（030）Spring Boot之RestTemplate访问web服务案例

　　每一个springboot工程都可以看做一个服务，这也是微服务的基础，使用RestTemplate访问springboot提供的web服务。如下：

String BASE_URL="http://127.0.0.1:8080";
RestTemplate res=new RestTemplate();
String body= res.getForObject(BASE_URL+"/soa/product/20",String.class);//请求服务，返回json字符串
System.out.println(body);
Gson gson=new Gson();
Response response=gson.fromJson(body,Response.class);//将json字符串转化为实体类
System.out.println(response);
System.out.println(response.getCode());
System.out.println(response.getMsg());
System.out.println(response.getData());

　　创建过程及源码如下：

（一）首先新建一个springboot工程，mall-product

　　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>

    <groupId>com.edu.spring.mall</groupId>
    <artifactId>mall-product</artifactId>
    <version>1.0.0</version>

    <name>mall-product</name>
    <!-- FIXME change it to the project's website -->
    <url>http://www.example.com</url>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>2.0.4.RELEASE</version>
                <scope>import</scope>
                <type>pom</type>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.1.1</version>
        </dependency>
    </dependencies>
</project>

　　Product.java

package com.edu.spring.mall.product.bean;

import java.sql.Timestamp;

public class Product {

    private Integer pid;
    private String pname;
    private String type;
    private double price;
    private Timestamp createTime;
    
    public Integer getPid() {
        return pid;
    }
    public void setPid(Integer pid) {
        this.pid = pid;
    }
    public String getPname() {
        return pname;
    }
    public void setPname(String pname) {
        this.pname = pname;
    }
    public String getType() {
        return type;
    }
    public void setType(String type) {
        this.type = type;
    }
    public Timestamp getCreateTime() {
        return createTime;
    }
    public void setCreateTime(Timestamp createTime) {
        this.createTime = createTime;
    }
    public double getPrice() {
        return price;
    }
    public void setPrice(double price) {
        this.price = price;
    }
    @Override
    public String toString() {
        return "Product [pid=" + pid + ", pname=" + pname + ", type=" + type
                + ", price=" + price + ", createTime=" + createTime + "]";
    }
    
}

　　ProductMapper.java

package com.edu.spring.mall.product.bean;

import java.util.List;

import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;

@Mapper
public interface ProductMapper {

    @Insert("insert into t_products (pname,type,price) values (#{pname},#{type},#{price})")
    Integer add(Product product);
    
    @Delete("delete from t_products where pid=#{arg1}")
    Integer deleteById(Integer id);
    
    @Update("update t_products set pname=#{pname},type=#{type},price=#{price} where pid=#{pid}")
    Integer update(Product product);
    
    @Select("select * from t_products where pid=#{arg1}")
    Product getById(Integer id);
    
    @Select("select * from t_products order by pid desc ")
    List<Product> queryByLists();
}

　　Response.java

package com.edu.spring.mall.product.web;

public class Response {

    private String code;
    private String msg;
    private Object data;

    public Response(String code, String msg) {
        this.code = code;
        this.msg = msg;
    }
    
    public Response(String code, String msg, Object data) {
        this.code = code;
        this.msg = msg;
        this.data = data;
    }
    public String getCode() {
        return code;
    }
    public void setCode(String code) {
        this.code = code;
    }
    public String getMsg() {
        return msg;
    }
    public void setMsg(String msg) {
        this.msg = msg;
    }
    public Object getData() {
        return data;
    }
    public void setData(Object data) {
        this.data = data;
    }
    
}

　　ProductController.java

package com.edu.spring.mall.product.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;

import com.edu.spring.mall.product.bean.Product;
import com.edu.spring.mall.product.bean.ProductMapper;
import com.edu.spring.mall.product.web.Response;

@RestController
public class ProductController {

    @Autowired
    private ProductMapper productMapper;
    
    @PostMapping("/soa/product/add")
    public Object add(Product product){
        Integer res=productMapper.add(product);
        return res==1?new Response("200","ok"):new Response("500","fail");
    }
    
    @DeleteMapping("/soa/product/{id}")
    public Object delete(@PathVariable("id") Integer id){
        Integer res=productMapper.deleteById(id);
        return res==1?new Response("200","ok"):new Response("500","fail");
    }
    
    @PostMapping("/soa/product/update")
    public Object update(Product product){
        Integer res=productMapper.update(product);
        return res==1?new Response("200","ok"):new Response("500","fail");
    }
    
    
    @GetMapping("/soa/product/{id}")
    public Object getById(@PathVariable("id") Integer id){
        Product product=productMapper.getById(id);
        return new Response("200","OK", product);
    }
    
    @GetMapping("/soa/product/list")
    public Object list(){
        return new Response("200","OK",productMapper.queryByLists());
    }
}

　　App.java

package com.edu.spring.mall.product;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class App 
{
    public static void main( String[] args )
    {
        SpringApplication.run(App.class, args);
    }
}

　　application.properties

spring.datasource.url=jdbc:mysql://127.0.0.1:3309/db_products
spring.datasource.username=root
spring.datasource.password=123456

　　product.sql

create database db_products default charset utf8;
create table t_products(pid int not null primary key auto_increment,pname varchar(200),type varchar(10),price double,createTime timestamp) 

（二）创建一个客户端工程，mall-web

　　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>

    <groupId>com.edu.spring.web</groupId>
    <artifactId>mall-web</artifactId>
    <version>1.0.0</version>

    <name>mall-web</name>
    <!-- FIXME change it to the project's website -->
    <url>http://www.example.com</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.7</maven.compiler.source>
        <maven.compiler.target>1.7</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.8.5</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.1.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>5.1.0.RELEASE</version>
        </dependency>
    </dependencies>


</project>

　　Product.java

package com.edu.spring.mall.web.bean;

public class Product {

    private Integer pid;
    private String pname;
    private String type;
    private double price;
    private String createTime;
    
    public Integer getPid() {
        return pid;
    }
    public void setPid(Integer pid) {
        this.pid = pid;
    }
    public String getPname() {
        return pname;
    }
    public void setPname(String pname) {
        this.pname = pname;
    }
    public String getType() {
        return type;
    }
    public void setType(String type) {
        this.type = type;
    }
    public String getCreateTime() {
        return createTime;
    }
    public void setCreateTime(String createTime) {
        this.createTime = createTime;
    }
    public double getPrice() {
        return price;
    }
    public void setPrice(double price) {
        this.price = price;
    }
    @Override
    public String toString() {
        return "Product [pid=" + pid + ", pname=" + pname + ", type=" + type
                + ", price=" + price + ", createTime=" + createTime + "]";
    }
    
}

　　Response.java

package com.edu.spring.mall.web.bean;

public class Response {

    private String code;
    private String msg;
    private Product data;

    public Response(String code, String msg) {
        this.code = code;
        this.msg = msg;
    }
    
    public Response(String code, String msg, Product data) {
        this.code = code;
        this.msg = msg;
        this.data = data;
    }
    public String getCode() {
        return code;
    }
    public void setCode(String code) {
        this.code = code;
    }
    public String getMsg() {
        return msg;
    }
    public void setMsg(String msg) {
        this.msg = msg;
    }
    public Object getData() {
        return data;
    }
    public void setData(Product data) {
        this.data = data;
    }

    @Override
    public String toString() {
        return "Response [code=" + code + ", msg=" + msg + ", data=" + data
                + "]";
    }
    
}

　　App.java

package com.edu.spring.web;

import org.springframework.web.client.RestTemplate;

import com.edu.spring.mall.web.bean.Response;
import com.google.gson.Gson;

public class App 
{
    public static void main( String[] args )
    {
        String BASE_URL="http://127.0.0.1:8080";
        RestTemplate res=new RestTemplate();
        String body= res.getForObject(BASE_URL+"/soa/product/20",String.class);
        System.out.println(body);
        Gson gson=new Gson();
        Response response=gson.fromJson(body,Response.class);
        System.out.println(response);
        System.out.println(response.getCode());
        System.out.println(response.getMsg());
        System.out.println(response.getData());
    }
}

　　（三）首先启动 mall-product，然后启动 mall-web，截图如下：