当SpringMVC在进行参数转换的时候出错时，浏览器就会提示400错误 

自定义参数类型转换器

首先定义一个Book类做model，基本数据类型和数组类型都可以自动转换，由于springMVC默认可以识别的日期字符串格式为：yyyy/MM/dd hh:mm:ss，当格式不同时，就需要日期类型转换器。

book模板 

默认情况下，变量名必须和表单中的name一致。如果不一致的话，可以通过@RequestParam(String name)注解进行配置，添加了这个注解后，默认就是必填参数，required=false之后就是非必填参数，或者添加一个默认值defaultValue

package com.qfedu.demo.model;

import java.util.Arrays;
import java.util.Date;

public class Book {
    private String name;
    private String author;
    private Double price;
    private String[] tags;
    private Date publishDate;

    @Override
    public String toString() {
        return "Book{" +
                "name='" + name + '\'' +
                ", author='" + author + '\'' +
                ", price=" + price +
                ", tags=" + Arrays.toString(tags) +
                ", publishDate=" + publishDate +
                '}';
    }

    public Date getPublishDate() {
        return publishDate;
    }

    public void setPublishDate(Date publishDate) {
        this.publishDate = publishDate;
    }

    public String[] getTags() {
        return tags;
    }

    public void setTags(String[] tags) {
        this.tags = tags;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public Double getPrice() {
        return price;
    }

    public void setPrice(Double price) {
        this.price = price;
    }

}

book控制器

package com.qfedu.demo.controller;

import com.qfedu.demo.model.Book;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class BookController {
    @GetMapping("/book")
    public String bookPage() {
        return "addbook";
    }

    @PostMapping("/addBook")
    @ResponseBody
    //本质上还是key-value的形式
    public void addBook(Book book) {
        System.out.println("book = " + book);
    }
}

日期类型转换器

package com.qfedu.demo.converter;

import org.springframework.core.convert.converter.Converter;
import org.springframework.stereotype.Component;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * 自定义日期类型转换器
 */
@Component
public class DateConverter implements Converter<String, Date> {
    private SimpleDateFormat sdf = new SimpleDateFormat("y-M-d");

    /**
     * @param source 前端上传的日期字符串
     * @return 将字符串转为日期之后的对象
     */
    @Override
    public Date convert(String source) {
        try {
            return sdf.parse(source);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return null;
    }
}

配置文件spring-context.xml

这里需要类型类型转换器，注意在配置之后，还要再driven中添加

<?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:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <context:component-scan base-package="com.qfedu.demo"/>
    <!--配置类型转换器后，还要在这里添加conversion-service，也就是配置的类型转换器-->
    <mvc:annotation-driven conversion-service="conversionServiceFactoryBean"/>
    <!--配置类型转换器-->
    <bean class="org.springframework.format.support.FormattingConversionServiceFactoryBean"
          id="conversionServiceFactoryBean">
        <property name="converters">
            <set>
                <!--将自定义的日期类型转换器配置给FormattingConversionServiceFactoryBean-->
                <ref bean="dateConverter"/>
            </set>
        </property>
    </bean>
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>
</beans>

 中文乱码问题

     <filter>
        <filter-name>encodingFilter</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>utf-8</param-value>
        </init-param>
        <init-param>
            <param-name>forceRequestEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
        <init-param>
            <param-name>forceResponseEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>encodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

前端代码addbook.jsp

<html>
<head>
    <title>Title</title>
</head>
<body>
<form action="/s/addBook" method="post">
    <table>
        <tr>
            <td>图书名：</td>
            <td><input type="text" name="name"></td>
        </tr>
        <tr>
            <td>图书价格：</td>
            <td><input type="text" name="price"></td>
        </tr>
        <tr>
            <td>作者：</td>
            <td><input type="text" name="author"></td>
        </tr>
        <tr>
            <td>标签：</td>
            <td>
                <input type="checkbox" name="tags" value="通俗小说">通俗小说
                <input type="checkbox" name="tags" value="小说">小说
                <input type="checkbox" name="tags" value="散文">散文
                <input type="checkbox" name="tags" value="诗歌">诗歌
            </td>
        </tr>
        <tr>
            <td>出版日期：</td>
            <td><input type="date" name="publishDate"></td>
        </tr>
        <tr>
            <td><input type="submit" value="提交"></td>
        </tr>
    </table>
</form>
</body>
</html>