不使用spring boot创建spring rest服务

Question

我遵循了关于构建REEST服务https://spring.io/guides/gs/rest-service/的spring.io入门教程。问题是，本教程只解释了如何使用spring boot生成嵌入了tomcat的独立运行jar。

有没有一种方法可以从头开始创建一个项目来生成一个war来进行部署，例如在一个已经存在的tomcat实例上？

PS:我之前在stackoverflow上发现了一个关于同样问题的线程Spring RESTful Service as a WAR instead of JAR in Tomcat。问题是，被接受的答案和建议并不能完全解决我的问题，因为我不是在寻找修改standalone-app spring boot项目的方法，以便它能在外部tomcat容器上工作，而是希望找到一个根本不涉及spring boot的“更干净”的解决方案。(我不太确定在这里该怎么做，因为我在stackoverflow上还是个新手。我希望打开一个新问题是正确的过程)。

Answer 1

创建rest控制器不需要Spring Boot。

请遵循spring框架文档，了解如何设置MVC https://docs.spring.io/spring/docs/current/spring-framework-reference/web.html#spring-web。

MVC设置( DispatcherServlet)取决于您的spring版本，您可以使用xml，也可以通过编程方式进行设置：https://docs.spring.io/spring/docs/current/spring-framework-reference/web.html#mvc-servlet

设置完成后，您可以向应用程序添加rest控制器。请注意，rest控制器( @RestController注释)是一个组合了@ResponseBody和@Controller的构造型注释，换句话说，控制器在响应主体中返回一个对象，而不是返回一个视图。

这是一个完美的例子，解释了我上面所说的：http://www.programming-free.com/2014/01/spring-mvc-40-restful-web-services.html

Answer 2

下面是另一个示例：

目录布局：

.
├── ./pom.xml
└── ./src
    └── ./src/main
        ├── ./src/main/java
        │   └── ./src/main/java/biz
        │       └── ./src/main/java/biz/tugay
        │           └── ./src/main/java/biz/tugay/restfulspring
        │               └── ./src/main/java/biz/tugay/restfulspring/config
        │                   ├── ./src/main/java/biz/tugay/restfulspring/config/RestfulHello.java
        │                   └── ./src/main/java/biz/tugay/restfulspring/config/WebAppInitalizer.java
        └── ./src/main/webapp
            └── ./src/main/webapp/WEB-INF
                └── ./src/main/webapp/WEB-INF/web.xml

pom.xml

<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/maven-v4_0_0.xsd">

    <modelVersion>4.0.0</modelVersion>
    <groupId>biz.tugay</groupId>
    <artifactId>restfulSpring</artifactId>

    <packaging>war</packaging>
    <version>1.0-SNAPSHOT</version>
    <name>restfulSpring Maven Webapp</name>

    <url>http://maven.apache.org</url>

    <dependencies>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.0.1</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>4.3.16.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>4.3.16.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>4.3.16.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>4.3.16.RELEASE</version>
        </dependency>
    </dependencies>

    <build>
        <finalName>restfulSpring</finalName>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.eclipse.jetty</groupId>
                <artifactId>jetty-maven-plugin</artifactId>
                <version>9.2.1.v20140609</version>
            </plugin>
        </plugins>
    </build>

</project>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
                             http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
         version="3.0">
</web-app>

WebAppInitalizer.java

package biz.tugay.restfulspring.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

@Configuration
@EnableWebMvc
@ComponentScan("biz.tugay.restfulspring")
public class WebAppInitalizer extends AbstractAnnotationConfigDispatcherServletInitializer {

    @Override
    protected String[] getServletMappings() {
        return new String[]{"/*"};
    }

    @Override
    protected Class<?>[] getRootConfigClasses() {
        return new Class<?>[]{WebAppInitalizer.class};
    }

    @Override
    protected Class<?>[] getServletConfigClasses() {
        return new Class[0];
    }
}

RestfulHello.java

package biz.tugay.restfulspring.config;

import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping(value = "/")
public class RestfulHello {

    @RequestMapping(value = "hello")
    public ResponseEntity<String> sayHello() {
        final HttpHeaders httpHeaders= new HttpHeaders();
        httpHeaders.setContentType(MediaType.APPLICATION_JSON);
        return new ResponseEntity<String>("{\"msg\": \"Hello World\"}", httpHeaders, HttpStatus.OK);
    }
}

构建并运行：

mvn clean install
mvn jetty:start

测试：

> GET /hello HTTP/1.1
> Host: localhost:8080
> User-Agent: insomnia/5.15.0
> Accept: */*
< HTTP/1.1 200 OK
< Date: Fri, 27 Apr 2018 00:06:07 GMT
< Content-Type: application/json
< Content-Length: 22
< Server: Jetty(9.2.1.v20140609)

接收的内容：

{
    "msg": "Hello World"
}