老王学jsp之DAO设计模式

现在感觉之前学习的java就是个渣渣。完全没掌握好。

DAO设计模式
1）：数据库结构
CREATE TABLE emp(
   empno            INT(4)            PRIMARY KEY,
   ename            VARCHAR(10),
   job                VARCHAR(9),
   hiredate            DATE,
   sal                FLOAT(7,2)
) ;

2）：Emp.java
package cn.mldn.lxh.vo ;
import java.util.Date ;
public class Emp {
    private int empno ;
    private String ename ;
    private String job ;
    private Date hiredate ;
    private float sal ;
    public void setEmpno(int empno){
        this.empno = empno ;
    }
    public void setEname(String ename){
        this.ename = ename ;
    }
    public void setJob(String job){
        this.job = job ;
    }
    public void setHiredate(Date hiredate){
        this.hiredate = hiredate ;
    }
    public void setSal(float sal){
        this.sal = sal ;
    }
    public int getEmpno(){
        return this.empno ;
    }
    public String getEname(){
        return this.ename ;
    }
    public String getJob(){
        return this.job ;
    }
    public Date getHiredate(){
        return this.hiredate ;
    }
    public float getSal(){
        return this.sal ;
    }
}

3):IEmpDAO.java 功能接口 
package cn.mldn.lxh.dao ;
import java.util.* ;
import cn.mldn.lxh.vo.* ;
public interface IEmpDAO {
    public boolean doCreate(Emp emp) throws Exception ;
    public List<Emp> findAll(String keyWord) throws Exception ;
    public Emp findById(int empno) throws Exception ;
}

4）：EmpDAOImpl.java 接口实现
package cn.mldn.lxh.dao.impl ;
import java.util.* ;
import java.sql.* ;
import cn.mldn.lxh.dao.* ;
import cn.mldn.lxh.vo.* ;

public class EmpDAOImpl implements IEmpDAO {
    private Connection conn = null ;
    private PreparedStatement pstmt = null ;
    public EmpDAOImpl(Connection conn){
        this.conn = conn ;
    }
    public boolean doCreate(Emp emp) throws Exception{
        boolean flag = false ;
        String sql = "INSERT INTO emp(empno,ename,job,hiredate,sal) VALUES (?,?,?,?,?)" ;
        this.pstmt = this.conn.prepareStatement(sql) ;
        this.pstmt.setInt(1,emp.getEmpno()) ;
        this.pstmt.setString(2,emp.getEname()) ;
        this.pstmt.setString(3,emp.getJob()) ;
        this.pstmt.setDate(4,new java.sql.Date(emp.getHiredate().getTime())) ;
        this.pstmt.setFloat(5,emp.getSal()) ;
        if(this.pstmt.executeUpdate() > 0){
            flag = true ;
        }
        this.pstmt.close() ;
        return flag ;
    }
    public List<Emp> findAll(String keyWord) throws Exception{
        List<Emp> all = new ArrayList<Emp>() ;
        String sql = "SELECT empno,ename,job,hiredate,sal FROM emp WHERE ename LIKE ? OR job LIKE ?" ;
        this.pstmt = this.conn.prepareStatement(sql) ;
        this.pstmt.setString(1,"%"+keyWord+"%") ;
        this.pstmt.setString(2,"%"+keyWord+"%") ;
        ResultSet rs = this.pstmt.executeQuery() ;
        Emp emp = null ;
        while(rs.next()){
            emp = new Emp() ;
            emp.setEmpno(rs.getInt(1)) ;
            emp.setEname(rs.getString(2)) ;
            emp.setJob(rs.getString(3)) ;
            emp.setHiredate(rs.getDate(4)) ;
            emp.setSal(rs.getFloat(5)) ;
            all.add(emp) ;
        }
        this.pstmt.close() ;
        return all ;
    }
    public Emp findById(int empno) throws Exception{
        Emp emp = null ;
        String sql = "SELECT empno,ename,job,hiredate,sal FROM emp WHERE empno=?" ;
        this.pstmt = this.conn.prepareStatement(sql) ;
        this.pstmt.setInt(1,empno) ;
        ResultSet rs = this.pstmt.executeQuery() ;
        if(rs.next()){
            emp = new Emp() ;
            emp.setEmpno(rs.getInt(1)) ;
            emp.setEname(rs.getString(2)) ;
            emp.setJob(rs.getString(3)) ;
            emp.setHiredate(rs.getDate(4)) ;
            emp.setSal(rs.getFloat(5)) ;
        }
        this.pstmt.close() ;
        return emp ;
    }
}

5）：DatabaseConnection.java 数据库的对象的创建
package cn.mldn.lxh.dbc ;
import java.sql.Connection ;
import java.sql.DriverManager ;
public class DatabaseConnection {
    private static final String DBDRIVER = "org.gjt.mm.mysql.Driver" ; 
    private static final String DBURL = "jdbc:mysql://localhost:3306/mldn" ;
    private static final String DBUSER = "root" ;
    private static final String DBPASSWORD = "mysqladmin" ;
    private Connection conn ;
    public DatabaseConnection() throws Exception {
        Class.forName(DBDRIVER) ;
        this.conn = DriverManager.getConnection(DBURL,DBUSER,DBPASSWORD) ;
    }
    public Connection getConnection(){
        return this.conn ;
    }
    public void close() throws Exception {
        if(this.conn != null){
            try{
                this.conn.close() ;
            }catch(Exception e){
                throw e ;
            }
        }
    }
}
6）：EmpDAOProxy.java 操作代理
package cn.mldn.lxh.dao.proxy ;
import java.util.* ;
import java.sql.* ;
import cn.mldn.lxh.dao.* ;
import cn.mldn.lxh.dbc.* ;
import cn.mldn.lxh.dao.impl.* ;
import cn.mldn.lxh.vo.* ;

public class EmpDAOProxy implements IEmpDAO {
    private DatabaseConnection dbc = null ;
    private IEmpDAO dao = null ;
    public EmpDAOProxy() throws Exception {
        this.dbc = new DatabaseConnection() ;
        this.dao = new EmpDAOImpl(this.dbc.getConnection()) ;
    }
    public boolean doCreate(Emp emp) throws Exception{
        boolean flag = false ;
        try{
            if(this.dao.findById(emp.getEmpno()) == null){
                flag = this.dao.doCreate(emp) ;
            }
        }catch(Exception e){
            throw e ;
        }finally{
            this.dbc.close() ;
        }
        return flag ;
    }
    public List<Emp> findAll(String keyWord) throws Exception{
        List<Emp> all = null ;
        try{
            all = this.dao.findAll(keyWord) ;
        }catch(Exception e){
            throw e ;
        }finally{
            this.dbc.close() ;
        }
        return all ;
    }
    public Emp findById(int empno) throws Exception{
        Emp emp = null ;
        try{
            emp = this.dao.findById(empno) ;
        }catch(Exception e){
            throw e ;
        }finally{
            this.dbc.close() ;
        }
        return emp ;
    }
}

7）：DAOFactory.java 工厂 实例化操作代理对象
package cn.mldn.lxh.factory ;
import cn.mldn.lxh.dao.IEmpDAO ;
import cn.mldn.lxh.dao.proxy.EmpDAOProxy ;
public class DAOFactory {
    public static IEmpDAO getIEmpDAOInstance() throws Exception{
        return new EmpDAOProxy() ;
    }
}