Spring Boot2如何实现调用REST服务的发布步骤？

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开发环境：IntelliJ IDEA 2019.2.2 + Spring Boot 版本：2.1.8

1.发布REST服务

2.在IDEA中创建名为rest-server的Spring Boot项目

3.创建实体类User

javapackage com.example.restserver.domain;

public class User {}

开发环境：IntelliJ IDEA 2019.2.2
Spring Boot版本：2.1.8

一、发布REST服务

1、IDEA新建一个名称为rest-server的Spring Boot项目

2、新建一个实体类User.java

package com.example.restserver.domain; public class User { String name; Integer age; public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } }

3、新建一个控制器类 UserController.java

package com.example.restserver.web; import com.example.restserver.domain.User; import org.springframework.localhost:8080/user/lc，页面显示：

{"name":"lc","age":30}

二、使用RestTemplae调用服务

1、IDEA新建一个名称为rest-client的Spring Boot项目

2、新建一个含有main方法的普通类RestTemplateMain.java，调用服务

package com.example.restclient; import com.example.restclient.domain.User; import org.springframework.web.client.RestTemplate; public class RestTemplateMain { public static void main(String[] args){ RestTemplate tpl = new RestTemplate(); User u = tpl.getForObject("localhost:8080/user/lc", User.class); System.out.println(u.getName() + "," + u.getAge()); } }

右键Run 'RestTemplateMain.main()'，控制台输出：lc,30

3、在bean里面使用RestTemplate，可使用RestTemplateBuilder，新建类UserService.java

package com.example.restclient.service; import com.example.restclient.domain.User; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.web.client.RestTemplateBuilder; import org.springframework.context.annotation.Bean; import org.springframework.stereotype.Service; import org.springframework.web.client.RestTemplate; @Service public class UserService { @Autowired private RestTemplateBuilder builder; @Bean public RestTemplate restTemplate(){ return builder.rootUri("localhost:8080").build(); } public User userBuilder(String name){ User u = restTemplate().getForObject("/user/" + name, User.class); return u; } }

4、编写一个单元测试类，来测试上面的UserService的bean。

package com.example.restclient.service; import com.example.restclient.domain.User; import org.junit.Assert; import org.junit.Test; import org.junit.runner.RunWith; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.test.context.SpringBootTest; import org.springframework.test.context.junit4.SpringRunner; @RunWith(SpringRunner.class) @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.NONE) public class UserServiceTest { @Autowired private UserService userService; @Test public void testUser(){ User u = userService.userBuilder("lc"); Assert.assertEquals("lc", u.getName()); } }

5、控制器类UserController.cs 中调用

配置在application.properties 配置端口和8080不一样，如server.port = 9001

@Autowired private UserService userService; @RequestMapping(value="/user/{name}", produces = MediaType.APPLICATION_JSON_VALUE) public User user(@PathVariable String name) { User u = userService.userBuilder(name); return u; }

三、使用Feign调用服务

继续在rest-client项目基础上修改代码。

1、pom.xml添加依赖

<dependency> <groupId>io.github.openfeign</groupId> <artifactId>feign-core</artifactId> <version>9.5.0</version> </dependency> <dependency> <groupId>io.github.openfeign</groupId> <artifactId>feign-gson</artifactId> <version>9.5.0</version> </dependency>

2、新建接口UserClient.java

package com.example.restclient.service; import com.example.restclient.domain.User; import feign.Param; import feign.RequestLine; public interface UserClient { @RequestLine("GET /user/{name}") User getUser(@Param("name")String name); }

3、在控制器类UserController.java 中调用

decoder(new GsonDecoder()) 表示添加了解码器的配置，GsonDecoder会将返回的JSON字符串转换为接口方法返回的对象。
相反的，encoder(new GsonEncoder())则是编码器，将对象转换为JSON字符串。

@RequestMapping(value="/user2/{name}", produces = MediaType.APPLICATION_JSON_VALUE) public User user2(@PathVariable String name) { UserClient service = Feign.builder().decoder(new GsonDecoder()) .target(UserClient.class, "localhost:8080/"); User u = service.getUser(name); return u; }

4、优化第3步代码，并把请求地址放到配置文件中。

（1）application.properties 添加配置

复制代码 代码如下:application.client.url = localhost:8080

（2）新建配置类ClientConfig.java

package com.example.restclient.config; import com.example.restclient.service.UserClient; import feign.Feign; import feign.gson.GsonDecoder; import org.springframework.beans.factory.annotation.Value; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; @Configuration public class ClientConfig { @Value("${application.client.url}") private String clientUrl; @Bean UserClient userClient(){ UserClient client = Feign.builder() .decoder(new GsonDecoder()) .target(UserClient.class, clientUrl); return client; } }

（3）控制器 UserController.java 中调用

@Autowired private UserClient userClient; @RequestMapping(value="/user3/{name}", produces = MediaType.APPLICATION_JSON_VALUE) public User user3(@PathVariable String name) { User u = userClient.getUser(name); return u; }

UserController.java最终内容：

package com.example.restclient.web; import com.example.restclient.domain.User; import com.example.restclient.service.UserClient; import com.example.restclient.service.UserService; import feign.Feign; import feign.gson.GsonDecoder; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.localhost:8080/"); User u = service.getUser(name); return u; } @RequestMapping(value="/user3/{name}", produces = MediaType.APPLICATION_JSON_VALUE) public User user3(@PathVariable String name) { User u = userClient.getUser(name); return u; } }

项目结构

先后访问下面地址，可见到输出正常结果

localhost:9001/user/lc
localhost:9001/user2/lc2
localhost:9001/user3/lc3

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