1、配置依赖
<dependencies><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.18.10</version></dependency><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.12</version><scope>test</scope></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.28</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>druid</artifactId><version>1.2.16</version></dependency></dependencies>
2、Fruit 实体类
package com.csdn.fruit.pojo; import lombok.AllArgsConstructor; import lombok.Data; import lombok.NoArgsConstructor; import java.io.Serializable; @Data @NoArgsConstructor @AllArgsConstructor public class Fruit implements Serializable {private Integer fid;private String fname;private Integer price;private Integer fcount;private String remark;public Fruit(String fname, Integer price, Integer fcount, String remark) {this.fname = fname;this.price = price;this.fcount = fcount;this.remark = remark;}@Overridepublic String toString() {return fname + "\t\t" + price + "\t\t" + fcount + "\t\t" + remark;} }
3、设计数据访问对象层DAO接口
package com.csdn.fruit.dao; import com.csdn.fruit.pojo.Fruit; import java.util.List; //dao :Data Access Object 数据访问对象 //接口设计 public interface FruitDao {void addFruit(Fruit fruit);void delFruit(String fname);void updateFruit(Fruit fruit);List<Fruit> getFruitList();Fruit getFruitByFname(String fname); }
4、设计DAO层的实现类
package com.csdn.fruit.dao.impl; import com.csdn.fruit.dao.FruitDao; import com.csdn.fruit.pojo.Fruit; import com.csdn.mymvc.dao.BaseDao; import java.util.List; public class FruitDaoImpl extends BaseDao<Fruit> implements FruitDao {@Overridepublic void addFruit(Fruit fruit) {String sql = "insert into t_fruit values (0,?,?,?,?)";super.executeUpdate(sql, fruit.getFname(), fruit.getPrice(), fruit.getFcount(), fruit.getRemark());}@Overridepublic void delFruit(String fname) {String sql = "delete from t_fruit where fname=?";super.executeUpdate(sql, fname);}@Overridepublic void updateFruit(Fruit fruit) {String sql = "update t_fruit set fcount=? where fname = ?";super.executeUpdate(sql, fruit.getFcount(), fruit.getFname());}@Overridepublic List<Fruit> getFruitList() {return super.executeQuery("select * from t_fruit");}@Overridepublic Fruit getFruitByFname(String fname) {return load("select * from t_fruit where fname = ?", fname);} }
5、编写 jdbc 配置文件
jdbc.driver=com.mysql.cj.jdbc.Driver jdbc.url=jdbc:mysql:///fruitdb jdbc.user=root jdbc.pwd=123456 jdbc.init_size=5 jdbc.max_active=20 jdbc.max_wait=3000
6、 设计数据库操作层(抽象类)
package com.csdn.mymvc.dao; import com.alibaba.druid.pool.DruidDataSource; import com.csdn.mymvc.util.ClassUtil; import javax.sql.DataSource; import java.io.IOException; import java.io.InputStream; import java.lang.reflect.ParameterizedType; import java.lang.reflect.Type; import java.sql.*; import java.util.ArrayList; import java.util.List; import java.util.Properties; public abstract class BaseDao<T> {private String entityClassName;public BaseDao() {// this 是谁? this代表的是 FruitDaoImpl 的实例对象,因为 BaseDao是抽象类,不能直接创建对象,所以 new 的是它的子类对象 FruitDaoImpl// this.getClass() 获取的是 FruitDaoImpl 的Class对象// getGenericSuperclass() 获取到的是:BaseDao<Fruit>// Type 是顶层接口,表示所有的类型。它有一个子接口:ParameterizedTypeParameterizedType genericSuperclass = (ParameterizedType) this.getClass().getGenericSuperclass();// Actual:实际的// getActualTypeArguments() 获取实际的类型参数Type[] actualTypeArguments = genericSuperclass.getActualTypeArguments();Type actualTypeArgument = actualTypeArguments[0];// System.out.println(actualTypeArgument.getTypeName());//com.csdn.fruit.pojo.FruitentityClassName = actualTypeArgument.getTypeName();initDataSource();}private DataSource dataSource;//加载jdbc.properties文件private void initDataSource() {try {InputStream inputStream = getClass().getClassLoader().getResourceAsStream("jdbc.properties");Properties properties = new Properties();properties.load(inputStream);String driver = properties.getProperty("jdbc.driver", "com.mysql.cj.jdbc.Driver");String url = properties.getProperty("jdbc.url", "jdbc:mysql:///fruitdb");String user = properties.getProperty("jdbc.user", "root");String pwd = properties.getProperty("jdbc.pwd", "123456");Integer initSize = Integer.parseInt(properties.getProperty("jdbc.init_size", "5"));Integer maxActive = Integer.parseInt(properties.getProperty("jdbc.max_active", "10"));Integer maxWait = Integer.parseInt(properties.getProperty("jdbc.max_wait", "5000"));DruidDataSource druidDataSource = new DruidDataSource();druidDataSource.setDriverClassName(driver);druidDataSource.setUrl(url);druidDataSource.setUsername(user);druidDataSource.setPassword(pwd);druidDataSource.setInitialSize(initSize);druidDataSource.setMaxActive(maxActive);druidDataSource.setMaxWait(maxWait);dataSource = druidDataSource;} catch (IOException e) {throw new RuntimeException(e);}}private Connection getConn() throws SQLException {return dataSource.getConnection();}private void close(Connection conn, PreparedStatement psmt, ResultSet rs) {try {if (rs != null) {rs.close();}if (psmt != null) {psmt.close();}if (conn != null && !conn.isClosed()) {conn.close();}} catch (SQLException e) {throw new RuntimeException(e);}}//抽取执行更新方法//执行更新,返回影响行数//如果是执行 insert,那么可以尝试返回自增列的值protected int executeUpdate(String sql, Object... params) {boolean insertFlag = sql.trim().toUpperCase().startsWith("INSERT");Connection conn = null;PreparedStatement psmt = null;try {conn = getConn();psmt = insertFlag ? conn.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS) : conn.prepareStatement(sql);setParams(psmt, params);int count = psmt.executeUpdate();if (insertFlag) {ResultSet rs = psmt.getGeneratedKeys();if (rs.next()) {Long id = rs.getLong(1);count = id.intValue();}}return count;} catch (SQLException e) {throw new RuntimeException(e);} finally {close(conn, psmt, null);}}//设置参数private void setParams(PreparedStatement psmt, Object... params) throws SQLException {if (params != null && params.length > 0) {for (int i = 0; i < params.length; i++) {psmt.setObject(i + 1, params[i]);}}}//执行查询,返回集合protected List<T> executeQuery(String sql, Object... params) {List<T> list = new ArrayList<>();Connection conn = null;PreparedStatement psmt = null;ResultSet rs = null;try {conn = getConn();psmt = conn.prepareStatement(sql);setParams(psmt, params);rs = psmt.executeQuery();ResultSetMetaData rsmd = rs.getMetaData();//元数据,结果集的结构数据while (rs.next()) {//T t = new T(); T仅仅是一个符号,所以不能 newT t = (T) ClassUtil.createInstance(entityClassName);int columnCount = rsmd.getColumnCount();//获取结果集的列的数据//jdbc中都是从 1 开始,所以要把 i 改成 从 1 开始for (int i = 1; i <= columnCount; i++) {//假设循环 5 次,得到 5 个值,应该对应的是一个对象的 5 个属性的值String columnName = rsmd.getColumnLabel(i);Object columnValue = rs.getObject(i);//给 t 这个对象的 columnName 属性赋 columnValue 值ClassUtil.setProperty(t, columnName, columnValue);}list.add(t);}return list;} catch (SQLException e) {throw new RuntimeException(e);} finally {close(conn, psmt, rs);}}protected T load(String sql, Object... params) {Connection conn = null;PreparedStatement psmt = null;ResultSet rs = null;try {conn = getConn();psmt = conn.prepareStatement(sql);setParams(psmt, params);rs = psmt.executeQuery();ResultSetMetaData rsmd = rs.getMetaData();//元数据,结果集的结构数据if (rs.next()) {//T t = new T(); T仅仅是一个符号,所以不能 newT t = (T) ClassUtil.createInstance(entityClassName);int columnCount = rsmd.getColumnCount();//获取结果集的列的数据//jdbc中都是从 1 开始,所以要把 i 改成 从 1 开始for (int i = 1; i <= columnCount; i++) {//假设循环 5 次,得到 5 个值,应该对应的是一个对象的 5 个属性的值String columnName = rsmd.getColumnLabel(i);Object columnValue = rs.getObject(i);//给 t 这个对象的 columnName 属性赋 columnValue 值ClassUtil.setProperty(t, columnName, columnValue);}return t;}} catch (SQLException e) {throw new RuntimeException(e);} finally {close(conn, psmt, rs);}return null;}//select max(age) as max_age , avg(age) as avg_age from t_user// 28 24.5//select deptNo,avg(sal) as avg_sal from emp group by deptNo/*** d001 3500* d002 3650* d003 2998*/protected List<Object[]> executeComplexQuery(String sql, Object... params) {List<Object[]> list = new ArrayList<>();Connection conn = null;PreparedStatement psmt = null;ResultSet rs = null;try {conn = getConn();psmt = conn.prepareStatement(sql);setParams(psmt, params);rs = psmt.executeQuery();ResultSetMetaData rsmd = rs.getMetaData();//元数据,结果集的结构数据while (rs.next()) {int columnCount = rsmd.getColumnCount();//获取结果集的列的数据Object[] arr = new Object[columnCount];//jdbc中都是从 1 开始,所以要把 i 改成 从 1 开始for (int i = 1; i <= columnCount; i++) {Object columnValue = rs.getObject(i);//数组从 0 开始,所以要减 1arr[i - 1] = columnValue;}list.add(arr);}return list;} catch (SQLException e) {throw new RuntimeException(e);} finally {close(conn, psmt, rs);}} }
7、 设计Class工具类
package com.csdn.mymvc.util; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; public class ClassUtil {public static Object createInstance(String entityClassName) {try {return Class.forName(entityClassName).getDeclaredConstructor().newInstance();} catch (InstantiationException | IllegalAccessException | InvocationTargetException | NoSuchMethodException |ClassNotFoundException e) {throw new RuntimeException(e);}}public static void setProperty(Object instance, String propertyName, Object propertyValue) {Class<?> aClass = instance.getClass();try {Field field = aClass.getDeclaredField(propertyName);field.setAccessible(true);field.set(instance, propertyValue);} catch (NoSuchFieldException | IllegalAccessException e) {throw new RuntimeException(e);}} }
8、测试DAO层实现类
package com.csdn.dao.impl; import com.csdn.fruit.dao.FruitDao; import com.csdn.fruit.dao.impl.FruitDaoImpl; import com.csdn.fruit.pojo.Fruit; import org.junit.Test; import java.util.List; public class FruitDaoImplTest {private FruitDao fruitDao = new FruitDaoImpl();@Testpublic void testAddFruit() {Fruit fruit = new Fruit("香蕉", 7, 77, "波罗蜜是一种神奇的水果!");fruitDao.addFruit(fruit);}@Testpublic void testDelFruit() {fruitDao.delFruit("哈密瓜");}@Testpublic void testUpdateFruit() {Fruit fruit = new Fruit("波罗蜜", 5, 1000, "好吃");fruitDao.updateFruit(fruit);}@Testpublic void testGetFruitList() {List<Fruit> fruitList = fruitDao.getFruitList();fruitList.stream().forEach(System.out::println);}@Testpublic void testGetFruitByFname() {Fruit fruit = fruitDao.getFruitByFname("波罗蜜");System.out.println(fruit);}/*// this 是谁? this代表的是 FruitDaoImpl 的实例对象,因为 BaseDao是抽象类,不能直接创建对象,所以 new 的是它的子类对象 FruitDaoImpl// this.getClass() 获取的是 FruitDaoImpl 的Class对象// getGenericSuperclass() 获取到的是:BaseDao<Fruit>// Type 是顶层接口,表示所有的类型。它有一个子接口:ParameterizedTypeParameterizedType genericSuperclass = (ParameterizedType) this.getClass().getGenericSuperclass();// Actual:实际的// getActualTypeArguments() 获取实际的类型参数Type[] actualTypeArguments = genericSuperclass.getActualTypeArguments();Type actualTypeArgument = actualTypeArguments[0];// System.out.println(actualTypeArgument.getTypeName());//com.csdn.fruit.pojo.FruitentityClassName = actualTypeArgument.getTypeName();loadJdbcProperties(); */@Testpublic void testActualTypeArgument() {//这个方法是用来测试 actualTypeArgument 实际返回的参数} }
9、设计控制台操作菜单
package com.csdn.fruit.view; import com.csdn.fruit.dao.FruitDao; import com.csdn.fruit.dao.impl.FruitDaoImpl; import com.csdn.fruit.pojo.Fruit; import java.util.List; import java.util.Scanner; public class Menu {Scanner input = new Scanner(System.in);private FruitDao fruitDao = new FruitDaoImpl();//显示主菜单public int showMainMenu() {System.out.println("================欢迎使用水果库存系统===================");System.out.println("1.显示库存列表");System.out.println("2.添加库存记录");System.out.println("3.查看特定库存");System.out.println("4.水果下架");System.out.println("5.退出");System.out.println("====================================================");System.out.print("请选择:");return input.nextInt();}//显示库存列表public void showFruitList() {List<Fruit> fruitList = fruitDao.getFruitList();System.out.println("----------------------------------------------------");System.out.println("名称\t\t单价\t\t库存\t\t备注");if (fruitList == null || fruitList.size() <= 0) {System.out.println("对不起,库存为空!");} else {/* fruitList.forEach(new Consumer<Fruit>() {@Overridepublic void accept(Fruit fruit) {System.out.println(fruit);}});*///fruitList.forEach(fruit -> System.out.println(fruit));fruitList.forEach(System.out::println);}System.out.println("----------------------------------------------------");}//添加库存记录public void addFruit() {System.out.print("请输入水果名称:");String fname = input.next();Fruit fruit = fruitDao.getFruitByFname(fname);if (fruit == null) {System.out.print("请输入水果单价:");Integer price = input.nextInt();System.out.print("请输入水果库存:");Integer fcount = input.nextInt();System.out.print("请输入水果备注:");String remark = input.next();fruit = new Fruit(fname, price, fcount, remark);fruitDao.addFruit(fruit);} else {System.out.print("请输入追加的库存量:");Integer fcount = input.nextInt();fruit.setFcount(fruit.getFcount() + fcount);fruitDao.updateFruit(fruit);}System.out.println("添加成功!");}//查看特定库存记录public void showFruitInfo() {System.out.print("请输入水果名称:");String fname = input.next();Fruit fruit = fruitDao.getFruitByFname(fname);if (fruit == null) {System.out.println("对不起,没有找到对应的库存记录!");} else {System.out.println("----------------------------------------------------");System.out.println("名称\t\t单价\t\t库存\t\t备注");System.out.println(fruit);System.out.println("----------------------------------------------------");}}//水果下架public void delFruit() {System.out.print("请输入水果名称:");String fname = input.next();Fruit fruit = fruitDao.getFruitByFname(fname);if (fruit == null) {System.out.println("对不起,没有找到需要下架的库存记录!");} else {System.out.print("是否确认下架?(Y/N)");String confirm = input.next();if ("y".equalsIgnoreCase(confirm)) {fruitDao.delFruit(fname);}}}//退出public boolean exit() {System.out.print("是否确认退出?(Y/N)");String confirm = input.next();boolean flag= !"y".equalsIgnoreCase(confirm);return flag;} }
10、设计客户端
package com.csdn.fruit.view; public class Client {public static void main(String[] args) {Menu m = new Menu();boolean flag = true;while (flag) {int slt = m.showMainMenu();switch (slt) {case 1:m.showFruitList();break;case 2:m.addFruit();break;case 3:m.showFruitInfo();break;case 4:m.delFruit();break;case 5://方法设计时是否需要返回值,依据是:是否在调用的地方需要留下一些值用于再运算flag = m.exit();break;default:System.out.println("你不按套路出牌!");break;}}System.out.println("谢谢使用!再见!");} }