SpringMVC使用注解实现登录

心已赠人 2023-10-17 08:01 12阅读 0赞

**一、使用Component\\Controller\\Service\\Repository四大注解类：**

•@Component 是通用标注

•@Controller 标注 web 控制器

•@Service 标注 Servicec 层的服务

•@Respository 标注 DAO层的数据访问

•这些注解都是类级别的，可以不带任何参数，也可以带一个参数，代表bean名字，在进行注入的时候就可以通过名字进行注入了。

**二、@Resource和@Autowired注解的异同**

• @Autowired默认按类型装配，默认情况下必须要求依赖对象必须存在，如果要允许null值，可以设置它的required属性为false，

例如：@Autowired(required=false)，如果我们想使用名称装配可以结合@Qualifier注解进行使用

• @Resource，默认安装名称进行装配，名称可以通过name属性进行指定，如果没有指定name属性，当注解写在字段上时，默认取字段名进行安装名称查找 ，如果注解写在setter方法上默认取属性名进行装配 。当找不到与名称匹配的bean时才按照类型进行装配。但是需要注意的是，如果name属性一旦指定，就只会按照名称进行装配。

**三、其他注解类**

（1） PathVariable注解类

@RequestMapping注解中使用占位符的情况下，需要使用@PathVariable注解指定占位符参数

（2） RequestParam注解类

表单提交数据时，可以通过这个注解来解决request.getParameter("uname")

（3） CookieValue注解类

如果要保存字符串数据，可以使用这个注解

（4） SessionAttributes注解类

如果希望在多个请求之间公用某个模型属性数据，则可以在控制器类标注一个@SessionAttributes，SpringMVC会将模型中对应的属性暂存到HttpSerssion中除了SessionAttributes，还可以直接用原生态的request.getSession()来处理

（5） ResponseBody注解类

用于将Controller的方法返回的对象，通过适当的HttpMessageConverter（转换器）转换为指定格式后，写入到Response对象的body数据区；  返回如json、xml等时使用

（6）RequestHeader注解类

@RequestHeader注解，可以把Request请求header部分的值绑定到方法的参数上

**四、应用注解来实现登录**

1)创建工程如下：

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**(2)配置文件pom.xml(主要是修改：dependencies的内容)**

<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>springmvc</groupId>
    	<artifactId>springmvc</artifactId>
    	<version>0.0.1-SNAPSHOT</version>
    	<packaging>war</packaging>
    	<name />
    	<description />
    	<properties>
    		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    	</properties>
    	<dependencies>
    
    		<dependency>
    			<groupId>org.springframework</groupId>
    			<artifactId>spring-webmvc</artifactId>
    			<version>4.1.6.RELEASE</version>
    		</dependency>
    
    		<dependency>
    			<groupId>org.springframework</groupId>
    			<artifactId>spring-tx</artifactId>
    			<version>4.1.6.RELEASE</version>
    		</dependency>
    		<dependency>
    			<groupId>javax.servlet</groupId>
    			<artifactId>javax.servlet-api</artifactId>
    			<version>3.1-b05</version>
    		</dependency>
    
    		
    
    		<dependency>
    			<groupId>com.fasterxml.jackson.core</groupId>
    			<artifactId>jackson-core</artifactId>
    			<version>2.1.0</version>
    		</dependency>
    		<dependency>
    			<groupId>com.fasterxml.jackson.core</groupId>
    			<artifactId>jackson-databind</artifactId>
    			<version>2.1.0</version>
    		</dependency>
    		<dependency>
    			<groupId>com.fasterxml.jackson.core</groupId>
    			<artifactId>jackson-annotations</artifactId>
    			<version>2.1.0</version>
    		</dependency>
    		
    	</dependencies>
    	<build>
    		<finalName>springmvc</finalName>
    		<sourceDirectory>${basedir}/src</sourceDirectory>
    		<outputDirectory>${basedir}/WebRoot/WEB-INF/classes</outputDirectory>
    		<resources>
    			<resource>
    				<directory>${basedir}/src</directory>
    				<excludes>
    					<exclude>**/*.java</exclude>
    				</excludes>
    			</resource>
    		</resources>
    		<plugins>
    			<plugin>
    				<artifactId>maven-war-plugin</artifactId>
    				<configuration>
    					<webappDirectory>${basedir}/WebRoot</webappDirectory>
    					<warSourceDirectory>${basedir}/WebRoot</warSourceDirectory>
    				</configuration>
    			</plugin>
    			<plugin>
    				<artifactId>maven-compiler-plugin</artifactId>
    				<configuration>
    					<source>1.6</source>
    					<target>1.6</target>
    				</configuration>
    			</plugin>
    		</plugins>
    	</build>
    </project>

**(3)spring-mvc.xml文件**

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans" xmlns:p="http://www.springframework.org/schema/p" 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"
        xmlns:util="http://www.springframework.org/schema/util"
        xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
    		http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
    		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
    		http://www.springframework.org/schema/util  http://www.springframework.org/schema/util/spring-util-3.0.xsd
    		">
    	
    	<context:component-scan base-package="com.hlx.*" />
    
       <bean
            class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
            <property name="messageConverters">
                <util:list >
                	
                    <ref bean="mappingJackson2HttpMessageConverter" />
                </util:list>
    
            </property>
        </bean>
     
     
      <bean id="mappingJackson2HttpMessageConverter" class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
        <property name="supportedMediaTypes">
         <list>
          <value>text/html;charset=UTF-8</value>
         </list>
        </property>
      </bean>
      
    </beans>

（4）web.xml文件同前一个springmvc中的文件相同

（5）JSP页面(省略）

(6) 创建src/main/java 下 bean,dao.service,controller

package com.hlx.bean;
    
    public class User {
    	private String uname;
    	private String upass;
    
    	public String getUname() {
    		return uname;
    	}
    
    	public void setUname(String uname) {
    		this.uname = uname;
    	}
    
    	public String getUpass() {
    		return upass;
    	}
    
    	public void setUpass(String upass) {
    		this.upass = upass;
    	}
    	
    	
    
    	public User() {
    		super();
    	}
    
    	public User(String uname, String upass) {
    		super();
    		this.uname = uname;
    		this.upass = upass;
    	}
    
    	@Override
    	public String toString() {
    		return "User [uname=" + uname + ", upass=" + upass + "]";
    	}
    
    	
    }

package com.hlx.dao;
    
    import org.springframework.stereotype.Repository;
    
    import com.hlx.bean.User;
    
    @Repository
    public class UserDao {
    
    	/**
    	 * 根据用户名来查询
    	 * @param uname
    	 * @return
    	 */
    	public User selectByName(String uname) {
    		if ("admin".equals(uname)) {
    			User user = new User("admin", "aaa");
    			return user;
    		}
    		return null;
    	}
    
    }

package com.hlx.service;
    
    import javax.annotation.Resource;
    
    import org.springframework.stereotype.Service;
    import org.springframework.web.servlet.ModelAndView;
    
    import com.hlx.bean.User;
    import com.hlx.dao.UserDao;
    
    @Service
    public class UserService {
    
    	@Resource
    	private UserDao userDao;
    
    	/**
    	 * 登录处理
    	 * @param uname
    	 * @param upass
    	 * @return
    	 * @throws Exception
    	 */
    	public User doLogin(String uname, String upass) throws Exception {
    		// 判断
    		if (uname == null || "".equals(uname)) {
    			throw new Exception("用户名不能为空！");
    		}
    		if (upass == null || "".equals(upass)) {
    			throw new Exception("密码不能为空！");
    		}
    
    		User user = userDao.selectByName(uname);
    
    		if (user == null) {
    			throw new Exception("用户名不存在！");
    		}
    
    		if (!user.getUpass().equals(upass)) {
    			throw new Exception("密码不正确！");
    		}
    
    		return user;
    
    	}
    }

package com.hlx.controller;
    
    import javax.annotation.Resource;
    import javax.servlet.http.HttpServletRequest;
    
    import org.springframework.stereotype.Controller;
    import org.springframework.ui.ModelMap;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import org.springframework.web.bind.annotation.RequestParam;
    import org.springframework.web.bind.annotation.SessionAttributes;
    import org.springframework.web.bind.support.SessionStatus;
    
    
    import com.hlx.bean.User;
    import com.hlx.service.UserService;
    
    @Controller
    @SessionAttributes("user") //保存user对象
    public class UserController {
    
    	//业务层
    	@Resource
    	private UserService userService;
    	
    	@RequestMapping("login")
    	public String toLoginPage(){
    		return "jsp/login.jsp";
    	}
    	/**
    	 * 
    	 * @param uname 表单传过来的参数
    	 * @param upass 
    	 * @param request  请求对象
    	 * @return
    	 */
    	@RequestMapping(value="dologin",method=RequestMethod.POST)
    	public String doLogin(@RequestParam String uname,@RequestParam String upass,HttpServletRequest request,ModelMap map){
    		try {
    			//调用方法
    		 User user=userService.doLogin(uname,upass);
    		 
    		 //存入user
    		 map.put("user", user);
    		 ///
    		 
    		} catch (Exception e) {
    			// TODO: handle exception
    			request.setAttribute("error", e.getMessage());  //提示错误消息
    			return "jsp/login.jsp";  //返回登录页面
    		}
    		return "jsp/success.jsp";
    	}
    	
    	/**
    	 * 退出
    	 * @return
    	 */
    	@RequestMapping("dologout")
    	public String doLogout(SessionStatus status){
    		//清空session
    		status.setComplete();
    		//返回登录页面
    		return "jsp/login.jsp";
    	}
    	
    }

效果：

![Center 1][]

![Center 2][]

package com.hlx.controller;
    
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.ResponseBody;
    
    import com.hlx.bean.User;
    
    @Controller
    public class JSONController {
    
    	@ResponseBody
    	@RequestMapping("/getJson")
    	public User getUserinfo(){
    		User user = new User("mike", "123456");
    		return user;
    	}
    }

效果：

![Center 3][]

package com.hlx.controller;
    
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.ResponseBody;
    
    import com.hlx.bean.User;
    
    @Controller
    public class PathVariableControler {
    	
    	@ResponseBody
    	@RequestMapping("/pathvariable/{uname}")
    	public User test1(@PathVariable String uname){
    		User user = new User();
    		user.setUname("john");
    		return user;
    	}
    	@ResponseBody
    	@RequestMapping("/pathvariable2/{intval}")
    	public User test1(@PathVariable Integer intval){
    		User user = new User();
    		user.setUname(intval + "");
    		return user;
    	}
    
    }

效果：

![Center 4][]

注意：这里是数字

![Center 5][]

注意：这里只能是数字,不能字符串，否则找不到页面!

![Center 6][]

总结：

**应用了四大注解类Component、Controller、Service、Repository；掌握PathVariable，RequestParam注解类**

[Center]: https://img-blog.csdn.net/20160718163949186?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center
[Center 1]: https://img-blog.csdn.net/20160718164853870?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center
[Center 2]: https://img-blog.csdn.net/20160718164914682?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center
[Center 3]: https://img-blog.csdn.net/20160718165014763?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center
[Center 4]: https://img-blog.csdn.net/20160718165152448?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center
[Center 5]: https://img-blog.csdn.net/20160718165227542?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center
[Center 6]: https://img-blog.csdn.net/20160718165243136?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center