目录
前言
在上一篇的博客中我们初步的了解学习SpringMVC基础知识，我们继续来学习SpringMVC常用注解、参数传递、返回值，希望这篇博客能够帮助到您！！！
一、常用注解
一、SpringMVC之常用注解
1.Controller：用于标识一个类是SpringMVC的控制器，它接收用户请求并返回相应的视图或数据。2.RequestMapping：用于映射请求的URL路径到控制器的处理方法。可以在类级别和方法级别使用，用于处理各种HTTP请求（GET、POST、PUT等）。
标注在方法上
用于方法上，表示在类的父路径下追加方法上注解中的地址将会访问到该方法
@Controller public class HelloController { @RequestMapping("/requestTest") public String requestTest(){ return "index"; } }标注在类和方法上
用于类上，表示类中的所有响应请求的方法都是以该地址作为父路径。注意：当你在类上添加RequestMapping注解后，如果要请求映射，就意味着请求要先映射到标注类的位置，然后再映射到该类的方法上
@Controller @RequestMapping("/hello") public class HelloController { @RequestMapping("/requestTest") public String requestTest(){ return "index"; } }
3.RequestParam：用于将请求参数绑定到处理方法的参数上。可以指定参数的名称、是否必须以及默认值。
4.PathVariable：用于将URL中的占位符参数绑定到处理方法的参数上。通常用于RESTful风格的URL。
5.ResponseBody：用于将方法的返回值直接作为HTTP响应的内容返回给客户端。适用于返回JSON、XML等非HTML格式的数据。
6.ModelAttribute：用于将请求参数绑定到一个对象上，并将该对象添加到模型中，可以在视图中获取。
7.RequestHeader：注解可以获取指定的请求头信息。
8.CookieValue：主要是将请求的Cookie数据，映射到功能处理方法的参数上。
具体操作
1.将pom.xml文件中原有的log4j的插件依赖替换为Slf4j的插件依赖
替换 pom.xml文件，（这里全部替换，未免大家copy错）
<?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.yx</groupId>
<artifactId>yx_ssm</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>
<name>yx_ssm Maven Webapp</name>
<!-- FIXME change it to the project's website -->
<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>
<maven.compiler.plugin.version>3.7.0</maven.compiler.plugin.version>
<!--添加jar包依赖-->
<!--1.spring 5.0.2.RELEASE相关-->
<spring.version>5.0.2.RELEASE</spring.version>
<!--2.mybatis相关-->
<mybatis.version>3.4.5</mybatis.version>
<!--mysql-->
<mysql.version>5.1.44</mysql.version>
<!--pagehelper分页jar依赖-->
<pagehelper.version>5.1.2</pagehelper.version>
<!--mybatis与spring集成jar依赖-->
<mybatis.spring.version>1.3.1</mybatis.spring.version>
<!--3.dbcp2连接池相关 druid-->
<commons.dbcp2.version>2.1.1</commons.dbcp2.version>
<commons.pool2.version>2.4.3</commons.pool2.version>
<!--4.log日志相关-->
<!-- 替换为slf4j日志相关 -->
<log4j2.version>2.9.1</log4j2.version>
<log4j2.disruptor.version>3.2.0</log4j2.disruptor.version>
<slf4j.version>1.7.13</slf4j.version>
<!--5.其他-->
<junit.version>4.12</junit.version>
<servlet.version>4.0.0</servlet.version>
<lombok.version>1.18.2</lombok.version>
<!-- jstl+standard -->
<jstl.version>1.2</jstl.version>
<standard.version>1.1.2</standard.version>
<!-- spring -->
<spring.version>5.0.2.RELEASE</spring.version>
</properties>
<dependencies>
<!--1.spring相关-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-orm</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aspects</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring.version}</version>
</dependency>
<!--2.mybatis相关-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>${mybatis.version}</version>
</dependency>
<!--mysql-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql.version}</version>
</dependency>
<!--pagehelper分页插件jar包依赖-->
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper</artifactId>
<version>${pagehelper.version}</version>
</dependency>
<!--mybatis与spring集成jar包依赖-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>${mybatis.spring.version}</version>
</dependency>
<!--3.dbcp2连接池相关-->
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-dbcp2</artifactId>
<version>${commons.dbcp2.version}</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-pool2</artifactId>
<version>${commons.pool2.version}</version>
</dependency>
<!--4.log日志相关依赖-->
<!--核心log4j2jar包-->
<!--替换为 slf4j包 -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>jcl-over-slf4j</artifactId>
<version>${slf4j.version}</version>
<scope>runtime</scope>
</dependency>
<!--核心log4j2jar包-->
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-api</artifactId>
<version>${log4j2.version}</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-core</artifactId>
<version>${log4j2.version}</version>
</dependency>
<!--用于与slf4j保持桥接-->
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-slf4j-impl</artifactId>
<version>${log4j2.version}</version>
</dependency>
<!--web工程需要包含log4j-web，非web工程不需要-->
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-web</artifactId>
<version>${log4j2.version}</version>
<scope>runtime</scope>
</dependency>
<!--需要使用log4j2的AsyncLogger需要包含disruptor-->
<dependency>
<groupId>com.lmax</groupId>
<artifactId>disruptor</artifactId>
<version>${log4j2.disruptor.version}</version>
</dependency>
<!--5.其他-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>${servlet.version}</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>compile</scope>
</dependency>
<!-- spring mvc相关依赖 -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>jstl</groupId>
<artifactId>jstl</artifactId>
<version>${jstl.version}</version>
</dependency>
<dependency>
<groupId>taglibs</groupId>
<artifactId>standard</artifactId>
<version>${standard.version}</version>
</dependency>
</dependencies>
<build>
<finalName>yx_ssm</finalName>
<resources>
<!--解决mybatis-generator-maven-plugin运行时没有将XxxMapper.xml文件放入target文件夹的问题-->
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.xml</include>
</includes>
</resource>
<!--解决mybatis-generator-maven-plugin运行时没有将jdbc.properites文件放入target文件夹的问题-->
<resource>
<directory>src/main/resources</directory>
<includes>
<include>jdbc.properties</include>
<include>*.xml</include>
</includes>
</resource>
</resources>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>${maven.compiler.plugin.version}</version>
<configuration>
<source>${maven.compiler.source}</source>
<target>${maven.compiler.target}</target>
<encoding>${project.build.sourceEncoding}</encoding>
</configuration>
</plugin>
<plugin>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-maven-plugin</artifactId>
<version>1.3.2</version>
<dependencies>
<!--使用Mybatis-generator插件不能使用太高版本的mysql驱动 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql.version}</version>
</dependency>
</dependencies>
<configuration>
<overwrite>true</overwrite>
</configuration>
</plugin>
<plugin>
<artifactId>maven-clean-plugin</artifactId>
<version>3.1.0</version>
</plugin>
<!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->
<plugin>
<artifactId>maven-resources-plugin</artifactId>
<version>3.0.2</version>
</plugin>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.0</version>
</plugin>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.22.1</version>
</plugin>
<plugin>
<artifactId>maven-war-plugin</artifactId>
<version>3.2.2</version>
</plugin>
<plugin>
<artifactId>maven-install-plugin</artifactId>
<version>2.5.2</version>
</plugin>
<plugin>
<artifactId>maven-deploy-plugin</artifactId>
<version>2.8.2</version>
</plugin>
</plugins>
</build>
</project>
测试插件是否成功安装
二、参数传递
配置运行项目
1. 基础类型+String类型
package com.lya.web;
import com.lya.model.Book;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;
import javax.servlet.http.HttpServletRequest;
import java.util.Map;
/**
* @author 程序猿-小李哥
* @site www.xiaolige.com
* @company 猪八戒有限集团
* @create 2023-09-05-15:50
*/
@Slf4j
@Controller
@RequestMapping("/param")
public class ParamController {
@RequestMapping("/hello1")
public String index(Integer bid ,String bname) {
log.info("简单参数：bid:{},bname:{} ",bid,bname);
return "index";
}
}2. 复杂类型
@RequestMapping("/hello2")
public String hello2(Book book , HttpServletRequest httpServletRequest) {
log.info("复杂参数：bid:{},bname:{} ",
httpServletRequest.getParameter("bid"),
httpServletRequest.getParameter("bname"));
log.info("复杂参数：book:{} ",
book.toString());
return "index";
}
3. @RequestParam
@RequestMapping("/hello3")
public String toHello3(@RequestParam Integer bid,
@RequestParam(required = false,value = "price") Integer bookPrice,
@RequestParam("bookName") String bname){
log.info(">>>> 使用@RequestParam注解传递参数：{},{},{}", bid,bname,bookPrice);
return "index";
}
控制台输出
不会输出任何结果。
注：@RequestParam的required属性
该参数是否为必传项。默认是true，表示请求中一定要传入对应的参数，否则会报404错误，如果设置为false时，当请求中没有此参数，将会默认为null,而对于基本数据类型的变量，则必须有值，这时会抛出空指针异常。如果允许空值，则接口中变量需要使用包装类来声明。
4. @PathVariable
@RequestMapping("/hello4/{bid}")
public String toHello4(@PathVariable("bid") Integer bid){
log.info(">>>> 使用@PathVariable注解传递参数：{}", bid);
return "index";
}5.@RequestBody
<jackson.version>2.9.3</jackson.version>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>${jackson.version}</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>${jackson.version}</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-annotations</artifactId>
<version>${jackson.version}</version>
</dependency>测试代码
@RequestMapping("/hello5")
public String toHello5(@RequestBody Map map){
System.out.println(map);
return "index";
}请使用postman或者apipost/eolink等工具发送请求数据。因为浏览器无法携带集合参数，所以借助第三方软件进行测试。
6. @RequestHeader
@RequestMapping("/hello7")
public String toHello7(Book book, @RequestBody Map map, @RequestHeader("jwt") String jwt){
System.out.println(map);
System.out.println(book);
System.out.println(jwt);
return "index";
}三、方法返回值
创建一个ReturnController类模拟测试案例
一：void
借助工具类
package com.lya.untils;
import com.fasterxml.jackson.databind.ObjectMapper;
import javax.servlet.http.HttpServletResponse;
import java.io.PrintWriter;
public class ResponseUtil {
public static void write(HttpServletResponse response,Object o)throws Exception{
response.setContentType("text/html;charset=utf-8");
PrintWriter out=response.getWriter();
out.println(o.toString());
out.flush();
out.close();
}
public static void writeJson(HttpServletResponse response,Object o)throws Exception{
ObjectMapper om = new ObjectMapper();
write(response, om.writeValueAsString(o));
}
}代码
package com.lya.web;
import com.lya.untils.ResponseUtil;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import javax.servlet.http.HttpServletResponse;
import java.util.HashMap;
import java.util.Map;
/**
* @author 程序猿-小李哥
* @site www.xiaolige.com
* @company 猪八戒有限集团
* @create 2023-09-06-15:50
*/
@Controller
@RequestMapping("/rs")
public class ReturnController {
@RequestMapping("/hello1")
public void hello1(HttpServletResponse response){
Map<String,Object> map=new HashMap<>();
map.put("code",200);
map.put("msg","成功添加...");
try {
ResponseUtil.writeJson(response,map);
} catch (Exception e) {
e.printStackTrace();
}
}
}二：String
该返回值类型在前面的参数传递中已经体现了。
三：String+model
<%--
Created by IntelliJ IDEA.
User: 86158
Date: 2023/9/5
Time: 15:49
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>Hello</h1>
名称：${name}
地址：${address}
</body>
</html>测试代码
package com.lya.web;
import com.lya.untils.ResponseUtil;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.HashMap;
import java.util.Map;
/**
* @author 程序猿-小李哥
* @site www.xiaolige.com
* @company 猪八戒有限集团
* @create 2023-09-06-16:50
*/
@Controller
@RequestMapping("/rs")
public class ReturnController {
@RequestMapping("/hello2")
public String hello2(Model model,
HttpServletRequest request){
model.addAttribute("name","刘彬彬");
request.setAttribute("address","傻鸟");
return "index";
}
}四：ModelAndView
测试代码
package com.lya.web;
import com.lya.untils.ResponseUtil;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.HashMap;
import java.util.Map;
/**
* @author 程序猿-小李哥
* @site www.xiaolige.com
* @company 猪八戒有限集团
* @create 2023-09-05-15:50
* 测试类
*/
@Controller
@RequestMapping("/rs")
public class ReturnController {
@RequestMapping("/hello3")
public ModelAndView hello3(){
ModelAndView mv=new ModelAndView();
mv.addObject("sign","耗子没有摸鱼");
mv.setViewName("index");
return mv;
}
}四、页面跳转
转发（forward:path）和重定向（redirect:path）这两种跳转方式将会绕开视图解析器的前缀和后缀；还有就是如果是在同一controller中则不用使用"/"从根目录开始,而如果是在不同的controller则一定要从根目录开始。
path为请求处理方法名，而非逻辑视图名。
-
转发（地址栏不变）
@RequestMapping("/helloPage1") public String toHelloPage1(){ System.out.println("helloPage1"); return "forward:toHello2"; }
它相当于“request.getRequestDispatcher("url").forward(request,response)”。使用转发，既可以转发到jsp， 也可以转发到其他的控制器方法。
-
重定向（地址栏改变）
@RequestMapping("/helloPage2")
public String toHelloPage2(){
System.out.println("helloPage2");
return "redirect:toHello2";
}它相当于“response.sendRedirect(url)”。需要注意的是，如果重定向到jsp页面，则jsp页面不能写在WEB-INF目录中，否则无法找到。
跳其它的controller
@RequestMapping("/helloPage3")
public String toHelloPage3(){
System.out.println("helloPage3");
return "forward:/demo/hello";
}
@RequestMapping("/helloPage4")
public String toHelloPage4(){
System.out.println("helloPage4");
return "redirect:/demo/hello";
}
