SpringMVC学习笔记六:类型转换器及类型转换异常处理

SpringMVC内部有类型转换器,当从Request中获取参数后,放入Controller中时,会根据Controller中指定的类型进行自动转换,当指的类型SpringMVC不能自动转换时,就需要自定义类转换器

项目目录树:

请求页面index.jsp

<%@ page language="java" contentType="text/html; charset=GBK"
    pageEncoding="GBK"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jstl/core" %>
<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>    
<%
    String path = request.getContextPath();
    String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GBK">
<base href="<%=basePath %>">
<title>IndexPage</title>
</head>
<body>
<c:out value="${ex.message }"></c:out>
<form action="converter/converter">
    name: <input type="text" name="name"><br>
    age: <input type="text" name="age"><br>
    Date: <input type="text" name="date"><br>
    <input type="submit" value="submit">
</form>
</body>
</html>

控制器ConverterController.java

package com.orange.controller;

import java.util.Date;

import javax.servlet.http.HttpServletRequest;

import org.springframework.beans.TypeMismatchException;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

@Controller
@RequestMapping(value="/converter")
public class ConverterController {

    @RequestMapping(value="/converter")
    public ModelAndView doConverter(String name, int age, Date date, ModelAndView mav){
        
        mav.addObject("name", name);
        mav.addObject("age", age);
        mav.addObject("date", date);
        mav.setViewName("/showConverter.jsp");
        
        return mav;
    }
    
    //注释式异常处理方式,当发生类型转换异常时,必须使用注解式异常处理,应该该异常在进入Controller之前就已经发生
    @ExceptionHandler(value=TypeMismatchException.class)
    public ModelAndView exceptionResolver(Exception ex, HttpServletRequest request){
        ModelAndView mav = new ModelAndView();
        mav.addObject("ex", ex);
        
        mav.setViewName("/index.jsp");
        
        return mav;
    }
}

自定义类型转换器

package com.orange.converter;

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

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

public class MyDateConverter implements Converter<String, Date> {

    public Date convert(String source) {
        
        try {
            SimpleDateFormat sdf = getSimpleDateFormat(source);
            return sdf.parse(source);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        
        return null;
    }
    
    private SimpleDateFormat getSimpleDateFormat(String source){
        SimpleDateFormat sdf = null;
        
        if(Pattern.matches("^\d{4}-\d{2}-\d{2}$", source)){
            sdf = new SimpleDateFormat("yyyy-MM-dd");
        }else if(Pattern.matches("^\d{4}\d{2}\d{2}$", source)){
            sdf = new SimpleDateFormat("yyyyMMdd");
        }else if(Pattern.matches("^\d{4}/\d{2}/\d{2}$", source)){
            sdf = new SimpleDateFormat("yyyy/MM/dd");
        }
        
        return sdf;
    }

}

注册类型转换器,配置spring-mvc.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/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">
    
    <!-- 扫描注解 -->
    <context:component-scan base-package="com.orange.controller" />    
    
    <!-- 开启类型转换服务 -->
    <mvc:annotation-driven conversion-service="conversionService"/>
    
    <!-- 注册自定义类型转换器 -->
    <bean id="dateConverter" class="com.orange.converter.MyDateConverter"></bean>
    
    <!-- 注册类型转换服务 -->
    <bean id="conversionService" class="org.springframework.context.support.ConversionServiceFactoryBean">
        <property name="converters" ref="dateConverter"></property>
    </bean>
    
</beans>

跳转后的页面showConverter.jsp

<%@ page language="java" contentType="text/html; charset=GBK"
    pageEncoding="GBK"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jstl/core" %>
<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>    
<%
    String path = request.getContextPath();
    String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GBK">
<base href="<%=basePath %>">
<title>showController Page</title>
</head>
<body>
<c:out value="${name }"></c:out><br>
<c:out value="${age }"></c:out>
<c:out value="${date }"></c:out>
</body>
</html>

 当输入信息正确时

当输入格式不支持时(自定义类型转换器支持yyyy-MM-dd,yyyyMMMdd,yyyy/MM/dd)

可以把异常信息展示到输入的页面

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原文地址：https://www.cnblogs.com/djoker/p/6618864.html