Spring4 MVC RESTFul WebServices CRUD实例+RestTemplate

简单介绍REST

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。

在基于 REST 的设计中，资源被一套通用动词操作使用。

• 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

这意味着，作为一个 REST 服务开发人员或客户端，应符合上述标准，以便 REST 操作。

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。

基于REST的控制器

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。

这就是我们的 REST API 功能/作用：

• 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