如何封装查询记录到Java对象数组

                          如何封装查询记录到Java对象数组

 

1：通过Vector的toArray()方法：

 

举例如下：

 

（１）MySQL数据库中创建一个职位表，其中只包含两个字段，职位ID，职位名称，  建表语句如下：

CREATE TABLE POST (

       POST_CODE                      int                    PRIMARY KEY ,

       POST_NAME                     varchar(50)      UNIQUE NOT NULL

) ；

 

 

（２）

插入几条测试记录：略。

 

（３）

创建VO：

 

package org.mixih.db;

 

public class PostRec {

   

    private int postCode ;

    private String postName ;

   

    public PostRec() {

    }

   

    public PostRec(int PostCode ,String postName){

       this.postCode = postCode ;

        this.postName = postName ;

    }

   

    }

 

    public int getPostCode() {

       return postCode;

    }

 

    public void setPostCode(int postCode) {

       this.postCode = postCode;

    }

 

    public String getPostName() {

       return postName;

    }

 

    public void setPostName(String postName) {

       this.postName = postName;

    }  

}

 

 

（４）创建数据库访问类：

 

package org.mixih.db;

 

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.util.Vector;

 

public class OprPost {

 

    String error;

 

    Connection con;

 

    public OprPost() {

    }

 

    public void connect() throws ClassNotFoundException, SQLException,

           Exception {

       try {

           Class.forName("com.mysql.jdbc.Driver");

 

           System.out.println("JDBC driver loaded");

 

 con = DriverManager.getConnection( "jdbc:mysql://localhost:3306/hrsys", "test", "test");

           System.out.println("Database Connection established");

 

       } catch (ClassNotFoundException e) {

 

           error = "Cound not locate DB driver";

 

           throw new ClassNotFoundException(error);

 

       } catch (SQLException e) {

 

           error = "SQLException : cound not connect to database.";

 

           throw new SQLException(error);

 

       } catch (Exception e) {

 

           error = "Exception : an error occurred while connecting  to database ";

 

           throw new Exception(error);

       }

    }

 

    public void disConnect() throws SQLException {

       try {

           if (con != null) {

 

              con.close();

 

           }

       } catch (SQLException e) {

 

           error = "SQLExcepion : Unable to close the database connection.";

 

           throw new SQLException(error);

       }

    }

 

    public PostRec[] viewPost() throws SQLException, Exception {

      

       ResultSet rs = null;

       Vector vForTemp = new Vector();

      

       try {        

           String queryString = "select * from post ;";

           Statement stmt = con.createStatement();

 

           rs = stmt.executeQuery(queryString);

                                                                  

           while(rs.next()){

              int postCode = rs.getInt(1);

              String postName = rs.getString(2);           

              PostRec postRec = new PostRec(postCode ,

                                           postName );          

              vForTemp.add(postRec) ;           

           }

 

       } catch (SQLException e) {

 

           error = " An exception occurred execute query .";

 

           throw new SQLException(error);

 

       } catch (Exception e) {

 

           error = "Aneception occurred while while retriving books.";

 

           throw new Exception(error);

       }

       return (PostRec[])vForTemp.toArray( new PostRec[0]);

    }

 

   

    public static void main(String[] args) throws Exception {

 

       OprPost myOprPost = new OprPost();

 

       myOprPost.connect();

      

       PostRec[] postRecs = myOprPost.viewPost();

      

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

           System.out.println(postRecs[i].getPostCode());

           System.out.println(postRecs[i].getPostName());

       }     

       myOprPost.disConnect();

    }

}