文件上传、数据校验（后台）、拦截器

1. 文件上传

需要上传的jar包——fileploat

网页端
表单必须是post提交，编码必须是multipart/form-data 文件上传文本框必须起名

<form method="post" enctype="multipart/form-data" action="stuUpload">
    姓名：<input type="text" name="name"/>
    年龄：<input type="text" name="age"/>
    上传文件:<input type="file" name="photo"/>
    <input type="submit" value="提交"/>
</form>

在springMVC中配置文件上传解析器

<!--配置文件上传解析器-->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<!-- 设置文件上传的大小限制，单位：字节 -->
<property name="maxUploadSize" value="99999999"></property>
</bean>

在控制层处理代码

package com.alibaba.wlq.controller;
import java.io.File;
import java.io.IOException;
import javax.servlet.http.HttpServletRequest;
import org.apache.commons.io.FileUtils;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.multipart.MultipartFile;
import com.alibaba.wlq.bean.Student;
@Controller
public class StudentController {
@RequestMapping("stuUpload")
public String addStudent(MultipartFile photo,Student stu,HttpServletRequest request,Model model) {
    //获取文件上传的真实保存路径
    String path = request.getServletContext().getRealPath("/photo");
    File file = new File(path);
    if(!file.exists()) {
        file.mkdirs();
    }
    String filename = System.currentTimeMillis()+photo.getOriginalFilename();
    stu.setSphoto("photo/"+filename);
    File targetFile = new File(path+"/"+filename);
    try {
        FileUtils.writeByteArrayToFile(targetFile, photo.getBytes());
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    model.addAttribute("stu",stu);
    return "index";
}
}

Student 实体类

package com.alibaba.wlq.bean;
public class Student {
private String name;
private Integer age;
//注意：Student实体类中图片的属性名称不能和文件上传中名臣属性的值一致，否则会出现400错误
private String sphoto;
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public Integer getAge() {
    return age;
}
public void setAge(Integer age) {
    this.age = age;
}
public String getSphoto() {
    return sphoto;
}
public void setSphoto(String sphoto) {
    this.sphoto = sphoto;
}
}

2.拦截器

什么是拦截器？

Spring MVC中的拦截器（Interceptor）类似于Servlet中的过滤器（Filter），它主要用于拦截用户请求并作相应的处理。例如通过拦截器可以进行权限验证、记录请求信息的日志、判断用户是否登录等。
要使用Spring MVC中的拦截器，就需要对拦截器类进行定义和配置。

创建一个类，实现HandlerInterceptor接口并且重写接口中的方法

package com.alibaba.wlq.interceptor;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
public class Interceptor implements HandlerInterceptor{
@Override
public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, Exception arg3)
        throws Exception {
    // TODO Auto-generated method stub      
}
@Override
public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, ModelAndView arg3)
        throws Exception {
    // TODO Auto-generated method stub  
}
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object arg2) throws Exception {
    Object user = request.getSession().getAttribute("user");
    if(user!=null) {
        return true;
    }else {
        response.sendRedirect("toLogin");
        return false;
    }
}
}

把创建的类配置到SpringMVC的配置文件中

<!-- 配置拦截器 -->
<mvc:interceptors>
    <mvc:interceptor>
            <!--表示拦截所有user下以及user下子类的请求-->
            <mvc:mapping path="/user/**"/>
            <!---->
            <mvc:exclude-mapping path="/user/toLogin"/>
            <mvc:exclude-mapping path="/user/login"/>
            <mvc:exclude-mapping path="/user/toRegister"/>
            <mvc:exclude-mapping path="/user/register"/>
            <mvc:exclude-mapping path="/user/index"/>
            <bean class="com.alibaba.wlq.interceptor.Interceptor"/>
    </mvc:interceptor>
</mvc:interceptors>

3.数据校验（后台校验）

导入jar包（validate）

在相应的实体类中加入注解

package com.alibaba.wlq.bean;

import javax.validation.constraints.NotNull;
import javax.validation.constraints.Pattern;

import org.hibernate.validator.constraints.Length;
import org.hibernate.validator.constraints.NotEmpty;

public class User {
    @NotEmpty(message="账号不能为空")
    @NotNull(message="账号不能为空")
    private String account;
    @NotEmpty(message="密码不能为空")
    @NotNull(message="密码不能为空")
    @Length(min=6,max=12,message="密码的长度在6~12之间")
    private String password;
    @Pattern(regexp="/^(13[0-9]{9})|(18[0-9]{9})|(14[0-9]{9})|(17[0-9]{9})|(15[0-9]{9})$/",message="手机号码格式不正确")
    private String phone;
    public String getPhone() {
        return phone;
    }
    public void setPhone(String phone) {
        this.phone = phone;
    }
    public User(String account, String password, String phone) {
        super();
        this.account = account;
        this.password = password;
        this.phone = phone;
    }
    public String getAccount() {
        return account;
    }
    public void setAccount(String account) {
        this.account = account;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public User(String account, String password) {
        super();
        this.account = account;
        this.password = password;
    }
    public User() {
        super();
    }
}

控制层接受参数时

@RequestMapping("register")
public String register(@Valid User user,BindingResult br,Model model) {
    if(br.hasErrors()) {
        List<FieldError> fieldList = br.getFieldErrors();
        Map<String,Object> errorMsg = new HashMap<>();
        for (FieldError f : fieldList) {
            errorMsg.put(f.getField(), f.getDefaultMessage());
        }
        model.addAttribute("errorMsg",errorMsg);
        return "register";
    }
    return "login";
}

在网页中拿到错误信息

<body>  
<form action="register" method="post">
    账号:<input type="text" name="account"/>${errorMsg.account }<br>
    密码:<input type="text" name="password"/>${errorMsg.password }<br>
    手机号:<input type="text" name="phone"/>${errorMsg.phone}<br>
    <input type="submit" value="提交"/>
</form>
</body>

文件上传、数据校验（后台）、拦截器

1. 文件上传

2.拦截器

3.数据校验（后台校验）

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