07【SpringMVC常用注解】
文章目录
- 一、SpringMVC常用注解
-
- 1.1 @PathVariable
- 1.2 @RequestParam
- 1.3 @CookieValue
- 1.4 @RequestHeader
- 1.5 @SessionAttribute
- 1.6 @SessionAttributes
- 1.7 @RequestAttribute
- 1.8 @ModelAttribute
一、SpringMVC常用注解
搭建项目，引入Maven依赖：
<dependencies>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-webmvcartifactId>
<version>5.2.9.RELEASEversion>
dependency>
<dependency>
<groupId>org.apache.tomcatgroupId>
<artifactId>tomcat-apiartifactId>
<version>8.5.41version>
dependency>
<dependency>
<groupId>org.projectlombokgroupId>
<artifactId>lombokartifactId>
<version>1.18.18version>
dependency>
dependencies>
- 实体类：
package com.dfbz.entity;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
/**
* @author lscl
* @version 1.0
* @intro:
*/
@Data
@AllArgsConstructor
@NoArgsConstructor
public class City {
private Integer id; // 城市id
private String cityName; // 城市名称
private Double GDP; // 城市GDP,单位亿元
private Boolean capital; // 是否省会城市
}
- web.xml：
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
version="2.5">
<filter>
<filter-name>characterEncodingFilterfilter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilterfilter-class>
filter>
<filter-mapping>
<filter-name>characterEncodingFilterfilter-name>
<url-pattern>/*url-pattern>
filter-mapping>
<servlet>
<servlet-name>dispatcherservlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServletservlet-class>
<init-param>
<param-name>contextConfigLocationparam-name>
<param-value>classpath:springmvc.xmlparam-value>
init-param>
servlet>
<servlet-mapping>
<servlet-name>dispatcherservlet-name>
<url-pattern>/url-pattern>
servlet-mapping>
web-app>
- springmvc.xml：
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
<context:component-scan base-package="com.dfbz"/>
<mvc:default-servlet-handler/>
<mvc:annotation-driven />
beans>
1.1 @PathVariable
作用：用于接收Rest风格请求的路径参数；将方法形参和url 的占位符进行绑定；
- 源码：
@Target({ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface PathVariable {
@AliasFor("name")
String value() default "";
@AliasFor("value")
String name() default "";
boolean required() default true;
}
name/value：当url中的占位符和方法形参名称不一致时，可以使用name/value属性进行绑定；required：是否必须提供占位符，默认为true；
- 测试：
package com.dfbz.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
* @author lscl
* @version 1.0
* @intro: @PathVariable注解
*/
@Controller
@RequestMapping("/demo01")
public class Demo01Controller_PathVariable {
@GetMapping("/{id}/{name}")
public void test(
@PathVariable Integer id,
@PathVariable(value = "name") String cityName, // 把url上的name值赋值给cityName
HttpServletResponse response) throws IOException {
response.setContentType("text/html;charset=utf8");
response.getWriter().write("id: "+id+"
");
response.getWriter().write("cityName: "+cityName+"
");
}
@GetMapping("/{id}")
public void test2(
@PathVariable Integer id,
@PathVariable(value = "aaa",required = false) String cityName, // 没有aaa占位符也没关系
HttpServletResponse response) throws IOException {
response.setContentType("text/html;charset=utf8");
response.getWriter().write("id: "+id+"
");
response.getWriter().write("cityName: "+cityName+"
");
}
}
1.2 @RequestParam
作用：接收前端提交的参数（POST/GET提价都可以接收）；当接收的参数的变量名与表单的name属性不一样时可以使用@RequestParam来绑定，同时可以封装其他类型的对象，如List、Set、Map
- 源码：
@Target({ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface RequestParam {
@AliasFor("name")
String value() default "";
@AliasFor("value")
String name() default "";
boolean required() default true;
String defaultValue() default "\n\t\t\n\t\t\n\ue000\ue001\ue002\n\t\t\t\t\n";
}
name/value：当前端传递的参数名称和方法形参名称不一致时，可以使用name/value属性进行绑定；required：是否必须提供传递此参数，默认为true；defaultValue：如果前端没有传递此参数，默认为defaultValue的值；
- 测试：
package com.dfbz.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;
import java.util.Map;
/**
* @author lscl
* @version 1.0
* @intro: @RequestParam注解
*/
@Controller
@RequestMapping("/demo02")
public class Demo02Controller_RequestParam {
@GetMapping("/demo01")
public void demo01(Integer id,
@RequestParam("name") String cityName, // 将前端传递的name参数与cityName进行绑定(name参数必须传递)
HttpServletResponse response) throws IOException {
response.setContentType("text/html;charset=utf8");
response.getWriter().write("id: " + id + "
");
response.getWriter().write("cityName: " + cityName + "
");
}
@GetMapping("/demo02")
public void demo02(@RequestParam(required = false) Integer id, // id可以不传递
@RequestParam(defaultValue = "guangzhou") String cityName, // cityName参数如果没有传递默认为guangzhou
HttpServletResponse response) throws IOException {
response.setContentType("text/html;charset=utf8");
response.getWriter().write("id: " + id + "
");
response.getWriter().write("cityName: " + cityName + "
");
}
/**
* map类型
* @param maps
* @param response
* @throws IOException
*/
@GetMapping("/demo03")
public void demo03(@RequestParam Map<String, Object> maps,
HttpServletResponse response) throws IOException {
response.setContentType("text/html;charset=utf8");
response.getWriter().write("id: " + maps.get("id") + "
");
response.getWriter().write("cityName: " + maps.get("cityName") + "
");
}
/**
* List类型
* @param ids
* @param response
* @throws IOException
*/
@PostMapping("/demo04")
public void demo04(@RequestParam("ids") List<Integer> ids,
HttpServletResponse response) throws IOException {
response.setContentType("text/html;charset=utf8");
response.getWriter().write("id: " + ids.toString() + "
");
}
}
1.3 @CookieValue
作用：获取Cookie中的数据
- 源码：
@Target({ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface CookieValue {
@AliasFor("name")
String value() default "";
@AliasFor("value")
String name() default "";
boolean required() default true;
String defaultValue() default "\n\t\t\n\t\t\n\ue000\ue001\ue002\n\t\t\t\t\n";
}
name/value：Cookie中的参数名称和方法形参名称不一致时，可以使用name/value属性进行绑定；required：是否必须提供此参数Cookie参数，默认为true；defaultValue：如果Cookie中没有此参数，默认为defaultValue的值；
- 测试：
package com.dfbz.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.CookieValue;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
* @author lscl
* @version 1.0
* @intro: @CookieValue
*/
@Controller
@RequestMapping("/demo03")
public class Demo03Controller_CookieValue {
@GetMapping("/demo01")
public void demo01(@CookieValue String JSESSIONID,
HttpServletResponse response) throws IOException {
response.setContentType("text/html;charset=utf8");
response.getWriter().write("JSESSIONID: " + JSESSIONID + "
");
}
}
1.4 @RequestHeader
作用：获取请求头中的数据
- 源码：
@Target({ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface RequestHeader {
@AliasFor("name")
String value() default "";
@AliasFor("value")
String name() default "";
boolean required() default true;
String defaultValue() default "\n\t\t\n\t\t\n\ue000\ue001\ue002\n\t\t\t\t\n";
}
- 测试代码：
package com.dfbz.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestHeader;
import org.springframework.web.bind.annotation.RequestMapping;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
* @author lscl
* @version 1.0
* @intro: @RequestHeader
*/
@Controller
@RequestMapping("/demo04")
public class Demo04Controller_RequestHeader {
@GetMapping("/demo01")
public void demo01(@RequestHeader String Host,
HttpServletResponse response) throws IOException {
response.setContentType("text/html;charset=utf8");
response.getWriter().write("Host: " + Host + "
");
}
}
1.5 @SessionAttribute
作用：从session中获取一个值封装到参数中
- 源码：
@Target({ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface SessionAttribute {
@AliasFor("name")
String value() default "";
@AliasFor("value")
String name() default "";
boolean required() default true;
}
- 测试代码：
package com.dfbz.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.SessionAttribute;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
/**
* @author lscl
* @version 1.0
* @intro: @SessionAttribute
*/
@Controller
@RequestMapping("/demo05")
public class Demo05Controller_SessionAttribute {
@GetMapping("/demo01")
public String demo01(HttpSession session) throws IOException {
session.setAttribute("loginUser", "zhangsan");
return "/demo05/demo02";
}
/**
* 从session中取出loginUser(必须要有这个属性)
* @param loginUser
* @param response
* @throws IOException
*/
@GetMapping("/demo02")
public void demo02(@SessionAttribute String loginUser,
HttpServletResponse response) throws IOException {
response.setContentType("text/html;charset=utf8");
response.getWriter().write("loginUser: " + loginUser + "
");
}
}
1.6 @SessionAttributes
作用：把BindingAwareModelMap中的指定的key或者指定的属性的值也存入一份进session域
tips：@SessionAttributes注解并不能把存入request域的值也存入session中
- 源码：
@Target({ElementType.TYPE}) // 标注在类上的
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface SessionAttributes {
@AliasFor("names")
String[] value() default {};
@AliasFor("value")
String[] names() default {};
Class<?>[] types() default {};
}
- 测试代码：
package com.dfbz.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.SessionAttributes;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.util.Map;
/**
* @author lscl
* @version 1.0
* @intro: @SessionAttributes
*/
// 把BindingAwareModelMap中的username属性和所有的Integer类型的属性都存入一份在session中
@SessionAttributes(value = {"username"}, types = {Integer.class})
@Controller
@RequestMapping("/demo06")
public class Demo06Controller_SessionAttributes {
@GetMapping("/demo01")
public String demo01(Map<String, Object> map, HttpServletRequest request) throws IOException {
map.put("username", "admin");
map.put("password", "123");
map.put("age", 23);
map.put("tall", 1.78);
// 存入request域的值不能被存入session
request.setAttribute("test",111);
return "/demo06/demo02";
}
@GetMapping("/demo02")
public void demo02(HttpSession session, HttpServletResponse response) throws IOException {
response.setContentType("text/html;charset=utf8");
response.getWriter().write("username: " + session.getAttribute("username") + "
");
response.getWriter().write("password: " + session.getAttribute("password") + "
");
response.getWriter().write("age: " + session.getAttribute("age") + "
");
response.getWriter().write("tall: " + session.getAttribute("tall") + "
");
response.getWriter().write("test: " + session.getAttribute("test") + "
");
}
}
1.7 @RequestAttribute
作用：获取request域中的数据；
测试代码：
package com.dfbz.controller;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
* @author lscl
* @version 1.0
* @intro:
*/
@Controller
@RequestMapping("/demo07")
public class Demo07Controller_RequestAttribute {
@GetMapping("/demo01")
public String demo01(Model model) throws IOException {
// 在请求域中添加几个属性
model.addAttribute("username", "zhangsan");
model.addAttribute("password", "123");
return "/demo07/demo02";
}
@GetMapping("/demo02")
public void demo02(
@RequestAttribute("username") String name, // 获取请求域中的username属性值
@RequestAttribute String password, // 获取请求域中password属性值
HttpServletResponse response
) throws IOException {
response.getWriter().println("username: "+name);
response.getWriter().println("password: "+password);
}
}
1.8 @ModelAttribute
作用：@ModelAttribute注解可以作用于方法和参数上
-
作用于方法上：在执行Controller其他所有方法之前执行@ModelAttribute注解标注的方法
-
作用于参数上：获取ModelAttribute标注的方法中BingMap中的某个值到某个属性到形参上，并且此次的BingMap会传递到下一个handler方法；BingMap中的值以前端传递的为准，如果前端传递了参数则以前端为准，如果没有传递参数则保持@ModelAttribute标注方法中的默认值；
-
源码：
@Target({ElementType.PARAMETER, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface ModelAttribute {
@AliasFor("name")
String value() default "";
@AliasFor("value")
String name() default "";
boolean binding() default true;
}
- 测试代码：
package com.dfbz.controller;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Map;
/**
* @author lscl
* @version 1.0
* @intro: @ModelAttribute注解作用与方法上
*/
@Controller
@RequestMapping("/demo08")
public class Demo08Controller_ModelAttribute {
@ModelAttribute
public void model(Model model, ModelMap modelMap, Map map) {
model.addAttribute("username", "zhangsan");
modelMap.addAttribute("password", "admin");
map.put("email","[email protected]");
}
@RequestMapping("/demo01")
public void demo01(
@ModelAttribute("username") String username, // 注意: 形参名和BindingMap中的key一样也要写
@ModelAttribute("password") String password,
@ModelAttribute("email") String email,
HttpServletResponse response
) throws Exception {
response.getWriter().println("username: " + username);
response.getWriter().println("password: " + password);
response.getWriter().println("email: " + email);
}
}
Tips：
@ModelAttribute只能获取BingMap中的数据，不能获取request中的数据；
应用场景：现在需要修改一个City信息，有某些应用信息前端不提交（默认为null），
- 表单：
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
Title
- Controller：
package com.dfbz.controller;
import com.dfbz.entity.City;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import java.io.IOException;
import java.util.Map;
/**
* @author lscl
* @version 1.0
* @intro: @ModelAttribute注解作用与方法上
*/
@Controller
@RequestMapping("/demo09")
public class Demo09Controller_ModelAttribute02 {
/**
* ModelAttribute标注的方法在所有的handler方法之前执行
*
* @param maps
* @throws IOException
*/
@ModelAttribute
public void model(Map<String, Object> maps) throws IOException {
maps.put("city", new City(1, "南宁", 4700.00, true));
System.out.println("model方法执行了...");
}
@RequestMapping("/demo01")
public void demo01(@ModelAttribute("city") City city, HttpServletResponse response) throws Exception{ // 如果前端没有传递则以@ModelAttribute标注的为准,如果传递了则以前端参数为准
response.setContentType("text/html;charset=utf8");
response.getWriter().println(city);
}
}