# SpringMVCStudy

**Repository Path**: amespaces/spring-mvcstudy

## Basic Information

- **Project Name**: SpringMVCStudy
- **Description**: 学习springmvc
- **Primary Language**: Unknown
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2022-03-30
- **Last Updated**: 2022-07-04

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# SpringMVC

## 简介

轻量级web开发框架

### 入门案例

- 导入坐标

  ```xml
   <dependencies>
      <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>3.1.0</version>
        <scope>provided</scope>
      </dependency>
      <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>5.2.8.RELEASE</version>
      </dependency></dependencies>
  ```

- 初始化servlet容器配置类：加载SpringMvc环境，并设置SpringMvc请求拦截的路径

  ```java
  public class ServletContainersInitConfig extends AbstractDispatcherServletInitializer {
      protected WebApplicationContext createServletApplicationContext() {
          AnnotationConfigWebApplicationContext annotationConfigWebApplicationContext = new AnnotationConfigWebApplicationContext();
          annotationConfigWebApplicationContext.register(SpringMvcConfig.class);
          return annotationConfigWebApplicationContext;
      }
  
      protected String[] getServletMappings() {
          return new String[]{"/"};//所有请求
      }
  
      protected WebApplicationContext createRootApplicationContext() {
          return null;
      }
  }
  
  ```

  - AbstractDispatcherServletInitializer类是SpringMVC提供的快速初始化Web3.0容器的抽象类
  - 提供三个接口方法供用户实现
    1. createServletApplicationContext()方法，创建servlet容器时加载SpringMVC对应的bean并放入
    2. getServletMappings()方法，设定SpringMvc对应的请求映射路径，设置/表示拦截所有的请求，任意请求都将转入到SpringMvc进行处理
    3. createRootApplicationContext()方法，创建servlet容器时需要加载非SpringMvc对应的bean，

- 控制器类:设定请求方法的返回值为字符串类型，并返回自定义的json数据

  ```java
  @Controller
  public class UserController {
      @RequestMapping("/save")//设置当前控制器方法请求访问路径
      @ResponseBody//返回结果为提供的结果
      public String save(){
          System.out.println("user save ...");
          return "{'info':'springmvc'}";
      }
  }
  ```


## 请求与响应

## Rest风格

### 简介

- REST(Representational State Transfer)表现形式状态转换
- 优点
  - 隐藏资源的访问行为，无法通过地址得知对资源是何种操作
  - 书写简化
- 根据REST风格对资源进行访问称为RESTful 
- 注解
  - **@RequestBody**用于接收url地址传参或者表单传参
  - **@RequsetParam**用于接收json数据
  - **@PathVariable**用于接收路径参数，使用{参数名称}描述路径参数
- 应用
  - 当参数超过一个以json为主，@RequestBody应用较广
  - 如果非json数据，选用@RequestParam接收请求参数
  - 采用@Restful进行开发参数较少时，采用@PathVariable

## 快速开发

- @RestController：等同于@Controller与@ResponseBody两个注解
- PostMapping
- GetMapping
- @RequestBody

### 案例(放行！！别的资源)

```java
@Configuration
@ComponentScan({"com.itheima.controller","com.itheima.config"})
@EnableWebMvc
public class SpringMvcConfig {
}

```

静态资源访问不到这里走pages,不走mvc

```java
@Configuration
public class SpringMvcSupport extends WebMvcConfigurationSupport {
    @Override
    protected void addResourceHandlers(ResourceHandlerRegistry registry) {
        //当访问pages/的文件时不走mvc
        registry.addResourceHandler("/pages/**").addResourceLocations("/pages/");
    }
}

```

前端页面通过异步提交访问后台控制器

```html
 //添加
                saveBook () {
                    axios.post("/books",this.formData).then((res)=>{

                    });
                },

                //主页列表查询
                getAll() {
                   axios.get("/books").then((result)=>{
                        this.dataList=result.data;
                   });
                },

```

# SSM整合

## SSM整合流程

1. 创建工程
2. SSM整合
   - Spring
     - SpringConfig
   - Mybatis
     - MybatisConfig
     - JdbcConfig
     - Jdbc.properties
   - SpringMVC
     - ServletConfig
     - SpringMvcConfig
3. 功能模块
   - 表与实体类
   - dao(接口+自动代理)
   - service(接口+实现类)
     - 业务层接口测试(整合JUnit)
   - controller
     - 表现层接口测试（PostMan)

### 导入坐标

```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.itheima</groupId>
  <artifactId>springmvc_08_ssm</artifactId>
  <version>1.0-SNAPSHOT</version>
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.tomcat.maven</groupId>
        <artifactId>tomcat7-maven-plugin</artifactId>
        <version>2.2</version>
        <configuration>
          <path>/</path>
          <port>80</port>
        </configuration>
      </plugin></plugins>
  </build>
  <dependencies>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>5.2.8.RELEASE</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-jdbc</artifactId>
      <version>5.2.8.RELEASE</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-test</artifactId>
      <version>5.2.8.RELEASE</version>
    </dependency>

    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.5.5</version>
    </dependency>

    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis-spring</artifactId>
      <version>2.0.5</version>
    </dependency>

    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.46</version>
    </dependency>

    <dependency>
      <groupId>com.alibaba</groupId>
      <artifactId>druid</artifactId>
      <version>1.1.12</version>
    </dependency>

    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
      <scope>provided</scope>
    </dependency>

    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.13</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>2.11.4</version>
    </dependency>

  </dependencies>
  <packaging>war</packaging>


</project>

```

### 整合

### 接口测试

```java

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = SpringConfig.class)
public class BookServiceTest {
    @Autowired
    private BookService bookService;
    @Test
    public void testGetById(){
        Book book = bookService.getById(1);
        System.out.println(book);
    }

    @Test
    public void testGetAll(){
        List<Book> list= bookService.getAll();
        System.out.println(list);
    }
}

```

### 与前端数据传输

Code

```java
package com.itheima.controller;

public class Code {

    public static final Integer SAVE_OK=20011;
    public static final Integer DELETE_OK=20021;
    public static final Integer UPDATE_OK=20031;
    public static final Integer GET_OK=20041;
    public static final Integer SAVE_ERR=20010;
    public static final Integer DELETE_ERR=20020;
    public static final Integer UPDATE_ERR=20030;
    public static final Integer GET_ERR=20040;

}

```

Result

```java
package com.itheima.controller;

public class Result {
    private Object data;
    private Integer code;
    private String msg;

    public Result() {
    }

    public Result(Integer code, Object data ) {
        this.data = data;
        this.code = code;
    }

    public Result(Integer code, Object data, String msg) {
        this.data = data;
        this.code = code;
        this.msg = msg;
    }

    @Override
    public String toString() {
        return "Result{" +
                "data=" + data +
                ", code=" + code +
                ", msg='" + msg + '\'' +
                '}';
    }

    public Object getData() {
        return data;
    }

    public void setData(Object data) {
        this.data = data;
    }

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }
}

```

### 异常处理

```java
@RestControllerAdvice
public class ProjectExceptionAdvice {
    @ExceptionHandler(Exception.class )
    public void doException(Exception e){


    }
}

```

#### 项目异常处理方案

- 项目异常分类(BusinessException)
  - 规范的用户行为产生的异常
  - 不规范
- 系统异常(Systemexception)
  - 项目运行过程中可预计且无法避免的异常
- 其他异常(Exception)
  - 编程人员未预期到的异常

拦截并处理异常

```java
@RestControllerAdvice
public class ProjectExceptionAdvice {
    @ExceptionHandler(SystemException.class )
    public Result doSystemException(SystemException e){
        //记录日志
        //发送消息给运维
        //发送邮件给开发人员
        return new Result(e.getCode(),null,e.getMessage());

    }

    @ExceptionHandler(BusinessException.class )
    public Result doBusinessException(BusinessException e){
        return new Result(e.getCode(),null,e.getMessage());

    }

    @ExceptionHandler(Exception.class)
    public Result doException(Exception e){
        //记录日志
        //发送消息给运维
        //发送邮件给开发人员，e对象发送给开发人员
        return new Result(Code.SYSTEM_TIMEOUT_ERR,null,"系统繁忙，请稍后再试");
    }
}
```

# 拦截器

## 概念

拦截器(interceptor)是一种动态拦截方法调用的机制，在SpringMvc中动态拦截控制器方法的执行

- 作用
  - 在指定的方法前后调用前后执行预先设定的代码
  - 阻止原始方法的执行

## 拦截器与过滤器的区别

- 归属不同：Filter属于Servlet技术，Interceptor属于SpringMvc技术
- 拦截内容不同：Filter对所用访问进行增强，Interceptor仅针对SpringMvc的访问进行增强



## 入门案例

1.声明拦截器的bean,并实现HandlerInterceptot接口，需要扫描加 载bean

```java
@Component

public class ProjectInterceptior implements HandlerInterceptor {

    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        return false;
    }

    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

    }

    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
}
```

2.定义配置类，基层继承WebMvcConfigurationSupport,实现addInterceptor方法(需要扫描加载配置类)

```java
@Configuration
public class SpringMvcSupport extends WebMvcConfigurationSupport {
    @Autowired
    private ProjectInterceptior projectInterceptior;
    @Override
    protected void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/pages/**").addResourceLocations("/pages/");
    }

    @Override
    protected void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(projectInterceptior).addPathPatterns("/books");
    }
}

```

3.使用标准的接口WebMvcConfigurer简化开发(侵入式强)

```java
@Configuration
@ComponentScan({"com.itheima.controller"})
@EnableWebMvc
public class SpringMvcConfig implements WebMvcConfigurer {
    @Autowired
    private ProjectInterceptior projectInterceptior;
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(projectInterceptior).addPathPatterns("/books");
    }
}

```

## 拦截器执行顺序

- preHandle
  - return true
    - controller
    - postHandle
    - afterCompletion
  - return false
    - 结束

## 拦截器参数

- handle
- ModelAndView
- Exception ex
- request
- response

## 多拦截器执行顺序

- 当配置多个拦截器时，形成拦截器链

- 拦截器的运行顺序参照拦截器添加顺序为准

- 当拦截器中出现对原始处理器的拦截，后面的拦截器均终止运行
###运行顺序

- preHandle:与配置顺序相同，必运行
- postHandle：与配置顺序相反，可能不运行
- afterCompletion:与配置顺序相同，可能不运行