jsp&servlet 学生管理系统总结

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1.post表单提交，中文乱码：request.setCharacterEncoding("utf-8");

2.提高用户体验，密码用户名输入错误后返回登录界面，表单内容未被清除：可以在servlet中传入值，在jsp页面接收

servlet中：

request.setAttribute("userName", userName);
request.setAttribute("password", password);

jsp页面中：

<input type="text" value="${userName }" name="userName" id="userName"/>

<input type="password" value="${password }" name="password" id="password"/>

3.权限验证 Session:

//获取Session
HttpSession session = request.getSession();
session.setAttribute("currentUser",currentUser);

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4.页面级验证用户是否登录：

<%
　　//权限验证
　　if(session.getAttribute("currentUser")==null){
　　　　System.out.println("滚");
　　　　response.sendRedirect("index.jsp");
　　　　return;
　　}
%>

5.Mysql分页

page 当前页

rows 每页的记录数

String * from table limit start,size;

start=(page-1)*rows;

6.json jar包导入

 Json-lib-2.2.3-jdk15.jar, JSONArray格式为name:value,

封装方法将ResultSet转成JSONArray格式

public static JSONArray formatRsToJsonArray(ResultSet rs) throws Exception{
		ResultSetMetaData md = rs.getMetaData();
		int num=md.getColumnCount();
		JSONArray array = new JSONArray();
		while(rs.next()){
			JSONObject mapOfColValues = new JSONObject();
			for(int i=1; i<=num; i++){
				mapOfColValues.put(md.getColumnClassName(i),rs.getObject(i));
			}
		}
		return null;
	}

7.封装向页面输出：

public class ResponseUtil {
	public static void write(HttpServletResponse response, JSONObject
			jsonObject)throws Exception{
		response.setContentType("text/html;charset=utf-8");
		PrintWriter out = response.getWriter();
		out.println(jsonObject.toString());
		out.flush();
		out.close();
	}

8.使用SimpleDateFormat封装日期格式，使用instanceof判断对象类型　　

	public static String formatDate(Date date, String format){
		String result = "";
		SimpleDateFormat sdf = new SimpleDateFormat(format);
		if(date != null){
			result = sdf.format(date);
		}
		return result;
	}

　　　　　　　　　　　　　Object o = rs.getObject(i);
				if(o instanceof Date){
					mapOfColValues.put(md.getColumnName(i),DateUtil.formatDate((Date)o, "yyyy-MM-dd"));
				}else{
					mapOfColValues.put(md.getColumnName(i),rs.getObject(i));
				}

9.多表关联时，要注意主键id命名时的区分，否则系统会不知道怎么处理

　　

10.取异步数据

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		Connection con = null;
		try {
			con = dbUtil.getCon();
			JSONArray jsonArray = new JSONArray();
			JSONObject jsonObject = new JSONObject();
			jsonObject.put("id", "");
			jsonObject.put("gradeName", "请选择...");
			jsonArray.add(jsonObject);
			jsonArray.addAll(JsonUtil.formatRsToJsonArray(gradeDao.gradeList(con, null, null)));
			ResponseUtil.write(response, jsonArray);
		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		} finally{
			try {
				dbUtil.closeCon(con);
			} catch (Exception e2) {
				// TODO: handle exception
				e2.printStackTrace();
			}
		}
	}

data-options="editable:false,valueField:'id',textField:'gradeName',url:'gradeComboList'"

11.jquery取值　　

　　$("#s_stuNo").val()

12.使用StringBuffer类的append方法时注意空格

public ResultSet studentList(Connection con, PageBean pageBean, Student student, String bbrithday, String ebrithday) throws Exception{
		StringBuffer sb = new StringBuffer("select * from t_student s, t_grade g where g.id=s.gradeId");
		if(StringUtil.isNotEmpty(student.getStuNo())){
			sb.append(" and s.stuNo like '%"+student.getStuNo()+"%' ");
		}
		if(StringUtil.isNotEmpty(student.getStuName())){
			sb.append("and s.stuName like '%"+student.getStuName()+"%' ");
		}
		if(StringUtil.isNotEmpty(student.getSex())){
			sb.append("and s.sex ='"+student.getSex()+"' ");
		}
		if(StringUtil.isNotEmpty(bbrithday)){
			sb.append("and TO_DAYS(s.brithday) >= TO_DAYS('"+bbrithday+"') ");
		}if(StringUtil.isNotEmpty(ebrithday)){
			sb.append("and TO_DAYS(s.brithday) <= TO_DAYS('"+ebrithday+"') ");
		}
		if(student.getGradeId() != -1){
			sb.append("and s.gradeId ='"+student.getGradeId()+"' ");
		}
		if(pageBean != null){
			sb.append(" limit "+pageBean.getStart()+","+pageBean.getRows());
		}
		PreparedStatement pstmt = con.prepareStatement(sb.toString());
		return pstmt.executeQuery();
	}

　　

　　

　　

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