使用JFreeChart构造统计图

技术2022-05-11 61

public class ChartServlet extends HttpServlet { // 请求处理方法 public void doPost( HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 得到用户的投票信息 String id = request.getParameter( "id" ); IVoteDAO dao = DAOFactory.getVoteDAO(); Vote vote = dao.getVote( id ); // 得到JFreeChart对象的实例 JFreeChart chart = getChart( vote ); // 设置输出对象的类型 response.setContentType( "image/jpeg" ); // 输出图形 ChartUtilities.writeChartAsJPEG( response.getOutputStream(), 100, chart, 400, 300, null); } // 请求处理方法 public void doGet( HttpServletRequest request, HttpServletResponse response ) throws ServletException, IOException { doPost( request, response ); } // 得到JFreeChart对象的实例 public static JFreeChart getChart( Vote vote ) { JFreeChart chart = null; // 判断是否为饼图 if( vote.getPictype().indexOf( "PIE" ) == 0 ) { // 组织生成饼图的数据 DefaultPieDataset data = new DefaultPieDataset(); Iterator it = vote.getVoteitems().iterator(); while( it.hasNext() ) { VoteItem vi = (VoteItem)it.next(); data.setValue( vi.getTitle(), vi.getVotenum() ); } // 判断是否为普通饼图 if( "PIE".equals( vote.getPictype() ) ) { chart = ChartFactory.createPieChart( vote.getTitle(), data, false, false, false ); } else // 3D饼图 { chart = ChartFactory.createPieChart3D( vote.getTitle(), data, false, false, false ); } } else { // 组织柱状图的数据 DefaultCategoryDataset data = new DefaultCategoryDataset(); Iterator it = vote.getVoteitems().iterator(); while( it.hasNext() ) { VoteItem vi = (VoteItem)it.next(); data.addValue( vi.getVotenum(), "选项", vi.getTitle() ); } // 判断是否为普通柱状图 if( "BAR".equals( vote.getPictype() ) ) { chart = ChartFactory.createBarChart( vote.getTitle(), "选项", "数量", data, PlotOrientation.VERTICAL, false, false, false ); } else // 3D柱状图 { chart = ChartFactory.createBarChart3D( vote.getTitle(), "选项", "数量", data, PlotOrientation.VERTICAL, false, false, false ); } } return chart; }}

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