建立表单参数和Bean属性之间的关联

  

      Using jsp:setProperty



    name="entry"
    property="itemID"
    value="<%=request.getParameter("itemID")%>" />

    name="entry"
    property="numItems"
    param="numItems" />


    name="entry"
    property="discountCode"
    param="discountCode" />






  
Item ID
Unit Price
Number Ordered
Total Price
  

  
$
  

  
$

package bean;

/** Simple bean to illustrate the various forms
 *  of jsp:setProperty.
 */

public class SaleEntry {
  private String itemID = "unknown";
  private double discountCode = 1.0;
  private int numItems = 0;

  public String getItemID() {
    return(itemID);
  }

  public void setItemID(String itemID) {
    if (itemID != null) {
      this.itemID = itemID;
    } else {
      this.itemID = "unknown";
    }
  }

  public double getDiscountCode() {
    return(discountCode);
  }

  public void setDiscountCode(double discountCode) {
    this.discountCode = discountCode;
  }

  public int getNumItems() {
    return(numItems);
  }

  public void setNumItems(int numItems) {
    this.numItems = numItems;
  }

  // Replace this with real database lookup.

  public double getItemCost() {
    double cost;
    if (itemID.equals("a1234")) {
      cost = 12.99*getDiscountCode();
    } else {
      cost = -9999;
    }
    return(roundToPennies(cost));
  }

  private double roundToPennies(double cost) {
    return(Math.floor(cost*100)/100.0);
  }

  public double getTotalCost() {
    return(getItemCost() * getNumItems());
  }
}