通过模拟Atm取款，测试代码
Sql中的表为：
| username | password | balance |
1、数据库查询包，实现了包装增删改查，多条查询,其中三个方法可以实现增、删、改、单条查询、多条查询
package util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import AtmoPo.Rowmapper;
import AtmoPo.RowmapperAll;
//接口，为实现多条查询做准备
public class JdbcTemplament {
//数据库的链接
public Connection getConn() {
Connection conn=null;
try {
//加载驱动
Class.forName("oracle.jdbc.driver.OracleDriver");
conn=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl", "scott", "123456");
} catch (ClassNotFoundException e) {
System.out.println("驱动加载失败！");
e.printStackTrace();
} catch (SQLException e) {
System.out.println("链接数据库失败！");
e.printStackTrace();
}
return conn;
}
//update()可以实现增删改,注意数组中的元素要与sql中一致；
public void update (String sql,Object[] values) {
Connection conn=getConn();
PreparedStatement ps=null;
try {
ps=conn.prepareStatement(sql);
for(int i=0;i<values.length;i++) {
ps.setObject(i+1, values[i]);
}
ps.executeUpdate();
} catch (SQLException e) {
System.out.println("update方法创建Prepare失败");
e.printStackTrace();
}finally {
try {
ps.close();
conn.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
//单条查询
public Object load(String sql,Object[] values,Rowmapper rm) {
Object ojb=null;
Connection conn=getConn();
PreparedStatement ps=null;
try {
ps=conn.prepareStatement(sql);
for(int i=0;i<values.length;i++) {
ps.setObject(i+1, values[i]);
}
ResultSet rs=ps.executeQuery();
//接收查询出的结果
ojb=rm.rowMapper(rs);
} catch (SQLException e) {
System.out.println("单条查询中创建PrepareStatement失败");
e.printStackTrace();
}finally {
try {
ps.close();
conn.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return ojb;
}
//多条查询
public List<Object> queryAll(String sql,Object[] values,RowmapperAll ra) {
Connection conn=getConn();
PreparedStatement ps=null;
List<Object> list=new ArrayList<Object>();
try {
ps=conn.prepareStatement(sql);
for(int i=0;i<values.length;i++) {
ps.setObject(i+1, values[i]);
}
ResultSet rs=ps.executeQuery();
//接收查询出的结果
list=ra.rowMapperAll(rs);
} catch (SQLException e) {
System.out.println("多条查询中创建PrepareStatement失败");
e.printStackTrace();
}finally {
try {
ps.close();
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
return list;
}
}
2.连个接口，单条查询与多条查询依赖的两个接口、实现单挑或者多条信息的映射
package AtmoPo;
import java.sql.ResultSet;
public interface Rowmapper {
//此处根据需求，将rs查询的结果集用对象接收；
public Object rowMapper(ResultSet rs);
}
package AtmoPo;
import java.sql.ResultSet;
import java.util.List;
public interface RowmapperAll {
public List<Object> rowMapperAll(ResultSet rs);
}
3、Atm映射
package AtmoPo;
public class Atm {
private String username;
private String password;
private int balance;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public int getBalance() {
return balance;
}
public void setBalance(int balance) {
this.balance = balance;
}
@Override
public String toString() {
return "Atm [username=" + username + ", password=" + password + ", balance=" + balance + "]";
}
}
4.数据链接层，实现以上两个接口
package ATMDao;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import AtmoPo.Atm;
import AtmoPo.Rowmapper;
import AtmoPo.RowmapperAll;
import util.JdbcTemplament;
public class AtmDao implements Rowmapper,RowmapperAll {
//存款
public void cunkuanDao(String username,int money) {
JdbcTemplament jtl=new JdbcTemplament();
Atm atm=load(username);
atm.setBalance(atm.getBalance()+money);
String sql1="update tb_atm set balance=? where username=?";
jtl.update(sql1, new Object[] {atm.getBalance(),atm.getUsername()});
}
//取款
public void quqianDao(String username,int money) {
JdbcTemplament jtl=new JdbcTemplament();
Atm atm=load(username);
if(atm.getBalance()>money) {
atm.setBalance(atm.getBalance()-money);
String sql1="update tb_atm set balance=? where username=?";
jtl.update(sql1, new Object[] {atm.getBalance(),atm.getUsername()});
}else {
System.out.println("余额不足！");
}
}
//转账
public void zhuanzhangDao(String username,int money,String rusername) {
JdbcTemplament jtl=new JdbcTemplament();
Atm atm=load(username);
if(atm.getBalance()>money) {
atm.setBalance(atm.getBalance()-money);
String sql1="update tb_atm set balance=? where username=?";
jtl.update(sql1, new Object[] {atm.getBalance(),atm.getUsername()});
//对转入账户的操作
Atm atm1=load(rusername);
atm1.setBalance(atm1.getBalance()+money);
String sql3="update tb_atm set balance=? where username=?";
jtl.update(sql3, new Object[] {atm1.getBalance(),atm1.getUsername()});
}else {
System.out.println("余额不足！");
}
}
//查询余额
public int chaxunyue(String username) {
Atm atm=load(username);
return atm.getBalance();
}
//封装单条查询
public Atm load(String username) {
JdbcTemplament jtl=new JdbcTemplament();
String sql="select * from tb_atm where username=?";
Atm atm=(Atm)jtl.load(sql, new Object[] {username}, this);
return atm;
}
//多条查询
public List<Object> queryAllDao(int start,int end){
JdbcTemplament jtl=new JdbcTemplament();
String sql="Select * from(select rownum r ,tb_atm.* from tb_atm)t where t.r between ? and ?";
List<Object> list=jtl.queryAll(sql, new Object[] {start,end}, this);
return list;
}
@Override
public Object rowMapper(ResultSet rs) {
Atm atm=null;
try {
if(rs.next()) {
atm=new Atm();
atm.setUsername(rs.getString("username"));
atm.setPassword(rs.getString("pasword"));
atm.setBalance(rs.getInt("balance"));
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return atm;
}
@Override
public List<Object> rowMapperAll(ResultSet rs) {
List<Object> list= new ArrayList<Object>();
Atm atm=null;
try {
while(rs.next()) {
atm=new Atm();
atm.setUsername(rs.getString("username"));
atm.setPassword(rs.getString("pasword"));
atm.setBalance(rs.getInt("balance"));
list.add(atm);
}
} catch (SQLException e) {
e.printStackTrace();
}
return list;
}
}
5.业务层
package Service;
import ATMDao.AtmDao;
import AtmoPo.Atm;
public class AtmService {
public void cunkuan(String username,int money) {
AtmDao ad=new AtmDao();
ad.cunkuanDao(username, money);
}
public void zhuanzhang(String username,int money,String rusername) {
AtmDao ad=new AtmDao();
ad.zhuanzhangDao(username, money, rusername);
}
public void qukuan(String username,int money) {
AtmDao ad=new AtmDao();
ad.quqianDao(username, money);
}
public int yue(String username) {
AtmDao ad=new AtmDao();
return ad.chaxunyue(username);
}
public void queryAll(int start,int end){
AtmDao ad=new AtmDao();
for(Object arr: ad.queryAllDao(start, end)){
System.out.println((Atm)arr);
}
}
}
6.测试
package test;
import Service.AtmService;
public class Test {
public static void main(String[] args) {
AtmService as=new AtmService();
System.out.println("马云的存款前余额为："+as.yue("马云"));
as.cunkuan("马云", 10000);
System.out.println("马云的存款后余额为："+as.yue("马云"));
System.out.println("小王收款前余额为："+as.yue("小王"));
as.zhuanzhang("马云", 2000, "小王");
System.out.println("马云的转账后余额为："+as.yue("马云"));
System.out.println("小王收款后余额为："+as.yue("小王"));
as.qukuan("小王", 1000);
System.out.println("小王取款后余额为："+as.yue("小王"));
as.queryAll(1, 2);
}
}