jdbc baseDAO 以及每个类的继承

首先是baseDAO，用来作为DAO的父类

package dao;

import java.lang.reflect.Field;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.ResultSetMetaData;

import java.util.ArrayList;

import jdbc.utils.JDBCUtils;

public abstract class BaseDAO {

    //使用PreparedStatement实现对不同表的通用的返回一个对象的查询操作

    //使用泛型机制，参数里先传入一个类的类型

    public <T> T getInstance(Connection con,Class<T> clazz,String sql,Object...args) {

        PreparedStatement ps = null;

        ResultSet res = null;

        try {

            ps=con.prepareStatement(sql);

            for(int i=0;i<args.length;i++) {

                ps.setObject(i+1, args[i]);

            }

            //获得数据集和元数据集

            res = ps.executeQuery();

            ResultSetMetaData rsmd = res.getMetaData();

            int col = rsmd.getColumnCount();

            if(res.next()) {

                T t = clazz.newInstance();

                for(int i=0;i<col;i++) {

                    Object value = res.getObject(i+1);          //要获得的数据值

                    String colLabel = rsmd.getColumnLabel(i+1);    //要获得的元数据名称

                    //通过反射给t对象指定的colName属性赋值为value

                    Field field = clazz.getDeclaredField(colLabel);

                    field.setAccessible(true);

                    field.set(t,value);

                }

                System.out.println("执行成功");

                return t;

            }

        }

        catch(Exception ex) {

            ex.printStackTrace();

        }

        finally {

            JDBCUtils.closeResource(null, ps, res);

        }

        return null;

    }

    //返回对不同表的通用的返回多个对象的查询操作 --考虑上事物的版本

    public <T> ArrayList<T> getForList(Connection con,Class<T> clazz,String sql,Object...args){

        PreparedStatement ps = null;

        ResultSet res = null;

        try {

            ps=con.prepareStatement(sql);

            for(int i=0;i<args.length;i++) {

                ps.setObject(i+1, args[i]);

            }

            //获得数据集和元数据集

            res = ps.executeQuery();

            ResultSetMetaData rsmd = res.getMetaData();

            int col = rsmd.getColumnCount();

            ArrayList<T> list = new ArrayList<T>();

            while(res.next()) {

                T t = clazz.newInstance();

                for(int i=0;i<col;i++) {

                    Object value = res.getObject(i+1);          //要获得的数据值

                    String colLabel = rsmd.getColumnLabel(i+1);    //要获得的元数据名称

                    //通过反射给t对象指定的colName属性赋值为value

                    Field field = clazz.getDeclaredField(colLabel);

                    field.setAccessible(true);

                    field.set(t,value);

                }

                list.add(t);

            }

            System.out.println("执行成功");

            return list;

        }

        catch(Exception ex) {

            ex.printStackTrace();

        }

        finally {

            JDBCUtils.closeResource(null, ps, res);

        }

        return null;

    }

    //用来处理聚合函数等只返回一个值的sql语句

    public <T>T getValue(Connection con,String sql,Object...args){

        PreparedStatement ps = null;

        ResultSet res = null;

        try {

            ps = con.prepareStatement(sql);

            for(int i=0;i<args.length;i++) {

                ps.setObject(i+1, args[i]);

            }

            res = ps.executeQuery();

            System.out.println("查询成功");

            if(res.next()) {

                return (T)res.getObject(1);

            }

        }

        catch(Exception ex) {

            ex.printStackTrace();

        }

        finally {

            JDBCUtils.closeResource(null, ps, res);

        }

        return null;

    }

    //通用增删改，参数为预编译的sql，和可变形参args用来充当占位符 --可处理事物版本

    public int update(Connection con,String sql,Object ...args) {

        PreparedStatement ps=null;

        try {

            //2.预编译sql，返回ps实例

            ps=con.prepareStatement(sql);

            //填充占位符，sql中的占位符个数=args数组长度

            for(int i=0;i<args.length;i++) {

                ps.setObject(i+1, args[i]);

            }

            //4.执行, excute()方法如果执行查询操作，则此方法返回true，如果执行增删改，则返回false

            //ps.execute();

            System.out.println("修改成功");

            return ps.executeUpdate();

        }

        catch (Exception ex) {

            ex.printStackTrace();

        }

        finally {

            //5.关闭资源

            JDBCUtils.closeResource(null, ps);

        }

        return 0;

    }

}

设有一个类是student类

package bean;

import java.sql.Date;

public class Student {

    private int studentId;

    private String studentName;

    private int studentAge;

    private boolean studentSexy;

    private Date studentBirthday;

    private String classId;

    public Student() {

        super();

    }

    public Student(int studentId, String studentName, int studentAge, boolean studentSexy, Date studentBirthday,

            String classId) {

        super();

        this.studentId = studentId;

        this.studentName = studentName;

        this.studentAge = studentAge;

        this.studentSexy = studentSexy;

        this.studentBirthday = studentBirthday;

        this.classId = classId;

    }

    public int getStudentId() {

        return studentId;

    }

    public void setStudentId(int studentId) {

        this.studentId = studentId;

    }

    public String getStudentName() {

        return studentName;

    }

    public void setStudentName(String studentName) {

        this.studentName = studentName;

    }

    public int getStudentAge() {

        return studentAge;

    }

    public void setStudentAge(int studentAge) {

        this.studentAge = studentAge;

    }

    public boolean getStudentSexy() {

        return studentSexy;

    }

    public void setStudentSexy(boolean studentSexy) {

        this.studentSexy = studentSexy;

    }

    public Date getStudentBirthday() {

        return studentBirthday;

    }

    public void setStudentBirthday(Date studentBirthday) {

        this.studentBirthday = studentBirthday;

    }

    public String getClassId() {

        return classId;

    }

    public void setClassId(String classId) {

        this.classId = classId;

    }

    @Override

    public String toString() {

        return "Student [studentId=" + studentId + ", studentName=" + studentName + ", studentAge=" + studentAge

                + ", studentSexy=" + studentSexy + ", studentBirthday=" + studentBirthday + ", classId=" + classId

                + ", getStudentId()=" + getStudentId() + ", getStudentName()=" + getStudentName() + ", getStudentAge()="

                + getStudentAge() + ", getStudentSexy()=" + getStudentSexy() + ", getStudentBirthday()="

                + getStudentBirthday() + ", getClassId()=" + getClassId() + ", getClass()=" + getClass()

                + ", hashCode()=" + hashCode() + ", toString()=" + super.toString() + "]";

    }

}

其对应的 sql中表的格式为

要实现student的DAO，先设计一个接口类，申明所有方法

package dao;

import java.sql.Connection;

import java.sql.Date;

import java.util.ArrayList;

import bean.Student;

public interface StudentDAO {

    void insert(Connection con,Student stu);

    void deleteById(Connection con,int id);

    //把标号为id的表记录属性改为stu

    void updateById(Connection con,int id,Student stu);

    Student getById(Connection con,int id);

    ArrayList<Student> getAll(Connection con);

    Long getCount(Connection con);

    String getMaxBirthday(Connection con);

}

然后是实现以上方法的studentDAOImpl

package dao;

import java.sql.Connection;

import java.sql.Date;

import java.util.ArrayList;

import java.util.Calendar;

import bean.Student;

import jdbc.utils.JDBCUtils;

public class StudentDAOImpl extends BaseDAO implements StudentDAO{

    @Override

    public void insert(Connection con, Student stu) {

        String sql = "insert into student values(?,?,?,?,?,?)";

        update(con,sql,stu.getStudentId(),stu.getStudentName(),stu.getStudentAge(),

                    stu.getStudentSexy(),stu.getStudentBirthday(),stu.getClassId());

    }

    @Override

    public void deleteById(Connection con, int id) {

        String sql = "delete from student where stuid = ?";

        update(con,sql,id);

    }

    @Override

    public void updateById(Connection con, int id, Student stu) {

        String sql = "update student set stuName = ?,stuAge = ?,stuSexy = ?,stuBirthday = ?,classId = ?";

        update(con,sql,stu.getStudentName(),stu.getStudentAge(),

                stu.getStudentSexy(),stu.getStudentBirthday(),stu.getClassId());

    }

    @Override

    public Student getById(Connection con, int id) {

        String sql = "select stuId as studentId,stuName as studentName,stuAge as studentAge from student where stuid = ?";

        Student stu = getInstance(con,Student.class,sql,id);

        return stu;

    }

    @Override

    public ArrayList<Student> getAll(Connection con) {

        String sql = "select stuId as studentId,stuName as studentName,stuAge as studentAge from student";

        ArrayList<Student> list= getForList(con,Student.class,sql);

        return list;

    }

    @Override

    public Long getCount(Connection con) {

        String sql = "select count(*) from student";

        Long res = Long.valueOf(getValue(con,sql).toString());

        return res;

    }

    @Override

    public String getMaxBirthday(Connection con) {

        String sql = "select max(stuBirthday) from student";

        return getValue(con,sql).toString();

    }

    static public void main(String []args) {

        Connection con = null;

        StudentDAOImpl ob = new StudentDAOImpl();

        try {

            con = JDBCUtils.getConnection();

            java.util.Date d = new java.util.Date(99,0,26);//从1900-1-1开始，

            java.sql.Date date = new java.sql.Date(d.getTime());

            Student stu = new Student(111,"周恩杰",20,true,date,"09031");

            //ob.insert(con, stu);

            //ob.deleteById(con, 111);

            stu.setStudentAge(21);

            //ob.updateById(con, 111, stu);

            Student stu1 = ob.getById(con, 101);

            System.out.println(stu1);

            ArrayList<Student> list = ob.getAll(con);

            list.forEach(System.out::println);

            Long res = ob.getCount(con);

            String ss = ob.getMaxBirthday(con);

            System.out.println(res);

            System.out.println(ss);

        }

        catch(Exception ex) {

            ex.printStackTrace();

        }

        finally {

            JDBCUtils.closeResource(con, null, null);

        }

    }

}

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jdbc baseDAO 以及每个类的继承

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巴特西

jdbc baseDAO 以及 每个类的继承

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jdbc baseDAO 以及每个类的继承