Spring REST Template 快速入门

本篇将使用Spring Boot发布REST Service，使用Spring REST Template来调用服务

本篇代码均已上传到GITHUB，https://github.com/IloveZiHan/restfultemplate.git

介绍

我们之前都使用过HttpClient来发送HTTP请求，但我们很多时间都需要将HttpClient请求或者响应的数据转换为Java对象，HttpClient需要我们自己手动来解析。我们今天要介绍的Spring REST Template比HttpClient用起来更加方便简洁。

背景

案例分为两个部分：

1. CRM_MANAGEMENT——后台主要提供RESTFUL Service服务，因为尽量使案例简单，所以数据部分是直接使用内存中的列表来模拟

2. PORTAL——门户，也就是前端系统，用来处理浏览器提交的请求，接收到用户请求会使用Spring REST Template来提交RESTFUL Service请求

环境说明

• 本案例基于Maven构建，使用Spring Boot 2.x开发

• 可以选择IDEA或者Eclipse导入案例运行

项目开发

CRM_DOMAIN实体

POM依赖

• pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>resttemplate_common</artifactId>
        <groupId>com.itheima</groupId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
​
    <artifactId>crm_domain</artifactId>
    <packaging>jar</packaging>
</project>

• User实体类

package com.itheima.crm.domain;
​
public class User {
​
    private Integer id;     // id
    private String username; // 用户名
    private String password; // 密码
​
    public Integer getId() {
        return id;
    }
​
    public void setId(Integer id) {
        this.id = id;
    }
​
    public String getPassword() {
        return password;
    }
​
    public void setPassword(String password) {
        this.password = password;
    }
​
    public String getUsername() {
        return username;
    }
​
    public void setUsername(String username) {
        this.username = username;
    }
​
    public boolean matchUsernameAndPassword(String username, String password) {
        if(this.username.equals(username) && this.password.equals(password)) {
            return true;
        }
        else {
            return false;
        }
    }
}
​

ResResult——封装响应结果

package com.itheima.crm.domain;
​
/**
 * 响应结果
 */
public class ResResult {
​
    private Boolean success; // 是否操作成功
    private String message; // 消息
​
    public ResResult() {
    }
​
    public ResResult(Boolean success, String message) {
        this.success = success;
        this.message = message;
    }
​
    public Boolean getSuccess() {
        return success;
    }
​
    public void setSuccess(Boolean success) {
        this.success = success;
    }
​
    public String getMessage() {
        return message;
    }
​
    public void setMessage(String message) {
        this.message = message;
    }
}
​

CRM_MANAGEMENT后台

POM依赖

• pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
​
    <modelVersion>4.0.0</modelVersion>
​
    <artifactId>crm_management</artifactId>
​
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
​
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>
​
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
​
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
​
        <dependency>
            <groupId>com.itheima</groupId>
            <artifactId>crm_domain</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
    </dependencies>
​
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

RESTFUL Service接口开发

package com.itheima.crm.webservice;
​
import com.itheima.crm.domain.ResResult;
import com.itheima.crm.domain.User ;
import com.itheima.crm.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
​
import java.util.List;
​
@RestController
@RequestMapping("/user")
public class UserRestService {
​
    @Autowired
    private UserService userService;
​
    /**
     * 注册服务
     * @param user 用户
     * @return
     */
    @RequestMapping(method = RequestMethod.POST)
    public ResResult regist(@RequestBody User user) {
        try {
            userService.regist(user);
            return new ResResult(true, "添加成功");
        } catch (Exception e) {
            e.printStackTrace();
            return new ResResult(false, "添加失败");
        }
    }
​
    /**
     * 登录服务
     * @param username 用户名
     * @param password 密码
     * @return
     */
    @RequestMapping(value = "/{username}/{password}", method = RequestMethod.GET)
    public User login(@PathVariable("username") String username, @PathVariable("password") String password) {
        try {
            return userService.login(username, password);
        } catch (Exception e) {
            return null;
        }
    }
​
    @RequestMapping(method = RequestMethod.GET)
    public List<User> findAll() {
        return userService.findAll();
    }
}
​

Service层开发

• UserService接口

package com.itheima.crm.service;
​
import com.itheima.crm.domain.User ;
​
import java.util.List;
​
public interface UserService {
    void regist(User user);
​
    User login(String username, String password);
​
    List<User> findAll();
}
​

• UserServiceImpl实现类

package com.itheima.crm.service;
​
import com.itheima.crm.dao.UserDao;
import com.itheima.crm.domain.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
​
import java.util.List;
​
@Service
public class UserServiceImpl implements UserService{
​
    @Autowired
    private UserDao userDao;
​
    @Override
    public void regist(User user) {
        userDao.save(user);
    }
​
    @Override
    public User login(String username, String password) {
        return userDao.findOne(username, password);
    }
​
    @Override
    public List<User> findAll() {
        return userDao.findAll();
    }
}
​

DAO层开发

• UserDao接口

package com.itheima.crm.dao;
​
import com.itheima.crm.domain.User ;
​
import java.util.List;
​
public interface UserDao {
    /**
     * 保存用户
     * @param user 用户
     */
    void save(User user);
​
    User findOne(String username, String password);
​
    List<User> findAll();
}

• UserDaoImpl实现类

package com.itheima.crm.dao;
​
import com.itheima.crm.domain.User;
import org.springframework.stereotype.Repository;
​
import java.util.ArrayList;
import java.util.List;
​
@Repository
public class UserDaoImpl implements UserDao{
​
    private List<User> users = new ArrayList<>();
​
    @Override
    public void save(User user) {
        users.add(user);
    }
​
    @Override
    public User findOne(String username, String password) {
        User userTmp = new User();
        userTmp.setUsername(username);
        userTmp.setPassword(password);
​
        for(User user : users) {
            if(user.matchUsernameAndPassword(username, password)) {
                return user;
            }
        }
​
        return null;
    }
​
    @Override
    public List<User> findAll() {
        return users;
    }
​
    public UserDaoImpl() {
        // 添加一些测试的用户
        User user1 = new User();
        user1.setId(1);
        user1.setUsername("zhangsan");
        user1.setPassword("0");
​
        User user2 = new User();
        user2.setId(2);
        user2.setUsername("lisi");
        user2.setPassword("0");
​
        User user3 = new User();
        user3.setId(3);
        user3.setUsername("wangwu");
        user3.setPassword("0");
​
        User user4 = new User();
        user4.setId(4);
        user4.setUsername("zhaoliu");
        user4.setPassword("0");
​
        users.add(user1);
        users.add(user2);
        users.add(user3);
        users.add(user4);
    }
}
​

Spring Boot入口

• 配置文件(application.properties)

server.port=9001
server.servlet.context-path=/

• 入口

package com.itheima.crm;
​
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
​
@SpringBootApplication
public class Application {
​
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}
​

RESTFUL Service接口调用URL

• 添加用户

  Requsest URL: http://localhost:9001/user/ Request Method: POST

• 根据用户名密码查询用户

  Requsest URL: http://localhost:9001/user/用户名/密码 Request Method: GET

• 查询所有用户

  Requeset URL: http://localhost:9001/user/ Request Method: GET

PORTAL门户

POM依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
​
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
​
    <modelVersion>4.0.0</modelVersion>
    <artifactId>portal</artifactId>
​
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>
​
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
​
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.28</version>
        </dependency><dependency>
            <groupId>com.itheima</groupId>
            <artifactId>crm_domain</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
    </dependencies>
​
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

Controller开发

package com.itheima.portal.controller;
​
import com.itheima.crm.domain.ResResult;
import com.itheima.crm.domain.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
​
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
​
@RestController
@RequestMapping("/user")
public class UserController {
​
    @Autowired
    private RestTemplate restTemplate;
​
    private String USERSERVICE_URL = "http://localhost:9001/user";
​
    @RequestMapping("/login")
    public Map login(String username, String password) {
        // 构建要传递的参数
        Map<String, String> params = new HashMap<>();
        params.put("username", username);
        params.put("password", password);
        // 发送GET请求
        User user = restTemplate.getForObject(USERSERVICE_URL + "/{username}/{password}", User.class, params);
        Map<String, Object> result = new HashMap<>();
        if(user != null) {
             result.put("success", true);
        }
        else {
            result.put("success", false);
            result.put("message", "登录失败");
        }
​
        return result;
    }
​
    @RequestMapping("/regist")
    public ResResult login(@RequestBody  User user) throws IOException {
        // 使用REST Template发送POST请求
        return restTemplate.postForObject(USERSERVICE_URL + "/", user, ResResult.class);
    }
}

Spring Boot入口

• 配置文件(application.properties)

server.port=9002
server.servlet.context-path=/

• 入口

package com.itheima.portal;
​
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;
​
@SpringBootApplication
public class Application {
​
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
​
    /**
     * 创建RestTemplate Bean
     */
    @Bean
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }
}
​

• 前端页面

1. 导入jquery.js

2. login.html登录页面

<!doctype html>
<html lang="`">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>登录</title>
    <script src="jquery-1.11.3.js"></script>
</head>
<body>
    <table class="table">
        <tr>
            <td>用户名</td>
            <td><input type="text" id="username"></td>
        </tr>
        <tr>
            <td>密码</td>
            <td><input type="text" id="password"></td>
        </tr>
        <tr>
            <td></td>
            <td>
                <button id="btn">登录</button>
                <button id="btn1">注册</button>
            </td>
        </tr>
    </table>
​
    <script type="text/javascript">
        $(function() {
           $('#btn').click(function() {
               $.get('user/login?username=' + $('#username').val() + '&password=' + $('#password').val(), function(data) {
                  if(!data.success) {
                      alert(data.message);
                  }
                  else {
                      window.location.href = "success.html";
                  }
               });
           });
​
            $('#btn1').click(function() {
                var user = {
                        username: $('#username').val(),
                        password: $('#password').val()
                };
                $.ajax({
                    type:'POST',
                    url:'user/regist',
                    dataType:"json",
                    contentType:"application/json",
                    data:JSON.stringify(user),
                    success:function(data){
                        if(!data.success) {
                            alert(data.message);
                        }
                        else {
                            alert("注册成功！");
                        }
                    }
                });
            });
        });
    </script>
</body>
</html>

3. success.html登录成功页面

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>登录成功</title>
</head>
<body>
    <h1>登录成功</h1>
</body>
</html>

总结

Spring REST Template比HttpClient更加快捷方便的调用RS服务，它自动封装和解析Java对象。而且可以很方便的与Spring整合，快速注入Spring的bean对象。

注意

注意Jquery $.get、$.post、$.ajax的区别

• $.get(url, json对象)表示发送一个get请求，使用queryString的方式提交。url?username=tom...

• $.post(url, json对象)表示发送一个post请求，数据部分类似于提交表单。

• $.ajax可以选择数据传递的格式、类型等。我们要将一个json串发送到spring mvc @RequestBody来接收需要使用$.ajax。下面是示例代码

$.ajax({
  type:'POST',
  url:'user/regist',
  dataType:"json",
  contentType:"application/json",
  data:JSON.stringify(user),
  success:function(data){
    if(!data.success) {
      alert(data.message);
    }
    else {
      alert("注册成功！");
    }
  }
});