简单的封装数据的模板

 

   public boolean delete(int a ) {
        boolean flag=false;//删除  搜索并删除表 no1 中 A 列为 a 的那一行
        Connection conn =link.Link.getConnection();
        Statement st=null;
        try {
            st=conn.createStatement();
            st.executeUpdate("delete from no1 where A='"+a+"'");
            flag=true;
        } catch (SQLException e) {
            e.printStackTrace();
        }
        finally{
            link.Link.close(st, conn);
        }
        return flag;
    }
    
    public boolean update(Bean bean) {
        boolean flag=false;//更改  更改表 no1 中 A 列为 bean.getA() 的那一行
        Connection conn=link.Link.getConnection();
        Statement st=null;
        try {
            st=conn.createStatement();
            st.executeUpdate("update no1 set A='"+bean.geta()+"',B='"+bean.getb()+"',C='"+bean.getc()+"'where A='"+bean.geta()+"'");
            flag=true;
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return flag;
    }
    
    public List<Bean> list(){
        Connection conn=link.Link.getConnection();
        Statement st=null;//浏览 表 no1 中 A 列  
        List<Bean> list=new ArrayList<>();
        ResultSet rs=null;
        Bean bean=null;
        try {
            st=conn.createStatement();
            rs=st.executeQuery("select * from no1 order by A");
            while(rs.next()) {
                int A=rs.getInt("A");
                String B = rs.getString("B");
                String C = rs.getString("C");
                bean=new Bean(A,B,C);
                list.add(bean);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        finally {
            link.Link.close(rs, st, conn);
        }
        return list;
    }
    
    public List<Bean> searchByName(String str) throws SQLException{
        Connection conn=link.Link.getConnection();
        Statement st=null;//查询 表 no1 中 B 或 C 列中存在 str 的  
        PreparedStatement pt = conn.prepareStatement("select * from no1 where(B like '%"+str+"%' or C like '%"+str+"%')");
        List<Bean> search=new ArrayList<>();
        ResultSet rs=null;
        Bean bean=null;
        try {
            rs=pt.executeQuery();
            while(rs.next()) {
            	int A=rs.getInt("A");
                String B = rs.getString("B");
                String C = rs.getString("C");
                bean=new Bean(A,B,C);
                search.add(bean);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        finally {
            link.Link.close(rs, st, conn);
        }
        return search;
    }   
    
}

　　Link

package link;

import java.sql.*;

public class Link {
    private static String url = "jdbc:mysql://localhost:3306/end?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT%2B8";
    private static String user = "root";
    private static String password = "123456";
    public static  Connection getConnection() {
        Connection con=null;
        try {
            con=DriverManager.getConnection(url, user, password);
            System.out.println("连接成功");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return con;
    }
    public static void close(Connection con) {
        if(con!=null)
            try {
                con.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }       
    }
    public static void close(Statement state, Connection conn) {
        if(state!=null) {
            try {
                state.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(conn!=null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }  
    public static void close(ResultSet rs, Statement state, Connection conn) {
        if(rs!=null) {
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(state!=null) {
            try {
                state.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(conn!=null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

　　Servlet.java

package servlet;
import java.io.*;
import java.util.List;
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 bean.Bean;
import dao.Dao;
@WebServlet("/servlet")

public class Servlet extends HttpServlet {
    Dao Dao=new dao.Dao();
    private static final long serialVersionUID = 1L;
    public Servlet() {
        super();
    } 
    
    private void insert(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
        request.setCharacterEncoding("utf-8");
        int A = Integer.parseInt(request.getParameter("A"));
        String B = request.getParameter("B");
        String C = request.getParameter("C");
        Bean bean=new Bean(A,B,C);
        if(Dao.insert(bean)) {
            request.setAttribute("message", "添加成功");
            request.getRequestDispatcher("index.jsp").forward(request, response);
        }
    }
    
    private void delete(HttpServletRequest request, HttpServletResponse response) throws Exception, IOException {
        request.setCharacterEncoding("UTF-8");
        int A=Integer.parseInt(request.getParameter("A"));
        Dao.delete(A);
        request.setAttribute("message", "删除成功");
        request.getRequestDispatcher("servlet?method=list").forward(request, response);
    }  
    
    private void list(HttpServletRequest request, HttpServletResponse response) throws Exception, IOException {
        request.setCharacterEncoding("UTF-8");
        List<Bean> list = Dao.list();
        request.setAttribute("list", list);
        request.getRequestDispatcher("list.jsp").forward(request, response);
    }
    
    private void update(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        int A = Integer.parseInt(request.getParameter("A"));
        String B = request.getParameter("B");
        String C = request.getParameter("C");
        Bean bean=new Bean(A,B,C);
        Dao.update(bean);
        request.setAttribute("message", "修改成功");
        request.getRequestDispatcher("servlet?method=list").forward(request, response);
    }
    
    private void search(HttpServletRequest request, HttpServletResponse response) throws Exception, IOException {
        request.setCharacterEncoding("UTF-8");
        request.setAttribute("search", "查询成功");
        request.getRequestDispatcher("list.jsp").forward(request, response);
    }
    
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        String method=request.getParameter("method");
        if("insert".equals(method)) {
            insert(request,response);           
        }else if("delete".equals(method)) {
            try {
                delete(request,response);
            }catch (Exception e) {
                e.printStackTrace();
            }          
        }else if("update".equals(method)) {
            update(request,response);
        }else if("list".equals(method)) {
            try {
                list(request,response);
            }catch (Exception e) {
                e.printStackTrace();
            }     
        }else if("search".equals(method)) {
            try {
                search(request,response);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }    
    }
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);     
    }
}

　　

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>这里是标题</title>
</head>
<body>
    <%
        Object message = request.getAttribute("message");
        if (message != null && !"".equals(message)) {
    	%>
    	<script type="text/javascript">   alert("<%=request.getAttribute("message")%>");    </script>
    	<%}%>
<div align="center">
	<h1>表名</h1>
  	<a href="A.jsp">跳转A</a>     
  <form action="servlet?method=insert" method="post">
      <table id="addTable" class="table table-bordered  ">
        	<tr> 
            	<td class="col-sm-2">输入框A</td>
                <td class="col-sm-4"><input type="text" class="form-control"  name="输入框A" id="输入框A" ></td>
           	<tr>
                <td class="col-sm-2">输入框B</td>
                <td><input type="text" class="form-control"  name="输入框B" id="输入框B" placeholder="输入框B"></td>
            <tr>
                <td class="col-sm-2">选择框</td>
                <td class="col-sm-4">
                  	<input type="radio"  name="选择框" id="选择框" value="内容A">内容A
                  	<input type="radio"  name="选择框" id="选择框" value="内容B">内容B
                  	</td>  <tr>  <td></td>  <td>
                  	<input type="radio"  name="选择框" id="选择框" value="内容C">内容C
                </td>
            <tr>
                <td>下拉框</td>
                <td colspan="3">
                  	<select class="form-control" id="下拉框" name="下拉框">
                    	<option value="下拉框A">下拉框A</option>
                    	<option value="下拉框B">下拉框B</option>
                    	<option value="下拉框C">下拉框C</option>
                  	</select>
                </td>
            <tr>
      </table>
      <input type="submit" value="确认"  onclick= "return check()" /> 
  </form> 
</div>
</body>
<script type="text/javascript">
        function check()                   
        {
        	if(document.getElementById('输入框A').value=='') {            
        		alert('输入框A不能为空！');
        		document.getElementById('输入框A').focus();
        		return false;
            }else if(document.getElementById('输入框A').value%1!=0){
        		alert('输入框A不是整数！');
        		document.getElementById('输入框A').focus();
        		return false;
        	}        	
        	if(document.getElementById('输入框B').value=='') {            
        		alert('输入框B不能为空！');
        		document.getElementById('输入框B').focus();
        		return false;
            }else if(document.getElementById('输入框B').value.length!=18) {
      		  alert('输入框B位数错误！');
      		  document.getElementById('输入框B').focus();
      		  return false;
      		}
        }      
    </script>
</html>

　　

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>这里是标题</title>
</head>
<body>
<% 
Object message =request.getAttribute("message");
if(message!=null&&!"".equals(message)){
	%>
    <script type="text/javascript">alert("<%=request.getAttribute("message")%>");</script>
	<%}%>	
	
    <p style="text-align:center;color:black;font-family:宋体,serif; font-size:30px">   
    	这里是介绍
    </p>
    <p style="text-align:center"> 
            <br>
            <input type="button" value="跳转A" onclick="location.href='A.jsp'" />
            <br><br>
            <input type="button" value="跳转B" onclick="location.href='B.jsp'" /> 
            <br><br> 
            <input type="button" value="返回上一页" onclick="javascript:history.back(-1)" />
    </p>
</body>
</html>