RESTful Web Services方法

正如我們討論至今認爲RESTful web服務使得重用HTTP動詞，以確定要執行所指定的資源(多個)的操作。下表使用HTTP動詞常用狀態的例子。

S.N.

HTTP方法，URI和操作

GET
http://localhost:8080/UserManagement/rest/UserService/users
獲取用戶列表
(只讀)

GET
http://localhost:8080/UserManagement/rest/UserService/users/1
獲取ID爲1的用戶
(只讀)

PUT
http://localhost:8080/UserManagement/rest/UserService/users/2
使用ID爲2插入用戶
(等冪)

POST
http://localhost:8080/UserManagement/rest/UserService/users/2
更新ID爲2的用戶
(N/A)

DELETE
http://localhost:8080/UserManagement/rest/UserService/users/1
刪除ID爲2用戶
(等冪)

OPTIONS
http://localhost:8080/UserManagement/rest/UserService/users
列出Web服務支持的操作
(只讀)

HEAD
http://localhost:8080/UserManagement/rest/UserService/users
僅返回HTTP頭，沒有主體。
(只讀)

下面是要考慮的重要問題：

GET 僅是讀操作並且是安全的。
PUT 和 DELETE 操作冪等意味着他們的結果總是相同的，無論多少次，這些操作可被調用。
PUT 和 POST 動作幾乎相同，區別僅位於在結果其中PUT操作是等冪，POST操作可能導致不同的結果。

例子

讓我們來更新RESTful Web服務創建示例 - 第一應用教程創建Web服務它可以執行CRUD（創建，讀取，更新，刪除）操作。爲簡單起見，這裏使用了一個文件I/O，以取代數據庫操作。

現在更新User.java，UserDao.java和UserService.java文件在com.yiibai包下。

User.java

package com.yiibai; 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.yiibai; 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.yiibai; 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="success"; private static final String FAILURE_RESULT="failure"; @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); } @PUT @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; } @POST @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 "GET, PUT, POST, DELETE"; } }

現在使用Eclipse，導出應用程序爲war文件，並部署在Tomcat中。要使用eclipse創建WAR文件，按照選項 File -> export -> Web > War File 最後選擇項目UserManagement和目標文件夾。要將WAR文件部署在Tomcat，將UserManagement.war文件放置在Tomcat的安裝目錄下 > webapps 目錄並啓動Tomcat。

測試Web服務

Jersey提供的API來創建Web服務客戶端並測試Web服務。我們已經創建了一個示例測試類 WebServiceTester.java 在com.yiibai下在的同一個項目中。

WebServiceTester.java

package com.yiibai; 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="success"; 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) .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: 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) .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: 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 ); } }

現在運行測試，使用Eclipse。右鍵單擊該文件，並按照選項Run as -> Java Application. 你會看到下面的結果Eclipse控制檯：

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

RESTful教程

RESTful Web Services方法

例子

測試Web服務