Question

java怎么从数据库取出数据然后生成波形图

X轴是ID，Y轴是对应的值！求点拨，求思路谢谢~~

Answer 1

package com.tur.demo;

import javax.swing.*;
import java.awt.*;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Random;

class DataReceiver extends JPanel {
private List<Integer> values; // 保存接收到的数据的容器.
private static final int MAX_VALUE = 200; // 接收到的数据的最大值.
private static final int MAX_COUNT_OF_VALUES = 50; // 最多保存数据的个数.

public DataReceiver() {
values = Collections.synchronizedList(new ArrayList<Integer>());

// 使用一个线程模拟产生数据.
new Thread(new Runnable() {
@Override
public void run() {
Random rand = new Random();

try {
while (true) {
addValue(rand.nextInt(MAX_VALUE)); // 产生一个数据，并模拟接收并放到容器里.
repaint();
Thread.sleep(100);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}).start();
}

@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);

Graphics2D g2d = (Graphics2D) g;
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

int w = getWidth();
int h = getHeight();
int xDelta = w / MAX_COUNT_OF_VALUES;
int length = values.size();

for (int i = 0; i < length - 1; ++i) {
g2d.drawLine(xDelta * (MAX_COUNT_OF_VALUES - length + i), normalizeValueForYAxis(values.get(i), h),
xDelta * (MAX_COUNT_OF_VALUES - length + i + 1), normalizeValueForYAxis(values.get(i + 1), h));
}
}

/**
* 接收到的数据放入内存.
* @param value
*/
private void addValue(int value) {
// 循环的使用一个接收数据的空间.
// 最好是实现一个循环数组，而不是偷懒的使用ArrayList.
if (values.size() > MAX_COUNT_OF_VALUES) {
values.remove(0);
}

values.add(value);
}

/**
* 规一化y轴方向的值. 使得value在y轴的值为[0, height]之间.
*
* @param value
* @param height
* @return
*/
private int normalizeValueForYAxis(int value, int height) {
return (int) ((double) height / MAX_VALUE * value);
}

private static void createGuiAndShow() {
JFrame frame = new JFrame("");

frame.getContentPane().add(new DataReceiver());

// Set frame's close operation and location in the screen.
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(400, 400);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}

public static void main(String[] args) {
createGuiAndShow();
}
}

将代码中需要的数值从数据库查出即可

追问

这个程序是创建了一个gui窗口来显示波形表吗亲?