java - 使用 Spring 进行 REST

Question

我正在尝试使用 Spring 在 java 中创建一个名为 RESTServ 的 REST 服务项目，但我无法运行它。我正在使用 Wildfly 8.1 、 JDK 1.8 和 Spring - 4.2

这是我的用户 Bean:

package com.rest.service;

public class User {

    private int userid;
    private String firstName;
    private String lastName;
    private String email;

    public int getUserid() {
        return userid;
    }

    public void setUserid(int userid) {
        this.userid = userid;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    @Override
    public String toString() {
        return "User [userid=" + userid + ", firstName=" + firstName
                + ", lastName=" + lastName + ", email=" + email + "]";
    }

}

这是我的服务 Controller :

package com.rest.controller;

import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import com.rest.dao.UserService;
import com.rest.service.User;

@RestController
@RequestMapping("/user/")
public class SpringServiceController {

    UserService userService = new UserService();

    @RequestMapping(value = "/{id}", method = RequestMethod.GET, headers = "Accept=application/json")
    public User getUser(@PathVariable int id) {
        User user = userService.getUserById(id);
        return user;
    }
}

我创建了 DBUtility 和用户服务文件来从数据库获取数据。这是我的 web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>RESTServ</display-name>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <servlet-name>rest</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/rest-servlet.xml</param-value>
        </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>rest</servlet-name>
    <url-pattern>/*</url-pattern>
  </servlet-mapping>
  <listener>
    <listener-class>
        org.springframework.web.context.ContextLoaderListener
    </listener-class>
</listener>
</web-app>

这是我的rest-servlet.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation=" http://www.springframework.org/schema/beans    
        http://www.springframework.org/schema/beans/spring-beans-4.2.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-4.2.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-4.2.xsd">
    <context:component-scan base-package="com.rest.controller" />
    <mvc:annotation-driven />
</beans>

当我尝试通过 WildFly 8.1 上部署的 URL 访问 REST 服务时 - localhost:8080/RESTServ/user 或 localhost:8080/RESTServ/user/1它显示以下错误:

Context Path:/RESTServ
Servlet Path:
Path Info:/user
Query String:null
Stack Trace
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:982)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85)
io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:61)
io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25)
io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:113)
io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:56)
io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25)
io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:45)
io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:61)
io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:58)
io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:70)
io.undertow.security.handlers.SecurityInitialHandler.handleRequest(SecurityInitialHandler.java:76)
io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25)
org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)
io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25)
io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25)
io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:240)
io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:227)
io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:73)
io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:146)
io.undertow.server.Connectors.executeRootHandler(Connectors.java:177)
io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:727)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
java.lang.Thread.run(Thread.java:745)

我不知道我做错了什么...因为我是这个概念的新手，有人可以帮助我吗？

Answer 1

嗯，localhost:8080/RESTServ/user 没有映射到您的 Controller 中，只有 localhost:8080/RESTServ/user/{id} 是。所以你需要添加这个资源:

@RequestMapping(method = RequestMethod.GET)
public Iterable<User> getUsers() {
    return userService.listAll();
}

此外，类上的 @RequestMapping 应该是 @RequestMapping("/user") (末尾不带斜杠)。

<小时/>

顺便说一句，它在这里并不真正相关，但我很确定 UserService 应该是 Autowiring 的。