REST 表示状态传输。这是一个体系结构样式,可用于设计网络服务,可以被各种客户端消耗。核心思想是,不使用如CORBA,RPC或SOAP复杂的机制在机器之间进行连接,简单的 HTTP 用于使它们之间调用。
-
创建资源:应该使用 HTTP POST
-
要获取资源:应该使用HTTP GET
-
更新资源:应使用HTTP PUT
-
要删除资源:应使用HTTP DELETE
通常Rest 是基于Web服务返回JSON或XML数据格式作为响应,虽然它并不仅仅限于这些类型。客户端可以指定(使用 HTTP Accept 报头),他们所感兴趣的资源类型,并且服务器可以返回资源,指定它所服务的内容类型资源。
下面是一个可能基于 REST 的控制器,实现REST API。这里所说的“可能”,这意味着可以以另一种方式实现它,还是(或者更纯粹的方式)符合REST风格。
- GET 请求 /api/user/ 返回用户的列表
- GET 请求 /api/user/1 返回ID为1的用户
- POST 请求 /api/user/ 以用户对象的JSON格式创建新的用户
- PUT 请求 /api/user/3 以用户对象作为JSON更新ID为3的用户
- DELETE 请求 /api/user/4 删除ID为4的用户
- DELETE 请求 /api/user/ 删除所有的用户
需要用到的java包
java对象和json相互转化
jackson-mapper-asl
jackson-databind
pom.xml
<properties>
<springVersion>4.3.5.RELEASE</springVersion>
<jacksonVersion>2.7.4</jacksonVersion>
</properties>
<dependencies>
<!-- spring-test支持 -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${springVersion}</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
<!-- spring模块库 -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>${springVersion}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${springVersion}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${springVersion}</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.springframework/spring-tx -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
<version>${springVersion}</version>
</dependency>
<!-- Servlet dependencies -->
<!-- servlet(HttpServletRequest,HttpServletResponse) -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.codehaus.jackson/jackson-mapper-asl -->
<!-- java对象和json相互转化 -->
<dependency>
<groupId>org.codehaus.jackson</groupId>
<artifactId>jackson-mapper-asl</artifactId>
<version>1.9.13</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.7.4</version>
</dependency>
</dependencies>
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.6</version>
<configuration>
<warSourceDirectory>src/main/webapp</warSourceDirectory>
<warName>gugua11</warName>
<failOnMissingWebXml>false</failOnMissingWebXml>
</configuration>
</plugin>
</plugins>
</pluginManagement>
<finalName>gugua11</finalName>
</build>
user字段结构
user.java
package 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;
}
}
userService接口
package springmvc.service;
import java.util.List;
import springmvc.model.User;
public interface UserService {
User findById(long id);
User findByName(String name);
void saveUser(User user);
void updateUser(User usre);
void deleteUserById(long id);
List<User> findAllUser();
void deleteAllUser();
public boolean isUserExists(User user);
}
userServiceImplement接口实现
@Service("userService") #声明服务,用于自动装配
@Transactional #事务支持(类似于msql事务提交)
package 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 springmvc.model.User;
@Service("userService")
@Transactional
public class UserServiceImpl implements UserService {
private static final AtomicLong counter = new AtomicLong();
private static List<User> users;
static {
users = populateDummyUsers();
}
@Override
public List<User> findAllUser() {
// TODO Auto-generated method stub
return users;
}
@Override
public User findById(long id) {
// TODO Auto-generated method stub
for(User user: users)
{
if(user.getId() == id)
{
return user;
}
}
return null;
}
@Override
public User findByName(String name) {
// TODO Auto-generated method stub
for(User user: users)
{
if(user.getName().equals(name) )
{
return user;
}
}
return null;
}
@Override
public void saveUser(User user) {
// TODO Auto-generated method stub
user.setId(counter.incrementAndGet());
users.add(user);
}
@Override
public void updateUser(User user) {
// TODO Auto-generated method stub
int index = users.indexOf(user);
users.set(index, user);
}
@Override
public void deleteUserById(long id) {
// TODO Auto-generated method stub
for(Iterator<User> iterator = users.iterator(); iterator.hasNext();)
{
User user = iterator.next();
if(user.getId() == id)
{
iterator.remove();
}
}
}
@Override
public boolean isUserExists(User user) {
// TODO Auto-generated method stub
return findByName(user.getName())!=null;
}
@Override
public void deleteAllUser() {
// TODO Auto-generated method stub
users.clear();
}
//默认数据
public static List<User> populateDummyUsers()
{
List<User> users = new ArrayList<User>();
users.add(new User(counter.incrementAndGet(), "张三", 30, 700000));
users.add(new User(counter.incrementAndGet(), "李四", 35, 850000));
users.add(new User(counter.incrementAndGet(), "王五", 36, 900000));
users.add(new User(counter.incrementAndGet(), "田七", 38, 1000000));
return users;
}
}
输出头部信息
CORSFilter.java
package springmvc.configuration;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletResponse;
//支持跨域操作
public class CORSFilter implements Filter {
@Override
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
throws IOException, ServletException {
// TODO Auto-generated method stub
System.out.print("Filtering on .......");
HttpServletResponse response = (HttpServletResponse) res;
response.setHeader("Access-Control-Allow-Origin", "*");
response.setHeader("Access-Control-Allow-Methods", "POST, GET, PUT, OPTIONS, DELETE");
response.setHeader("Access-Control-Max-Age", "3600");
response.setHeader("Access-Control-Allow-Headers", "x-requested-with");
chain.doFilter(req, res);
}
@Override
public void init(FilterConfig arg0) throws ServletException {
// TODO Auto-generated method stub
}
@Override
public void destroy() {
// TODO Auto-generated method stub
}
}
springmvc,自动引入,配置声明
package springmvc.configuration;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
@Configuration
@EnableWebMvc
@ComponentScan(basePackages="springmvc")
public class HelloWorldConfiguration {
}
初始分Dispatcher转发功能
package springmvc.configuration;
import javax.servlet.Filter;
import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;
public class HelloWorldInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
@Override
protected Class<?>[] getRootConfigClasses() {
// TODO Auto-generated method stub
return new Class[] { HelloWorldConfiguration.class };
}
@Override
protected Class<?>[] getServletConfigClasses() {
// TODO Auto-generated method stub
return null;
}
@Override
protected String[] getServletMappings() {
// TODO Auto-generated method stub
return new String[]{"/"};
}
@Override
protected Filter[] getServletFilters()
{
Filter [] singleton = { new CORSFilter()};
return singleton;
}
}
控制器
package 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 springmvc.model.User;
import springmvc.service.UserService;
@RestController
public class HelloWorldRestController {
@Autowired
UserService userService;
@RequestMapping(value="/users", method=RequestMethod.GET)
public ResponseEntity<List<User>> listAllUsers()
{
List<User> users = userService.findAllUser();
if(users.isEmpty())
{
return new ResponseEntity<List<User>>(HttpStatus.NO_CONTENT);
}
return new ResponseEntity<List<User>>(users, HttpStatus.OK) ;
}
@RequestMapping(value="/user/{id}", method=RequestMethod.PUT, produces=MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<User> getUser(@PathVariable("id") long id)
{
User user = userService.findById(id);
if(user == null)
{
return new ResponseEntity<User>(HttpStatus.NOT_FOUND);
}
return new ResponseEntity<User>(user, HttpStatus.OK);
}
@RequestMapping(value="/user/{name}", method=RequestMethod.GET, produces=MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<User> getNameUser(@PathVariable("name") String name)
{
User user = userService.findByName(name);
if(user == null)
{
return new ResponseEntity<User>(HttpStatus.NOT_FOUND);
}
return new ResponseEntity<User>(user, HttpStatus.OK);
}
@RequestMapping(value="/user/create", method=RequestMethod.POST)
public ResponseEntity<Void> createUser(@RequestBody User user, UriComponentsBuilder uriBuilder)
{
if(userService.isUserExists(user))
{
return new ResponseEntity<Void>(HttpStatus.CONFLICT);
}
userService.saveUser(user);
HttpHeaders headers = new HttpHeaders();
headers.setLocation(uriBuilder.path("/user/{id}").buildAndExpand(user.getId()).toUri());
return new ResponseEntity<Void>(headers, HttpStatus.CREATED);
}
}
@RequestMapping(value="/user/delete/{id}", method=RequestMethod.GET, produces=MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<User> deleteUserOne(@PathVariable("id") long id)
{
User user = userService.findById(id);
if(user == null)
{
return new ResponseEntity<User>(HttpStatus.NOT_FOUND);
}
userService.deleteById(id);
return new ResponseEntity<User>(HttpStatus.NO_CONTENT);
}
@RequestMapping(value="/user/delete/all", method=RequestMethod.GET)
public ResponseEntity<User> deleteAllUsers()
{
userService.deleteAllUser();
return new ResponseEntity<User>(HttpStatus.NO_CONTENT);
}
大致访问:
http://localhost:8080/gugua11/users
http://localhost:8080/gugua11/user/1
......
用火狐插件RESTClient,注意添加HTTP头字段:
Content-Type: application/json