java基础教程4 ：Gui和绘图

在基础教程1中，我们简单介绍了Gui的设计，这里，我们进行进一步学习.

java.awt(抽象窗口工具包)是利用了操作系统提供的图形库向我们提供界面开发的方法，所以运行较快，因为其要具有平台无关性，所以awt显然只能提供不同操作系统图形库的交集功能。相比之下，swing是基于awt的，他利用awt提供的接口方法，通过模拟的方式实现了更丰富的界面。我们将awt控件称为重量级控件，将swing控件称之为轻量级控件。（不依赖本地代码的是轻量级，依赖本地代码的是重量级）在java中，所有swing控件都是大写字母J开头的。类图如下：

现在，我们展示基础的界面代码

import java.awt.Button;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JFrame;

 

public class TestGui {
    public static void main(String[] args)
    {
       //创建frame
       JFrame frame = new JFrame("welcome!!");
       //调整frame的大小和初始位置
       frame.setSize(400, 400);
       frame.setLocation(100, 100);
       //新建5个Button
       Button button1 = new Button("hello1");
       Button button2 = new Button("hello2");
       Button button3 = new Button("hello3");
       Button button4 = new Button("hello4");
       Button button5 = new Button("hello5");
       //将5个Button添加到frame中
       frame.add(button1,"East");
       frame.add(button2,"West");
       frame.add(button3,"South");
       frame.add(button4,"Center");
       frame.add(button5,"North");

       //增加窗口监听事件，使用内部类方法，并用监听器的默认适配器
       frame.addWindowListener(new WindowAdapter(){
           //重写窗口关闭事件
           @Override
           public void windowClosing(WindowEvent arg0) {
              System.exit(0);
           }
       });
       //显示窗体
       frame.setVisible(true);
    }  
}

下面展示向上述代码中添加绘图代码（使用java2D）

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.*;
public class TestGui extends JFrame{
	private myPanel p;
	public TestGui(String name){
		super();			//继承父类的构造方法
		setTitle(name);                 //名字
		setBounds(0,0,300,300);		//大小
		BorderLayout bl = new BorderLayout();
		bl.setHgap(20);
		bl.setVgap(20);
		getContentPane().setLayout(bl);//布局管理
	        p = new myPanel("jarvischu"); 
	        p.setBounds(0, 0, 150, 150);
	        getContentPane().add(p,bl.CENTER);
		this.setDefaultCloseOperation(EXIT_ON_CLOSE);//设置默认关闭操作
	}	                                                                                                        
	public static void main(String args[]){
		TestGui frame = new TestGui("JarvisChu");
		frame.setVisible(true);		
	} 
}
class myPanel extends JPanel{
	private String m_Name;
	public myPanel(String name){
		m_Name = name;
	}	
	public void paint(Graphics g){
		Graphics2D g2d = (Graphics2D)g;
		GradientPaint grdp = new GradientPaint(0,0,Color.blue,100,50,Color.RED);
                                                           //创建一个渐变填充的对象
		g2d.setPaint(grdp);                        //选中该Paint对象
		g2d.fillRect(0, 0, 200, 200);
	}
}

最后，让我们设计一个完整的读取数据，并进行用户界面交互的程序,利用jfreechart进行绘图

package DataShow;

import java.awt.CardLayout;
import java.awt.FlowLayout;
import java.awt.Color;
import java.awt.Font;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import javax.swing.*;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;

import org.jfree.chart.*;
import org.jfree.chart.axis.CategoryAxis;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.plot.CategoryPlot;
import org.jfree.chart.plot.PiePlot3D;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.title.TextTitle;
import org.jfree.data.general.DefaultPieDataset;
import org.jfree.data.general.PieDataset;
import org.jfree.data.category.DefaultCategoryDataset;


public class DataShow extends JFrame implements ItemListener{
	JCheckBox zhuzhuangtu;
	JCheckBox bingzhuangtu;
	CardLayout cLayout;
	JPanel chartPanel;
	static int[] data = new int[4];
	 //加载jdbc
	 static{
		 try{
			 Class.forName ( "org.gjt.mm.mysql.Driver" );
			 System.out.println ( "success loading mysql Driver...." );
	     } catch ( Exception e ){
	    	 System.out.println ( "Error loading mysql Driver....." );
	    	 e.printStackTrace ( );
	     }
	}
	
	
	public DataShow(){
		super();			//继承父类的构造方法
		setTitle("ShowData");                 //名字
		setBounds(0,0,300,300);		//大小
		FlowLayout layout = new FlowLayout();
		setLayout(layout);	
		JLabel label1 = new JLabel("选择绘制方式"); 
		add(label1); 
		zhuzhuangtu = new JCheckBox("条形图");
		bingzhuangtu = new JCheckBox("饼状图");
		add(zhuzhuangtu);
		add(bingzhuangtu);
		zhuzhuangtu.addItemListener(this);
		bingzhuangtu.addItemListener(this);
		
		cLayout  = new CardLayout();
		chartPanel = new JPanel(cLayout);


		//绘制饼状图
		PieDataset dataset1 = createDataset1();
		JFreeChart bingzhuangtuChart = createPieChart(dataset1, "各季度生产情况");
		ChartPanel bingzhuangtuChartPanel = new ChartPanel(bingzhuangtuChart);
		bingzhuangtuChartPanel.setPreferredSize(new java.awt.Dimension(500, 400));//设置组件尺寸

		//绘制柱状图
		DefaultCategoryDataset dataset2 = createDataset2();
		JFreeChart zhuzhuangtuChart = ChartFactory.createBarChart("各季度生产情况",null,null,dataset2,PlotOrientation.HORIZONTAL,true,false,false);
		TextTitle textTitle = zhuzhuangtuChart.getTitle();
		textTitle.setFont(new Font("黑体",Font.PLAIN,20));
		CategoryPlot categoryplot = (CategoryPlot)zhuzhuangtuChart.getPlot();
		categoryplot.getRenderer().setSeriesPaint(0,new Color(228,109,10));
		NumberAxis numberaxis = (NumberAxis) categoryplot.getRangeAxis();
		CategoryAxis domainAxis = categoryplot.getDomainAxis();
		//设置X轴坐标上的字体样式
		domainAxis.setTickLabelFont(new Font("sans-serif", Font.PLAIN, 11));
		//设置X轴的标题字体样式
		domainAxis.setLabelFont(new Font("宋体", Font.PLAIN, 12));
		//设置Y轴坐标上的字体样式
		numberaxis.setTickLabelFont(new Font("sans-serif", Font.PLAIN, 12));
		//设置Y轴的标题字体样式
		numberaxis.setLabelFont(new Font("黑体", Font.PLAIN, 12));
		//设置图片最底部字体样式
		if(zhuzhuangtuChart.getLegend()!=null){
			zhuzhuangtuChart.getLegend().setItemFont(new Font("宋体", Font.PLAIN, 12));
		}

		ChartPanel zhuzhuangtuChartPanel = new ChartPanel(zhuzhuangtuChart);
		zhuzhuangtuChartPanel.setPreferredSize(new java.awt.Dimension(300, 200));//设置组件尺寸			
		
		
		chartPanel.add(bingzhuangtuChartPanel,"bingzhuangtutuChartPanel");					
		chartPanel.add(zhuzhuangtuChartPanel,"zhuzhuangtutuChartPanel");
		add(chartPanel);		
		
		setDefaultCloseOperation(EXIT_ON_CLOSE);//设置默认关闭操作
		setVisible(true);	
		bingzhuangtu.setSelected(true);
	}	                                                                                                        
	public static void main(String args[]){		
		//读取数据库中的数据
		 try{
			 String url = "jdbc:mysql://localhost/sandbox";
	         //建立连接
	         Connection con = DriverManager.getConnection ( url, "root", "gaodaliang" );
	         //建立发送SQL命令的Statement对象
	         Statement stmt = con.createStatement ( );
	         //返回查询结果
	         ResultSet rs = stmt.executeQuery ( "select * from product_info" );
	         ResultSetMetaData md = rs.getMetaData ( );
	         //读取表头
	         int col = md.getColumnCount ( );
	         for ( int i = 1; i <= col; i++ ){
	                System.out.println ( md.getColumnName ( i ) + "/t" );
	         }
	         //读取数据
	         int temp = 0;
	         while ( rs.next ( ) ){
	        	 
	        	 String strData = "";
	             for ( int i = 1; i <= col; i++ ){
	            	 strData = strData + rs.getString ( i ) + "/t";
	            	 if(i==3){
	            		data[temp]=i=Integer.parseInt(rs.getString ( i ));           		
	            	 }
	             }
	             System.out.println ( strData );
	             temp++;
	         }
	         //断开Connection连接
	         rs.close();
	         stmt.close();
	         con.close ( );
		 } catch ( SQLException e ){
	            e.printStackTrace ( );
	     }
		 DataShow frame = new DataShow();	
		 frame.pack();
		 
	} 
	@Override
    public void itemStateChanged(ItemEvent e) {
		Object source = e.getItemSelectable();
		if ( source == bingzhuangtu){
			if(e.getStateChange()==ItemEvent.SELECTED){
				zhuzhuangtu.setSelected(false);
				//显示饼状图
				cLayout.show(chartPanel,"bingzhuangtutuChartPanel");				
			}			
		}
		if ( source == zhuzhuangtu){
			if(e.getStateChange()==ItemEvent.SELECTED){
				bingzhuangtu.setSelected(false);
				//绘制柱状图
				cLayout.show(chartPanel,"zhuzhuangtutuChartPanel");
			}	
		}
	}
	
	private PieDataset createDataset1() {
		DefaultPieDataset result = new DefaultPieDataset();//创建一个DefaultPieDataset实例，Dataset是图表的容器
		result.setValue("第一季度", data[0]);//Sets the data value for a key and 
		result.setValue("第二季度", data[1]);//sends  a DatasetChangeEvent to all registered listeners.
		result.setValue("第三季度", data[2]);//以上注释请自己翻译
		result.setValue("第四季度", data[3]);
		return result;//返回DefaultPieDataset对象
	}
	
	private DefaultCategoryDataset createDataset2() {
		DefaultCategoryDataset result = new DefaultCategoryDataset();//创建一个DefaultPieDataset实例，Dataset是图表的容器
		result.addValue(data[0],"生产数","第一季度");
		result.addValue(data[1],"生产数","第二季度");
		result.addValue(data[2],"生产数","第三季度");
		result.addValue(data[3],"生产数","第四季度");
		return result;//返回DefaultPieDataset对象
	}
	
	
	private JFreeChart createPieChart(PieDataset dataset, String title) {
		JFreeChart chart = ChartFactory.createPieChart3D(title, dataset, true,
				true, false);//创建一个3D饼图
		TextTitle textTitle = chart.getTitle();//获取图表的标题
		textTitle.setFont(new Font("黑体", Font.PLAIN, 20));//设置图表的标题字体，避免产生乱码
		chart.getLegend().setItemFont(new Font("宋体", Font.PLAIN, 12));//设置项目字体，避免产生乱码
		PiePlot3D plot = (PiePlot3D) chart.getPlot();//获取图表区域对象
		plot.setStartAngle(-30);//设置开始角度，默认的是90°
		plot.setLabelFont(new Font("黑体", Font.PLAIN, 20));//设置标签字体，避免乱码
		return chart;//返回JFreeChart对象
	}

}