Javaweb's Request/response Code cultivation chapter (v)

1. Solve Chinese character encoding problem

String str = "I love Java";//The first method Response.setcontenttype ("TEXT/HTML;CHARSET=GBK");(recommended)//The second method//response.setheader (" Content-type "," text/html;charset=utf-8 ");//The Third method//response.getoutputstream (). Write (" <meta http-equiv= " Content-type ' content= ' text/html;charset=utf-8 ' > '. getBytes ()); Response.getoutputstream (). Write (Str.getbytes ( ));

2. Firefox Chinese file name download problem

String path = "/web-inf/classes/hello. jpg"; String filename = path.substring (Path.lastindexof ("/") +1); String Absolutepath = Getservletcontext (). Getrealpath (path), if (Request.getheader ("User-agent"). Contains ("Firefox" ) {Response.setheader ("content-disposition", "attachment;filename=" +encodedownloadfilename (filename, "Firefox")) ;} else {response.setheader ("content-disposition", "attachment;filename=" +encodedownloadfilename (filename, "ie");} InputStream is = new FileInputStream (absolutepath); OutputStream os = Response.getoutputstream (); int len = -1;byte buf[] = New Byte[1024];while ((Len=is.read (BUF))! =-1) {os.write (buf, 0, Len);} Is.close ();p ublic string Encodedownloadfilename (string filename, string agent) throws IOException {if (Agent.contains (" Firefox ") {filename =" =? ") UTF-8? B? " +new Base64encoder (). Encode (Filename.getbytes ("Utf-8")) + "? =";} else {filename = urlencoder.encode (filename, "UTF-8");} return filename;}

3. Verification Code Picture

Control Browser timed Refresh Response.setheader ("Refresh", "10");//define height and width int width =, height = 25;//Create an image buffer BufferedImage Bimage = New BufferedImage (width, height, bufferedimage.type_int_rgb);//Get the brush graphics g = bimage.getgraphics ();//Set the brush color to draw a border, Fill background, draw lines, draw string G.setcolor (Color.Black), g.drawrect (0, 0, width, height);//Fill Background g.setcolor (Color.light_gray); G.fillrect (1, 1, width-2, height-2);//Draw lines random r = new Random () G.setcolor (Color.cyan); for (int i=0; i<20; i++) {G.dra Wline (R.nextint (width), r.nextint (height), r.nextint (width), r.nextint (height));} A string that sets the font style for fonts font = new Font ("italics", font.bold| Font.Italic, G.setfont (font); G.setcolor (color.red); String base = "\u7684\u4e00\u4e86\u662f\u6211\u4e0d\u5728"; for (int i=0; i<4; i++) {String ch = Base.charat (R.nextint ( Base.length ())) + ""; g.drawstring (CH, 20+ (20*i), 20);} Set header information to display data type Response.setheader ("Content-type", "image/jpeg");//Empty cache information Response.setheader ("Expires", "0"); Response.setheader ("Cache-control", "No-cache"); Response.setheader ("Pragma", "no-Cache "); Imageio.write (bimage," JPG ", Response.getoutputstream ()); 

4. Set the cache time

Response.setcontenttype ("Text/html;charset=utf-8"); Response.setdateheader ("Expires", System.currenttimemillis () +60*60*1000); PrintWriter out = Response.getwriter (); Out.write ("Rene-10 years");

5.1 Get request parameter Mode 1

1. Gets the GET request parameter (the value in the text box) request.setcharacterencoding ("UTF-8"); Response.setcontenttype ("Text/html;charset=utf-8"); enumeration<string> names = Request.getparameternames (); while (Names.hasmoreelements ()) {/*string name = new String (Names.nextelement (). GetBytes ("Iso-8859-1"), "UTF-8"); String value = new String (request.getparameter (name). GetBytes ("Iso-8859-1"), "UTF-8"); */string name = Names.nextelement (); String value = request.getparameter (name); Response.getwriter (). Write (name+ ":  " +value);

5.2 Get request parameter Mode 2

2. Obtain request parameter request.setcharacterencoding ("UTF-8") by reflection; Response.setcontenttype ("Text/html;charset=utf-8"); User user = new user (); enumeration<string> names = Request.getparameternames (); while (Names.hasmoreelements ()) {String name = Names.nextelement (); String values[] = request.getparametervalues (name); Class clazz = User.getclass (); try {Field field = Clazz.getdeclaredfield (name); Field.setaccessible (true); if (values! = Null & values.length > 1) {field.set (user, (Object) values),} else {field.set (user, values[0]);}} catch (Exception e) {throw new RuntimeException (e);}} Response.getwriter (). Write (User.getusername () + ">>" + arrays.tostring (User.getpassword ()));

5.3 Get request parameter Mode 3

3. Get request parameter request.setcharacterencoding ("UTF-8") through introspection, Response.setcontenttype ("Text/html;charset=utf-8"); User user = new user (); map<string, string[]> map = Request.getparametermap (); for (map.entry<string, string[]> Entry:map.entrySet ()) {String name = Entry.getkey (); String values[] = Entry.getvalue (); try {propertydescriptor PD = new PropertyDescriptor (name, User.class); Method m = Pd.getwritemethod (), if (Values!=null && values.length>1) {m.invoke (user, (Object) values);} else { M.invoke (user, values[0]);}} catch (Exception e) {e.printstacktrace ();}} Response.getwriter (). Write (User.getusername () + ">>" +arrays.tostring (User.getpassword ()));

5.4 Get request parameter Mode 4

4. by Beanutils SetProperty () method request.setcharacterencoding ("UTF-8"); Response.setcontenttype ("text/html;charset= UTF-8 "); User user = new user (); map<string, string[]> map = Request.getparametermap (); for (map.entry<string, string[]> Entry:map.entrySet ()) {String name = Entry.getkey (); String values[] = Entry.getvalue (); try {if (values!=null && values.length>1) {beanutils.setproperty (user, Name, (Object) values);} else {beanutils.setproperty (user, name, values[0]);}} catch (Illegalaccessexception | InvocationTargetException e) {e.printstacktrace ();}} Response.getwriter (). Write (User.getusername () + ">>" + arrays.tostring (User.getpassword ()));

5.5 Get request parameter Mode 5

5. Request.setcharacterencoding ("UTF-8") through the Populator () method in Beanutils; Response.setcontenttype ("text/html;charset= UTF-8 "); User user = new user (); try {beanutils.populate (user, Request.getparametermap ());} catch (Illegalaccessexception | InvocationTargetException e) {e.printstacktrace ();} Response.getwriter (). Write (User.getusername () + ">>" + arrays.tostring (User.getpassword ()));

Javaweb's Request/response Code cultivation chapter (v)