REST（Representational State Transfer）,中文翻译叫“表述性状态转移”。是 Roy Thomas Fielding 在他2000年的博士论文中提出的。它与传统的 SOAP Web 服务区别在于，REST关注的是要处理的数据，而 SOAP 主要关注行为和处理。要理解好 REST，根据其首字母拆分出的英文更容易理解。
package com.websystique.springmvc.controller; import java.util.List; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.http.HttpHeaders; import org.springframework.http.HttpStatus; import org.springframework.http.MediaType; import org.springframework.http.ResponseEntity; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestBody; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import org.springframework.web.bind.annotation.RestController; import org.springframework.web.util.UriComponentsBuilder; import com.websystique.springmvc.model.User; import com.websystique.springmvc.service.UserService; @RestController public class HelloWorldRestController { @Autowired UserService userService; //Service which will do all data retrieval/manipulation work //-------------------Retrieve All Users-------------------------------------------------------- @RequestMapping(value = "/user/", method = RequestMethod.GET) public ResponseEntity > listAllUsers() { List users = userService.findAllUsers(); if(users.isEmpty()){ return new ResponseEntity >(HttpStatus.NO_CONTENT);//You many decide to return HttpStatus.NOT_FOUND } return new ResponseEntity >(users, HttpStatus.OK); } //-------------------Retrieve Single User-------------------------------------------------------- @RequestMapping(value = "/user/{id}", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE) public ResponseEntity getUser(@PathVariable("id") long id) { System.out.println("Fetching User with id " + id); User user = userService.findById(id); if (user == null) { System.out.println("User with id " + id + " not found"); return new ResponseEntity (HttpStatus.NOT_FOUND); } return new ResponseEntity (user, HttpStatus.OK); } //-------------------Create a User-------------------------------------------------------- @RequestMapping(value = "/user/", method = RequestMethod.POST) public ResponseEntity createUser(@RequestBody User user, UriComponentsBuilder ucBuilder) { System.out.println("Creating User " + user.getName()); if (userService.isUserExist(user)) { System.out.println("A User with name " + user.getName() + " already exist"); return new ResponseEntity (HttpStatus.CONFLICT); } userService.saveUser(user); HttpHeaders headers = new HttpHeaders(); headers.setLocation(ucBuilder.path("/user/{id}").buildAndExpand(user.getId()).toUri()); return new ResponseEntity (headers, HttpStatus.CREATED); } //------------------- Update a User -------------------------------------------------------- @RequestMapping(value = "/user/{id}", method = RequestMethod.PUT) public ResponseEntity updateUser(@PathVariable("id") long id, @RequestBody User user) { System.out.println("Updating User " + id); User currentUser = userService.findById(id); if (currentUser==null) { System.out.println("User with id " + id + " not found"); return new ResponseEntity (HttpStatus.NOT_FOUND); } currentUser.setName(user.getName()); currentUser.setAge(user.getAge()); currentUser.setSalary(user.getSalary()); userService.updateUser(currentUser); return new ResponseEntity (currentUser, HttpStatus.OK); } //------------------- Delete a User -------------------------------------------------------- @RequestMapping(value = "/user/{id}", method = RequestMethod.DELETE) public ResponseEntity deleteUser(@PathVariable("id") long id) { System.out.println("Fetching & Deleting User with id " + id); User user = userService.findById(id); if (user == null) { System.out.println("Unable to delete. User with id " + id + " not found"); return new ResponseEntity (HttpStatus.NOT_FOUND); } userService.deleteUserById(id); return new ResponseEntity (HttpStatus.NO_CONTENT); } //------------------- Delete All Users -------------------------------------------------------- @RequestMapping(value = "/user/", method = RequestMethod.DELETE) public ResponseEntity deleteAllUsers() { System.out.println("Deleting All Users"); userService.deleteAllUsers(); return new ResponseEntity (HttpStatus.NO_CONTENT); } }
package com.websystique.springmvc.service; import java.util.List; import com.websystique.springmvc.model.User; public interface UserService { User findById(long id); User findByName(String name); void saveUser(User user); void updateUser(User user); void deleteUserById(long id); List findAllUsers(); void deleteAllUsers(); public boolean isUserExist(User user); }
package com.websystique.springmvc.service; import java.util.ArrayList; import java.util.Iterator; import java.util.List; import java.util.concurrent.atomic.AtomicLong; import org.springframework.stereotype.Service; import org.springframework.transaction.annotation.Transactional; import com.websystique.springmvc.model.User; @Service("userService") @Transactional public class UserServiceImpl implements UserService{ private static final AtomicLong counter = new AtomicLong(); private static List users; static{ users= populateDummyUsers(); } public List findAllUsers() { return users; } public User findById(long id) { for(User user : users){ if(user.getId() == id){ return user; } } return null; } public User findByName(String name) { for(User user : users){ if(user.getName().equalsIgnoreCase(name)){ return user; } } return null; } public void saveUser(User user) { user.setId(counter.incrementAndGet()); users.add(user); } public void updateUser(User user) { int index = users.indexOf(user); users.set(index, user); } public void deleteUserById(long id) { for (Iterator iterator = users.iterator(); iterator.hasNext(); ) { User user = iterator.next(); if (user.getId() == id) { iterator.remove(); } } } public boolean isUserExist(User user) { return findByName(user.getName())!=null; } private static List populateDummyUsers(){ List users = new ArrayList (); users.add(new User(counter.incrementAndGet(),"Sam",30, 70000)); users.add(new User(counter.incrementAndGet(),"Tom",40, 50000)); users.add(new User(counter.incrementAndGet(),"Jerome",45, 30000)); users.add(new User(counter.incrementAndGet(),"Silvia",50, 40000)); return users; } public void deleteAllUsers() { users.clear(); } }
4、Model （模型）类
package com.websystique.springmvc.model; public class User { private long id; private String name; private int age; private double salary; public User(){ id=0; } public User(long id, String name, int age, double salary){ this.id = id; this.name = name; this.age = age; this.salary = salary; } public long getId() { return id; } public void setId(long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public double getSalary() { return salary; } public void setSalary(double salary) { this.salary = salary; } @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + (int) (id ^ (id >>> 32)); return result; } @Override public boolean equals(Object obj) { if (this == obj) return true; if (obj == null) return false; if (getClass() != obj.getClass()) return false; User other = (User) obj; if (id != other.id) return false; return true; } @Override public String toString() { return "User [id=" + id + ", name=" + name + ", age=" + age + ", salary=" + salary + "]"; } }