完整的项目案例： springmvc.zip
目录
实例
除了依赖spring-webmvc还需要依赖jackson-databind（用于转换json数据格式）
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.9.6</version>
</dependency> 项目结构：
配置web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
version="4.0"> <!-- 请求总控器 -->
<servlet>
<servlet-name>dispatcher</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:dispatcher-servlet.xml</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>dispatcher</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping> </web-app>
配置dispatcher-servlet.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <context:component-scan base-package="edu.nf.ch09"/> <mvc:annotation-driven/> <mvc:default-servlet-handler/> <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/jsp/"/>
<property name="suffix" value=".jsp"/>
</bean> </beans>
Controller （UserController）
package edu.nf.ch09.controller; import edu.nf.ch09.controller.vo.ResponseVO;
import edu.nf.ch09.entity.Users;
import edu.nf.ch09.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.ResponseBody; import javax.servlet.http.HttpSession; /**
* @author wangl
* @date 2018/11/5
*/
@Controller
public class UserController { @Autowired
private UserService userService; /**
* 局部异常处理方法
*
* @ExceptionHandler标注的方法用于专门处理请求方法抛出的异常
* value属性指定异常的Class对象(是一个数组，可以指定多个class)，
* 表示捕获什么样的异常对象,最后在标注的方法中传入一个异常参数，就可以得到相应的异常对象
* 注意：@ExceptionHandler标注的方法只在当前的Controller类中有效，
* 在其他类中必须重新编写相关的Handler异常处理方法,
* 如果希望让所有的Controller都共享一个Handler异常处理，那么可以配置为全局异常处理
*
* @return
*/
/*@ExceptionHandler(UserException.class)
public ResponseVO handlerException(RuntimeException e){
ResponseVO vo = new ResponseVO();
vo.setCode(401);
vo.setMessage(e.getMessage());
return vo;
}*/ /**
* 用户登陆
* @param user
* @param session
* @return
*/
@PostMapping("/userLogin")
@ResponseBody
public ResponseVO login(Users user, HttpSession session){
ResponseVO vo = new ResponseVO();
//如果login方法引发了异常，则会执行上面的handlerLoginException异常处理方法
user = userService.login(user);
session.setAttribute("user", user);
vo.setValue("index.html");
return vo;
} @PostMapping("/addUser")
@ResponseBody
public ResponseVO addUser(Users user){
userService.addUser(user);
return new ResponseVO();
}
}
ExceptionAdvice（全局的异常处理类）
package edu.nf.ch09.controller.advice; import edu.nf.ch09.controller.vo.ResponseVO;
import edu.nf.ch09.service.exception.DataAccessException;
import edu.nf.ch09.service.exception.UserException;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody; /**
* @author wangl
* @date 2018/11/5
* 定义一个全局的异常处理类（类似一个切面）
* 这个类中定义的所有方法都是异常处理方法，
* 也可以理解为是全局的异常通知
* value属性指定对哪些控制器进行切入拦截
*/
@ControllerAdvice("edu.nf.ch09.controller")
public class ExceptionAdvice { /**
* 全局异常处理方法
* 用于处理用户登陆异常
* @param e
* @return
*/
@ExceptionHandler(UserException.class)
@ResponseBody
public ResponseVO handlerLoginException(RuntimeException e){
ResponseVO vo = new ResponseVO();
vo.setCode(401);
vo.setMessage(e.getMessage());
return vo;
} /**
* 全局异常处理方法
* 用于处理crud操作
* @param e
* @return
*/
@ExceptionHandler(DataAccessException.class)
@ResponseBody
public ResponseVO handlerDataAccessException(RuntimeException e){
ResponseVO vo = new ResponseVO();
vo.setCode(500);
vo.setMessage(e.getMessage());
return vo;
}
}
持久层引发的异常
package edu.nf.ch09.dao.impl; import edu.nf.ch09.dao.UserDao;
import edu.nf.ch09.entity.Users;
import edu.nf.ch09.service.exception.DataAccessException;
import org.springframework.stereotype.Repository; /**
* @author wangl
* @date 2018/11/5
*/
@Repository
public class UserDaoImpl implements UserDao { @Override
public Users getUserByName(String userName) {
Users user = null;
if("user1".equals(userName)){
user = new Users();
user.setUserName("user1");
user.setPassword("123456");
}
return user;
} @Override
public void saveUser(Users user) {
System.out.println("insert into user_info values ...");
throw new DataAccessException("添加失败");
}
}
业务逻辑层引发的异常
package edu.nf.ch09.service.impl; import edu.nf.ch09.dao.UserDao;
import edu.nf.ch09.entity.Users;
import edu.nf.ch09.service.UserService;
import edu.nf.ch09.service.exception.UserException;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service; /**
* @author wangl
* @date 2018/11/5
*/
@Service
public class UserServiceImpl implements UserService { @Autowired
private UserDao userDao; @Override
public Users login(Users user) {
Users newUser = userDao.getUserByName(user.getUserName());
if(newUser == null){
throw new UserException("用户不存在");
}
if(!user.getPassword().equals(newUser.getPassword())){
throw new UserException("密码错误");
}
return newUser;
} @Override
public void addUser(Users user) {
userDao.saveUser(user);
}
}
页面收到异常消息
