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JDBC之在分層結構中實現業務

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以上篇文章為基礎完成以下操作

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一、添加驅動

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?在src下創建文件夾lib

?將MySQL數據庫驅動包放入lib文件夾并右鍵點擊build path

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二、創建jdbc.properties文件

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driver = com.mysql.jdbc.Driver jdbcUrl = jdbc:mysql://localhost:3306/bjsxt?useUnicode=true&characterEncoding=utf-8 username = root userpassword = mysql

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三、模型層（用于存儲數據庫中departments表的數據）

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在pojo包下，創建Departments實體類；

public class Departments{private int departmentId;private String departmentName;private int locationId;public int getDepartmentId(){return departmentId;} public void setDepartmentId(int departmentId){this.departmentId = departmentId;}public String getDepartmentName(){return departmentName;}public void setDepartmentName(String departmentName){this.departmentName = departmentName;}public int getLocationId(){return locationId;}public void setLocationId(int locationId){this.locationId = locationId;} }

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四、工具層（對departments表進行操作）

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在commons包下創建JdbcUtil工具類；

import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import java.util.ResourceBundle;public class JdbcUtil{private static String driver;private static String jdbcUrl;private static String username;private static String userpassword;static{//讀取properties文件ResourceBundle bundle = ResourceBundle.getBundle("jdbc");driver = bundle.getString("driver");jdbcUrl = bundle.getString("jdbcUrl");username = bundle.getString("username");userpassword = bundle.getString("userpassword");try{//驅動注冊Class.forName(driver);//通過jdk反射機制將數據庫驅動類實例化}catch(ClassNotFoundException e){e.printStackTrace();}}//獲取Connection對象public static Connection getConnection(){Connection conn = null;try{conn = DriverManager.getConnection(jdbcUrl,username,userpassword);}catch(SQLException e){e.printStackTrace();}return conn;}//關閉Statementpublic static void closeStatement(Statement state){if(state!=null){try{state.close();}catch(SQLException e){e.printStackTrace();}}}//關閉Connectionpublic static void closeConnection(Connection conn){if(conn!=null){try{conn.close();}catch(SQLException e){e.printStackTrace();}}}//關閉ResultSetpublic static void closeResultSet(ResultSet rs){if(rs!=null){try{rs.close();}catch(SQLException e){e.printStackTrace();}}} //關閉資源public static void closeResource(Statement state , Connection conn , ResultSet rs){closeStatement(state);closeConnection(conn);closeResultSet(rs);}public static void closeResource(Statement state , Connection conn){closeStatement(state);closeConnection(conn);}//事務回滾public static void rollback(Connection conn){if(conn!=null){try{conn.rollback();}catch(SQLException e){e.printStackTrace();}}} }

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五、持久層（數據訪問層）

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?持久層下接口的命名都是以“dao”結尾的；

?Dao代表data access object 數據庫訪問對象；

?抽象方法的命名規則：不要包含帶有業務邏輯的名稱；

?接口實現類命名規則：要實現的接口的名稱后+Impl；

在dao包下建立DepartmentsDao接口（對departments表進行操作）
包含那些對部門操作的抽象行為

import com.bjsxt.pojo.Departments;public interface DepartmentsDao{//根據部門名稱查詢部門信息的抽象方法public List<Departments> selectDeptByName(String deptName);//向部門表中添加信息的抽象方法public void insertDept(Departments dept); }

在dao.impl包下創建實現類；

import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.util.ArrayList; import java.util.List;import com.bjsxt.commons.JdbcUtil; import com.bjsxt.dao.DepartmentsDao; import com.bjsxt.pojo.Departments;public class DepartmentsDaoImpl implements DepartmentsDao{public List<Departments> selectDeptByName(String deptName){Connection conn = null;PreparedStatement ps = null;ResultSet rs = null;List<Departments> list = new ArrayList<Departments>();try{conn = JdbcUtil.getConnection();ps = conn.prepareStatement("select * from departments where department_name = ?");ps.setString(1,deptName);//捆值；rs = ps.executeQuery();while(rs.next()){Departments d = new Departments();/*如果查詢多條結果的情況下我們要在while中定義數據模型*/d.setDepartmentId(rs.getInt("department_id"));d.setDepartmentName(rs.getString("department_name"));d.setLocation_id(rs.getInt("location_id"));list.add(d);}}catch(Exception e){e.printStackTrace();}finally{JdbcUtil.closeResource(ps,conn);}return list; }public void insertDept(Departments dept){Connection conn = null;PreparedStatement ps = null;try{conn = JdbcUtil.getConnection();conn.setAutoCommit(false);ps = conn.prepareStatement("insert into departments values(0,?,?)");ps.setString(1,dept.getDepartmentName());ps.setInt(2,dept.getLocationId());ps.execute(); conn.commit();}catch(Exception e){e.printStackTrace();}finally{JdbcUtil.closeResource(ps,conn);}} }

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六、業務層

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?業務層的方法命名要貼近這次要做什么樣的業務處理；

在service包下創建DepartmentsSerivce接口；

//向Departments表中添加數據 public interface DepartmentsService{public void addDepartments(Departments dept); }

在serivce.impl包下創建實現類，實現類命名規則同上；

public class DepartmentsServiceImpl implements DepartmentsService{public void addDepartments(Departments dept){DepartmentsDao deptDao = new DepartmentsDaoImpl();deptDao.insertDept(dept);} }

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七、測試層

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在src下創建test包，并在其中創建Test類

public class Test{public static void main(String[] args){Departments dept = new Departments();dept.setDepartmentName("體育部");dept.setLocationId(30);DepartmentsService ds = new DepartmentsServiceImpl();ds.addDepartments(dept); } } 《新程序員》：云原生和全面數字化實踐50位技術專家共同創作，文字、視頻、音頻交互閱讀

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