使用JavaBean封装数据和业务逻辑
学习到JavaBean了，打个小栗子，大神勿喷
功能：输入三条边，判断是否构成三角形，并计算面积
Stringtonum.java：封装了三角形三条边及一个字符串分离出三条边
Triangle.java：封装了三角形三条边，判断是否构成三角形，并计算面积
index.jsp：用户访问页面
index.jsp
1 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> 2 <jsp:useBean id="angle" class="bean.Stringtonum" scope="page"></jsp:useBean> 3 <jsp:useBean id="tri" class="bean.Triangle" scope="page"></jsp:useBean> 4 5 6 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 7 <html> 8 <head> 9 10 <title>使用JavaBean封装数据和业务逻辑，输出三角形面积</title> 11 </head> 12 13 <body> 14 请输入三角形三条边的长度，并使用逗号分隔：<br /> 15 <form method="post"> 16 <input type="text" name="boy"> 17 <input type="submit" value="提交"> 18 </form> 19 <% 20 String str = request.getParameter("boy"); 21 if(!angle.strtonum(str)){ 22 out.println("请输入三个数"); 23 return; 24 } 25 tri.setEdge1(angle.getNum1()); 26 tri.setEdge2(angle.getNum2()); 27 tri.setEdge3(angle.getNum3()); 28 if(!tri.isTriangle()){ 29 out.println("您输入的三条边不能构成一个三角形"); 30 return; 31 }else{ 32 out.println("三角形的面积 = "+tri.calArea()); 33 } 34 %> 35 <br>您输入的三条边是：<% out.println(tri.getEdge1()); %>,<% out.println(tri.getEdge2()); %>,<% out.println(tri.getEdge3()); %> 36 </body> 37 </html>
Stringtonum.java
1 package bean; 2 3 /* 4 * 功能：获取输入的三个数字，并对这三个数字进行分割处理 5 */ 6 7 public class Stringtonum { 8 9 private double num1; 10 private double num2; 11 private double num3; 12 public Stringtonum(){} 13 public double getNum1() { 14 return num1; 15 } 16 public double getNum2() { 17 return num2; 18 } 19 public double getNum3() { 20 return num3; 21 } 22 public void setNum1(double n) { 23 num1 = n; 24 } 25 public void setNum2(double n) { 26 num2 = n; 27 } 28 public void setNum3(double n) { 29 num3 = n; 30 } 31 public boolean strtonum(String str){ 32 //取三边 33 double a[] = new double[3]; 34 int i; 35 if(str==null){ 36 return false; 37 } 38 String substr=","; 39 //字符串分割 40 String[] as = str.split(substr); 41 if(as.length != 3){ 42 return false; 43 }else{ 44 for(i=0;i<3;i++){ 45 //将字符类型a数组转换成double类型a数组 46 a[i] = Double.valueOf(as[i]); 47 } 48 } 49 num1 = a[0]; 50 num2 = a[1]; 51 num3 = a[2]; 52 if(num1<0.0||num2<0.0||num3<0.0){ 53 return false; 54 } 55 return true; 56 } 57 58 }
Triangle.java
1 package bean; 2 3 public class Triangle { 4 private double edge1; 5 private double edge2; 6 private double edge3; 7 public Triangle(){} 8 public Triangle(double e1,double e2,double e3){ 9 this.edge1 = e1; 10 this.edge2 = e2; 11 this.edge3 = e3; 12 } 13 public double getEdge1() { 14 return edge1; 15 } 16 public void setEdge1(double edge) { 17 this.edge1 = edge; 18 } 19 public double getEdge2() { 20 return edge2; 21 } 22 public void setEdge2(double edge) { 23 this.edge2 = edge; 24 } 25 public double getEdge3() { 26 return edge3; 27 } 28 public void setEdge3(double edge) { 29 this.edge3 = edge; 30 } 31 //判断是否构成三角形 32 public boolean isTriangle(){ 33 if(edge1 + edge2 > edge3 && edge1 + edge3 > edge2 && edge3 + edge2 > edge1){ 34 return true; 35 }else{ 36 return false; 37 } 38 } 39 public double calArea(){ 40 //海伦公式求三角形面积 41 double p = (edge1 + edge2 +edge3)/2; 42 return Math.sqrt(p * (p-edge1) * (p-edge2) * (p-edge3)); 43 } 44 }