Restful-methods

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RESTful Webサービス-メソッド

これまでに説明したように、RESTful WebサービスはHTTP動詞を頻繁に使用して、指定されたリソースで実行される操作を決定します。 次の表に、HTTP動詞の一般的な使用例を示します。

HTTP Method GET
URI http://localhost:8080/UserManagement/rest/UserService/users
Operation Get list of users
Operation Type Read Only
HTTP Method GET
URI http://localhost:8080/UserManagement/rest/UserService/users/1
Operation Get user of Id 1
Operation Type Read Only
HTTP Method POST
URI http://localhost:8080/UserManagement/rest/UserService/users/2
Operation Insert user with Id 2
Operation Type Non-Idempotent
HTTP Method PUT
URI http://localhost:8080/UserManagement/rest/UserService/users/2
Operation Update User with Id 2
Operation Type N/A
HTTP Method DELETE
URI http://localhost:8080/UserManagement/rest/UserService/users/1
Operation Delete User with Id 1
Operation Type Idempotent
HTTP Method OPTIONS
URI http://localhost:8080/UserManagement/rest/UserService/users
Operation List the supported operations in web service
Operation Type Read Only
HTTP Method HEAD
URI http://localhost:8080/UserManagement/rest/UserService/users
Operation Returns only HTTP Header, no Body
Operation Type Read Only

考慮すべき重要な点は次のとおりです。

  • GET操作は読み取り専用で安全です。
  • PUTおよびDELETE操作はi等です。これらの操作が何度呼び出されても、結果は常に同じです。
  • PUT操作とPOST操作はほぼ同じですが、PUT操作がi等で、POST操作が異なる結果を引き起こす可能性のある結果にのみ違いがあります。

例

link：/restful/restful_first_application [RESTful Web Services-First Application]チュートリアルで作成したサンプルを更新して、CRUD（作成、読み取り、更新、削除）操作を実行できるWebサービスを作成してみましょう。 簡単にするために、ファイル操作を使用してデータベース操作を置き換えました。

com.finddevguidesパッケージの下にある UserService.java 、 User.java 、 UserDao.java ファイルを更新します。

User.java 

package com.finddevguides;

import java.io.Serializable;

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
@XmlRootElement(name = "user")
public class User implements Serializable {

   private static final long serialVersionUID = 1L;
   private int id;
   private String name;
   private String profession;

   public User(){}

   public User(int id, String name, String profession){
      this.id = id;
      this.name = name;
      this.profession = profession;
   }

   public int getId() {
      return id;
   }
   @XmlElement
   public void setId(int id) {
      this.id = id;
   }
   public String getName() {
      return name;
   }
   @XmlElement
      public void setName(String name) {
      this.name = name;
   }
   public String getProfession() {
      return profession;
   }
   @XmlElement
   public void setProfession(String profession) {
      this.profession = profession;
   }

   @Override
   public boolean equals(Object object){
      if(object == null){
         return false;
      }else if(!(object instanceof User)){
         return false;
      }else {
         User user = (User)object;
         if(id == user.getId()
            && name.equals(user.getName())
            && profession.equals(user.getProfession())
         ){
            return true;
         }
      }
      return false;
   }
}

UserDao.java 

package com.finddevguides;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.List;

public class UserDao {
   public List<User> getAllUsers(){
      List<User> userList = null;
      try {
         File file = new File("Users.dat");
         if (!file.exists()) {
            User user = new User(1, "Mahesh", "Teacher");
            userList = new ArrayList<User>();
            userList.add(user);
            saveUserList(userList);
         }
         else{
            FileInputStream fis = new FileInputStream(file);
            ObjectInputStream ois = new ObjectInputStream(fis);
            userList = (List<User>) ois.readObject();
            ois.close();
         }
      } catch (IOException e) {
         e.printStackTrace();
      } catch (ClassNotFoundException e) {
         e.printStackTrace();
      }
      return userList;
   }

   public User getUser(int id){
      List<User> users = getAllUsers();

      for(User user: users){
         if(user.getId() == id){
            return user;
         }
      }
      return null;
   }

   public int addUser(User pUser){
      List<User> userList = getAllUsers();
      boolean userExists = false;
      for(User user: userList){
         if(user.getId() == pUser.getId()){
            userExists = true;
            break;
         }
      }
      if(!userExists){
         userList.add(pUser);
         saveUserList(userList);
         return 1;
      }
      return 0;
   }

   public int updateUser(User pUser){
      List<User> userList = getAllUsers();

      for(User user: userList){
         if(user.getId() == pUser.getId()){
            int index = userList.indexOf(user);
            userList.set(index, pUser);
            saveUserList(userList);
            return 1;
         }
      }
      return 0;
   }

   public int deleteUser(int id){
      List<User> userList = getAllUsers();

      for(User user: userList){
         if(user.getId() == id){
            int index = userList.indexOf(user);
            userList.remove(index);
            saveUserList(userList);
            return 1;
         }
      }
      return 0;
   }

   private void saveUserList(List<User> userList){
      try {
         File file = new File("Users.dat");
         FileOutputStream fos;

         fos = new FileOutputStream(file);

         ObjectOutputStream oos = new ObjectOutputStream(fos);
         oos.writeObject(userList);
         oos.close();
      } catch (FileNotFoundException e) {
         e.printStackTrace();
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}

UserService.java 

package com.finddevguides;

import java.io.IOException;
import java.util.List;

import javax.servlet.http.HttpServletResponse;
import javax.ws.rs.Consumes;
import javax.ws.rs.DELETE;
import javax.ws.rs.FormParam;
import javax.ws.rs.GET;
import javax.ws.rs.OPTIONS;
import javax.ws.rs.POST;
import javax.ws.rs.PUT;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;

@Path("/UserService")
public class UserService {

   UserDao userDao = new UserDao();
   private static final String SUCCESS_RESULT="<result>success</result>";
   private static final String FAILURE_RESULT="<result>failure</result>";


   @GET
   @Path("/users")
   @Produces(MediaType.APPLICATION_XML)
   public List<User> getUsers(){
      return userDao.getAllUsers();
   }

   @GET
   @Path("/users/{userid}")
   @Produces(MediaType.APPLICATION_XML)
   public User getUser(@PathParam("userid") int userid){
      return userDao.getUser(userid);
   }

   @POST
   @Path("/users")
   @Produces(MediaType.APPLICATION_XML)
   @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
   public String createUser(@FormParam("id") int id,
      @FormParam("name") String name,
      @FormParam("profession") String profession,
      @Context HttpServletResponse servletResponse) throws IOException{
      User user = new User(id, name, profession);
      int result = userDao.addUser(user);
      if(result == 1){
         return SUCCESS_RESULT;
      }
      return FAILURE_RESULT;
   }

   @PUT
   @Path("/users")
   @Produces(MediaType.APPLICATION_XML)
   @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
   public String updateUser(@FormParam("id") int id,
      @FormParam("name") String name,
      @FormParam("profession") String profession,
      @Context HttpServletResponse servletResponse) throws IOException{
      User user = new User(id, name, profession);
      int result = userDao.updateUser(user);
      if(result == 1){
         return SUCCESS_RESULT;
      }
      return FAILURE_RESULT;
   }

   @DELETE
   @Path("/users/{userid}")
   @Produces(MediaType.APPLICATION_XML)
   public String deleteUser(@PathParam("userid") int userid){
      int result = userDao.deleteUser(userid);
      if(result == 1){
         return SUCCESS_RESULT;
      }
      return FAILURE_RESULT;
   }

   @OPTIONS
   @Path("/users")
   @Produces(MediaType.APPLICATION_XML)
   public String getSupportedOperations(){
      return "<operations>GET, PUT, POST, DELETE</operations>";
   }
}

Eclipseを使用して、アプリケーションをwarファイルとしてエクスポートし、同じものをtomcatにデプロイします。 Eclipseを使用してWARファイルを作成するには、 File→ export→ Web> War File オプションに従って、最後にプロジェクトUserManagementと宛先フォルダーを選択します。 Tomcatにwarファイルをデプロイするには、* Tomcatインストールディレクトリ*> webappsディレクトリにUserManagement.warを配置し、Tomcatを起動します。

Webサービスのテスト

Jerseyは、WebサービスをテストするWebサービスクライアントを作成するAPIを提供します。 同じプロジェクトのcom.finddevguidesパッケージの下にサンプルテストクラス WebServiceTester.java を作成しました。

WebServiceTester.java 

package com.finddevguides;

import java.util.List;

import javax.ws.rs.client.Client;
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.client.Entity;
import javax.ws.rs.core.Form;
import javax.ws.rs.core.GenericType;
import javax.ws.rs.core.MediaType;

public class WebServiceTester  {

   private Client client;
   private String REST_SERVICE_URL = "http://localhost:8080/UserManagement/rest/UserService/users";
   private static final String SUCCESS_RESULT="<result>success</result>";
   private static final String PASS = "pass";
   private static final String FAIL = "fail";

   private void init(){
      this.client = ClientBuilder.newClient();
   }

   public static void main(String[] args){
      WebServiceTester tester = new WebServiceTester();
     //initialize the tester
      tester.init();
     //test get all users Web Service Method
      tester.testGetAllUsers();
     //test get user Web Service Method
      tester.testGetUser();
     //test update user Web Service Method
      tester.testUpdateUser();
     //test add user Web Service Method
      tester.testAddUser();
     //test delete user Web Service Method
      tester.testDeleteUser();
   }
  //Test: Get list of all users
  //Test: Check if list is not empty
   private void testGetAllUsers(){
      GenericType<List<User>> list = new GenericType<List<User>>() {};
      List<User> users = client
         .target(REST_SERVICE_URL)
         .request(MediaType.APPLICATION_XML)
         .get(list);
      String result = PASS;
      if(users.isEmpty()){
         result = FAIL;
      }
      System.out.println("Test case name: testGetAllUsers, Result: " + result );
   }
  //Test: Get User of id 1
  //Test: Check if user is same as sample user
   private void testGetUser(){
      User sampleUser = new User();
      sampleUser.setId(1);

      User user = client
         .target(REST_SERVICE_URL)
         .path("/{userid}")
         .resolveTemplate("userid", 1)
         .request(MediaType.APPLICATION_XML)
         .get(User.class);
      String result = FAIL;
      if(sampleUser != null && sampleUser.getId() == user.getId()){
         result = PASS;
      }
      System.out.println("Test case name: testGetUser, Result: " + result );
   }
  //Test: Update User of id 1
  //Test: Check if result is success XML.
   private void testUpdateUser(){
      Form form = new Form();
      form.param("id", "1");
      form.param("name", "suresh");
      form.param("profession", "clerk");

      String callResult = client
         .target(REST_SERVICE_URL)
         .request(MediaType.APPLICATION_XML)
         .put(Entity.entity(form,
            MediaType.APPLICATION_FORM_URLENCODED_TYPE),
            String.class);
      String result = PASS;
      if(!SUCCESS_RESULT.equals(callResult)){
         result = FAIL;
      }

      System.out.println("Test case name: testUpdateUser, Result: " + result );
   }
  //Test: Add User of id 2
  //Test: Check if result is success XML.
   private void testAddUser(){
      Form form = new Form();
      form.param("id", "2");
      form.param("name", "naresh");
      form.param("profession", "clerk");

      String callResult = client
         .target(REST_SERVICE_URL)
         .request(MediaType.APPLICATION_XML)
         .post(Entity.entity(form,
            MediaType.APPLICATION_FORM_URLENCODED_TYPE),
            String.class);

      String result = PASS;
      if(!SUCCESS_RESULT.equals(callResult)){
         result = FAIL;
      }

      System.out.println("Test case name: testAddUser, Result: " + result );
   }
  //Test: Delete User of id 2
  //Test: Check if result is success XML.
   private void testDeleteUser(){
      String callResult = client
         .target(REST_SERVICE_URL)
         .path("/{userid}")
         .resolveTemplate("userid", 2)
         .request(MediaType.APPLICATION_XML)
         .delete(String.class);

      String result = PASS;
      if(!SUCCESS_RESULT.equals(callResult)){
         result = FAIL;
      }

      System.out.println("Test case name: testDeleteUser, Result: " + result );
   }
}

次に、Eclipseを使用してテスターを実行します。 ファイルを右クリックし、[として実行→ Javaアプリケーション]オプションに従います。 Eclipseコンソールに次の結果が表示されます。 

Test case name: testGetAllUsers, Result: pass
Test case name: testGetUser, Result: pass
Test case name: testUpdateUser, Result: pass
Test case name: testAddUser, Result: pass
Test case name: testDeleteUser, Result: pass

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