyJerseyProject/webservice/studentWebService/selectAllStudents
    	@GET
        @Path("/selectAllStudents")
        @Produces("text/plain;charset=UTF-8")
        public String selectAllStudents(@Context HttpHeaders httpHeader) {
            try {
    			System.out.println("进入查询所有学生方法");
    			System.out.println(studentService); // 查看是bean是否注入，结果为null
                studentService.selectAllStudents();
            } catch (Exception e) {
    			e.printStackTrace();
            }
    		return "test";
        }
    }

当我访问[http://localhost:8080/MyJerseyProject/webservice/studentWebService/selectAllStudents][http_localhost_8080_MyJerseyProject_webservice_studentWebService_selectAllStudents]地址时，这个studentService为null，导致后面实际调用业务方法的时候报空指针异常

二、解决过程

首先百度了下，解决方案基本上都是说这个是不支持spring注入的，只能通过从spring容器中获取bean的方式给studentService赋值才行；但是，我还是上google看了下，看看有没有更直接一点的解决方法，经过一番探索，找到了解决方案。这两种解决方法这里都记录下

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTA5OTk4MDk_size_16_color_FFFFFF_t_70][]

方法一（从spring容器中获取service）：

先写个工具类，方便我们从spring容器中获取bean

public class SpringContextUtil {
    
        public static ApplicationContext getContext() {
            return ContextLoader.getCurrentWebApplicationContext();
        }
    
    	/**
         * 根据beanId获取javaBean
         * @param beanName
         * @return
         */
        public static Object getBeanByName(String beanName) {
            return getContext().getBean(beanName);
        }
    }

然后需要更改下webservice接口类StudentWebService，修改后的代码如下：

package com.kittycoder.webservice.service;
    
    @WebService("studentWebService")
    public class StudentWebService {
    	
    	private static StudentService studentService;
    	
    	static{
    		studentService = (StudentService) SpringContextUtil.getBeanByName("studentService");
    	}
    	
    	// 调用路径 http://localhost:8080/MyJerseyProject/webservice/studentWebService/selectAllStudents
    	@GET
        @Path("/selectAllStudents")
        @Produces("text/plain;charset=UTF-8")
        public String listUsers(@Context HttpHeaders httpHeader) {
            try {
    			System.out.println("进入查询所有学生方法");
    			System.out.println(studentService); // 查看是bean是否注入，结果为null
            } catch (Exception e) {
    			e.printStackTrace();
            }
    		return "test";
        }
    }

方法二（通过spring来自动注入）：

首先要引一个jar包（jersey-spring-1.19，版本和你自己jersey的版本对应即可），

然后在web.xml重新写下jersey配置，之前那个可以不用要了。新的jersey配置如下：

<servlet>
    	<servlet-name>jersey-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.kittycoder.webservice.service</param-value>
    	</init-param>
    	<load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
    	<servlet-name>jersey-serlvet</servlet-name>
    	<url-pattern>/webservice/*</url-pattern>
    </servlet-mapping>

然后webservice接口类StudentWebService写成下面的形式即可：

只需在类上添加@Component注解，在需要进行注入的service上添加@Autowired

package com.kittycoder.webservice.service;
    
    @Component
    @WebService("studentWebService")
    public class StudentWebService {
    	
    	@Autowired
    	public StudentService studentService;
    	
    	// 调用路径http://localhost:8080/MyJerseyProject/webservice/studentWebService/selectAllStudents
    	@GET
        @Path("/selectAllStudents")
        @Produces("text/plain;charset=UTF-8")
        public String selectAllStudents(@Context HttpHeaders httpHeader) {
            try {
    			System.out.println("进入查询所有学生方法");
    			System.out.println(studentService); // 查看是bean是否注入，结果为null
                studentService.selectAllStudents();
            } catch (Exception e) {
    			e.printStackTrace();
            }
    		return "test";
        }
    }

参考链接：

[https://www.mkyong.com/webservices/jax-rs/jersey-spring-integration-example/][https_www.mkyong.com_webservices_jax-rs_jersey-spring-integration-example]

[https://stackoverflow.com/questions/33834015/autowired-is-null-and-not-working-with-jersey-spring][https_stackoverflow.com_questions_33834015_autowired-is-null-and-not-working-with-jersey-spring]

[http_localhost_8080_MyJerseyProject_webservice_studentWebService_selectAllStudents]: http://localhost:8080/MyJerseyProject/webservice/studentWebService/selectAllStudents
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTA5OTk4MDk_size_16_color_FFFFFF_t_70]: /images/20210923/4a98f61abed7472eb55ffca9e84ef338.png
[https_www.mkyong.com_webservices_jax-rs_jersey-spring-integration-example]: https://www.mkyong.com/webservices/jax-rs/jersey-spring-integration-example/
[https_stackoverflow.com_questions_33834015_autowired-is-null-and-not-working-with-jersey-spring]: https://stackoverflow.com/questions/33834015/autowired-is-null-and-not-working-with-jersey-spring