使用 spring 注解实现 史上最简单的 spring mvc 内嵌 tomcat 启动

不用 spring boot 和xml文件，只使用 spring 注解实现最简单的 spring mvc 内嵌 tomcat 启动

主要用到的注解
@ComponentScan 扫描类添加到AnnotationConfigWebApplicationContext中

其他注解
@Service、@Autowired、@RestController、@GetMapping

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.gcy.demo</groupId>
    <artifactId>java-thread-demo</artifactId>
    <version>1.0.0</version>
    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.2.3.RELEASE</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-core</artifactId>
            <version>8.5.32</version>
            <scope>compile</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>8</source>
                    <target>8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
    <properties>
        <java.version>1.8</java.version>
    </properties>

</project>

MyService.java

package com.gcy.demo.javathreaddemo.myservlet;

import org.springframework.stereotype.Service;

@Service
public class MyService {
    public String getTest(){
        return "这是最简单的web项目测试";
    }
}

MyController

package com.gcy.demo.javathreaddemo.myservlet;

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

@RestController
public class MyController {


    @Autowired
    private MyService myService;
    
    //设置 produces 防止中文乱码
    @GetMapping(value = "/test",produces = "application/json; charset=utf-8")
    public String test(){
        String str = myService.getTest();
        System.out.println("------MyController "+str+"----------");
        return str;
    }
}

MyWebApplication.java 最主要启动类

package com.gcy.demo.javathreaddemo.myservlet;

import org.apache.catalina.LifecycleException;
import org.apache.catalina.Wrapper;
import org.apache.catalina.startup.Tomcat;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;
import java.io.File;

@ComponentScan
public class MyWebApplication {

    public static void main(String[] args) throws LifecycleException {
        File base = new File(System.getProperty("java.io.tmpdir"));

        Tomcat tomcat = new Tomcat();
        tomcat.setPort(8080);
        tomcat.addContext("/",base.getAbsolutePath());
        tomcat.start();

        //容器添加需要启动的ApplicationContext
        AnnotationConfigWebApplicationContext annotationConfigWebApplicationContext
                = new AnnotationConfigWebApplicationContext();
        annotationConfigWebApplicationContext.register(MyWebApplication.class);
        annotationConfigWebApplicationContext.refresh();

        //创建 servlet 并添加到 tomcat 中
        DispatcherServlet dispatcherServlet = new DispatcherServlet(annotationConfigWebApplicationContext);

        Wrapper wrapper = tomcat.addServlet("/","app",dispatcherServlet);
        wrapper.setLoadOnStartup(1);
        wrapper.addMapping("/");


        tomcat.getServer().await();
    }

}

请求地址：​​http://localhost:8080/test​​

请求成功