web组件工具之获取表单数据：webUtils

　　本文需要的架包:commons-beanutils-1.8.3.jar、commons-logging-1.1.3.jar、servlet-api.jar。

　　本文共分为五部分：1）封装通用工具类：从表单接收数据并封装到实体类中；2）绘制jsp页面：传输数据； 3）创建实体类：用来存放表单数据； 4）创建servlet类：调用工具类，实现数据封装; 5) 配置web.xml文件

　　注意：1）本工具类也同样适用于action；

　　　　　2）jsp中的表单名称与实体类中的属性名称必须一致。

1.封装通用工具类（WebUtils.java）

package com.BlueStar.util;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import javax.servlet.http.HttpServletRequest;
import org.apache.commons.beanutils.BeanUtils;
import org.apache.commons.beanutils.ConvertUtils;
import org.apache.commons.beanutils.Converter;

public class WebUtils {

    public static <T> T getData(HttpServletRequest req,Class<T> clazz){
        // convert Date start
        ConvertUtils.register(new Converter() {
            @Override
            public Object convert(Class type, Object value) {
                //filter
                if(type != Date.class) return null;
                if(value == null || "".equals(value.toString().trim())) return null;
                //convert
                SimpleDateFormat format = new SimpleDateFormat("yyyy/MM/dd");
                Date date = null;
                try {
                    date = format.parse(value.toString());
                } catch (ParseException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

                return date;
            }
        }, Date.class);
        // convert Date end

        T t = null;
        try {
            //newInstance
            t = clazz.newInstance();
            //set value from jsp
            BeanUtils.populate(t, req.getParameterMap());
        } catch (Exception e) {
            e.printStackTrace();
        }
        return t;
    }
}

2. 绘制jsp页面（userInfo.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=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
    <form action="info" method="post">
        姓名：<input type="text" name="userName" width="20%"/><br/><br/>
        密码：<input type="password" name="password" width="20%"/><br/><br/>
        生日：<input type="text" name="birthday" width="20%"/><br/><br/>

        <button type="submit" value="submit">submit</button>
        &nbsp;&nbsp;&nbsp;
        <button type="reset" value="reset">reset</button>
    </form>
</body>
</html>

3.创建实体类（UserInfoFormBean.java）

package com.BlueStar.entity;

import java.util.Date;

public class UserInfoFormBean {

    private String userName;
    private String password;
    private Date birthday;

    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }

    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    @Override
    public String toString() {
        return "UserInfoFormBean [userName=" + userName + ", password="
                + password + ", birthday=" + birthday + "]";
    }

}

4.创建servlet（UserInfoServlet.java）

package com.BlueStar.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.BlueStar.entity.UserInfoFormBean;
import com.BlueStar.util.WebUtils;

public class UserInfoServlet extends HttpServlet{

    private static final long serialVersionUID = 1L;

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {

        UserInfoFormBean formBean = WebUtils.getData(req, UserInfoFormBean.class);
        System.out.println(formBean);
    }
}

5. 配置web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>library</display-name>
  <welcome-file-list>
    <welcome-file>userInfo.jsp</welcome-file>
  </welcome-file-list>

  <servlet>
      <servlet-name>UserInfoServlet</servlet-name>
      <servlet-class>com.BlueStar.servlet.UserInfoServlet</servlet-class>
  </servlet>
  <servlet-mapping>
      <servlet-name>UserInfoServlet</servlet-name>
    <url-pattern>/info</url-pattern>
  </servlet-mapping>
</web-app>

　　更多内容，请访问：http://www.cnblogs.com/BlueStarWei/