EL：部门信息查询：
工具类DBUtil：连接数据库、SqlSession：用来接收一条sql语句，并执行，并把执行结果转为实体类对象,这几个类没写
DBUtil类：工具类：
package com.bjpowernode.util;
import java.sql.*;
/**
* author : 动力节点
* 2019/3/14 0014
*/
public class DBUtil {
private static String className="com.mysql.jdbc.Driver";
private static String url="jdbc:mysql://localhost:3306/bjpowernode";
private static String username="root";
private static String password="123456";
private static Connection conn=null;
private static PreparedStatement ps=null;
static{
try {
Class.forName(className);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
public static Connection getConn(){
try {
conn= DriverManager.getConnection(url, username,password);
//conn.setAutoCommit(false);//设置事务为手动提交
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}
public static PreparedStatement createStatement(String sql){
getConn();
try {
ps= conn.prepareStatement(sql);
}catch (Exception ex){
ex.printStackTrace();
}
return ps;
}
public static void close(ResultSet rs){
try {
if(rs!=null){
rs.close();
}
if(ps!=null){
ps.close();
}
if(conn!=null){
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
public static void close( PreparedStatement ps,Connection conn){
close(null, ps, conn);
}
public static void close(ResultSet rs, PreparedStatement ps,Connection conn){
if(rs!=null){
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(ps!=null){
try {
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(conn!=null){
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
RequestUtil类：这个工具类好像没用
package com.bjpowernode.util;
import javax.servlet.http.HttpServletRequest;
import java.lang.reflect.Field;
import java.util.Enumeration;
public class RequestUtil {
/*
* 功能：将请求协议包参数信息，赋值给对应的实体类对象
*
* 要求： 请求参数名称必须与实体类对象属性名【完全一致】
*/
public static Object init(HttpServletRequest request,Class classFile){
Object obj = null;
Enumeration paramNames=null;
//1.创建一个对应的实体类的对象
try {
obj = classFile.newInstance();
//2.得到当前请求协议包中所有的【参数名称】
paramNames =request.getParameterNames();
//3.读取请求参数并赋值
while (paramNames.hasMoreElements()){
String paramName =(String)paramNames.nextElement();//deptNo
String value = request.getParameter(paramName);
if(value!=null && !"".equals(value)){
Field fieldObj = classFile.getDeclaredField(paramName);//private Integer deptNo;
fieldObj.setAccessible(true);
String typeName = fieldObj.getType().getName();
if("java.lang.String".equals(typeName)){
fieldObj.set(obj, value);
}else if("java.lang.Integer".equals(typeName)){
fieldObj.set(obj, Integer.valueOf(value));
}else if("java.lang.Double".equals(typeName)){
fieldObj.set(obj, Double.valueOf(value));
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
return obj;
}
}
sqlSession：工具类
package com.bjpowernode.util;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
public class SqlSession {
/*
* 作用：
* 1）将接受一条查询语句,并执行
* 2）将得到执行结果数据行，转换为实体类对象
* 3）将实体类对象保存到List
*
*/
public static List selectList(String sql,Class classFile){
PreparedStatement ps = DBUtil.createStatement(sql);
ResultSet rs = null;
Field fieldArray[]=null;
List list = new ArrayList();
//1.推送查询语句得到一个结果集[ResultSet]
try {
rs =ps.executeQuery();
//2.获得实体类相关属性
fieldArray = classFile.getDeclaredFields();
//3.赋值转换
while(rs.next()){
Object obj = classFile.newInstance();
for(int i=0;i<fieldArray.length;i++){
Field fieldObj = fieldArray[i];//private Integer deptNo;
String fieldName = fieldObj.getName();//deptNo
String value =rs.getString(fieldName);
init(obj,value,fieldObj);
}
list.add(obj);
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
DBUtil.close(rs);
}
return list;
}
public static List selectList(String sql, Class classFile, HttpServletRequest request){
PreparedStatement ps=null;
Connection con = null;
ResultSet rs = null;
Field fieldArray[]=null;
List list = new ArrayList();
ServletContext application = request.getServletContext();
Map conPool=null;
//1.推送查询语句得到一个结果集[ResultSet]
try {
conPool = (Map)application.getAttribute("key");
Iterator it = conPool.keySet().iterator();
while(it.hasNext()){
con =(Connection) it.next();
boolean flag = (boolean)conPool.get(con);
if(flag==true){
conPool.put(con, false);
break;
}else{
con=null;
}
}
if(con==null){
//等待 Thread.wait();
//新建一个connection
}
ps = con.prepareStatement(sql);
rs =ps.executeQuery();
//2.获得实体类相关属性
fieldArray = classFile.getDeclaredFields();
//3.赋值转换
while(rs.next()){
Object obj = classFile.newInstance();
for(int i=0;i<fieldArray.length;i++){
Field fieldObj = fieldArray[i];//private Integer deptNo;
String fieldName = fieldObj.getName();//deptNo
String value =rs.getString(fieldName);
init(obj,value,fieldObj);
}
list.add(obj);
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
conPool.put(con, true);
}
return list;
}
private static void init(Object obj,String value,Field fieldObj){
//1.通知JVM，当前程序要使用fieldObj属性
fieldObj.setAccessible(true);
//2.赋值
try {
if(value==null){
fieldObj.set(obj, value);
}else{
String typeName = fieldObj.getType().getName();
if("java.lang.Integer".equals(typeName)){
fieldObj.set(obj, Integer.valueOf(value));
}else if("java.lang.Double".equals(typeName)){
fieldObj.set(obj, Double.valueOf(value));
}else if("java.lang.String".equals(typeName)){
fieldObj.set(obj, value);
}
}
} catch (NumberFormatException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
/*
* 1.根据接收的【实体类对象】自动生成一条INSERT
* 2.负责将INSERT推送到数据库中执行，返回操作行数
* INSERT INTO [表名] (字段1，字段2) value(值1，值2)
----------- ----- ------------ -------------
*
*/
public static int insert(Object obj){
String tableName=null;
StringBuffer columnStr = new StringBuffer("(");
StringBuffer valueStr = new StringBuffer(" value(");
StringBuffer sql = new StringBuffer("INSERT INTO ");
Field fieldArray[] = null;
PreparedStatement ps = null;
int flag =0;
//1.根据实体类获得操作的表名
tableName = getName(obj.getClass());
//2.获得需要赋值字段序列
try {
fieldArray = obj.getClass().getDeclaredFields();
for(int i=0;i<fieldArray.length;i++){
Field fieldObj = fieldArray[i];
fieldObj.setAccessible(true);
Object value = fieldObj.get(obj);
String typeName = fieldObj.getType().getName();
if("java.lang.String".equals(typeName)){
if(value!=null && !"".equals(value)){
if(columnStr.length()==1){
columnStr.append(fieldObj.getName());
valueStr.append("'");
valueStr.append(value);
valueStr.append("'");
}else{
columnStr.append(",");
columnStr.append(fieldObj.getName());
valueStr.append(",'");
valueStr.append(value);
valueStr.append("'");
}
}
}else if("java.lang.Integer".equals(typeName) || "java.lang.Double".equals(typeName)){
if(value!=null && ((Integer)value)!=0){
if(columnStr.length()==1){
columnStr.append(fieldObj.getName());
valueStr.append(value);
}else{
columnStr.append(",");
columnStr.append(fieldObj.getName());
valueStr.append(",");
valueStr.append(value);
}
}
}
}
columnStr.append(")");
valueStr.append(")");
sql.append(tableName);
sql.append(columnStr);
sql.append(valueStr);
System.out.println("sql: "+sql.toString());
ps = DBUtil.createStatement(sql.toString());
flag = ps.executeUpdate();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally{
DBUtil.close(null);
}
return flag;
}
//根据实体类得到类型名
private static String getName(Class classFile){
String classPath = classFile.getName();//com.bjpowernode.model.Dept
int index = classPath.lastIndexOf(".");
String typeName = classPath.substring(index+1);
return typeName;
}
/*
* 1.根据得到实体类对象内容，自动生成一条更新数据
* 2.自动执行更新语句
*/
public static int update(Object obj,String primaryKey){
String tableName = null;
StringBuffer setBuffer = new StringBuffer(" set ");
StringBuffer whereBuffer = new StringBuffer (" where ");
StringBuffer sql = new StringBuffer("update ");
Field fieldArray[]=null;
int flag = 0;
PreparedStatement ps =null;
//1.获得操作表名
tableName = getName(obj.getClass());
//2.设置需要更新字段信息
try {
fieldArray = obj.getClass().getDeclaredFields();
for(int i=0;i<fieldArray.length;i++){
Field fieldObj = fieldArray[i];
fieldObj.setAccessible(true);
String fieldName = fieldObj.getName();
String typeName = fieldObj.getType().getName();
Object value = fieldObj.get(obj);
if(fieldName.equals(primaryKey)){
whereBuffer.append(fieldName);
whereBuffer.append(" = ");
if("java.lang.String".equals(typeName) || "java.util.Date".equals(typeName)){
whereBuffer.append("'");
whereBuffer.append(value);
whereBuffer.append("'");
}else{
whereBuffer.append(value);
}
}else{
if(setBuffer.length()>5){
setBuffer.append(",");
}
setBuffer.append(fieldName);
setBuffer.append(" = ");
if("java.lang.String".equals(typeName) || "java.util.Date".equals(typeName)){
setBuffer.append("'");
setBuffer.append(value);
setBuffer.append("'");
}else{
setBuffer.append(value);
}
}
}
sql.append(tableName);
sql.append(setBuffer);
sql.append(whereBuffer);
System.out.println("sql : "+sql);
ps = DBUtil.createStatement(sql.toString());
flag = ps.executeUpdate();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally{
DBUtil.close(null);
}
return flag;
}
}
实体类Dept：
package com.bjpowernode.model;
public class Dept {
private Integer deptNo;
private String dname;
private String loc;
public Dept(Integer deptNo, String dname, String loc) {
this.deptNo = deptNo;
this.dname = dname;
this.loc = loc;
}
public Integer getDeptNo() {
return deptNo;
}
public void setDeptNo(Integer deptNo) {
this.deptNo = deptNo;
}
public String getDname() {
return dname;
}
public void setDname(String dname) {
this.dname = dname;
}
public String getLoc() {
return loc;
}
public void setLoc(String loc) {
this.loc = loc;
}
}
dao层：
package com.bjpowernode.dao;
import com.bjpowernode.model.Dept;
import com.bjpowernode.util.SqlSession;
import java.util.List;
public class DeptDao {
public Dept findById(String deptNo){
String sql="select * from dept where deptno="+deptNo;
List deptList= SqlSession.selectList(sql,Dept.class);
return (Dept) deptList.get(0);
}
}
控制层DeptFindIdSeervlet：
package com.bjpowernode.controller;
import com.bjpowernode.dao.DeptDao;
import com.bjpowernode.model.Dept;
import java.io.IOException;
public class DeptFindByIdServlet extends javax.servlet.http.HttpServlet {
protected void doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {
}
protected void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {
String deptNo=null;
DeptDao dao=new DeptDao();
Dept dept=null;
//1.读取来自浏览器发送的请求协议包中的请求参数【部门编号】
deptNo=request.getParameter("deptno");
//2.JDBC查询当前部门编号关联的详细信息(结果是Dept对象)
dept=dao.findById(deptNo);
//3.将查询到的信息添加到request
request.setAttribute("key",dept);
//4.向tomcat申请调用dept.jsp。将数据写入到响应包
request.getRequestDispatcher("/dept.jsp").forward(request,response);
}
}
dept.jsp:
<%--
Created by IntelliJ IDEA.
User: DELL
Date: 2022/7/20
Time: 12:31
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + path + "/";
%>
<%--需要加jstl的标签--%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<html>
<head>
<title>Title</title>
<base href="<%=basePath%>">
</head>
<body>
<center>
<table border="2">
<tr>
<td>部门编号</td>
<td><input type="text" value="${key.deptNo}"></td>
</tr>
<tr>
<td>部门名称</td>
<td><input type="text" value="${key.dname}"></td>
</tr>
<tr>
<td>部门位置</td>
<td><input type="text" value="${key.loc}"></td>
</tr>
</table>
</center>
</body>
</html>
JSTL:部门查询：
工具类是上方DBUtil类、SqlSession类
Dept类：
package com.bjpowernode.model;
public class Dept {
private Integer deptNo;
private String dname;
private String loc;
public Dept(Integer deptNo, String dname, String loc) {
this.deptNo = deptNo;
this.dname = dname;
this.loc = loc;
}
public Integer getDeptNo() {
return deptNo;
}
public void setDeptNo(Integer deptNo) {
this.deptNo = deptNo;
}
public String getDname() {
return dname;
}
public void setDname(String dname) {
this.dname = dname;
}
public String getLoc() {
return loc;
}
public void setLoc(String loc) {
this.loc = loc;
}
}
dao层：
package com.bjpowernode.dao;
import com.bjpowernode.model.Dept;
import com.bjpowernode.util.SqlSession;
import java.util.List;
public class DeptDap {
public List findAll(){
String sql="select * from dept";
List deptList= SqlSession.selectList(sql, Dept.class);
return deptList;
}
}
controller层：
DeptFindServlet：
package com.bjpowernode.controller;
import com.bjpowernode.dao.DeptDap;
import java.io.IOException;
import java.util.List;
public class DeptFindServlet extends javax.servlet.http.HttpServlet {
protected void doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {
}
protected void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {
List deptList=null;
DeptDap dao=new DeptDap();
//1.JDBC查询所有部门的信息
deptList=dao.findAll();
//2.部门信息添加到request
request.setAttribute("key",deptList);
//3.请求转发，向tomcat申请dept.jsp
request.getRequestDispatcher("/dept.jsp").forward(request,response);
}
}
dept.jsp:
<%--
Created by IntelliJ IDEA.
User: DELL
Date: 2022/7/20
Time: 12:01
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + path + "/";
%>
<%--需要加jstl的标签--%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<html>
<head>
<title>Title</title>
<base href="<%=basePath%>">
</head>
<body>
<center>
<table border="2">
<tr>
<td>部门编号</td>
<td>部门名称</td>
<td>部门位置</td>
</tr>
<c:forEach items="${key}" var="dept">
<tr>
<td>${dept.deptNo}</td>
<td>${dept.dname}</td>
<td>${dept.loc}</td>
</tr>
</c:forEach>
</table>
</center>
</body>
</html>
数据库中的表：
