RESTEasy實例

RESTEasy是JBoss的開源項目之一，是一個RESTful Web Services框架。

趁今天有空，學習一下RESTEasy。看了兩篇博客後，本身寫了一個demo。

1. 新建一個maven的web項目。

• 依賴以下：

  <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.fengyuan</groupId>
  <artifactId>RESTEasyDemo</artifactId>
  <packaging>war</packaging>
  <version>0.0.1-SNAPSHOT</version>
  <name>RESTEasyDemo Maven Webapp</name>
  <url>http://maven.apache.org</url>
  
  <dependencies>
      <dependency>
          <groupId>junit</groupId>
          <artifactId>junit</artifactId>
          <version>4.4</version>
          <scope>test</scope>
      </dependency>
      <dependency>
          <groupId>org.projectlombok</groupId>
          <artifactId>lombok</artifactId>
          <version>1.14.4</version>
      </dependency>
      <dependency>
          <groupId>org.jboss.resteasy</groupId>
          <artifactId>resteasy-jaxrs</artifactId>
          <version>2.2.3.GA</version>
      </dependency>
      <dependency>
          <groupId>org.jboss.resteasy</groupId>
          <artifactId>resteasy-jackson-provider</artifactId>
          <version>2.2.3.GA</version>
      </dependency>
  </dependencies>
  
  <build>
      <plugins>
          <plugin>
              <groupId>org.apache.maven.plugins</groupId>
              <artifactId>maven-compiler-plugin</artifactId>
              <configuration>
                  <source>1.7</source>
                  <target>1.7</target>
                  <encoding>UTF-8</encoding>
              </configuration>
          </plugin>
      </plugins>
  </build>
  </project>

2. 接着建立兩個服務，messageservice和userservice：

• UserService.java:

  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") // 服務路徑
  public class UserService {
      /**
       * 初始化三個用戶數據，存入map中，key爲用戶id，value爲用戶對象
       */
      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);
      }
  
      /**
       * 獲取指定id的用戶
       * 
       * @param id
       * @return
       */
      @GET
      @Path("user/{id}") // 具體服務的路徑, id是入參
      @Produces("application/json") // 返回的格式
      public User getById(@PathParam("id") Integer id) {
          return (User) userMap.get(id);
      }
  
      /**
       * 以json格式返回全部用戶
       * 
       * @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;
      }
  }

• MessageService.java:

  package com.fengyuan.restapi;
  import javax.ws.rs.GET;
  import javax.ws.rs.Path;  
  import javax.ws.rs.PathParam;  
  import javax.ws.rs.core.Response;  
     
  @Path("/messageservice")  
  public class MessageService {  
     public MessageService(){} 
      @GET 
      @Path("/{param}")  
      public Response printMessage(@PathParam("param") String msg) {  
          String result = "Hello : " + msg;  
     
          return Response.status(200).entity(result).build();  
      }  
  }

  User.java:

  package com.fengyuan.domain;
  
  import lombok.AllArgsConstructor;
  import lombok.Data;
  
  public @Data @AllArgsConstructor class User {
      private String name;
      private int age;
      private String tel;
  }

3. 配置web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0">
  <display-name>Restful Web Application</display-name>
  <context-param>
    <param-name>resteasy.scan</param-name>
    <param-value>true</param-value>
  </context-param>
  <!-- <context-param>
    <param-name>resteasy.resources</param-name>
    <param-value>com.fengyuan.restapi.MessageService, com.fengyuan.restapi.UserService</param-value>
  </context-param> -->
  <context-param>
    <param-name>resteasy.servlet.mapping.prefix</param-name>
    <param-value>/rest</param-value>
  </context-param>
  <listener>
    <listener-class>org.jboss.resteasy.plugins.server.servlet.ResteasyBootstrap</listener-class>
  </listener>
  <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>/rest/*</url-pattern>
  </servlet-mapping>
</web-app>

配置resteasy.scan爲true表示自動掃描服務。若是不配置，也能夠手動指定resteasy.resources，見註釋掉的部分。

4. 啓動tomcat，在瀏覽器輸入服務的url：

5. 除了能夠在瀏覽器直接訪問以外，也能夠用代碼調用：

package com.fengyuan.test;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

import junit.framework.TestCase;  
  
public class TestUserAPI extends TestCase {  
    public static final String USER_API =   
        "http://127.0.0.1:8080/resteasy-demo/rest/userservice/users";  
  
    public void testCreateUserAndGetUser() throws IOException {  
        URL url =   
            new URL(USER_API);  
        HttpURLConnection connection =   
            (HttpURLConnection) url.openConnection();  
        connection.setRequestMethod("GET");  
        connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");  
        connection.setConnectTimeout(1000);  
  
        byte[] bytes = new byte[1024];
        //讀取請求返回值
        InputStream inStream=connection.getInputStream();
        inStream.read(bytes, 0, inStream.available());
        System.out.println(new String(bytes, "utf-8"));
        
        connection.disconnect();  
    }  
}

• 控制檯輸出：

  [{"name":"Lee","tel":"138***","age":24},{"name":"Cathy","tel":"188***","age":25},{"name":"Aaron","tel":"186***","age":26}]

固然，這裏只是簡單了測試了GET類型的服務，還有POST等類型的服務等有空了再補充。

另外，我在寫這個demo項目的時候，發現若是使用了2.1.多版本的resteasy-jackson-provider和resteasy-jaxrs包，而且在web.xml中配置了resteasy.scan爲true的話，會出一些問題，這邊提醒一下，讓看這篇博文的同窗不用再踩進這個坑~。