springboot 学习（一）搭建

男娘i 2022-05-28 10:20 218阅读 0赞

### 一个请求 ###

添加springboot依赖

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.0.RELEASE</version>
      </parent>
    
      <dependencies>
        <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>
      </dependencies>
    
      <build>
        <plugins>
          <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
          </plugin>
        </plugins>
      </build>

启动类

@ComponentScan(basePackages = "com.cyh.controller")
    @EnableAutoConfiguration
    public class HelloWorld { 
        public static void main(String[] args) {
            SpringApplication.run(HelloWorld.class, args);
        }
    }

创建两个控制器， hello1 ， hello2

@RestController
    public class HelloController { 
    
        @RequestMapping("/hello1")
        public String hello(){
            return "hello1";
        }
    }

@RestController
    public class Hello2Controller { 
    
        @RequestMapping("/hello2")
        public String hello(){
            return "hello2";
        }
    }

分别请求localhost:8080/hello1， localhost:8080/hello2 网页成功显示hello1和hello2。

### 加载静态资源 ###

访问图片css等静态资源可以将文件放在resource下  
![这里写图片描述][70]

访问图片请求地址为： [http://localhost:8080/image/1.png][http_localhost_8080_image_1.png]

### 异常扑获 ###

修改hello1请求， /0引发一个500错误。

@RequestMapping("/hello1")
        public String hello(){
            int i = 12/ 0;
            return "hello1";
        }

创建异常扑获类。

@ControllerAdvice
    public class GlobalExeceptionHandler { 
        @ExceptionHandler(RuntimeException.class)
        @ResponseBody
        public Map<String, Object> exceptionHandler(){
            Map<String, Object> result = new HashMap<String, Object>();
            result.put("code","500");
            result.put("msg","系统错误");
            return result;
        }
    }

### 使用freeMarker ###

freeMarker：  
FreeMarker是一款模板引擎， 即一种基于模板和要改变的数据。

引入freeMarker的依赖包

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

在templates下创建ftl文件  
![这里写图片描述][70 1]

<!DOCTYPE html>
    <html>
    <head lang="en">
        <title>Spring Boot Demo - FreeMarker</title>
    </head>
    <body>
    <h1> ${name}</h1>
    </body>
    </html>

通过控制器访问index.ftl, “name”的值将会传到页面$\{name\}中

@Controller
    public class HelloController { 
        @RequestMapping("/index")
        public String hello(ModelMap map){
            map.addAttribute("name", "my");
            return "index";
        }
    }

在index.ftl是使用freemarker标签

<!DOCTYPE html>
    <html>
    <head lang="en">
        <title>Spring Boot Demo - FreeMarker</title>
    </head>
    <body>
    <h1> ${name}</h1>
    
    <#if sex==1>
        男
    <#elseif sex==2>
        女
    <#else >
        其他
    </#if>
    
    <#list userlist as user>
        ${user}
    </#list>
    
    </body>
    </html>

修改控制器如下：

@Controller
    public class HelloController { 
        @RequestMapping("/index")
        public String hello(ModelMap map){
            map.addAttribute("name", "my");
            map.put("sex", 1);
            List<String> userlist = new ArrayList<>();
            userlist.add("张三");
            userlist.add("李四");
            userlist.add("王五");
            map.put("userlist",userlist);
            return "index";
        }
    }

### 访问jsp页面 ###

在WEB-INF下创建jsp页面， 还需要配置application.properties  
myjsp.jsp

<html>
    <body>
    <h2>Hello ${name} </h2>
    </body>
    </html>

application.properties, 配置jsp页面的位置

spring.mvc.view.prefix=/WEB-INF/jsp/
    spring.mvc.view.suffix=.jsp

![这里写图片描述][70 2]

添加依赖

<dependency>
          <groupId>javax.servlet</groupId>
          <artifactId>javax.servlet-api</artifactId>
        </dependency>
    
        <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-tomcat</artifactId>
          <scope>provided</scope>
        </dependency>
    
        <dependency>
          <groupId>org.apache.tomcat.embed</groupId>
          <artifactId>tomcat-embed-jasper</artifactId>
        </dependency>
    
        <dependency>
          <groupId>javax.servlet</groupId>
          <artifactId>jstl</artifactId>
        </dependency>

控制层

@Controller
    public class HelloController { 
        @RequestMapping("/myjsp")
        public String hello(ModelMap map){
            map.addAttribute("name", "my");
            return "/myjsp";
        }
    }

[70]: /images/20220528/2cd8a39bebaa42be8a415169693bd1ed.png
[http_localhost_8080_image_1.png]: http://localhost:8080/image/1.png
[70 1]: /images/20220528/b71fbfbecb96439f8c6f2a4b19697cdd.png
[70 2]: /images/20220528/13bfd806ae4a4622990ba5917e749461.png