一、RESET API
REST API 的目标是提供对引擎所有相关接口的访问。
Spring是用于开发企业级应用程序的流行框架。经过多年的发展，SpringBoot登上了舞台。Spring是使用@RestController编写RESTful Web服务。
编写RESTful Web服务的方法有很多，Jersey是JAX-RS的开源框架实现，它是RESTful Web服务的Java API。JAX-RS是Java EE技术的一部分。
二、如何在在Spring使用Jersey呢？
本文将学习如何使用Spring Boot和Jersey框架，去配置和创建JAX-RS 2.0 REST API接口；
这个示例应用使用的是Jersey的Servlet容器去部署REST API接口；
（一）配置
工程目录
image.png
1.访问Spring Initializr网站，添加Jersey (JAX-RS)依赖，点击生成代码；
2.下载代码到本地，解压，导入代码到IDE中
3.检查下pom.xml代码里是否包含了spring-boot-starter-jersey依赖；
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jersey</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
（二）创建JAX-RS REST资源
先创建一个UserResource类，代码如下：
UserResource.java
package com.howtodoinjava.jerseydemo;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import javax.ws.rs.Consumes;
import javax.ws.rs.DELETE;
import javax.ws.rs.GET;
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.Response;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlRootElement;
@XmlAccessorType(XmlAccessType.NONE)
@XmlRootElement(name = "users")
@Path("/users")
public class UserResource
{
private static Map<Integer, User> DB = new HashMap<>();
@GET
@Produces("application/json")
public Users getAllUsers() {
Users users = new Users();
users.setUsers(new ArrayList<>(DB.values()));
return users;
}
@POST
@Consumes("application/json")
public Response createUser(User user) throws URISyntaxException
{
if(user.getFirstName() == null || user.getLastName() == null) {
return Response.status(400).entity("Please provide all mandatory inputs").build();
}
user.setId(DB.values().size()+1);
user.setUri("/user-management/"+user.getId());
DB.put(user.getId(), user);
return Response.status(201).contentLocation(new URI(user.getUri())).build();
}
@GET
@Path("/{id}")
@Produces("application/json")
public Response getUserById(@PathParam("id") int id) throws URISyntaxException
{
User user = DB.get(id);
if(user == null) {
return Response.status(404).build();
}
return Response
.status(200)
.entity(user)
.contentLocation(new URI("/user-management/"+id)).build();
}
@PUT
@Path("/{id}")
@Consumes("application/json")
@Produces("application/json")
public Response updateUser(@PathParam("id") int id, User user) throws URISyntaxException
{
User temp = DB.get(id);
if(user == null) {
return Response.status(404).build();
}
temp.setFirstName(user.getFirstName());
temp.setLastName(user.getLastName());
DB.put(temp.getId(), temp);
return Response.status(200).entity(temp).build();
}
@DELETE
@Path("/{id}")
public Response deleteUser(@PathParam("id") int id) throws URISyntaxException {
User user = DB.get(id);
if(user != null) {
DB.remove(user.getId());
return Response.status(200).build();
}
return Response.status(404).build();
}
static
{
User user1 = new User();
user1.setId(1);
user1.setFirstName("John");
user1.setLastName("Wick");
user1.setUri("/user-management/1");
User user2 = new User();
user2.setId(2);
user2.setFirstName("Harry");
user2.setLastName("Potter");
user2.setUri("/user-management/2");
DB.put(user1.getId(), user1);
DB.put(user2.getId(), user2);
}
}
（三）Users.java
package com.howtodoinjava.jerseydemo;
import java.util.ArrayList;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
@XmlAccessorType(XmlAccessType.NONE)
@XmlRootElement(name = "users")
public class Users {
@XmlElement(name="user")
private ArrayList<User> users;
public ArrayList<User> getUsers() {
return users;
}
public void setUsers(ArrayList<User> users) {
this.users = users;
}
}
（四）User.java
package com.howtodoinjava.jerseydemo;
import java.io.Serializable;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
@XmlAccessorType(XmlAccessType.NONE)
@XmlRootElement(name = "user")
public class User implements Serializable {
private static final long serialVersionUID = 1L;
@XmlAttribute(name = "id")
private int id;
@XmlAttribute(name="uri")
private String uri;
@XmlElement(name = "firstName")
private String firstName;
@XmlElement(name = "lastName")
private String lastName;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getUri() {
return uri;
}
public void setUri(String uri) {
this.uri = uri;
}
}
（五）配置Jersey
到目前为止，我们已经创建了一个JAX-RS资源，现在我们想通过spring boot应用去访问它，步骤如下；
1.首先我们要注册改资源为Jersey资源，代码如下：
package com.howtodoinjava.jerseydemo;
import org.glassfish.jersey.server.ResourceConfig;
import org.springframework.stereotype.Component;
@Component
public class JerseyConfig extends ResourceConfig
{
public JerseyConfig()
{
register(UserResource.class);
}
}
注意需要加上 @Component注解，以便Spring Boot能够扫描到；
2.其次JerseyConfig需要继承ResourceConfig，该类提供了很多高级功能，简化了JAX-RS组件的注册工作；
3.最后Spring Boot Application启动类需要继承SpringBootServletInitializer
package com.howtodoinjava.jerseydemo;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.support.SpringBootServletInitializer;
@SpringBootApplication
public class JerseydemoApplication extends SpringBootServletInitializer
{
public static void main(String[] args)
{
new JerseydemoApplication().configure(new SpringApplicationBuilder(JerseydemoApplication.class)).run(args);
}
}
（六）演示
启动Spring Boot应用，访问user 资源
image.png
