Servlet实现请假-ajax方式-马育民老师

# 说明

创建封装类 `JsonResult`，封装返回结果，并将 java对象 转成 `json` 字符串

# html

```
<script src="js/jquery-1.11.0.min.js" ></script>

</head>
<body>

<h1>请假</h1>
	<div>
	假期类型：
	<select name="type" id="type">
		<option value='-1'>请选择</option>
		<option value='1'>事假</option>
		<option value='2'>病假</option>
		<option value='3'>产假</option>
		<option value='4'>婚假</option>
	</select>
	</div>
	<div>
	开始日期：<input type="date" name="start_date" id="start_date">
	</div>
	<div>
	结束日期：<input type="date" name="end_date" id="end_date">
	</div>
	<div>
	请假事由：<input type="text" name="reason" id="reason">
	
	</div>
	<input type="button" onclick="doSubmit()" value="提交">
	<div id="msg"></div>
```

# servlet

```
package com.zrgj.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;

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

import com.zrgj.util.DateUtil;
import com.zrgj.util.DbUtils;
import com.zrgj.vo.JsonResult;

@WebServlet(urlPatterns="/leaveServlet2")
public class LeaveServlet2 extends HttpServlet{

@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		req.setCharacterEncoding("UTF-8");
		resp.setContentType("text/html; charset=UTF-8");
		
		String type=req.getParameter("type");
		//start_date命名方式不符合java的规范，应用小驼峰命名方式
		String startDate=req.getParameter("start_date");
		String endDate=req.getParameter("end_date");//ctrl+alt+↓ 复制一行
		String reason=req.getParameter("reason");//ctrl+alt+↓ 复制一行
		
		PrintWriter out = resp.getWriter();
		
		//校验结束日期 大于等于 开始日期
		//比较日期时 ，就不能用String，用Date类型
		
		try{
			boolean b=DateUtil.beforeAndEquals(startDate, endDate);
			if(!b){ // ! 表示取反				
				out.write(  JsonResult.fail(100, "开始日期要早于结束日期，请重新填写！") );
				return;
			}
		}catch(Exception e){
			e.printStackTrace();
		}
		
		DbUtils dbUtils=new DbUtils();
		try { 
			dbUtils.connect("com.mysql.jdbc.Driver" 
					, "jdbc:mysql://127.0.0.1:3308/scott?useSSL=false&useUnicode=true&characterEncoding=utf-8"
					,"root"
					,"");
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		
		String sql="INSERT INTO t_leave (l_type,start_date,end_date,reason,user_name) "
				+ "VALUES (?,?,?,?,?)";
		String[] paras={type,startDate,endDate,reason,null};
		try {
			int i = dbUtils.update(sql, paras);
			System.out.println("影响的行数："+i); //在公司开发中，不要打印
			if(i>0){
				//TODO:用转发实现			
				
				out.write( JsonResult.success("提交成功！") );
			}else{
				
				out.write(  JsonResult.fail(100, "提交失败，请联系管理员！") );
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		try {
			dbUtils.close();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}
}

```

# JsonResult

详见：
https://www.malaoshi.top/show_1IX2rn0kwlcB.html

原文出处：http://www.malaoshi.top/show_1IX2mFBwC1Ak.html