java - 如何在java中为mysql中的数据编写条形图

Question

我已经使用 xml dom 解析成功地将数据插入到 mysql 中，现在我想在我的条形图上显示 mysql 数据，所以请帮助提供正确的代码。

我的数据库有4列，分别是“姓名”、“学院”、“年级”、“自然”

所以我插入了 4 个不同的名字，在 4 个名字中，有 2 个共享同一所大学。每个都有不同的等级，如好坏和中等。等级也是如此，比如一、二、三等。所以现在我需要为此编写条形图。请帮帮我。

Answer 1

这里我做了一个例子。

• 提取数据库值并存储在数组的work[]andvalues[]中。
• 根据您的需要使用容器
• 我用过JApplet

import java.awt.*;
import javax.swing.JApplet;

public class BarChart extends JApplet
{
    private final  int n=5;
    private String work[];
    private int value[];

    @Override
    public void init()
    {

        work = new String[n];
        value = new int[n];

        work[0] ="name";
        work[1] = "college";
        work[2] = "grade";
        work[3] = "nature";
        work[4] = "extra";

        value[0] = 20;
        value[1] = 10;
        value[2] = 4;
        value[3] = 15;
        value[4] = 5;

    }

    @Override
    public void paint(Graphics g)
    {
        Font font = new Font("Arial",Font.BOLD,15);
        g.setFont(font);
        for(int i  = 0; i < n; i ++)
        {
            g.setColor(Color.BLUE);
            g.drawString(work[i], 20, i * 50 + 30);
            g.setColor(Color.RED);
            g.fillRect(70, i * 50 + 10, value[i], 40);
            g.drawString(String.valueOf(value[i]) + "%", 180, i * 50 + 35);
        }


    }
}

编辑 ：

对于您选择的 stmt。，我去谷歌并输入 -select query msql java 我得到了这个：

+----+------------+-----------+---------------------+----------+------------+
| id | first_name | last_name | date_created        | is_admin | num_points |
+----+------------+-----------+---------------------+----------+------------+
|  2 | Fred       | Flinstone | 2010-06-23 00:00:00 |        0 |       6000 | 
|  3 | Barney     | Rubble    | 2010-06-23 00:00:00 |        0 |       5000 | 
+----+------------+-----------+---------------------+----------+------------+

import java.sql.*;

/**
 * A Java MySQL SELECT statement example.
 * Demonstrates the use of a SQL SELECT statement against a
 * MySQL database, called from a Java program.
 * 
 * Created by Alvin Alexander, http://devdaily.com
 */
public class JavaMysqlSelectExample
{

  public static void main(String[] args)
  {
    try
    {
      // create our mysql database connection
      String myDriver = "org.gjt.mm.mysql.Driver";
      String myUrl = "jdbc:mysql://localhost/test";
      Class.forName(myDriver);
      Connection conn = DriverManager.getConnection(myUrl, "root", "");

      // our SQL SELECT query. 
      // if you only need a few columns, specify them by name instead of using "*"
      String query = "SELECT * FROM users";

      // create the java statement
      Statement st = conn.createStatement();

      // execute the query, and get a java resultset
      ResultSet rs = st.executeQuery(query);

      // iterate through the java resultset
      while (rs.next())
      {
        int id = rs.getInt("id");
        String firstName = rs.getString("first_name");
        String lastName = rs.getString("last_name");
        Date dateCreated = rs.getDate("date_created");
        boolean isAdmin = rs.getBoolean("is_admin");
        int numPoints = rs.getInt("num_points");

        // print the results
        System.out.format("%s, %s, %s, %s, %s, %s\n", id, firstName, lastName, dateCreated, isAdmin, numPoints);
      }
      st.close();
    }
    catch (Exception e)
    {
      System.err.println("Got an exception! ");
      System.err.println(e.getMessage());
    }
  }
}