springmvc--数据绑定自动绑定&自定义绑定
1.什么是数据绑定
springmvc项目启动后，客户端发起的请求有时需要传输数据，那么这个传输的过程中如何准确的发出与接收数据？
- 1.springmvc把ServletRequest对象传递给DataBinder;
- 2.将处理方法的入参对象传递给DataBinder;
- 3.DataBinder调用ConversionService组件进行数据类型转换、数据格式化，并将ServletRequest对象中的消息填充到参数对象中；
- 4.调用Validator组件对已经绑定了请求数据的参数对象进行数据合法性检测；
- 5.校验完成后会生成数据绑定结果BindingResult对象，springmvc会将BindingResult对象中的内容赋给处理方法的对应参数；
2.实例准备
2.1创建项目
2.2导入jar包
2.3springmvc配置
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app.xsd">
<servlet>
<!-- 配置前端过滤器 -->
<servlet-name>springmvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<!-- 初始化时加载配置文件 -->
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:springmvc-config.xml</param-value>
</init-param>
<!-- 容器启动时加载servlet -->
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>springmvc</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>
2.4创建springmvc-config.xml
springmvc-config.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: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
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd
">
<!-- 指定需要扫描的包 -->
<context:component-scan base-package="controller"></context:component-scan>
<!-- 定义视图解析器 -->
<bean id="viewResolver"
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<!-- 设定前缀 -->
<property name="prefix" value="/WEB-INF/jsp/"></property>
<!-- 设定后缀 -->
<property name="suffix" value=".jsp"></property>
</bean>
</beans>
2.5创建controller
使用注解。
3.绑定默认数据类型
常用的默认数据类型：
- 1.HttpServletRequest:通过request对象获取请求信息
- 2.HttpServletResponse:通过response处理响应信息
- 3.HttpSession:通过session对象得到session中存储的对象
- 4.Model/ModelMap:Model是一个接口，ModelMap是一个接口实现，作用是将model数据填充到request
例子：
3.1 在controller中新增方法
@RequestMapping("/request")
public String singleBingding(HttpServletRequest httpServletRequest,Model model){
model.addAttribute("message", httpServletRequest.getParameter("id"));
return "first";
}3.2创建jsp文件
first.jsp
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<!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=utf-8">
<title>Hello Spring MVC</title>
</head>
<body>
${message}
</body>
</html>
3.3启动项目访问
因为我们从HttpServletReques中获取参数的名字为id，所以传输参数的形参名必须为id.(类型为基本类型)
4.绑定简单类型
简单数据类型不用做任何处理，发起请求是什么简单类型，接收的时候直接接收简单类型即可：
4.1在controller中增加方法
@RequestMapping("/integer")
public String singleBindingInteger(Integer integer,Model model){
model.addAttribute("message", integer);
return "first";
}4.2测试
其他类型则会出现异常
5.参数别名
在发起请求的时候，有时候前台不知道后台接收的参数名字是什么，为了前后台完全解耦，会让前台定一个参数名字列表，后台接收的时候需要对参数名字进行转换。
springmvc提供了一个注解用来控制参数：
@RequestParam:
value:参数的别名
name:请求头绑定的别名
required:是否必须传输
defaultValue:参数中没有此项时默认的值
5.1在controller中增加方法
@RequestMapping("/parameter")
public String singleBindingComment(
@RequestParam(value = "v_id", required = true) Integer id,
Model model) {
model.addAttribute("message", id);
return "first";
}5.2测试
可以看到前台传输的参数和后台接收的名字并不相同。
6.绑定POJO类型
POJO类型就是一个简单的JavaBean对象：私有的属性，get,set方法。
6.1增加实体类
package domain;
import java.io.Serializable;
public class People implements Serializable{
/**
*
*/
private static final long serialVersionUID = -1364237643930318187L;
private Long id;
private String name;
private Integer age;
private Integer sex;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
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 Integer getSex() {
return sex;
}
public void setSex(Integer sex) {
this.sex = sex;
}
@Override
public String toString() {
return "[id=" + this.id + ",name=" + this.name + ",age=" + this.age
+ ",sex" + this.sex + "]";
}
}
6.2在controller中增加方法
@RequestMapping("/getPeople")
public String pojoBinding(People people,
Model model){
System.out.println(people);
model.addAttribute("message", people.toString());
return "first";
}
@RequestMapping("/toPeople")
public String toPeopeJSP(){
return "people";
}因为POJO对象需要使用from 表单提交，所以需要一个跳转的方法，其中toPeople就是访问提交POJO的jsp页面，getPeople接收POJO对象。
6.3增加jsp
people.jsp
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<!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=utf-8">
<title>POJO people</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/test/getPeople" method="post">
id:<input type="text" name="id"><br/>
姓名:<input type="text" name="name"><br/>
年龄:<input type="text" name="age"><br/>
性别:<input type="text" name="sex"><br/>
<input type="reset" value="重置"><input type="submit" value="提交">
</form>
</body>
</html>
jsp中input的名字必须与POJO的属性名字相同，否则会出现找不到对应属性的get,set方法的异常。
6.4测试
说明：参数的类型也必须一致，在传输的过程中会隐式的做类型转换。
注意
如果出现中文乱码，可以使用以下方式解决：
1.在web.xml中增加
<!-- 配置编码过滤器 -->
<filter>
<filter-name>CharacterEncodingFilter</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>
</filter>
<filter-mapping>
<filter-name>CaracterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
2.使用utf-8的jsp（本人使用utf-8的jsp没有遇到中文乱码）
3.自定义过滤器
Servlet过滤器HTML中文乱码
7.嵌套POJO类型
有时候数据过于复杂，需要使用嵌套的POJO类型，就是另一个POJO作为本POJO的属性
7.1创建实体
package domain;
import java.io.Serializable;
import java.util.List;
public class Server implements Serializable{
/**
*
*/
private static final long serialVersionUID = -3793545656487562942L;
private Long id;
private String name;
private String remark;
private List<People> peoples;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getRemark() {
return remark;
}
public void setRemark(String remark) {
this.remark = remark;
}
public List<People> getPeoples() {
return peoples;
}
public void setPeoples(List<People> peoples) {
this.peoples = peoples;
}
@Override
public String toString() {
return "id=" + this.id + ",name=" + this.name + ",remark="
+ this.remark + ",peoples=" + this.peoples + "]";
}
}
7.2在controller中增加方法
@RequestMapping("/toServer")
public String toServer(){
return "server";
}
@RequestMapping("/getServer")
public String pojoBindingServer(Server server,
Model model){
System.out.println(server);
model.addAttribute("message", server.toString());
return "first";
}7.3增加jsp
server.jsp
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<!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=utf-8">
<title>POJO server</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/test/getServer" method="post">
id:<input type="text" name="id"><br/>
名称:<input type="text" name="name"><br/>
备注:<input type="text" name="remark"><br/>
people.id:<input type="text" name="peoples[0].id"><br/>
people姓名:<input type="text" name="peoples[0].name"><br/>
people年龄:<input type="text" name="peoples[0].age"><br/>
people性别:<input type="text" name="peoples[0].sex"><br/>
<input type="reset" value="重置"><input type="submit" value="提交">
</form>
</body>
</html>
注意:
输入框的名字与POJO的类型一致，如果是属性为POJO类型需要用.来调用，如果是数组的POJO属性，使用下标调用。
7.4测试
8.自定义数据绑定-Converter
8.1Converter
能够将任意类型转换为指定的任意类型：
S是源类型，T是目标类型。
比如字符串->日期
8.2增加自定义的Converter类
package my_convert;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import org.springframework.core.convert.converter.Converter;
public class DateConverter implements Converter<String, Date>{
private String pattern = "yyyy-MM-dd HH:mm:ss,s";
@Override
public Date convert(String arg0) {
SimpleDateFormat simpleDateFormat = new SimpleDateFormat(pattern);
try{
return simpleDateFormat.parse(arg0);
} catch(ParseException parseException) {
throw new IllegalArgumentException("this pattern"+pattern);
}
}
}
8.3springmvc-config.xml配置
<?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
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd
">
<!-- 指定需要扫描的包 -->
<context:component-scan base-package="controller"></context:component-scan>
<!-- 定义视图解析器 -->
<bean id="viewResolver"
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<!-- 设定前缀 -->
<property name="prefix" value="/WEB-INF/jsp/"></property>
<!-- 设定后缀 -->
<property name="suffix" value=".jsp"></property>
</bean>
<!-- 显示的装配自定义类型转换器 -->
<mvc:annotation-driven conversion-service="conversionService">
</mvc:annotation-driven>
<!-- 自定义类型转换器配置 -->
<bean id="conversionService"
class="org.springframework.context.support.ConversionServiceFactoryBean">
<property name="converters">
<set>
<bean class="my_convert.DateConverter"></bean>
</set>
</property>
</bean>
</beans>
8.4创建jsp
date.jsp
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<!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=utf-8">
<title>converter Date</title>
</head>
<body>
<form action="${pageContext.request.contextPath }/test/getDate" method="get">
<input type="text" name="date"><br/>
<input type="submit" value="提交">
</form>
</body>
</html>
8.5在controller中增加方法
@RequestMapping("/toDate")
public String toDate(){
return "date";
}
@RequestMapping("/getDate")
public String converterDate(Date date,Model model){
model.addAttribute("message", date);
return "first";
}8.6测试
字符串必须符合在自定义Converter中定义的格式
否则会出现异常
异常信息：
警告: Resolved [org.springframework.web.method.annotation.MethodArgumentTypeMismatchException: Failed to convert value of type 'java.lang.String' to required type 'java.util.Date'; nested exception is org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type [java.util.Date] for value '2019/03/15 19:48:55,63155'; nested exception is java.lang.IllegalArgumentException: this patternyyyy-MM-dd HH:mm:ss,s]
9.自定义数据绑定-Formatter
Formatter与Converter的作用相同，但是Formatter的源类型必须是字符串。
9.1增加自定义的Formatter类
package my_formatter;
import java.text.ParseException;
import java.util.Locale;
import org.springframework.format.Formatter;
import domain.People;
public class PeopleFormatter implements Formatter<People>{
@Override
public String print(People arg0, Locale arg1) {
return "people:" + arg0 + ",Locale:" + arg1.toString();
}
@Override
public People parse(String arg0, Locale arg1) throws ParseException {
//id=12,name=你好,age=23,sex=25
String[] pStrings = arg0.split(",");
People people = new People();
people.setId(Long.valueOf(pStrings[0].split("=")[1]));
people.setName(pStrings[1].split("=")[1]);
people.setAge(Integer.valueOf(pStrings[2].split("=")[1]));
people.setSex(Integer.valueOf(pStrings[3].split("=")[1]));
return people;
}
}
9.2springmvc-config.xml配置
<?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
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd
">
<!-- 指定需要扫描的包 -->
<context:component-scan base-package="controller"></context:component-scan>
<!-- 定义视图解析器 -->
<bean id="viewResolver"
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<!-- 设定前缀 -->
<property name="prefix" value="/WEB-INF/jsp/"></property>
<!-- 设定后缀 -->
<property name="suffix" value=".jsp"></property>
</bean>
<!-- 显示的装配自定义类型转换器 -->
<!-- <mvc:annotation-driven conversion-service="conversionService">
</mvc:annotation-driven> -->
<!-- 自定义类型转换器配置 -->
<!-- <bean id="conversionService"
class="org.springframework.context.support.ConversionServiceFactoryBean">
<property name="converters">
<set>
<bean class="my_convert.DateConverter"></bean>
</set>
</property>
</bean> -->
<mvc:annotation-driven conversion-service="peopleConversionService">
</mvc:annotation-driven>
<bean id="peopleConversionService"
class="org.springframework.format.support.FormattingConversionServiceFactoryBean">
<property name="formatters">
<set>
<bean class="my_formatter.PeopleFormatter"></bean>
</set>
</property>
</bean>
</beans>
9.3创建jsp
formatPeople.jsp
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<!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=utf-8"><title>formatter people</title>
</head>
<body>
<form action="${pageContext.request.contextPath }/test/getFormatPeople"
method="get">
eg:id=12,name=小华,age=12,sex=0<br/>
<input type="text" name="people">
<input type="submit" value="提交">
</form>
</body>
</html>
9.5在controller中增加方法
@RequestMapping("/toFormatPeople")
public String toFormatPeople(){
return "formatPeople";
}
@RequestMapping("getFormatPeople")
public String getFormatPeople(People people,Model model){
model.addAttribute("message", people.toString());
return "first";
}9.6测试
10数组绑定
10.1在controller中增加方法
@RequestMapping("/toCheckBox")
public String toCheckBox(){
return "checkBox";
}
@RequestMapping("/getCheckBox")
public String getCheckBox(Integer[] array,Model model){
String message = "";
for(Integer integer : array){
message += "\n"+integer;
}
model.addAttribute("message", message);
return "first";
}10.2创建jsp
checkBox.jsp
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>check box</title>
</head>
<body>
<form action="${pageContext.request.contextPath }/test/getCheckBox" method="get">
<table border="1" width="20%">
<%
for (int i = 0; i < 10; i++) {
%>
<tr>
<td><input type="checkbox" name="array" value="<%=i%>"><br />
</td>
<td><%=i%></td>
</tr>
<%
}
%>
</table>
<input type="submit" value="提交">
</form>
</body>
</html>
10.3测试
