如何得到数据集得列数__String_public_classname_query_password_

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如何得到数据集得列数

来源: 互联网发布时间：2015-07-25

本文导语: 我想得到数据集的列数，然后通过序号操作数据集，怎样得到数据集的列数？ | 得到数据集的列数简单: Statement stmt = con.createStatement(); ResultSet rs = stmt.executeQuery(query); ResultSetMetaData rsmd ...

我想得到数据集的列数，然后通过序号操作数据集，怎样得到数据集的列数？

得到数据集的列数简单:
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery(query);
ResultSetMetaData rsmd = rs.getMetaData();

cols = rsmd.getColumnCount();

通过序号操作数据集不是很方便。

给你一个例子参考：

import java.io.*;
import java.util.*;
import java.sql.*;

public class JDBCBean {

    String classname ; // JDBC driver class
    String url ;
    String username ;
    String password ;
    String query ;  // the SQL statement.
    int rows, cols; // the number of rows and columns of the result.
    Vector result;

    public void setClassname(String classname) {
this.classname = classname;
    }

    public String getClassname() {
return classname;
    }

    public void setUrl(/tech-qa-java/String url/index.html) {
this.url = url;
    }

    public String getUrl(){
return url;
    }

    public void setUsername(String username) {
this.username = username;
    }

    public String getUsername() {
return username;
    }

    public void setPassword(String password) {
this.password = password;
    }

    public String getPassword() {
return password;
    }

    public void setQuery(String query) {
this.query = query;
    }

    public String getQuery() {
return query;
    }

    protected void go()
throws ClassNotFoundException, SQLException
    {

// Load the JDBC driver
Class.forName(classname);

// get the connection to the database
Connection con = DriverManager.getConnection(url, username,
     password);

// create and execute the query
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery(query);
ResultSetMetaData rsmd = rs.getMetaData();

cols = rsmd.getColumnCount();
rows = 0;
result = new Vector();

String s[] = new String[cols];
for (int i=1; i