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SpringMVC框架技术实战指南

第一天：响应数据与视图

返回值类型分类

1. 返回值是字符串

• 逻辑视图名解析：通过返回字符串指定逻辑视图名（如success），视图解析器会将其解析为物理视图地址（如/WEB-INF/pages/success.jsp）。
• 示例代码：

  @Controller
  @RequestMapping(path = "/user")
  public class UserController {
      @RequestMapping(path = "/returnString")
      public String returnString(Model model) {
          System.out.println("returnString方法执行了...");
          User user = new User();
          user.setUsername("张三");
          user.setPassword("123");
          user.setAge(20);
          model.addAttribute("user1", user);
          return "success";
      }
  }

• 对应页面：/WEB-INF/pages/success.jsp

2. 返回值是void

• 默认跳转：若返回void，默认跳转到方法名对应的JSP页面（如/returnVoid.jsp）。
• 手动跳转：可通过request.getRequestDispatcher或response.sendRedirect实现。
• 示例代码：

  @Controller
  @RequestMapping(path = "/returnVoid")
  public class UserController {
      @RequestMapping(path = "/returnVoid")
      public void returnVoid(HttpServletRequest request, HttpServletResponse response) throws Exception {
          System.out.println("returnVoid方法执行了...");
          request.getRequestDispatcher("/WEB-INF/pages/success.jsp").forward(request, response);
          response.sendRedirect(request.getContextPath() + "index.jsp");
          response.setContentType("text/html;charset=UTF-8");
          response.getWriter().print("你好");
      }
  }

3. 返回值是ModelAndView

• 功能说明：可用于传递模型数据和调整视图。
• 示例代码：

  @Controller
  @RequestMapping(path = "/returnModelAndView")
  public class UserController {
      @RequestMapping("returnModelAndView")
      public ModelAndView returnModelAndView() {
          System.out.println("returnModelAndView方法执行了...");
          ModelAndView mv = new ModelAndView();
          User user = new User();
          user.setUsername("李四");
          user.setPassword("345");
          user.setAge(28);
          mv.addObject("user1", user);
          mv.setViewName("success");
          return mv;
      }
  }

第二天：文件上传实现

文件上传基础

1. 前提条件

• 表单属性：
  • enctype="multipart/form-data"
  • method="post"
  • 包含<input type="file">标签
• 服务器端依赖：
  • commons-fileupload和commons-io jar包

2. 安装依赖

   
    
    
        
     
      commons-fileupload
     
        
     
      commons-fileupload
     
        
     
      1.3.1
     
    
    
    
    
        
     
      commons-io
     
        
     
      commons-io
     
        
     
      2.4
     
    
    
   

传统文件上传

1. jsp页面

   
    
    
     
        选择文件：
     
        
     
    
    
   

2. Controller逻辑

@RequestMapping("/fileUpload2")
public class UserController {
    @RequestMapping("/fileUpload2")
    public String fileUpload2(HttpServletRequest request, MultipartFile upload) throws Exception {
        System.out.println("文件上传处理...");
        String path = request.getServletContext().getRealPath("/uploads/");
        if (!new File(path).exists()) {
            new File(path).mkdirs();
        }
        String fileName = upload.getOriginalFilename();
        String uuid = UUID.randomUUID().toString().replace("-", "");
        fileName = uuid + "_" + fileName;
        upload.transferTo(new File(path, fileName));
        return "success";
    }
}

异常处理

自定义异常类

package cn.itcast.exception;
public class SysException extends Exception {
    private String message;
    public SysException(String message) {
        this.message = message;
    }
    @Override
    public String getMessage() {
        return message;
    }
}

异常处理器配置

• 异常处理器：

package cn.itcast.exception.resolver;
import cn.itcast.exception.SysException;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class SysExceptionResolver implements org.springframework.web.servlet.HandlerExceptionResolver {
    @Override
    public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object o, Exception e) {
        SysException exception = null;
        if (e instanceof SysException) {
            exception = (SysException) e;
        } else {
            exception = new SysException("服务器正在维护中...");
        }
        ModelAndView mv = new ModelAndView();
        mv.addObject("errorMsg", exception.getMessage());
        mv.setViewName("error");
        return mv;
    }
}

异常使用示例

@RequestMapping("/testException")
public String testException() throws SysException {
    System.out.println("执行testException方法");
    try {
        int x = 10 / 0;
    } catch (Exception e) {
        throw new SysException("系统异常：数据加载失败");
    }
    return "success";
}

拦截器实现

自定义拦截器

package cn.itcast.interceptor;
public class MyInterceptor1 implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("MyInterceptor1的preHandle方法执行了...");
        return true;
    }
}

拦截器配置

拦截器执行顺序

执行顺序：preHandle → Controller → postHandle → success.jsp → afterCompletion