中等的I/O读写技术，与反射、配置文件结合

页面

 1 <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
 2 
 3 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
 4 <html>
 5   <head>
 6     
 7     <title>利用反射的io-1</title>
 8     
 9     <meta http-equiv="pragma" content="no-cache">
10     <meta http-equiv="cache-control" content="no-cache">
11     <meta http-equiv="expires" content="0">    
12     <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
13     <meta http-equiv="description" content="This is my page">
14     <!--
15     <link rel="stylesheet" type="text/css" href="styles.css">
16     -->
17     <script type="text/javascript" src ="${pageContext.request.contextPath }/js/jquery-1.11.1.js"></script>
18     <script type="text/javascript">
19         // 1.创建一个xmlHttpRequest对象
20         var xmlHttpRequest = null;
21         // 2.判断浏览器类型
22         function getXmlHttpRequest() {
23             // 如果非IE
24             if(window.XMLHttpRequest) {
25                 xmlHttpRequest = new XMLHttpRequest();
26             } else if(window.ActiveXObject){
27                 xmlHttpRequest = new ActiveXObject("Microsoft.XMLHTTP");
28             } 
29         }
30         //ajax请求
31         function ajaxRequest(url, cb, clz, fileName) {
32             // 3.获得浏览器类型
33             getXmlHttpRequest();
34             if(xmlHttpRequest) {
35                 //4. 设置提交方式
36                 xmlHttpRequest.open("post", url, true);
37                 //5. 设置回调函数
38                 xmlHttpRequest.onreadystatechange = cb;
39                 // 用POST方式请求，必须加上头文件
40                 xmlHttpRequest.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
41                 //6. 正式发送请求（发送多个值（"clz=" + clz + "&fileName=" + fileName）用‘+’号连接，第二个键前加‘&’符）
42                 xmlHttpRequest.send("clz=" + clz + "&fileName=" + fileName);
43             }
44         }
45         //回调函数
46         function cb1 () {
47             if(xmlHttpRequest.readyState == 4 && 
48                 xmlHttpRequest.status == 200) {
49                 // 7.获取响应返回的结果
50                 var result = xmlHttpRequest.responseText;
51                 alert(result);
52             }
53         }
54         
55         function cb2 () {
56             if(xmlHttpRequest.readyState == 4 && 
57                 xmlHttpRequest.status == 200) {
58                 // 7.获取响应返回的结果
59                 var result = xmlHttpRequest.responseText;
60                 alert(result);
61                 // 8.通过eval("")函数将返回结果进行装载（注意eval("")的用法，里面必须用（）括起来result = eval("("+result+")");）
62                 result = eval("("+result+")");
63                 for(var v in result) {    //Js中的foreach,v为索引
64                     alert(result[v]);
65                 }
66             }
67         }
68         $(function(){
69             $("#InputEmpbtn").click(function(){
70                 // ( url,回调函数，反射需要的包类驱动，要加载的配置文件)
71                 ajaxRequest("../Jxl02Servlet",cb1,"entity.Emp","/user.properties");
72             });
73             $("#ExputEmpbtn").click(function(){
74                 ajaxRequest("../OJxl01Servlet",cb2,"entity.Emp");
75             });
76         })
77     </script>
78   </head>
79   
80   <body>
81       <input id="InputEmpbtn" type="button" value="员工导入" />
82     <input id="ExputEmpbtn" type="button" value="员工导出" />
83   </body>
84 </html>

servlet

 1 public void doPost(HttpServletRequest request, HttpServletResponse response)
 2             throws ServletException, IOException {
 3 
 4         try{
 5             response.setContentType("text/html");
 6             PrintWriter out = response.getWriter();
 7             // 获得‘包类驱动’
 8             String clzStr = request.getParameter("clz");
 9             // 获得配置文件信息
10             String fileName = request.getParameter("fileName");
11 /*********************************************反射开始***********************************************/
12             //1. 根据’包类驱动‘创建一个类
13             Class<?> c = Class.forName(clzStr);
14             //2. 根据1类创建一个对象
15             Object obj = c.newInstance();
16             //3. 创建一个集合得到2对象的所有属性
17             Field[] fields = obj.getClass().getDeclaredFields();
18             //4. 创建配置文件信息的对象
19             ReaderProperties reader = new ReaderProperties();
20             for (Field field : fields) {
21                 field.setAccessible(true);
22                 String name = field.getName();
23                 // 配置文件-----
24                 Properties properties =reader.loadProperties(fileName);
25                 Iterator<Entry<Object, Object>> it = properties.entrySet().iterator();  
26                 while (it.hasNext()) {  
27                     Entry<Object, Object> entry = it.next();  
28                     Object key = entry.getKey();  
29                     Object value = entry.getValue();  
30                     if(name.equals(key)) {
31                         // 判断字段类型并赋值
32                         if(field.getType().toString().equals("double")) {
33                             field.set(obj, Double.valueOf(value.toString()));
34                         } else {
35                             field.set(obj, value.toString());
36                         }
37                     }
38                 }  
39             }
40             reflectObj(obj);
41         } catch(Exception e){
42             e.printStackTrace();
43         }
44         
45     }
46 
47     private void reflectObj(Object obj) throws Exception {
48         File file = new File("d:/obj.xls");
49         WritableWorkbook book = Workbook.createWorkbook(file);
50         WritableSheet sheet = book.createSheet("第一个", 0);
51         Field[] fields = obj.getClass().getDeclaredFields();
52         for (int i = 0; i < fields.length; i++) {
53             Field field = fields[i];
54             field.setAccessible(true);
55             String name = field.getName();
56             String v = field.get(obj) == null ? "" : field.get(obj).toString();
57             Label label1 = new Label(i,0,name);
58             Label label2 = new Label(i,1,v);
59             sheet.addCell(label1);
60             sheet.addCell(label2);
61         }
62         book.write();
63         book.close();
64     }

配置文件
1.user.properties (注意：后缀名一定要写正确 .properties)

1 empNo=9527
2 empName=u5F20u4E09
3 salary=10000

2.dept.properties

1 deptNo=10
2 deptName=u8D22u52A1u90E8

 1 package test;
 2 
 3 import java.io.IOException;
 4 import java.io.InputStream;
 5 import java.util.Enumeration;
 6 import java.util.Iterator;
 7 import java.util.Properties;
 8 import java.util.Map.Entry;
 9 
10 public class ReaderProperties {
11 
12     public static void main(String[] args) {
13         Properties properties = new ReaderProperties().loadProperties("/jdbc.properties");
14         Enumeration<?> enu = properties.propertyNames();  
15         while (enu.hasMoreElements()) {  
16             Object key = enu.nextElement();  
17             System.out.println(key);  
18         }  
19         Enumeration<Object> enu2 = properties.elements();  
20         while (enu2.hasMoreElements()) {  
21             Object value = enu2.nextElement();  
22             System.out.println(value);  
23         }
24         
25         Iterator<Entry<Object, Object>> it = properties.entrySet().iterator();  
26         while (it.hasNext()) {  
27             Entry<Object, Object> entry = it.next();  
28             Object key = entry.getKey();  
29             Object value = entry.getValue();  
30             System.out.println("key   :" + key);  
31             System.out.println("value :" + value);  
32             System.out.println("---------------");  
33         }  
34     }
35 
36     
37     public Properties loadProperties(String resources) {
38         // 使用InputStream得到一个资源文件
39         InputStream inputstream = this.getClass()
40         .getResourceAsStream(resources);
41         // new 一个Properties
42         Properties properties = new Properties();
43         try {
44             // 加载配置文件
45             properties.load(inputstream);
46             return properties;
47         } catch (IOException e) {
48             throw new RuntimeException(e);
49         } finally {
50             try {
51                 inputstream.close();
52             } catch (IOException e) {
53                 throw new RuntimeException(e);
54             }
55         }
56 
57     }
58 }
【推广】 免费学中医，健康全家人
原文地址：https://www.cnblogs.com/cfb513142804/p/4216866.html