Article directory
- 1. Implement a bank transfer
- 2 Implementation steps
-
- 2.1 Environment Construction
- 2.2 Prepare the page
- 2.3 Create package
- 3. Complete code
-
- 3.1dao (data persistence layer)
- 3.2 service (business processing layer)
- 3.3web (presentation layer)
1. Implement a bank transfer
Prepare the database and the data in the database:
2 Implementation steps
2.1 Environment construction
(1) Create Maven WEB application in IDEA
(2) Configure web.xml to a higher version
That is to replace web.xml with:
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
version="4.0"
metadata-complete="true">
</web-app>
(3) Add dependencies
<dependencies>
<!--mybatis dependency-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.10</version>
</dependency>
<!--mysql driver dependency-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.37</version>
</dependency>
<!--logback dependency-->
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>1.2.11</version>
</dependency>
<!--servlet dependency-->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>4.0.1</version>
</dependency>
</dependencies>
(4) Configure the Tomcat server
(5) Copy the previous resources resource
(6) Modify mybatis-config.xml as follows:
<?xml version="1.0" encoding="UTF-8" ?>
<! DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<properties resource="jdbc.properties"/>
<environments default="sdnuDB">
<environment id="sdnuDB">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="${jdbc.driver}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="AccountMapper.xml"/>
</mappers>
</configuration>
2.2 Prepare page
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Bank account transfer</title>
</head>
<body>
<form action="/bank/transfer" method="post">
Transfer-out account: <input type="text" name="fromActno"><br>
Transfer to account: <input type="text" name="toActno"><br>
Amount transferred out: <input type="text" name="money"><br>
<input type="submit" value="transfer">
</form>
</body>
</html>
2.3 Create package
Create an Account in the pojo package
package com.sndu.bank.pojo;
/**
* Package account class
*
* @author Beyong
* @version 1.0
* @since 1.0
*/
public class Account {<!-- -->
private Long id;
private String actno;
private double balance;
public Account() {<!-- -->
}
public Account(Long id, String actno, Double balance) {<!-- -->
this.id = id;
this.actno = actno;
this. balance = balance;
}
public Long getId() {<!-- -->
return id;
}
public void setId(Long id) {<!-- -->
this.id = id;
}
public String getActno() {<!-- -->
return actno;
}
public void setActno(String actno) {<!-- -->
this.actno = actno;
}
public Double getBalance() {<!-- -->
return balance;
}
public void setBalance(Double balance) {<!-- -->
this. balance = balance;
}
@Override
public String toString() {<!-- -->
return "Account{" +
"id=" + id +
", actno='" + actno + '\'' +
", balance=" + balance +
'}';
}
}
Create a new SqlSessionUtil.java in the utils package
package com.sndu.bank.utils;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.io.IOException;
/**
* mybatis tool class
*/
public class SqlSessionUtil {<!-- -->
private static SqlSessionFactory sqlSessionFactory;
private SqlSessionUtil(){<!-- -->}
static {<!-- -->
try {<!-- -->
sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
} catch (IOException e) {<!-- -->
throw new RuntimeException(e);
}
}
public static SqlSession openSession(){<!-- -->
return sqlSessionFactory. openSession();
}
}
exception package
package com.sndu.bank.exceptions;
/**
* Insufficient balance exception
*/
public class MoneyNotEnoughException extends Exception{<!-- -->
public MoneyNotEnoughException() {<!-- -->
}
public MoneyNotEnoughException(String msg) {<!-- -->
super(msg);
}
}
package com.sndu.bank.exceptions;
public class TransferException extends Exception{<!-- -->
public TransferException() {<!-- -->
}
public TransferException(String message) {<!-- -->
super(message);
}
}
3. Complete code
3.1dao (data persistence layer)
AccountDao.java
package com.sndu.bank.dao;
import com.sndu.bank.pojo.Account;
/**
* The Dao object of the account, responsible for the CRUD of t_act in the table
* @author Beyong
* @version 1.0
* @since 1.0
*/
public interface AccountDao {<!-- -->
/**
* Query account information according to the account
* @param actno account number
* @return account information
*/
Account selectByActno(String actno);
/**
* Update account information
* @param act the account to update
* @return 1 means the update is successful, other means the update failed
*/
int updateByActno(Account act);
}
AccountDaoImpl.java
package com.sndu.bank.dao.impl;
import com.sndu.bank.dao.AccountDao;
import com.sndu.bank.pojo.Account;
import com.sndu.bank.utils.SqlSessionUtil;
import org.apache.ibatis.session.SqlSession;
public class AccountDaoImpl implements AccountDao {<!-- -->
@Override
public Account selectByActno(String actno) {<!-- -->
SqlSession sqlSession = SqlSessionUtil. openSession();
Account account = (Account)sqlSession.selectOne("account.selectByActno", actno);
return account;
}
@Override
public int updateByActno(Account act) {<!-- -->
SqlSession sqlSession = SqlSessionUtil. openSession();
int count = sqlSession. update("account. updateByActno", act);
return count;
}
}
3.2 service (business processing layer)
package com.sndu.bank.service;
import com.sndu.bank.exceptions.MoneyNotEnoughException;
import com.sndu.bank.exceptions.TransferException;
/**
* Account business class
* @author Beyong
* @version 1.0
* @since 1.0
*/
public interface AccountService {<!-- -->
/**
* transfer
* @param fromActno into account
* @param toActno transfer account
* @param money converted into amount
*/
void transfer(String fromActno, String toActno, double money) throws MoneyNotEnoughException, TransferException;
}
package com.sndu.bank.service.impl;
import com.sndu.bank.dao.AccountDao;
import com.sndu.bank.dao.impl.AccountDaoImpl;
import com.sndu.bank.exceptions.MoneyNotEnoughException;
import com.sndu.bank.exceptions.TransferException;
import com.sndu.bank.pojo.Account;
import com.sndu.bank.service.AccountService;
import com.sndu.bank.utils.SqlSessionUtil;
import org.apache.ibatis.session.SqlSession;
public class AccountServiceImpl implements AccountService {<!-- -->
private AccountDao accountDao = new AccountDaoImpl();
@Override
public void transfer(String fromActno, String toActno, double money) throws MoneyNotEnoughException, TransferException {<!-- -->
SqlSession sqlSession = SqlSessionUtil. openSession();
//1. Determine whether the account balance is sufficient (select)
Account fromAct = accountDao. selectByActno(fromActno);
if(fromAct.getBalance() < money){<!-- -->
//2. If the account balance is insufficient, notify the user
throw new MoneyNotEnoughException("Sorry, the balance is insufficient");
}
//3. If the account balance is sufficient, transfer and update the transferred account balance (update)
//First update the account balance of the memory java account object
Account toAct = accountDao. selectByActno(toActno);
fromAct.setBalance(fromAct.getBalance() - money);
toAct.setBalance(toAct.getBalance() + money);
int count = accountDao. updateByActno(fromAct);
// //Simulate null pointer exception
// String s = null;
// s.toString();
//4. Update the balance of the transferred account
count + = accountDao. updateByActno(toAct);
if(count != 2){<!-- -->
throw new TransferException("Transfer exception");
}
//commit transaction
sqlSession.commit();
//Close the transaction
SqlSessionUtil.close(sqlSession);
}
}
3.3web (presentation layer)
package com.sndu.bank.web;
import com.sndu.bank.exceptions.MoneyNotEnoughException;
import com.sndu.bank.exceptions.TransferException;
import com.sndu.bank.service.AccountService;
import com.sndu.bank.service.impl.AccountServiceImpl;
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 java.io.IOException;
@WebServlet("/transfer")
public class AccountServlet extends HttpServlet {<!-- -->
private AccountService accountService = new AccountServiceImpl();
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {<!-- -->
String fromActno = request. getParameter("fromActno");
String toActno = request. getParameter("toActno");
double money = Double. parseDouble(request. getParameter("money"));
//Call the service method to complete the transfer (call the business layer)
try {<!-- -->
accountService. transfer(fromActno, toActno, money);
response.sendRedirect(request.getContextPath() + "/success.html");
} catch (MoneyNotEnoughException e) {<!-- -->
response.sendRedirect(request.getContextPath() + "/error1.html");
} catch (TransferException e) {<!-- -->
response.sendRedirect(request.getContextPath() + "/error2.html");
} catch (Exception e){<!-- -->
response.sendRedirect(request.getContextPath() + "/error2.html");
}
}
}