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SpringMVC

1.SpringMVC介绍

springMVC是一种基于Java实现MVC模型的轻量级Web框架

优点：

• 使用简单，开发便捷（相较于Servelt）

• 灵活性强

使用SpringMVC技术开发web程序流程

1. 创建web工程（Maven结构）

2. 设置tomcat服务器，加载web工程（tomcat插件）

3. 导入坐标（SpringMVC+Servlet）

4. 定义处理请求的功能类（UserController）

5. 设置请求映射（配置映射关系）

6. 将SpringMVC设定加载到Tomcat容器中

SpringMVC入门案例

1. 导入SpringMVC坐标与Servlet坐标

   <dependency><groupId>javax.servlet</groupId><artifactId>servlet-api</artifactId><version>2.5</version><scope>provided</scope></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>5.1.5.RELEASE</version>
   </dependency>

2. 初始化SpringMVC环境

   @Configuration
   public class SpringMvcConfig {
   }

3. 创建SpringMVC控制器类（等同于Servlet功能）

   @Controller
   public class UserController {@RequestMapping("/save")@ResponseBodypublic String save(){System.out.println("user save ...");return "{'info':'springmvc'}";}
   }

4. 设定SpringMVC加载对应的bean

   @Configuration
   @ComponentScan("com.zkw.controller")
   public class SpringMvcConfig {
   }

5. 初始化Servlet容器，加载SpringMVC环境，并设置SpringMVC请求拦截的路径

   public class ServletContainersInitConfig extends AbstractDispatcherServletInitializer {@Overrideprotected WebApplicationContext createServletApplicationContext() {AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();ctx.register(SpringMvcConfig.class);return ctx;}
   ​@Overrideprotected String[] getServletMappings() {return new String[]{"/"}; //所有的请求都归springmvc处理}
   ​@Overrideprotected WebApplicationContext createRootApplicationContext() {return null;}
   }

部分代码介绍：

1. @RequestMapping：设置当前控制器方法请求访问路径

2. @ResponseBody：设置当前控制器方法响应内容为当前返回值，无需解析

3. createServletApplicationContext

   protected WebApplicationContext createServletApplicationContext()//加载容器 {AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();//初始化容器对象ctx.register(SpringMvcConfig.class);//将配置注册到容器中return ctx;}

4. getServletMappings：设定那些请求归springmvc处理

2.bean的加载控制

因为功能不同，如何避免Spring错误的加载到S平日那个MVC的bean？

A：加载Spring控制的bean的时候，排除掉SpringMVC控制的bean

方式一：设定扫描范围为com.zkw，排除掉controller包内的bean

@Configuration
@ComponentScan({"com.zkw.service","com.zkw.dao"})
public class SpringConfig{
}

方式二：设定扫描范围为精准范围，如service包、dao包等

@Configuration
@ComponentScan(value="com.zkw",excludeFilters = @ComponentScan.Filtertype = FilterType.ANNOTATION,//排除方法classes = Controller.class)
public class SpringConfig{
}

简化开发

public class ServletContainersInitConfig extend AbstractAnnotationConfigDispatcherServeletInitializer{protected Class<?>[] getServletConfigClasses() {return new Class[]{SpringMvcConfig.class};}protected String[] getServletMappings(){return new String[]{"/"};}protected Class<?>[] getRootConfigClasses(){return new Class[0];}
}

3.请求与响应

1.请求映射路

@Controller
@RequestMapping("/user")
public class UserController {@RequestMapping("/save")@ResponseBodypublic String save(){System.out.println("user save ...");return "{'module':'user save'}";}@RequestMapping("/delete")@ResponseBodypublic String delete(){System.out.println("user delete ...");return "{'module':'user delete'}";}
​
}

2.参数传递

Get请求传参

普通参数：url地址传参

public class UserController {@RequestMapping("/commonParam")@ResponseBodypublic String commonParam(String name){System.out.println("普通参数传递 name==>" + name);return "{'module':'common param'}";}
}

Post请求传参

传参汉字会出现乱码问题，添加字符过滤器

//乱码处理
​
@Override
protected Filter[] getServletFilters() {CharacterEncodingFilter filter = new CharacterEncodingFilter();filter.setEncoding("UTF-8");return new Filter[]{filter};
}

普通参数：请求参数名与形参名不同

public class UserController {@RequestMapping("/commonParam")@ResponseBodypublic String commonParam(@RequestParam("name") String userName){System.out.println("普通参数传递 name ==>" + userName);return "{'module':'common param'}";}
}

集合参数

public class UserController {@RequestMapping("/listParam")@ResponseBodypublic String commonParam(@RequestParam List<String> likes){System.out.println("集合参数传递 likes ==>" + likes);return "{'module':'list param'}";}
}

传递json数据

1. 导入JSON坐标

   <dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId><version>2.9.0</version>
   </dependency>

2. @EnableWebMvc：开启自动转换json对象的支持

3. 集合参数：json格式 在方法体里不在RequestParam中

   public String listParamForJson(@RequestBody List<String> likes) {System.out.println("list common(json)参数传递 list ==>" + likes);return "{'module':'list common for json param'}";
   }

POJO参数：JSON格式

{"name":"itcast","age";"15"
}

@RequestBody和@RequestParam区别

• 区别：

  • @RequestParam用于接收url地址传参，表单传参

  • @RequestBody用于接收json数据

• 应用

  • 后期开发中，发送json格式数据为主，@RequestBody应用较广

  • 如果发送非json格式数据，选用@RequestParam接收请求参数

日期类型参数传递

接收形参时，根据不同的日期格式设置不同的接收方式

@RequestMapping("/dataParam")
@ResponseBody
public String dataParam(Date date,@DateTimeFormat(pattern="yyyy-MM-dd")Date date1,@DateTimeFormat(pattern="yyyy/MM/dd HH:mm:ss")Date date2){System.out.println(...);System.out.println(...);System.out.println(...);return "{'module':'data param'}";}

3.响应

• 响应页面

  @RequestMapping("/toPage")
  public String toPage(){return "page.jsp";
  }

• 响应文本数据

  @RequestMapping("/toPage")
  @ResponseBody
  public String toPage(){return "page.jsp";
  }

• 响应json数据

  @RequestMapping("/toJsonPOJO")
  @ResponseBody
  public String toJsonPOJO(){User user = new User();user.setName("赵云");user.setAge(41);return user;
  }

• 响应json数据，集合

  @RequestMapping("/toJsonPOJO")
  @ResponseBody
  public String toJsonPOJO(){User user = new User();user.setName("赵云");user.setAge(41);return user;User user2 = new User();user2.setName("神赵云");user2.setAge(40);List<User> userList = new ArrayList<User>();userList.add(user1);userList.add(user2);return userList;
  }

4.REST风格

REST（Representational State Transfer），表现形式状态转换

可以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

1. 设置http请求动作（RequestMethod）

   public class UserController {@RequestMapping(value = "/users",method = RequestMethod.POST)@ResponseBodypublic String save(){System.out.println("user save ...");return "{'module':'user save'}";}@RequestMapping(value = "/users",method = RequestMethod.PUT)@ResponseBodypublic String update(){System.out.println("user update ...");return "{'module':'user update'}";}@RequestMapping(value = "/users",method = RequestMethod.GET)@ResponseBodypublic String getAll(){System.out.println("user getAll ...");return "{'module':'user getAll'}";}
   }

2. 设定请求参数（"/users/{id}" 和 @PathVariable)

   @RequestMapping(value = "/users/{id}",method = RequestMethod.DELETE)@ResponseBodypublic String delete(@PathVariable Integer id){System.out.println("user delete ..." + id);return "{'module':'user delete'}";}@RequestMapping(value = "/users/{id}",method = RequestMethod.GET)@ResponseBodypublic String getById(@PathVariable Integer id){System.out.println("user getById ...");return "{'module':'user getById'}";

@PathVariable

用于接收路径参数，使用{参数名称}描述路劲参数

RESTful快速开发

@RestController
@RequestMapping("/books")
public class UserController {@PostMappingpublic String save(){System.out.println("user save ...");return "{'module':'user save'}";}@PutMappingpublic String update(){System.out.println("user update ...");return "{'module':'user update'}";}@DeleteMappingpublic String delete(@PathVariable Integer id){System.out.println("user delete ..." + id);return "{'module':'user delete'}";}@GetMappingpublic String getById(@PathVariable Integer id){System.out.println("user getById ...");return "{'module':'user getById'}";}@GetMappingpublic String getAll(){System.out.println("user getAll ...");return "{'module':'user getAll'}";}
}

@RestController:@Controller和@ResponseBody两个注解组合功能