架构实战篇（六）：Spring Boot RestTemplate的使用

三、Java 客户端

让我们先来看下项目的目录结构

目录结构

四、配置maven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">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.itunion</groupId>
    <artifactId>spring-boot-resttemplate</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.1.RELEASE</version>
    </parent>

    <dependencies>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger2</artifactId>
            <version>2.7.0</version>
        </dependency>
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger-ui</artifactId>
            <version>2.7.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
        </dependency>
        <!-- 打war包用 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>
    </dependencies>
    <packaging>war</packaging>

    <properties>
        <java.version>1.7</java.version>
    </properties>
    <build>
        <!-- 打war包用 -->
        <finalName>swagger</finalName>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <!-- 打war包用,maven打包的时候告诉maven不需要web.xml,否刚会报找不到web.xml错误 -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>2.1.1</version>
                <configuration>
                    <failOnMissingWebXml>false</failOnMissingWebXml>
                </configuration>
            </plugin>
            <!-- -->
        </plugins>
    </build></project>

五、编写程序入口

程序的入口基本都一样

package com.itunion;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import java.io.IOException;@SpringBootApplicationpublic class Application {    public static void main(String[] args) throws IOException {
        SpringApplication.run(Application.class, args);
    }
}

六、RestTemplate 配置

在这里我们可以设置连接的超时时间 代理 等信息

package com.itunion.config;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.http.client.ClientHttpRequestFactory;import org.springframework.http.client.SimpleClientHttpRequestFactory;import org.springframework.web.client.RestTemplate;@Configurationpublic class ApiConfig {    @Bean
    public RestTemplate restTemplate(ClientHttpRequestFactory factory) {        return new RestTemplate(factory);
    }    @Bean
    public ClientHttpRequestFactory simpleClientHttpRequestFactory() {
        SimpleClientHttpRequestFactory factory = new SimpleClientHttpRequestFactory();
        factory.setReadTimeout(5000);//单位为ms
        factory.setConnectTimeout(5000);//单位为ms
        return factory;
    }
}

七、编写API 返回对象

API 请求肯定少不了返回对象，为了方便类型转换我们把User类复制了过来（实际开发中可以把api 公共的domain 等类带jar 包出来)

package com.itunion.model;import com.fasterxml.jackson.annotation.JsonIgnore;import io.swagger.annotations.ApiModel;import io.swagger.annotations.ApiModelProperty;@ApiModel("用户")public class User {    @ApiModelProperty("编号")    private Long id;    @ApiModelProperty("用户名")    private String username;    @ApiModelProperty("姓")    private String firstName;    @ApiModelProperty("名")    private String lastName;    @ApiModelProperty("邮箱")    private String email;    @ApiModelProperty(hidden = true)// 密码不传输
    @JsonIgnore
    private String password;    @ApiModelProperty("状态")    private Integer userStatus;    // get set

    @Override
    public String toString() {        return "User{" +                "id=" + id +                ", username='" + username + '\'' +                ", firstName='" + firstName + '\'' +                ", lastName='" + lastName + '\'' +                ", email='" + email + '\'' +                ", password='" + password + '\'' +                ", userStatus=" + userStatus +                '}';
    }
}

异常类

package com.itunion.model;import java.o.Serializable;public class ErrorBody implements Serializable {    private Integer code;    private String message;    private long timestamp = System.currentTimeMillis();    // get set
    @Override
    public String toString() {        return "ErrorBody{" +                "code=" + code +                ", message='" + message + '\'' +                ", timestamp=" + timestamp +                '}';
    }
}

八、使用RestTemplate 远程调用

这里我们写了两个方法

1. 当远程接口正常返回结果的时候我们会封装成User对象返回到前端

2. 当远程调用返回 RestClientResponseException 异常的时候封装成ErrorBody对象(比如传入参数不合法等数据验证，不能返回逾期结果的时候会返回Error信息，这时候需要做处理)

package com.itunion.controller;import com.fasterxml.jackson.databind.ObjectMapper;import com.itunion.model.ErrorBody;import com.itunion.model.User;import io.swagger.annotations.Api;import io.swagger.annotations.ApiOperation;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.*;import org.springframework.web.client.HttpClientErrorException;import org.springframework.web.client.RestTemplate;import java.io.IOException;@Api(value = "用户", description = "用户")@RequestMapping("/user")@RestControllerpublic class UserController {    @Autowired
    private RestTemplate restTemplate;    @ApiOperation(value = "调用远程用户服务", notes = "调用远程用户服务")    @RequestMapping(value = "/info/{userId}", method = RequestMethod.GET)    public User info(@PathVariable("userId") String userId) throws IOException {
        String apiURL = "http://localhost:8081/swagger/user/info/" + userId;        return restTemplate.getForObject(apiURL, User.class);
    }    @ExceptionHandler(RestClientResponseException.class)    public ErrorBody exceptionHandler(HttpClientErrorException e) throws IOException {        return new ObjectMapper().readValue(e.getResponseBodyAsString(), ErrorBody.class);
    }
}

九、修改端口

为了同时启动两个服务端口肯定是不能一样的了

server.port=8082

server.context-path=/

swagger.enable=true

十、启动程序和验证

服务端成功启动

服务端成功启动

客户端成功启动

客户端成功启动

访问客户端页面
http://localhost:8082/swagger-ui.html

测试正确的请求参数

设置参数

验证正确结果

测试错误的请求参数

设置参数

验证异常结果

作者：IT实战联盟咖啡
链接：https://www.jianshu.com/p/c96049624891