不知道数据库中表的列类型的前提下,使用JDBC正确的取出数据(转)

概要: 使用jdbc 如果在不知道表结构的情况下,如何读出表信息?

使用ResultSetMetaData;

然后使用getColumnType 获取column 类型

使用getColumnName 获取column名字

根据类型,使用ResultSet 的getInt("column1")....获取每个字段的值

本文使用 Vector 做为容器,把拿到的查询结果,临时放在容器内。

1.   数据库准备

     a. create database study;

  b. create table 

 

CREATE TABLE `test` (   `id` int(11) NOT NULL DEFAULT '0',   `name` varchar(10) DEFAULT NULL, 
`birthday` datetime DEFAULT NULL, `score` double DEFAULT NULL, `info` text,
PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8

 

mysql> desc test;
+----------+-------------+------+-----+---------+-------+
| Field    | Type        | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| id       | int(11)     | NO   | PRI | 0       |       |
| name     | varchar(10) | YES  |     | NULL    |       |
| birthday | datetime    | YES  |     | NULL    |       |
| score    | double      | YES  |     | NULL    |       |
| info     | text        | YES  |     | NULL    |       |
+----------+-------------+------+-----+---------+-------+

  c. 插入几条数据

mysql> insert into test values(20131026,'Marry','1983-10-18 21:11:13',65.5,'she
is so nice');

2. 下载mysql jdbc connector

http://dev.mysql.com/downloads/connector/j/

3.创建相应的类

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import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.util.Scanner;
public class DBConnection {

    public static Connection getDBConnection() throws Exception {
       try{
        Connection con = null;
        Scanner input=new Scanner(System.in);
        System.out.println("please enter the IP");
        String ip=input.next();
        if(ip.matches("\\d{1,3}.\\d{1,3}.\\d{1,3}.\\d{1,3}"))
        {
            System.out.println("Your IP is:\n"+ip);
        }
        else
        {
            ip="127.0.0.1";
            System.out.println("Invaild IP address use default:\n"+ip);
        }
        System.out.println("please enter the ODBC port");
        int port=input.nextInt();
        if(1000 
    
复制代码
复制代码
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Types;
import java.util.Vector;
public class mysql {

    static void runquery() throws SQLException
    {
        Connection con=null ;       
          
        long start=System.currentTimeMillis();          //count runtime
        ResultSetMetaData resultMetaData;
        try{
            
            con = DBConnection.getDBConnection();
            if(con==null){
                System.out.println("can't open DBConnection");
            }
            con.setAutoCommit(false);
           
               System.out.println("enter the sql you want excute\n eg select * from test;");
              Statement stmt = con.createStatement();
              String sql=new Scanner(System.in).nextLine(); ResultSet rs =stmt.executeQuery(sql); resultMetaData=rs.getMetaData(); int cols = resultMetaData.getColumnCount(); //get the count of all the coulums ,this will be 5 Vector currentRow = new Vector(); while(rs.next()) { for (int j = 1; j < cols; j++) { switch (resultMetaData.getColumnType(j)) //translate the column of table type to java type then write to vector { case Types.VARCHAR: currentRow.addElement(rs.getString(resultMetaData.getColumnName(j))); break; case Types.INTEGER: currentRow.addElement(new Integer(rs.getInt(resultMetaData.getColumnName(j)))); break; case Types.TIMESTAMP: currentRow.addElement(rs.getDate(resultMetaData.getColumnName(j))); break; case Types.DOUBLE: currentRow.addElement(rs.getDouble(resultMetaData.getColumnName(j))); break; case Types.FLOAT: currentRow.addElement(rs.getFloat(resultMetaData.getColumnName(j))); break; case Types.CLOB: currentRow.addElement(rs.getBlob(resultMetaData.getColumnName(j))); break; default: currentRow.add("error"); } } System.out.println(currentRow); currentRow.clear(); } } catch (Exception e) { e.printStackTrace(); } con.close(); long end=System.currentTimeMillis(); System.out.println(end-start); } public static void main(String[] args) throws SQLException { // TODO Auto-generated method stub System.out.println("enter the query SQL you want run\nex. select * from test ") ; runquery(); }
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运行结果:

ex. select * from test 
please enter the IP
localhost
Invaild IP address use default:
127.0.0.1
please enter the ODBC port
3306
your port is :
3306
please enter the UserName
root
please enter the Password
3edc4rfv
jdbc:mysql://127.0.0.1:3306/study
Connected to:jdbc:mysql://127.0.0.1:3306/study
Driver MySQL Connector Java
enter the sql you want excute
 eg select * from test;
select * from test;
[20131024, Jason, 1980-05-07, 60.5]
[20131025, Young, 1988-01-09, 56.8]
[20131026, Marry, 1983-10-18, 65.5]
31977
enter the  instert SQL you want run

http://www.cnblogs.com/tobecrazy/p/3390021.html

 

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