Maven实现学生管理系统
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2022-05-06 16:11:36
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Maven web项目结构:
JDBC工具包在之前的博客内有
log4j.properties:
# DEBUG\u8BBE\u7F6E\u8F93\u51FA\u65E5\u5FD7\u7EA7\u522B\uFF0C\u7531\u4E8E\u4E3ADEBUG\uFF0C\u6240\u4EE5ERROR\u3001WARN\u548CINFO \u7EA7\u522B\u65E5\u5FD7\u4FE1\u606F\u4E5F\u4F1A\u663E\u793A\u51FA\u6765
log4j.rootLogger=DEBUG,RollingFile
#\u5C06\u65E5\u5FD7\u4FE1\u606F\u8F93\u51FA\u5230\u63A7\u5236\u53F0
log4j.appender.Console=org.apache.log4j.ConsoleAppender
log4j.appender.Console.layout=org.apache.log4j.PatternLayout
log4j.appender.Console.layout.ConversionPattern= [%-5p]-[%d{yyyy-MM-dd HH:mm:ss}] -%l -%m%n
#\u5C06\u65E5\u5FD7\u4FE1\u606F\u8F93\u51FA\u5230\u64CD\u4F5C\u7CFB\u7EDFD\u76D8\u6839\u76EE\u5F55\u4E0B\u7684log.log\u6587\u4EF6\u4E2D
log4j.appender.RollingFile=org.apache.log4j.DailyRollingFileAppender
log4j.appender.RollingFile.File=D://log.log
log4j.appender.RollingFile.layout=org.apache.log4j.PatternLayout
log4j.appender.RollingFile.layout.ConversionPattern=%d [%t] %-5p %-40.40c %X{traceId}-%m%n
其中log4j.rootLogger=DEBUG,Console,RollingFile
Console表示显示在控制台上
RollingFile表示显示在文件中
db.properties:
db.username=root
db.password=root
db.url=jdbc:mysql://127.0.0.1:3306/test
PropertiesTool:
package com.jd.tool;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
public class PropertiesTool {
private static Properties properties = new Properties();
static {
InputStream inputStream = PropertiesTool.class.getClassLoader().getResourceAsStream("db.properties");// 将db.properties变为javaIO流对象
try {
properties.load(inputStream);
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] ages) {
String userName = properties.getProperty("db.username");
System.out.print(userName);
}
public static String getValue(String key) {
return properties.getProperty(key);
}
}
IRowMapper:
package com.jd.tool.db;
import java.sql.ResultSet;
public interface IRowMapper {
void rowMapper(ResultSet rs);
}
DBLink:
package com.jd.tool.db;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import org.apache.log4j.Logger;
import com.jd.tool.PropertiesTool;
/**
* 数据库管理工具类
*
* @author DJ
*/
public class DBLink {
private Logger logger = Logger.getLogger(DBLink.class);
/**
* 获取数据库连接
*
* @author DJ
*/
private Connection getConnection() {
try {
Class.forName("com.mysql.jdbc.Driver");// 加载驱动
String userName = PropertiesTool.getValue("db.username");
String password = PropertiesTool.getValue("db.password");
String url = PropertiesTool.getValue("db.url");
return DriverManager.getConnection(url, userName, password);// 获取连接
} catch (Exception e) {
logger.debug(e.getMessage(), e);
}
return null;
}
/**
* 查询数据
*
* @author DJ
*/
public void select(String sql, IRowMapper rowMapper) {// 接口无法创建对象,所以rowMapper参数一定指向IRowMapper接口实现类对象
Connection connection = null;
Statement statement = null;
ResultSet resultSet = null;
try {
connection = getConnection();// 获取连接
statement = connection.createStatement();
resultSet = statement.executeQuery(sql);// 执行sql,将查询的数据存到ResultSet类型的变量中
rowMapper.rowMapper(resultSet);// 因为rowMapper参数指向IRowMapper接口实现类对象,所以此处将调用接口实现类中所实现的rowMapper方法 多态
} catch (Exception e) {
e.printStackTrace();
} finally {
close(resultSet, statement, connection);
}
}
/**
* 查询数据
*
* @author DJ
*/
public void select(String sql, IRowMapper rowMapper, Object... params) {// 接口无法创建对象,所以rowMapper参数一定指向IRowMapper接口实现类对象
Connection connection = null;
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
try {
connection = getConnection();// 获取连接
preparedStatement = connection.prepareStatement(sql);
for (int i = 0; i < params.length; i++) {
preparedStatement.setObject(i + 1, params[i]);// 为?赋值
}
resultSet = preparedStatement.executeQuery();// 执行sql,将查询的数据存到ResultSet类型的变量中
rowMapper.rowMapper(resultSet);// 因为rowMapper参数指向IRowMapper接口实现类对象,所以此处将调用接口实现类中所实现的rowMapper方法 多态
} catch (Exception e) {
e.printStackTrace();
} finally {
close(resultSet, preparedStatement, connection);
}
}
/**
* 判断SQL语句是否能查出数据
*
* @author DJ
*/
public boolean exist(String sql) {
Connection connection = null;
Statement statement = null;
ResultSet resultSet = null;
try {
connection = getConnection();
statement = connection.createStatement();
resultSet = statement.executeQuery("select id,name,mobile,address from first_class");
return resultSet.next();
} catch (Exception e) {
e.printStackTrace();
} finally {
close(resultSet, statement, connection);
}
return false;
}
/**
* 判断SQL语句是否能查出数据
*
* @author DJ
*/
public boolean exist(String sql, Object... params) {
Connection connection = null;
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
try {
connection = getConnection();
preparedStatement = connection.prepareStatement(sql);
for (int i = 0; i < params.length; i++) {
preparedStatement.setObject(i + 1, params[i]);// 为?赋值
}
resultSet = preparedStatement.executeQuery();//执行sql,将查询的数据存到ResultSet类型的变量中
return resultSet.next();
} catch (Exception e) {
e.printStackTrace();
} finally {
close(resultSet, preparedStatement, connection);
}
return false;
}
/**
* 修改(insert、update和delete)数据
*
* @author DJ
*/
public boolean update(String sql) {
Connection connection = null;
Statement statement = null;
try {
connection = getConnection();
statement = connection.createStatement();
int result = statement.executeUpdate(sql);
// statement.close();//如果上面代码出现异常,则该行代码及其下面代码无法执行,比如sql语句语法错误,则statement和connection无法释放
// connection.close();
return result > 0;// 处理结果
} catch (Exception e) {
e.printStackTrace();
} finally {// 即便有异常也会执行代码
close(statement, connection);
}
return false;
}
/**
* 修改(insert、update和delete)数据
*
* @author DJ
*/
public boolean update(String sql, Object... params) {
Connection connection = null;
PreparedStatement preparedStatement = null;
try {
connection = getConnection();
preparedStatement = connection.prepareStatement(sql);// 不完整的sql,含有?占位符的sql
for (int i = 0; i < params.length; i++) {
preparedStatement.setObject(i + 1, params[i]);// 为?赋值
}
return preparedStatement.executeUpdate() > 0;
} catch (Exception e) {
e.printStackTrace();
} finally {
close(preparedStatement, connection);
}
return false;
}
/**
* 释放资源
*
* @author DJ
*/
private void close(Statement statement, Connection connection) {
try {
if (statement != null) {// 可能由于异常导致statement没有赋值,比如url出错
statement.close();
}
} catch (SQLException e1) {
e1.printStackTrace();
}
try {
if (connection != null) {
connection.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
/**
* 释放资源
*
* @author DJ
*/
private void close(ResultSet resultSet, Statement statement, Connection connection) {
try {
if (resultSet != null) {
resultSet.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
close(statement, connection);
}
}
Main:
package com.zzu.client;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Scanner;
import com.zzu.tool.db.DBLink;
import com.zzu.tool.db.IRowMapper;
public class Main {
private static DBLink db = new DBLink();
public static void main(String[] args) {
System.out.println("*********************************");
System.out.println("*\t\t\t\t*");
System.out.println("*\t欢迎使用学生信息管理系统\t*");
System.out.println("*\t\t\t\t*");
System.out.println("*********************************");
while (true) {
menu();
}
}
static void menu() {
System.out.println("1、添加学生信息");
System.out.println("2、删除学生信息");// 学号
System.out.println("3、修改学生信息");// 地址传递
System.out.println("4、查询学生信息");// name
System.out.println("请输入操作,以Enter键结束:");
Scanner scanner = new Scanner(System.in);
int option = scanner.nextInt();
switch (option) {
case 1: {
System.out.println("请输入学生学号:");
String id = scanner.next();
String sql = "select id from student where id=?";
if (db.exist(sql, id)) {
System.out.println("学生学号已存在,请重新输入!");
return;
}
System.out.println("请输入学生姓名:");
String name = scanner.next();
System.out.println("请输入学生电话:");
String mobile = scanner.next();
System.out.println("请输入学生地址:");
String address = scanner.next();
sql = "insert into student (id,name,mobile,address)values(?,?,?,?)";
if (db.update(sql, id, name, mobile, address)) {
System.out.println("添加学生信息成功!");
return;
}
System.out.println("添加学生信息失败!");
break;
}
case 2: {
System.out.println("请输入要删除的学生学号:");
String id = scanner.next();
String sql = "delete from student where id =?";
if (db.update(sql, id)) {
System.out.println("成功删除学生信息!");
return;
}
System.out.println("删除失败!学号不存在");
break;
}
case 3: {
System.out.println("请输入要修改的学生学号:");
String id = scanner.next();
String sql = "select name from student where id = ?";
if (!db.exist(sql, id)) {
System.out.println("学号不存在,操作终止!");
return;
}
System.out.println("请输入新的学生姓名:");
String name = scanner.next();
System.out.println("请输入新的学生电话:");
String mobile = scanner.next();
System.out.println("请输入新的学生地址:");
String address = scanner.next();
sql = "update student set name=?,mobile=?,address=? where id=?";
if (db.update(sql, name, mobile, address,id)) {
System.out.println("修改成功!");
return;
}
System.out.println("修改失败!");
break;
}
case 4: {
System.out.println("请输入要查询的学生学号:");
String id = scanner.next();
String sql = "select id,name,mobile,address from student where id =?";
/*class RowMapper implements IRowMapper {
@Override
public void rowMapper(ResultSet rs) {
try {
if (rs.next()) {
String id = rs.getString("id");
String name = rs.getString("name");
String mobile = rs.getString("mobile");
String address = rs.getString("address");
System.out.println(id + "," + name + "," + mobile + "," + address);
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
IRowMapper rowMapper = new RowMapper();
db.select(sql, rowMapper, id);*/
db.select(sql, (rs) -> {
String name;
try {
if (rs.next()) {
name = rs.getString("name");
String mobile = rs.getString("mobile");
String address = rs.getString("address");
System.out.println(id + "," + name + "," + mobile + "," + address);
return;
}
System.out.println("查询失败!");
} catch (SQLException e) {
e.printStackTrace();
}
}, id);
break;
}
default:
System.out.println("I'm Sorry,there is not the " + option + " option,please try again.");
}
}
}
补充:
在实现查询功能时使用了Lambda表达式,须将创建的Maven web项目升级为JDK8.0+
可以在pom.xml中添加:
<profiles>
<profile>
<id>jdk1.8</id>
<activation>
<activeByDefault>true</activeByDefault>
<jdk>1.8</jdk>
</activation>
<properties>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
<maven.compiler.compilerVersion>1.8</maven.compiler.compilerVersion>
</properties>
</profile>
</profiles>
然后选择Maven ——> Update project即可
注:如果创建Maven web项目报错,可能是缺少servlet
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