Spring RestTemplate示例

春季 RestTemplate 提供了一种方便的方式来测试 RESTful 网络服务。

春天的RestTemplate

• Spring RestTemplate class is part of spring-web, introduced in Spring 3.
• We can use RestTemplate to test HTTP based restful web services, it doesn’t support HTTPS protocol.
• RestTemplate class provides overloaded methods for different HTTP methods, such as GET, POST, PUT, DELETE etc.

春季的RestTemplate示例

让我们来看一个Spring RestTemplate的例子，我们将测试在Spring Data JPA文章中创建的REST web服务。下表展示了该REST web服务支持的URI。

Spring RestTemplate Maven Dependencies
春季 RestTemplate Maven 依赖

我们需要spring-framework的spring-core和spring-context依赖。然后我们需要包含RestTemplate类的spring-web组件。我们还需要jackson-mapper-asl来通过Jackson API支持Spring JSON。

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="https://maven.apache.org/POM/4.0.0" xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="https://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>com.Olivia.spring</groupId>
	<artifactId>SpringRestTemplate</artifactId>
	<version>1.0-SNAPSHOT</version>
	<properties>
		<spring.framework>4.3.0.RELEASE</spring.framework>
		<spring.web>3.0.2.RELEASE</spring.web>
		<serializer.version>2.8.1</serializer.version>
	</properties>
	<dependencies>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-core</artifactId>
			<version>${spring.framework}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-context</artifactId>
			<version>${spring.framework}</version>
		</dependency>
		<dependency>
			<groupId>org.codehaus.jackson</groupId>
			<artifactId>jackson-mapper-asl</artifactId>
			<version>1.9.4</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-web</artifactId>
			<version>${spring.web}</version>
		</dependency>
	</dependencies>
</project>

春天配置类

我们需要为RestTemplate类定义一个Spring Bean，在AppConfig类中完成。

package com.Olivia.spring.config;

import org.codehaus.jackson.map.ObjectMapper;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.json.MappingJacksonHttpMessageConverter;
import org.springframework.web.client.RestTemplate;

@Configuration
@ComponentScan("com.Olivia.spring")
public class AppConfig {

	@Bean
	RestTemplate restTemplate() {
		RestTemplate restTemplate = new RestTemplate();
		MappingJacksonHttpMessageConverter converter = new MappingJacksonHttpMessageConverter();
		converter.setObjectMapper(new ObjectMapper());
		restTemplate.getMessageConverters().add(converter);
		return restTemplate;
	}
}

请注意，RestTemplate使用MessageConverter，并且我们需要在RestTemplate bean中设置该属性。在我们的示例中，我们使用MappingJacksonHttpMessageConverter来从JSON格式中获取数据。

模型类

由于我们试图使用Jackson映射器将由Web服务返回的JSON转换为java对象，因此我们需要为此创建模型类。请注意，这个模型类将和Web服务中使用的模型类非常相似，只是我们不需要JPA注解。

package com.Olivia.spring.model;

public class Person {

	private Long id;

	private Integer age;

	private String firstName;

	private String lastName;

	public Person() {
	}

	public Long getId() {
		return id;
	}

	public void setId(Long id) {
		this.id = id;
	}

	public Integer getAge() {
		return age;
	}

	public void setAge(Integer age) {
		this.age = age;
	}

	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;
	}

	@Override
	public String toString() {
		return "Person{" + "id=" + id + ", age=" + age + ", firstName='" + firstName + '\'' + ", lastName='" + lastName
				+ '\'' + '}';
	}
}

春季RestTemplate客户端类

最后一步是创建客户端类，这些类将使用上面定义的RestTemplate bean。

package com.Olivia.spring.config;

import java.util.List;

import org.springframework.http.HttpStatus;

import com.Olivia.spring.model.Person;

public interface PersonClient {
	List<Person> getAllPerson();

	Person getById(Long id);

	HttpStatus addPerson(Person person);

	void updatePerson(Person person);

	void deletePerson(Long id);
}

package com.Olivia.spring.config;

import java.util.Arrays;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

import com.Olivia.spring.model.Person;

@Service
public class PersonClientImpl implements PersonClient {

	@Autowired
	RestTemplate restTemplate;

	final String ROOT_URI = "https://localhost:8080/springData/person";

	public List<Person> getAllPerson() {
		ResponseEntity<Person[]> response = restTemplate.getForEntity(ROOT_URI, Person[].class);
		return Arrays.asList(response.getBody());

	}

	public Person getById(Long id) {
		ResponseEntity<Person> response = restTemplate.getForEntity(ROOT_URI + "/"+id, Person.class);
		return response.getBody();
	}

	public HttpStatus addPerson(Person person) {
		ResponseEntity<HttpStatus> response = restTemplate.postForEntity(ROOT_URI, person, HttpStatus.class);
		return response.getBody();
	}

	public void updatePerson(Person person) {
		restTemplate.put(ROOT_URI, person);
	}

	public void deletePerson(Long id) {
		restTemplate.delete(ROOT_URI + id);

	}
}

代码是自解释的，我们根据URI和HTTP方法调用RestTemplate方法，并根据需要传递适当的请求对象。

Spring RestTemplate测试类

现在是时候测试我们的Spring RestTemplate示例项目了，在下面的类中展示了如何以Spring的方式使用RestTemplate方法。

package com.Olivia.spring;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.http.HttpStatus;

import com.Olivia.spring.config.AppConfig;
import com.Olivia.spring.config.PersonClient;
import com.Olivia.spring.model.Person;

public class Main {

	public static void main(String[] args) {
		AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(AppConfig.class);

		PersonClient client = applicationContext.getBean(PersonClient.class);

		System.out.println("Getting list of all people:");

		for (Person p : client.getAllPerson()) {
			System.out.println(p);
		}

		System.out.println("\nGetting person with ID 2");

		Person personById = client.getById(2L);

		System.out.println(personById);

		System.out.println("Adding a Person");
		Person p = new Person();
		p.setAge(50);
		p.setFirstName("David");
		p.setLastName("Blain");
		HttpStatus status = client.addPerson(p);
		System.out.println("Add Person Response = " + status);

		applicationContext.close();
	}
}

当我在我的本地设置上运行上述程序时，我得到以下输出。

Getting list of all people:
Person{id=2, age=30, firstName='Oksi', lastName=' Bahatskaya'}
Person{id=1, age=30, firstName='Vlad', lastName='Mateo'}

Getting person with ID 2
Person{id=2, age=30, firstName='Oksi', lastName=' Bahatskaya'}
Adding a Person
Add Person Response = 201

下载 Spring RestTemplate 示例项目

参考：API文档