resteasy简单实例

1.建一个maven web项目

新建一个maven项目，next，第一个框不要勾选

选择maven-archetype-webapp，建一个web项目

键入项目组织id与项目id

一般此时搭建的只是最基本的骨架，还缺了很多东西，我们可以自己按需求去增加。

右键项目，build path，编辑jre，选择默认

web项目的基本构造就出来了

再新建目录，在main和test下面新建resources，然后再build path里的source添加关联

最后再增加服务器jboss的包，整个web项目框架就基本没有报错的搭建起来了

2.最基本的讲完了，现在开始做一个resteasy的简单实例。

2.1首先，配置pom.xml，为项目添加下载resteasy的jar，下面给出jar的配置版本（可去网上查看最新版本）

  <dependencies>
    <dependency>
        <groupId>org.jboss.resteasy</groupId>
        <artifactId>resteasy-jaxrs</artifactId>
        <version>2.2.1.GA</version>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.16.10</version>
    </dependency>
  </dependencies>

lombok是一个用来简化代码的工具，后面给出的代码有用到，也可以不用，但要自己写set，get及类的初始化

ps1：此时可能出现的错误，提示缺少依赖包，如下图，解决办法：右键maven---update project 一下，使新的包在本地生效，一般就能解决问题。

ps2：如果update项目后报JavaServer Faces 2.0 requires Dynamic Web Module 2.5 or newer之类的错误，就是你的web版本太旧，此时项目右键properties—project facets—Dynamic Web Module，修改为3.0的版本，一般就能解决。

ps3：如果在面版不能修改，此时，你就需要去底层修改web的版本了，首先更改maven生成的web.xml的web-app标签内容，再去项目底层demo\.settings路径下，修改org.eclipse.wst.common.project.facet.core.xml文件的配置，将其都改为3.0的版本。下面分别为旧的web.xml，新的web.xml，以及.core.xml的配置

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Archetype Created Web Application</display-name>
</web-app>

<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">

</web-app>

2.2配置web.xml，注册resources的模式有三种：

2.2.1手动注册resources的模式

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
    <display-name>Archetype Created Web Application</display-name>
    <!-- 1. 使用手动注册resources的模式，必须启动ResteasyBootstrap监听 -->
    <!-- 要发布成resteasy服务的资源类 -->
    <context-param>
             <param-name>resteasy.resources</param-name>
             <param-value>com.fengyuan.restapi.UserService</param-value>
    </context-param>

    <!-- 对应<servlet-mapping>的url，必须设置prefix做初始过滤，访问例子：http://localhost:8080/demo/service/userservice/users -->
    <context-param>
             <param-name>resteasy.servlet.mapping.prefix</param-name>
             <param-value>/service</param-value>
    </context-param>

    <!-- 启动服务监听器，初始化resteasy核心组件 -->
    <listener>
        <listener-class>
                 org.jboss.resteasy.plugins.server.servlet.ResteasyBootstrap
        </listener-class>
    </listener>

    <!-- url服务请求的分发控制器 -->
    <servlet>
             <servlet-name>resteasy-servlet</servlet-name>
             <servlet-class>org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher</servlet-class>
    </servlet>
    <servlet-mapping>
             <servlet-name>resteasy-servlet</servlet-name>
             <url-pattern>/service/*</url-pattern>
    </servlet-mapping>

</web-app>

2.2.2手动指定Application的模式

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
    <display-name>Archetype Created Web Application</display-name>
    <!-- 方法2：不启用手动注册resources的模式和ResteasyBootstrap监听，创建一个类并且继承javax.ws.rs.core.Application，并且手动增加REST服务 -->

    <!-- 对应<servlet-mapping>的url，必须设置prefix做初始过滤，访问例子：http://localhost:8080/demo/service/userservice/users -->
    <context-param>
             <param-name>resteasy.servlet.mapping.prefix</param-name>
             <param-value>/service</param-value>
    </context-param>
    <!-- url服务请求的分发控制器 -->
    <servlet>
             <servlet-name>resteasy-servlet</servlet-name>
             <servlet-class>org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher</servlet-class>
             <init-param>
                 <param-name>javax.ws.rs.Application</param-name>
                 <param-value>com.mk.rest.RestApplication</param-value>
             </init-param>
    </servlet>
    <servlet-mapping>
             <servlet-name>resteasy-servlet</servlet-name>
             <url-pattern>/service/*</url-pattern>
    </servlet-mapping>

</web-app>

2.2.3自动Scan的模式，我使用这种模式，启动项目时，会报类似下面的错误

::, ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[default-host].[/demo]] (MSC service thread -) Exception sending context initialized event to listener instance of class org.jboss.resteasy.plugins.server.servlet.ResteasyBootstrap: java.lang.RuntimeException: Unable to find a public constructor for class org.jboss.resteasy.core.AsynchronousDispatcher
    at org.jboss.resteasy.plugins.server.resourcefactory.POJOResourceFactory.registered(POJOResourceFactory.java:) [resteasy-jaxrs-2.3..Final.jar:]
    at org.jboss.resteasy.core.ResourceMethodRegistry.addResourceFactory(ResourceMethodRegistry.java:) [resteasy-jaxrs-2.3..Final.jar:]
    at org.jboss.resteasy.core.ResourceMethodRegistry.addResourceFactory(ResourceMethodRegistry.java:) [resteasy-jaxrs-2.3..Final.jar:]
    at org.jboss.resteasy.core.ResourceMethodRegistry.addResourceFactory(ResourceMethodRegistry.java:) [resteasy-jaxrs-2.3..Final.jar:]
    at org.jboss.resteasy.core.ResourceMethodRegistry.addPerRequestResource(ResourceMethodRegistry.java:) [resteasy-jaxrs-2.3..Final.jar:]
    at org.jboss.resteasy.spi.ResteasyDeployment.registration(ResteasyDeployment.java:) [resteasy-jaxrs-2.3..Final.jar:]
    at org.jboss.resteasy.spi.ResteasyDeployment.start(ResteasyDeployment.java:) [resteasy-jaxrs-2.3..Final.jar:]
    at org.jboss.resteasy.plugins.server.servlet.ResteasyBootstrap.contextInitialized(ResteasyBootstrap.java:) [resteasy-jaxrs-2.3..Final.jar:]
    at org.apache.catalina.core.StandardContext.contextListenerStart(StandardContext.java:) [jbossweb-7.0..Final.jar:]
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:) [jbossweb-7.0..Final.jar:]
    at org.jboss.as.web.deployment.WebDeploymentService.start(WebDeploymentService.java:) [jboss-as-web-7.1..Final.jar:7.1..Final]
    at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:)
    at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:) [rt.jar:1.7.0_80]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:) [rt.jar:1.7.0_80]
    at java.lang.Thread.run(Thread.java:) [rt.jar:1.7.0_80]

::, ERROR [org.apache.catalina.core.StandardContext] (MSC service thread -) Error listenerStart
::, ERROR [org.apache.catalina.core.StandardContext] (MSC service thread -) Context [/demo] startup failed due to previous errors
::, ERROR [org.jboss.msc.service.fail] (MSC service thread -) MSC00001: Failed to start service jboss.web.deployment.default-host./demo: org.jboss.msc.service.StartException in service jboss.web.deployment.default-host./demo: JBAS018040: Failed to start context
    at org.jboss.as.web.deployment.WebDeploymentService.start(WebDeploymentService.java:)
    at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:) [jboss-msc-1.0..GA.jar:1.0..GA]
    at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:) [jboss-msc-1.0..GA.jar:1.0..GA]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:) [rt.jar:1.7.0_80]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:) [rt.jar:1.7.0_80]
    at java.lang.Thread.run(Thread.java:) [rt.jar:1.7.0_80]

::, INFO  [org.jboss.as.server] (DeploymentScanner-threads - ) JBAS015870: Deploy of deployment "demo.war" was rolled back with failure message {"JBAS014671: Failed services" => {"jboss.web.deployment.default-host./demo" => "org.jboss.msc.service.StartException in service jboss.web.deployment.default-host./demo: JBAS018040: Failed to start context"}}
::, INFO  [org.jboss.as.server.deployment] (MSC service thread -) JBAS015877: Stopped deployment demo.war in 59ms
::, INFO  [org.jboss.as.controller] (DeploymentScanner-threads - ) JBAS014774: Service status report
JBAS014777:   Services which failed to start:      service jboss.web.deployment.default-host./demo: org.jboss.msc.service.StartException in service jboss.web.deployment.default-host./demo: JBAS018040: Failed to start context

::, ERROR [org.jboss.as.server.deployment.scanner] (DeploymentScanner-threads - ) {"JBAS014653: Composite operation failed and was rolled back. Steps that failed:" => {"Operation step-2" => {"JBAS014671: Failed services" => {"jboss.web.deployment.default-host./demo" => "org.jboss.msc.service.StartException in service jboss.web.deployment.default-host./demo: JBAS018040: Failed to start context"}}}}

原因不明，下面我的自动扫描配置，希望有大神能指点下

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
    <display-name>Archetype Created Web Application</display-name>
    <!-- 方法3： 使用自动Scan的模式，必须启动ResteasyBootstrap监听，报错，原因不明 -->
    <context-param>
        <param-name>resteasy.scan</param-name>
        <param-value>true</param-value>
    </context-param>

    <!-- 对应<servlet-mapping>的url，必须设置prefix做初始过滤，访问例子：http://localhost:8080/wang/service/userservice/users -->
    <context-param>
             <param-name>resteasy.servlet.mapping.prefix</param-name>
             <param-value>/service</param-value>
    </context-param>

    <!-- 启动服务监听器，初始化resteasy核心组件 -->
    <listener>
        <listener-class>
                 org.jboss.resteasy.plugins.server.servlet.ResteasyBootstrap
        </listener-class>
    </listener>

    <!-- url服务请求的分发控制器 -->
    <servlet>
             <servlet-name>resteasy-servlet</servlet-name>
             <servlet-class>org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher</servlet-class>
    </servlet>
    <servlet-mapping>
             <servlet-name>resteasy-servlet</servlet-name>
             <url-pattern>/service/*</url-pattern>
    </servlet-mapping>

</web-app>

2.3下面给出简单的java类

新建一个简单的User类，使用了lombok插件注解（可以简化代码，自动生成set，get等方法），lombok的安装方法自行百度，安装后还要在pxm.xml里配置，见上文

package com.fengyuan.domain;

import lombok.AllArgsConstructor;
import lombok.Data;

@Data
@AllArgsConstructor
public class User {
    private String name;
    private int age;
    private String tel;
}

要发布的资源类UserService

package com.fengyuan.restapi;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import com.fengyuan.domain.User;

@Path("userservice") // 服务路径
public class UserService {
    /**
     * 初始化三个用户数据，存入map中，key为用户id，value为用户对象
     */
    static Map<Integer, User> userMap = new HashMap<>();

    static {
        User user1 = new User("Lee", 24, "138***");
        userMap.put(1, user1);
        User user2 = new User("Cathy", 25, "188***");
        userMap.put(2, user2);
        User user3 = new User("Aaron", 26, "186***");
        userMap.put(3, user3);
    }

    /**
     * 获取指定id的用户
     *
     * @param id
     * @return
     */
    @GET
    @Path("user/{id}") // 具体服务的路径, id是入参
    @Produces("application/json") // 返回的格式
    public User getById(@PathParam("id") Integer id) {
        return (User) userMap.get(id);
    }

    /**
     * 以json格式返回所有用户
     *
     * @return
     */
    @GET
    @Path("users")
    @Produces("application/json")
    public List<User> getUsers() {
        List<User> userList = new ArrayList<User>();
        for (Entry<Integer, User> user : userMap.entrySet()) {
            userList.add(user.getValue());
        }
        return userList;
    }
}

测试结果

下面给出Application的模式的代码

package com.mk.rest;

import java.util.HashSet;
import java.util.Set;
import com.fengyuan.restapi.UserService;

public class RestApplication extends javax.ws.rs.core.Application{

    private Set<Object> singletons = new HashSet<Object>();
    /*在这里增加资源类*/
    public RestApplication () {
        singletons.add(new MessageRestService());
        singletons.add(new UserService());
    }
    @Override
    public Set<Object> getSingletons() {
        return singletons;
    }
}

后续会边学习边给出resteasy的其他复杂实例，欢迎随时指正～～～～