SpringMVC项目请求(请求映射路径)

àì夳堔傛蜴生んèń 2024-04-01 13:45 25阅读 0赞

SpringMVC是web层的框架，主要的作用是接收请求、接收数据、响应结果，分成四部分内容:

*  请求映射路径
 *  请求参数
 *  日期类型参数传递
 *  响应json数据

本次介绍的是设置请求映射路径。

### 1. 环境准备 ###

*  创建一个Web的Maven项目
 *  pom.xml添加Spring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.dcxuexi</groupId>
          <artifactId>springmvc_03_request_mapping</artifactId>
          <version>1.0-SNAPSHOT</version>
          <packaging>war</packaging>
        
          <name>springmvc_03_request_mapping Maven Webapp</name>
          
          <url>http://www.example.com</url>
        
          <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</groupId>
              <artifactId>spring-webmvc</artifactId>
              <version>5.2.15.RELEASE</version>
            </dependency>
            <dependency>
              <groupId>javax.servlet</groupId>
              <artifactId>javax.servlet-api</artifactId>
              <version>3.1.0</version>
              <scope>provided</scope>
            </dependency>
        
          </dependencies>
        
          <build>
            <plugins>
              <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <version>2.1</version>
                <configuration>
                  <port>80</port>
                  <path>springmvc</path>
                </configuration>
              </plugin>
            </plugins>
          </build>
        </project>
 *  创建对应的配置类SpringMvcConfig和ServletContainersInitConfig
    
        @Configuration
        @ComponentScan("com.dcxuexi.controller")
        public class SpringMvcConfig {
              
        }
    
        public class ServletContainersInitConfig extends AbstractAnnotationConfigDispatcherServletInitializer {
              
            @Override
            protected Class<?>[] getRootConfigClasses() {
              
                return new Class[]{
              SpringMvcConfig.class};
            }
        
            @Override
            protected Class<?>[] getServletConfigClasses() {
              
                return new Class[0];
            }
        
            @Override
            protected String[] getServletMappings() {
              
                return new String[]{
              "/"};
            }
        }
 *  编写UserController和CityController
    
        @Controller
        public class UserController {
              
        
            @RequestMapping("/select")
            @ResponseBody
            public String select(){
              
                System.out.println("UserController select ,running .....");
                return "{\"username\":\"xiaochuang\"}";
            }
        
            @RequestMapping("/delete")
            @ResponseBody
            public String delele(){
              
                System.out.println("UserController delele ,running .....");
                return "user xiaochuang is deleted.";
            }
        }
    
        @Controller
        public class CityController {
              
        
            @RequestMapping("/select")
            @ResponseBody
            public String select(){
              
                System.out.println("CityController select ,running .....");
                return "{\"cityName\":\"shanghai\"}";
            }
        
            @RequestMapping("/delete")
            @ResponseBody
            public String delele(){
              
                System.out.println("CityController delele ,running .....");
                return "city shanghai is deleted.";
            }
        }

最终创建好的项目结构如下:

![在这里插入图片描述][42cc30a7ef974bb0b57d5337a40d32dc.png_pic_center]

把环境准备好后，启动Tomcat服务器，后台会报错:

![在这里插入图片描述][38d5d87eb16c4130ad5d421dcf9949c4.png_pic_center]

从错误信息可以看出:

*  UserController有一个select方法，访问路径为`http://localhost/springmvc/select`
 *  CityController也有一个select方法，访问路径为`http://localhost/springmvc/select`
 *  当访问`http://localhost/springmvc/select`的时候，到底是访问UserController还是CityController?

### 2. 问题分析 ###

团队多人开发，每人设置不同的请求路径，冲突问题该如何解决?

解决思路:为不同模块设置模块名作为请求路径前置

对于UserController模块的select,将其访问路径设置`http://localhost/springmvc/user/select`

对于CityController模块的select,将其访问路径设置`http://localhost/springmvc/city/select`

这样在同一个模块中出现命名冲突的情况就比较少了。

### 3. 设置映射路径 ###

#### 步骤1:修改Controller ####

@Controller
    public class UserController {
        
    
        @RequestMapping("/user/select")
        @ResponseBody
        public String select(){
        
            System.out.println("UserController select ,running .....");
            return "{\"username\":\"xiaochuang\"}";
        }
    
        @RequestMapping("/user/delete")
        @ResponseBody
        public String delele(){
        
            System.out.println("UserController delele ,running .....");
            return "user xiaochuang is deleted.";
        }
    }

@Controller
    public class CityController {
        
    
        @RequestMapping("/city/select")
        @ResponseBody
        public String select(){
        
            System.out.println("CityController select ,running .....");
            return "{\"cityName\":\"shanghai\"}";
        }
    
        @RequestMapping("/city/delete")
        @ResponseBody
        public String delele(){
        
            System.out.println("CityController delele ,running .....");
            return "city shanghai is deleted.";
        }
    }

启动Tomcat服务器:

![在这里插入图片描述][b624c79e985c4e018cd2f96642846614.png_pic_center]

问题是解决了，但是每个方法前面都需要进行修改，写起来比较麻烦而且还有很多重复代码，如果/user后期发生变化，所有的方法都需要改，耦合度太高。

#### 步骤2:优化路径配置 ####

优化方案:

@Controller
    @RequestMapping("/user")
    public class UserController {
        
    
        @RequestMapping("/select")
        @ResponseBody
        public String select(){
        
            System.out.println("UserController select ,running .....");
            return "{\"username\":\"xiaochuang\"}";
        }
    
        @RequestMapping("/delete")
        @ResponseBody
        public String delele(){
        
            System.out.println("UserController delele ,running .....");
            return "user xiaochuang is deleted.";
        }
    }

@Controller
    @RequestMapping("/city")
    public class CityController {
        
    
        @RequestMapping("/select")
        @ResponseBody
        public String select(){
        
            System.out.println("CityController select ,running .....");
            return "{\"cityName\":\"shanghai\"}";
        }
    
        @RequestMapping("/delete")
        @ResponseBody
        public String delele(){
        
            System.out.println("CityController delele ,running .....");
            return "city shanghai is deleted.";
        }
    }

**注意:**

*  当类上和方法上都添加了`@RequestMapping`注解，前端发送请求的时候，要和两个注解的value值相加匹配才能访问到。
 *  @RequestMapping注解value属性前面加不加`/`都可以

扩展小知识:

对于PostMan如何觉得字小不好看，可以使用`ctrl+=`调大，`ctrl+-`调小。

### 项目代码 ###

*  [gitee 代码下载][gitee]
 *  [github 代码下载][github]

[42cc30a7ef974bb0b57d5337a40d32dc.png_pic_center]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/01/d5588faebbff4bad87503c83770454e7.png
[38d5d87eb16c4130ad5d421dcf9949c4.png_pic_center]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/01/e17ae96fc52a43e08749e0c2e10b95e1.png
[b624c79e985c4e018cd2f96642846614.png_pic_center]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/01/6b9a4d6ac5554120b67bb6ba21a13bfe.png
[gitee]: https://gitee.com/DchuangDB/SpringMVCProject
[github]: https://github.com/dcbut/SpringMVCProject