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Servlet/Jsp实现当参数确实或缺失重新显示输入表单
(1)在有些时候我们的表单需要用户填写,但是没有填写就提交了,我们需要保留已经填写的数据然后再让用户填写没有填写的数据
(2)以一个处理拍卖竞标的servlet来实现功能:
BidInfo.java
package com.lc.ch04jingbiao; import com.lc.ch04Biaodanshuju.ServletUtilities; public class BidInfo { private String itemID = ""; private String itemName = ""; private String bidderName = ""; private String emailAddress = ""; private double bidPrice = 0; private boolean autoIncrement = false; public String getItemName() { return(itemName); } public void setItemName(String itemName) { this.itemName = ServletUtilities.filter(itemName); } public String getItemID() { return(itemID); } public void setItemID(String itemID) { this.itemID = ServletUtilities.filter(itemID); } public String getBidderName() { return(bidderName); } public void setBidderName(String bidderName) { this.bidderName = ServletUtilities.filter(bidderName); } public String getEmailAddress() { return(emailAddress); } public void setEmailAddress(String emailAddress) { this.emailAddress = ServletUtilities.filter(emailAddress); } public double getBidPrice() { return(bidPrice); } public void setBidPrice(double bidPrice) { this.bidPrice = bidPrice; } public boolean isAutoIncrement() { return(autoIncrement); } public void setAutoIncrement(boolean autoIncrement) { this.autoIncrement = autoIncrement; } /**判断是否完成 */ public boolean isComplete() { return(hasValue(getItemID()) && hasValue(getItemName()) && hasValue(getBidderName()) && hasValue(getEmailAddress()) && (getBidPrice() > 0)); } //判断是否有 没有填写的项 public boolean isPartlyComplete() { boolean flag = (hasValue(getItemID()) || hasValue(getItemName()) || hasValue(getBidderName()) || hasValue(getEmailAddress()) || (getBidPrice() > 0) || isAutoIncrement()); return(flag); } private boolean hasValue(String val) { return((val != null) && (!val.equals(""))); } }
BidServlet代码如下:
package com.lc.ch04jingbiao; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.lc.ch04Biaodanshuju.BeanUtilities; public class BidServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { BidInfo bid = new BidInfo(); BeanUtilities.populateBean(bid, request); if (bid.isComplete()) { // All required form data was supplied: show result. showBid(request, response, bid); } else { // Form data was missing or incomplete: redisplay form. showEntryForm(request, response, bid); } } /** All required data is present: show the results page. */ private void showBid(HttpServletRequest request, HttpServletResponse response, BidInfo bid) throws ServletException, IOException { submitBid(bid); response.setContentType("text/html"); PrintWriter out = response.getWriter(); String title = "Bid Submitted"; out.println (DOCTYPE + "<HTML>\n" + "<HEAD><TITLE>" + title + "</TITLE></HEAD>\n" + "<BODY BGCOLOR=\"#FDF5E6\"><CENTER>\n" + "<H1>" + title + "</H1>\n" + "Your bid is now active. If your bid is successful,\n" + "you will be notified within 24 hours of the close\n" + "of bidding.\n" + "<P>\n" + "<TABLE BORDER=1>\n" + " <TR><TH BGCOLOR=\"BLACK\"><FONT COLOR=\"WHITE\">" + bid.getItemName() + "</FONT>\n" + " <TR><TH>Item ID: " + bid.getItemID() + "\n" + " <TR><TH>Name: " + bid.getBidderName() + "\n" + " <TR><TH>Email address: " + bid.getEmailAddress() + "\n" + " <TR><TH>Bid price: $" + bid.getBidPrice() + "\n" + " <TR><TH>Auto-increment price: " + bid.isAutoIncrement() + "\n" + "</TABLE></CENTER></BODY></HTML>"); } private void showEntryForm(HttpServletRequest request, HttpServletResponse response, BidInfo bid) throws ServletException, IOException { boolean isPartlyComplete = bid.isPartlyComplete(); response.setContentType("text/html"); PrintWriter out = response.getWriter(); String title = "Welcome to Auctions-R-Us. Please Enter Bid."; out.println (DOCTYPE + "<HTML>\n" + "<HEAD><TITLE>" + title + "</TITLE></HEAD>\n" + "<BODY BGCOLOR=\"#FDF5E6\"><CENTER>\n" + "<H1>" + title + "</H1>\n" + warning(isPartlyComplete) + "<FORM>\n" + inputElement("Item ID", "itemID", bid.getItemID(), isPartlyComplete) + inputElement("Item Name", "itemName", bid.getItemName(), isPartlyComplete) + inputElement("Your Name", "bidderName", bid.getBidderName(), isPartlyComplete) + inputElement("Your Email Address", "emailAddress", bid.getEmailAddress(), isPartlyComplete) + inputElement("Amount Bid", "bidPrice", bid.getBidPrice(), isPartlyComplete) + checkbox("Auto-increment bid to match other bidders?", "autoIncrement", bid.isAutoIncrement()) + "<INPUT TYPE=\"SUBMIT\" VALUE=http://www.mamicode.com/"Submit Bid/">/n" +>(3)配置好servlet后,演示效果:
完全填写好表单:
如果没有完全填写表单:
提交后的结果:(提示让填写missing的Data)
ok!
Servlet/Jsp实现当参数确实或缺失重新显示输入表单
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