Easily implement data pie chart 4 on the JSP page

Appendix: all source code in this article

Listing E

<% @ Page language = "java" %> <% @ Page import = "java. io. OutputStream" %> <% @ Page import = "java. SQL. *" %> <% @ Page import = "java. awt. *" %> <% @ Page import = "java. awt. geom. *" %> <% @ Page import = "java. awt. image. BufferedImage" %> <% @ Page import = "com.sun.image.codec.jpeg. *" %> <%! //////////////////////////////////////// //////////////////// // PieColors class manages the colors used in the pie chart //////////////////////////////////////// //////////////////// Class PieColors { Color pieColorArray [] = { New Color (60,210, 60), new Color (210, 60), new Color (60, 60 ), New Color (120, 60, 60,120,210), new Color (210,120), new Color (, 60) }; Int curPieColor = 0; Public Color getPieColor () { Return pieColorArray [curPieColor]; } Public void setNewColor () { CurPieColor ++; If (curPieColor> = pieColorArray. length) {CurPieColor = 0 ;} } } %> <%! String driver = "com. mysql. jdbc. driver "; String dburl =" jdbc: mysql: // localhost/articles "; String dbuid =" myuid "; String dbpwd =" mypwd "; //////////////////////////////////////// //////////////////// // Get the products from the database as a String array //////////////////////////////////////// //////////////////// Public String [] getProducts () { String [] arr = new String [0]; Connection con; Statement stmt; ResultSet rs; Int count = 0; String SQL = "select * from p_products order by productID "; Try { // Load Driver: Class. forName (driver ); // Connect to the database with the url Con = DriverManager. getConnection (dburl, dbuid, dbpwd ); Stmt = con. createStatement (); // Get ResultSet Rs = stmt.exe cuteQuery (SQL ); // Count the records While (rs. next () {count ++; } // Create an array of the correct size Arr = new String [count]; // Get ResultSet (the most portable way of using rs a second time) Rs = stmt.exe cuteQuery (SQL ); While (rs. next ()) { Arr [rs. getInt ("productID")] = rs. getString ("productname "); } Stmt. Close (); Con. Close (); } Catch (Java. Lang. Exception ex) {Arr [0] = ex. tostring ();} Return arr; } //////////////////////////////////////// //////////////////// // Get the sales totals from the database //////////////////////////////////////// //////////////////// Public float [] getsales (INT products) { Float [] arr = new float [products]; Connection con; Statement stmt; Resultset RS; String SQL = "select productid, amount from p_sales "; Try { // Load driver: Class. forname (driver ); // Connect to the database with the URL Con = drivermanager. getconnection (dburl, dbuid, dbpwd ); Stmt = con. createStatement (); // Get ResultSet Rs = stmt.exe cuteQuery (SQL ); While (rs. next () {int product = rs. getInt ("productID "); // Check that the productID is valid If (product> = 0 & product <products) { // Add to product total Arr [product] + = rs. getFloat ("amount "); } } Stmt. close (); Con. close (); } Catch (java. lang. Exception ex) {arr [0] =-1.0f ;} Return arr ;}%> <% // Get an array that contains the product names String products [] = getProducts (); // Read the data and store the totals in an array Float sales [] = getSales (products. length ); // Declare PieColors Pc = new PieColors (); // Colors Color DropShadow = new Color (240,240,240 ); // Inner padding to make sure bars never touch the outer border Int innerOffset = 20; // Set the graph's outer width & height Int WIDTH = 400; Int HEIGHT = 200; Int pieHeight = HEIGHT-(innerOffset * 2 ); Int pieWidth = pieHeight; // To make a square (circular) pie Int halfWidth = WIDTH/2; // Width of the inner graphable area Int innerWIDTH = WIDTH-(innerOffset * 2 ); // Graph dimensions Dimension GraphDim = new Dimension (WIDTH, HEIGHT ); Rectangle graphRect = new Rectangle (graphDim ); // Border dimensions Dimension borderDim = new Dimension (halfWidth-2, HEIGHT-2 ); Rectangle borderRect = new Rectangle (borderDim ); //////////////////////////////////////// ///////////////////// // Set up the graph //////////////////////////////////////// //////////////////// // Set content type Response. setContentType ("image/jpeg "); // Create BufferedImage & Graphics2D BufferedImage bi = new BufferedImage (WIDTH, HEIGHT, BufferedImage. TYPE_INT_RGB ); Graphics2D g2d = bi. createGraphics (); // Set Antialiasing RenderingHints RenderHints = new RenderingHints (RenderingHints. KEY_ANTIALIASING, RenderingHints. VALUE_ANTIALIAS_ON ); G2d. setRenderingHints (renderHints ); // Set graph background color to white: G2d. setColor (Color. white ); G2d. fill (graphRect ); // Draw black border G2d. setcolor (color. Black ); Borderrect. setlocation (1, 1 ); G2d. Draw (borderrect ); // Now draw border for legend Borderrect. setlocation (width/2) + 1, 1 ); G2d. Draw (borderrect ); //////////////////////////////////////// //////////////////////////// // Draw data onto the graph: //////////////////////////////////////// //////////////////////////// Int x_pie = inneroffset; Int y_pie = inneroffset; int border = 20; // Main chart Ellipse // Ellipse2d. double El = new ellipse2d. double (x_pie, y_pie, piewidth, pieheight); ellipse2d. double ELB = new ellipse2d. double (x_pie-border/2, y_pie-border/2, piewidth + border, pieheight + border ); // Shadow G2d. setcolor (dropshadow ); G2d. Fill (ELB ); // Border G2d. setcolor (color. Black ); G2d. Draw (ELB ); //////////////////////////////////////// ///////////////////////// // Calculate the total sales //////////////////////////////////////// ///////////////////////// Float salestotal = 0.0f; Int lastelement = 0; For (INT I = 0; I <products. length; I ++) { If (sales [I]> 0.0f) { Salestotal + = Sales [I]; Lastelement = I; } } //////////////////////////////////////// ////////////////////// // Draw the pie chart //////////////////////////////////////// ///////////////////// // Chart Variables Int startangle = 0; // Legend Variables Int legendWidth = 20; Int x_legendText = halfWidth + innerOffset/2 + legendWidth + 5; Int x_legendBar = halfWidth + innerOffset/2; Int textHeight = 20; Int curElement = 0; Int y_legend = 0; // Dimensions of the legend bar Dimension legendDim = new Dimension (legendWidth, textHeight/2 ); Rectangle legendRect = new Rectangle (legendDim ); For (int I = 0; I <products. length; I ++) { If (sales [I]> 0.0f) { // Calculate percentage sales float Perc = (sales [I]/salesTotal ); // Calculate new angle Int sweepAngle = (int) (perc * 360 ); // Check that the last element goes back to 0 position If (I = lastElement) { SweepAngle = 360-startAngle; } // Draw Arc G2d. setColor (pc. getPieColor ()); G2d. fillArc (x_pie, y_pie, pieWidth, pieHeight, startAngle, sweepAngle ); // Increment startAngle with the sweepAngle StartAngle + = sweepAngle; ///////////// // Draw Legend ///////////// // Set y position for bar Y_legend = curElement * textHeight + innerOffset; // Display the current product String display = products [I]; G2d. setColor (Color. black ); G2d. drawString (display, x_legendText, y_legend ); // Display the total sales Display = "" + (int) sales [I]; G2d. setColor (Color. black ); G2d. drawString (display, x_legendText + 80, y_legend ); // Display the sales percentage Display = "(" + (int) (perc * 100) + "% )"; G2d. setColor (Color. red ); G2d. drawString (display, x_legendText + 110, y_legend ); // Draw the bar G2d. setColor (pc. getPieColor ()); LegendRect. setLocation (x_legendBar, y_legend-textHeight/2 ); G2d. fill (legendRect ); // Set new pie color Pc. setNewColor (); // Increment CurElement ++; } } //////////////////////////////////////// //////// // Encode the graph ///////////////////////////////////////// OutputStream output = response. getOutputStream (); Required imageencoder encoder = required codec. createJPEGEncoder (output ); Encoder. encode (bi ); Output. close (); %>