Author's homepage: Programming Thousand Paper Cranes
About the author: Java, front-end, and Python have been developed for many years, and have worked as a senior engineer, project manager, and architect
Main content: Java project development, Python project development, university data and AI project development, MCU project design, interview technology arrangement, latest technology sharing
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Get the source code at the end of the article
Table of contents
Item number: BS-SC-056
1. Environmental introduction
Locale: Java: jdk1.8
Database: Mysql: mysql5.7
Application server: Tomcat: tomcat8.5.31
Development tools: IDEA or eclipse
Development technology: Java Web development technology (JSP, SERVLET, JDBC)
2. Project introduction
This project develops and implements a smart vegetable market system based on JavaWeb technology. Mainly complete the stall display and management of the vegetable market, commodity display and management, related notices, online messages, online shopping and other related operations. System users include front-end registered users and background management users. User management mainly implements user management, difficulty management, product classification management, product management, announcement management, order management, carousel map management, friendship connection management, etc. Front-end users can browse the information of vegetable market stalls and products operated by the stalls online, add shopping carts online, purchase orders online, browse announcement information, and so on.
Three, system display
Front page display
Commodity information inquiry
Booth information display
Announcement information display
Online message display
user registration
Background administrator management function
administrator management
Registered user management
Farmer Management
Booth Management
commodity management
order management
Announcement management
System Management
Fourth, the core code display
package dao;
import com.jntoo.db.utils.StringUtil;
import java.sql.*;
import java.util.*;
import javax.servlet.http.HttpServletRequest;
import util.Info;
/**
* 数据库连接类
*/
public class CommDAO {
// 数据库名称
public static final String database = "jspm12545zhcscxtdsjysx";
// 数据库账号
public static final String username = "root";
// 数据库密码
public static final String pwd = "root";
// 是否为 mysql8.0及以上、如果是则把 false 改成 true
public static final boolean isMysql8 = false; // 是否为mysql8
public static Connection conn = null;
/**
* 创建类时即连接数据库
*/
public CommDAO() {
conn = this.getConn();
}
/**
* 数据库链接类
* @return
*/
public static Connection getConn() {
try {
if (conn == null || conn.isClosed()) {
String connstr = getConnectString();
conn = DriverManager.getConnection(connstr, username, pwd);
}
} catch (Exception e) {
e.printStackTrace();
}
return conn;
}
public static String getConnectString() {
try {
String connstr;
if (!isMysql8) {
Class.forName("com.mysql.jdbc.Driver");
connstr = String.format("jdbc:mysql://localhost:3306/%s?useUnicode=true&characterEncoding=UTF-8&useOldAliasMetadataBehavior=true", database);
} else {
Class.forName("com.mysql.cj.jdbc.Driver");
connstr =
String.format(
"jdbc:mysql://localhost:3306/%s?useUnicode=true&characterEncoding=UTF-8&useSSL=FALSE&serverTimezone=UTC&useOldAliasMetadataBehavior=true",
database
);
}
return connstr;
} catch (Exception e) {
e.printStackTrace();
}
return "";
}
/**
* 根据表ID 获取数据
* @param id 数值
* @param table 表名称
* @return
*/
public HashMap getmap(String id, String table) {
List<HashMap> list = new ArrayList();
try {
Statement st = conn.createStatement();
//System.out.println("select * from "+table+" where id="+id);
ResultSet rs = st.executeQuery("select * from " + table + " where id=" + id);
ResultSetMetaData rsmd = rs.getMetaData();
while (rs.next()) {
HashMap map = new HashMap();
int i = rsmd.getColumnCount();
for (int j = 1; j <= i; j++) {
if (!rsmd.getColumnName(j).equals("ID")) {
String str = rs.getString(j) == null ? "" : rs.getString(j);
if (str.equals("null")) str = "";
map.put(rsmd.getColumnName(j), str);
} else map.put("id", rs.getString(j));
}
list.add(map);
}
rs.close();
st.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return list.get(0);
}
/**
* 根据sql 语句获取一行数据
* @param sql
* @return
*/
public HashMap find(String sql) {
HashMap map = new HashMap();
//List<HashMap> list = new ArrayList();
try {
Statement st = conn.createStatement();
System.out.println(sql);
ResultSet rs = st.executeQuery(sql);
ResultSetMetaData rsmd = rs.getMetaData();
while (rs.next()) {
//HashMap map = new HashMap();
int i = rsmd.getColumnCount();
for (int j = 1; j <= i; j++) {
if (!rsmd.getColumnName(j).equals("ID")) {
String str = rs.getString(j) == null ? "" : rs.getString(j);
if (str.equals("null")) str = "";
map.put(rsmd.getColumnName(j), str);
} else map.put("id", rs.getString(j));
}
//list.add(map);
break;
}
rs.close();
st.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
//e.printStackTrace();
int code = e.getErrorCode();
String message = e.getMessage();
System.err.println("SQL execute Error");
System.err.println("code:" + code);
System.err.println("Message:" + message);
}
return map;
}
/**
* 根据某字段的值获取一行数据
* @param nzd 字段名称
* @param zdz 条件值
* @param table 表
* @return
*/
public HashMap getmaps(String nzd, String zdz, String table) {
List<HashMap> list = new ArrayList();
try {
Statement st = conn.createStatement();
//System.out.println("select * from "+table+" where "+nzd+"='"+zdz+"'");
ResultSet rs = st.executeQuery("select * from " + table + " where " + nzd + "='" + zdz + "'");
ResultSetMetaData rsmd = rs.getMetaData();
while (rs.next()) {
HashMap map = new HashMap();
int i = rsmd.getColumnCount();
for (int j = 1; j <= i; j++) {
if (!rsmd.getColumnName(j).equals("ID")) {
String str = rs.getString(j) == null ? "" : rs.getString(j);
if (str.equals("null")) str = "";
map.put(rsmd.getColumnName(j), str);
} else map.put("id", rs.getString(j));
}
list.add(map);
}
rs.close();
st.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return list.get(0);
}
/**
* 获取前台提交的数据将数据写成Map<String , String> 形式，方便写入数据库
* @param request
* @return 返回值类型为Map<String, String>
*/
public static HashMap getParameterStringMap(HttpServletRequest request) {
Map<String, String[]> properties = request.getParameterMap(); //把请求参数封装到Map<String, String[]>中
HashMap returnMap = new HashMap<String, String>();
String name = "";
String value = "";
for (Map.Entry<String, String[]> entry : properties.entrySet()) {
name = entry.getKey();
String[] values = entry.getValue();
if (null == values) {
value = "";
} else {
value = StringUtil.join(",", values); //用于请求参数中请求参数名唯一
}
returnMap.put(name, value);
}
return returnMap;
}
/**
* 插入数据库
* @param request
* @param tablename
* @param extmap
* @return
*/
public String insert(HttpServletRequest request, String tablename, HashMap extmap) {
extmap.put("addtime", Info.getDateStr()); // 设置添加时间为当前时间
Query query = new Query(tablename); // 新建查询模块
HashMap post = getParameterStringMap(request); // 获取前台提交的数据将数据写成Map对象
post.putAll(extmap); // 扩展的数据以覆盖方式写到提交的数据中
return query.add(post); // 将数据生成sql insert语句,并执行,可以查看输出控制台中执行的SQL语句
}
/**
* 删除数据
* @param request
* @param tablename 表名称
*/
public void delete(HttpServletRequest request, String tablename) {
int i = 0;
try {
String did = request.getParameter("did");
if (did == null) did = request.getParameter("scid");
if (did == null) did = request.getParameter("id");
if (did != null) {
if (did.length() > 0) {
Statement st = conn.createStatement();
System.out.println("delete from " + tablename + " where id=" + did);
st.execute("delete from " + tablename + " where id=" + did);
st.close();
}
}
} catch (SQLException e) {
// TODO Auto-generated catch block
//e.printStackTrace();
int code = e.getErrorCode();
String message = e.getMessage();
System.err.println("SQL execute Error");
System.err.println("code:" + code);
System.err.println("Message:" + message);
}
}
/**
* 获取某表一列数据
* @param table
* @return
*/
public String getCols(String table) {
String str = "";
Connection conn = this.getConn();
try {
Statement st = conn.createStatement();
ResultSet rs = st.executeQuery("select * from " + table);
ResultSetMetaData rsmd = rs.getMetaData();
int i = rsmd.getColumnCount();
for (int j = 2; j <= i; j++) {
str += rsmd.getColumnName(j) + ",";
}
} catch (SQLException e) {
int code = e.getErrorCode();
String message = e.getMessage();
System.err.println("SQL execute Error");
System.err.println("code:" + code);
System.err.println("Message:" + message);
//e.printStackTrace();
}
str = str.substring(0, str.length() - 1);
return str;
}
/**
* 更新数据
* @param request
* @param tablename
* @param extmap
* @return
*/
public String update(HttpServletRequest request, String tablename, HashMap extmap) {
Query query = new Query(tablename);
HashMap post = getParameterStringMap(request);
post.putAll(extmap);
if (query.save(post)) {
return String.valueOf(post.get("id"));
}
return "";
}
/**
* 执行sql 语句
* @param sql
* @return
*/
public long commOper(String sql) {
System.out.println(sql);
long autoInsertId = -1;
try {
Statement st = conn.createStatement();
st.executeUpdate(sql, Statement.RETURN_GENERATED_KEYS);
ResultSet rs = st.getGeneratedKeys();
while (rs.next()) {
autoInsertId = rs.getLong(1);
}
rs.close();
st.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
//e.printStackTrace();
int code = e.getErrorCode();
String message = e.getMessage();
System.err.println("SQL execute Error");
System.err.println("code:" + code);
System.err.println("Message:" + message);
}
return autoInsertId;
}
/**
* 执行多条SQL语句
* @param sql
*/
public void commOperSqls(ArrayList<String> sql) {
try {
conn.setAutoCommit(false);
for (int i = 0; i < sql.size(); i++) {
Statement st = conn.createStatement();
System.out.println(sql.get(i));
st.execute(sql.get(i));
st.close();
}
conn.commit();
} catch (SQLException e) {
try {
conn.rollback();
} catch (SQLException e1) {
//e1.printStackTrace();
int code = e1.getErrorCode();
String message = e1.getMessage();
System.err.println("SQL execute Error");
System.err.println("code:" + code);
System.err.println("Message:" + message);
}
e.printStackTrace();
} finally {
try {
conn.setAutoCommit(true);
} catch (SQLException e) {
int code = e.getErrorCode();
String message = e.getMessage();
System.err.println("SQL execute Error");
System.err.println("code:" + code);
System.err.println("Message:" + message);
//e.printStackTrace();
}
}
}
/**
* 根据SQL语句获取数据行
* @param sql
* @return
*/
public List select(String sql) {
System.out.println(sql);
List<HashMap> list = new ArrayList();
try {
Statement st = conn.createStatement();
ResultSet rs = st.executeQuery(sql);
ResultSetMetaData rsmd = rs.getMetaData();
while (rs.next()) {
HashMap map = new HashMap();
int i = rsmd.getColumnCount();
for (int j = 1; j <= i; j++) {
if (!rsmd.getColumnName(j).equals("ID")) {
String str = rs.getString(j) == null ? "" : rs.getString(j);
if (str.equals("null")) str = "";
map.put(rsmd.getColumnName(j), str);
} else map.put("id", rs.getString(j));
}
list.add(map);
}
rs.close();
st.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
if (sql.equals("show tables")) list = select("select table_name from INFORMATION_SCHEMA.tables"); else {
int code = e.getErrorCode();
String message = e.getMessage();
System.err.println("SQL execute Error");
System.err.println("code:" + code);
System.err.println("Message:" + message);
}
//e.printStackTrace();
}
return list;
}
public void close() {}
/**
* 执行一条查询sql,以 List<hashmap> 的形式返回查询的记录，记录条数，和从第几条开始，由参数决定，主要用于翻页
* pageno 页码 rowsize 每页的条数
*/
public List select(String sql, int pageno, int rowsize) {
List<HashMap> list = new ArrayList();
List<HashMap> mlist = new ArrayList();
try {
list = this.select(sql);
int min = (pageno - 1) * rowsize;
int max = pageno * rowsize;
for (int i = 0; i < list.size(); i++) {
if (!(i < min || i > (max - 1))) {
mlist.add(list.get(i));
}
}
} catch (RuntimeException re) {
re.printStackTrace();
throw re;
}
return mlist;
}
public static void main(String[] args) {}
}
5. Display of related works
Practical projects based on Java development, Python development, PHP development, C# development and other related language development
Front-end practical projects developed based on Nodejs, Vue and other front-end technologies
Related works based on WeChat applet and Android APP application development
Development and application of embedded IoT based on 51 single-chip microcomputer
AI intelligent application based on various algorithms
Various data management and recommendation systems based on big data
