一个简单的springboot项目

项目整体包结构

步骤1：创建

　　这个地址可以查看如何创建一个空白项目：https://www.cnblogs.com/HelloM/p/14241721.html。

步骤2：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">
    <groupId>cn.howj</groupId>
    <artifactId>product-service</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <modelVersion>4.0.0</modelVersion>
    <packaging>war</packaging>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.3.RELEASE</version>
        <relativePath/>
    </parent>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
                
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <optional>true</optional> <!-- 这个需要为 true 热部署才有效 -->
        </dependency>    
        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>4.3.1</version>
        </dependency>                
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>        
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <configuration>
                    <failOnMissingWebXml>false</failOnMissingWebXml>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

步骤3：启动类ProductServiceApplication 

package cn.how2j.springboot;

import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;

import cn.hutool.core.util.NetUtil;
@SpringBootApplication
public class ProductServiceApplication {
    public static void main(String[] args) {
        int port = 8080;
        if(!NetUtil.isUsableLocalPort(port)) {
            System.err.printf("端口%d被占用了，无法启动%n", port );
            System.exit(1);
        }
        new SpringApplicationBuilder(ProductServiceApplication.class).properties("server.port=" + port).run(args);
    }
}

步骤4：实体类product

package cn.how2j.springboot.pojo;

public class Product {

    private int id;
    private String name;
    private int price;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getPrice() {
        return price;
    }
    public void setPrice(int price) {
        this.price = price;
    }
    public Product(int id, String name, int price) {
        super();
        this.id = id;
        this.name = name;
        this.price = price;
    }
}

步骤5：service业务处理

package cn.how2j.springboot.service;

import java.util.ArrayList;
import java.util.List;

import org.springframework.stereotype.Service;

import cn.how2j.springboot.pojo.Product;

@Service
public class ProductService {
    public List<Product> listProducts(){
        List<Product> ps = new ArrayList<>();
        ps.add(new Product(1,"product a", 50));
        ps.add(new Product(2,"product b", 100));
        ps.add(new Product(3,"product c", 150));
        return ps;
    }
}

步骤6：controller访问

package cn.how2j.springboot.web;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

import cn.how2j.springboot.pojo.Product;
import cn.how2j.springboot.service.ProductService;
 
@Controller
public class ProductController {
    @Autowired ProductService productService
    @RequestMapping("/products")
    public Object products(Model m) {
        List<Product> ps = productService.listProducts();
        m.addAttribute("ps", ps);
        return "products";
    }
}

步骤7：视图资源配置product.html

<!DOCTYPE HTML>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <title>products</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
    <style>

        table {
            border-collapse:collapse;
            width:400px;
            margin:20px auto;
        }
        td,th{
            border:1px solid gray;
        }
    </style>        
</head>
<body>
<div class="workingArea">
    <table>
        <thead>
            <tr>
                <th>id</th>
                <th>产品名称</th>
                <th>价格</th>
            </tr>
        </thead>
        <tbody>
            <tr th:each="p: ${ps}">
                <td th:text="${p.id}"></td>
                <td th:text="${p.name}"></td>
                <td th:text="${p.price}"></td>
            </tr>
        </tbody>
    </table>
</div>
</body>  
</html>

步骤8：配置文件properties

#thymeleaf 配置
spring.thymeleaf.mode=HTML5
spring.thymeleaf.encoding=UTF-8
spring.thymeleaf.content-type=text/html
#缓存设置为false, 这样修改之后马上生效，便于调试
spring.thymeleaf.cache=false
#上下文
server.context-path=/

步骤9：启动Application，访问测试项目是否运行成功

　　访问地址：http://localhost:8080/products

总结

这个项目很简单，就做了两件事：1.提供数据 2.展示数据。这就是典型的单体架构。
项目的缺点：1.如果想要修改数据的代码，就必须把整个项目都重新打包，部署。维护不方便
2.如果提供数据部分出现了问题，比如有的人把代码一不小心写错了，或者代码内部也抛出了异常，那整个项目都不能使用，展示数据的服务也宕掉了。
3.单体服务，性能瓶颈突破不了，当高并发访问量来的时候，只能有一个访问端口，服务器容器崩溃。