Servlet与Jsp学习笔记--8、JSTL
Choose
<%@ taglib uri="http://java.sun.com/jstl/core" prefix="c" %>
<html>
<head><title>Accessing a Scoped Value</title></head>
<body>
<h2>Hello
<c:choose>
<c:when test="${empty param.name}">
Esteemed Visitor
</c:when>
<c:otherwise>
<c:out value="${param.name}" />
</c:otherwise>
</c:choose>
</h2>
</body>
</html>
input_jstl
<%@ page contentType="text/html" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jstl/core" %>
<html>
<head>
<title>User Info Entry Form</title>
</head>
<body bgcolor="white">
<form action="input_jstl.jsp" method="post">
<table>
<tr>
<td>Name:</td>
<td>
<input type="text" name="userName">
</td>
</tr>
<tr>
<td>Birth Date:</td>
<td>
<input type="text" name="birthDate">
</td>
<td>(Use format yyyy-mm-dd)</td>
</tr>
<tr>
<td>Email Address:</td>
<td>
<input type="text" name="emailAddr">
</td>
<td>(Use format [email protected])</td>
</tr>
<tr>
<td>Gender:</td>
<td>
<input type="radio" name="gender" value="m" checked>Male<br>
<input type="radio" name="gender" value="f">Female
</td>
</tr>
<tr>
<td>Lucky number:</td>
<td>
<input type="text" name="luckyNumber">
</td>
<td>(A number between 1 and 100)</td>
</tr>
<tr>
<td>Favorite Foods:</td>
<td>
<input type="checkbox" name="food" value="z">Pizza<br>
<input type="checkbox" name="food" value="p">Pasta<br>
<input type="checkbox" name="food" value="c">Chinese
</td>
</tr>
<tr>
<td colspan=2>
<input type="submit" value="Send Data">
</td>
</tr>
</table>
</form>
You entered:<br>
Name: <c:out value="${param.userName}" /><br>
Birth Date: <c:out value="${param.birthDate}" /><br>
Email Address: <c:out value="${param.emailAddr}" /><br>
Gender: <c:out value="${param.gender}" /><br>
Lucky Number: <c:out value="${param.luckyNumber}" /><br>
Favorite Food:
<c:forEach items="${paramValues.food}" var="current">
<c:out value="${current}" />
</c:forEach>
</body>
</html>
pageContext.request
<%@ page contentType="text/html" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jstl/core" %>
<html>
<head>
<title>Request Info</title>
</head>
<body bgcolor="white">
The following information was received:
<ul>
<li>Request Method:
<c:out value="${pageContext.request.method}" />
<li>Request Protocol:
<c:out value="${pageContext.request.protocol}" />
<li>Context Path:
<c:out value="${pageContext.request.contextPath}" />
<li>Servlet Path:
<c:out value="${pageContext.request.servletPath}" />
<li>Request URI:
<c:out value="${pageContext.request.requestURI}" />
<li>Request URL:
<c:out value="${pageContext.request.requestURL}" />
<li>Server Name:
<c:out value="${pageContext.request.serverName}" />
<li>Server Port:
<c:out value="${pageContext.request.serverPort}" />
<li>Remote Address:
<c:out value="${pageContext.request.remoteAddr}" />
<li>Remote Host:
<c:out value="${pageContext.request.remoteHost}" />
<li>Secure:
<c:out value="${pageContext.request.secure}" />
<li>Cookies:<br>
<c:forEach items="${pageContext.request.cookies}" var="c">
<b><c:out value="${c.name}" /></b>:
<c:out value="${c.value}" /><br>
</c:forEach>
<li>Headers:<br>
<c:forEach items="${headerValues}" var="h">
<b><c:out value="${h.key}" /></b>:
<c:forEach items="${h.value}" var="value">
<br>
<c:out value="${value}" />
</c:forEach>
<br>
</c:forEach>
</ul>
</body>
</html>
validate
<%@ page contentType="text/html" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jstl/core" %>
<html>
<head>
<title>User Info Entry Form</title>
</head>
<body bgcolor="white">
<jsp:useBean id="userInfo"
class="com.ora.jsp.beans.userinfo.UserInfoBean">
<jsp:setProperty name="userInfo" property="*" />
</jsp:useBean>
<form action="validate_bean.jsp" method="post">
<input type="hidden" name="submitted" value="true">
<table>
<c:if test="${param.submitted && userInfo.userNameValid == false}">
<tr><td></td>
<td colspan="2"><font color="red">
Please enter your Name
</font></td></tr>
</c:if>
<tr>
<td>Name:</td>
<td>
<input type="text" name="userName"
value="<c:out value="${userInfo.userName}" />">
</td>
</tr>
<c:if test="${param.submitted && !userInfo.birthDateValid}">
<tr><td></td>
<td colspan="2"><font color="red">
Please enter a valid Birth Date
</font></td></tr>
</c:if>
<tr>
<td>Birth Date:</td>
<td>
<input type="text" name="birthDate"
value="<c:out value="${userInfo.birthDate}" />">
</td>
<td>(Use format yyyy-mm-dd)</td>
</tr>
<c:if test="${param.submitted && !userInfo.emailAddrValid}">
<tr><td></td>
<td colspan="2"><font color="red">
Please enter a valid Email Address
</font></td></tr>
</c:if>
<tr>
<td>Email Address:</td>
<td>
<input type="text" name="emailAddr"
value="<c:out value="${userInfo.emailAddr}" />">
</td>
<td>(Use format [email protected])</td>
</tr>
<c:if test="${param.submitted && !userInfo.genderValid}">
<tr><td></td>
<td colspan="2"><font color="red">
Please select a valid Gender
</font></td></tr>
</c:if>
<tr>
<td>Gender:</td>
<td>
<c:choose>
<c:when test="${userInfo.gender == 'f'}">
<input type="radio" name="gender" value="m">Male<br>
<input type="radio" name="gender" value="f" checked>Female
</c:when>
<c:otherwise>
<input type="radio" name="gender" value="m" checked>Male<br>
<input type="radio" name="gender" value="f">Female
</c:otherwise>
</c:choose>
</td>
</tr>
<c:if test="${param.submitted && !userInfo.luckyNumberValid}">
<tr><td></td>
<td colspan="2"><font color="red">
Please enter a Lucky Number between 1 and 100
</font></td></tr>
</c:if>
<tr>
<td>Lucky number:</td>
<td>
<input type="text" name="luckyNumber"
value="<c:out value="${userInfo.luckyNumber}" />">
</td>
<td>(A number between 1 and 100)</td>
</tr>
<c:if test="${param.submitted && !userInfo.foodValid}">
<tr><td></td>
<td colspan="2"><font color="red">
Please select only valid Favorite Foods
</font></td></tr>
</c:if>
<tr>
<td>Favorite Foods:</td>
<td>
<input type="checkbox" name="food" value="z"
<c:if test="${userInfo.pizzaSelected}">checked</c:if>>Pizza<br>
<input type="checkbox" name="food" value="p"
<c:if test="${userInfo.pastaSelected}">checked</c:if>>Pasta<br>
<input type="checkbox" name="food" value="c"
<c:if test="${userInfo.chineseSelected}">checked</c:if>>Chinese
</td>
</tr>
<tr>
<td colspan=2>
<input type="submit" value="Send Data">
</td>
</tr>
</table>
</form>
</body>
</html>
Bean
package com.ora.jsp.beans.userinfo;
import java.io.*;
import java.util.*;
import com.ora.jsp.util.*;
public class UserInfoBean implements Serializable {
// Validation constants
private static String DATE_FORMAT_PATTERN = "yyyy-MM-dd";
private static String[] GENDER_LIST = {"m", "f"};
private static String[] FOOD_LIST = {"z", "p", "c"};
private static int MIN_LUCKY_NUMBER = 1;
private static int MAX_LUCKY_NUMBER = 100;
// Properties
private String birthDate;
private String emailAddr;
private String[] food;
private String luckyNumber;
private String gender;
private String userName;
/**
* Returns the birthDate property value
*/
public String getBirthDate() {
return (birthDate == null ? "" : birthDate);
}
/**
* Sets the birthDate property value
*/
public void setBirthDate(String birthDate) {
this.birthDate = birthDate;
}
/**
* Validates the birthDate property
*
* @return true if the property is set to a valid value, false otherwise.
*/
public boolean isBirthDateValid() {
boolean isValid = false;
if (birthDate != null &&
StringFormat.isValidDate(birthDate, DATE_FORMAT_PATTERN)) {
isValid = true;
}
return isValid;
}
/**
* Returns the emailAddr property value
*/
public String getEmailAddr() {
return (emailAddr == null ? "" : emailAddr);
}
/**
* Sets the emailAddr property value
*/
public void setEmailAddr(String emailAddr) {
this.emailAddr = emailAddr;
}
/**
* Validates the emailAddr property
*
* @return true if the property is set to a valid value, false otherwise.
*/
public boolean isEmailAddrValid() {
boolean isValid = false;
if (emailAddr != null &&
StringFormat.isValidEmailAddr(emailAddr)) {
isValid = true;
}
return isValid;
}
/**
* Returns the food property value
*/
public String[] getFood() {
return (food == null ? new String[0] : food);
}
/**
* Sets the food property value
*/
public void setFood(String[] food) {
this.food = food;
}
/**
* Validates the food property
*
* @return true if the property is set to a valid value, false otherwise.
*/
public boolean isFoodValid() {
boolean isValid = false;
if (food == null ||
StringFormat.isValidString(food, FOOD_LIST, true)) {
isValid = true;
}
return isValid;
}
/**
* Returns true if the food property includes the marker for
* pizza
*/
public boolean isPizzaSelected() {
return isFoodTypeSelected("z");
}
/**
* Returns true if the food property includes the marker for
* pasta
*/
public boolean isPastaSelected() {
return isFoodTypeSelected("p");
}
/**
* Returns true if the food property includes the marker for
* Chinese
*/
public boolean isChineseSelected() {
return isFoodTypeSelected("c");
}
/**
* Returns the luckyNumber property value
*/
public String getLuckyNumber() {
return (luckyNumber == null ? "" : luckyNumber);
}
/**
* Sets the luckyNumber property value
*/
public void setLuckyNumber(String luckyNumber) {
this.luckyNumber = luckyNumber;
}
/**
* Validates the luckyNumber property
*
* @return true if the property is set to a valid value, false otherwise.
*/
public boolean isLuckyNumberValid() {
boolean isValid = false;
if (luckyNumber != null &&
StringFormat.isValidInteger(luckyNumber, MIN_LUCKY_NUMBER,
MAX_LUCKY_NUMBER)) {
isValid = true;
}
return isValid;
}
/**
* Returns the gender property value
*/
public String getGender() {
return (gender == null ? "" : gender);
}
/**
* Sets the gender property value
*/
public void setGender(String gender) {
this.gender = gender;
}
/**
* Validates the gender property
*
* @return true if the property is set to a valid value, false otherwise.
*/
public boolean isGenderValid() {
boolean isValid = false;
if (gender != null &&
StringFormat.isValidString(gender, GENDER_LIST, true)) {
isValid = true;
}
return isValid;
}
/**
* Returns the userName property value
*/
public String getUserName() {
return (userName == null ? "" : userName);
}
/**
* Sets the userName property value
*/
public void setUserName(String userName) {
this.userName = userName;
}
/**
* Validates the gender property
*
* @return true if the property is set to a valid value, false otherwise.
*/
public boolean isUserNameValid() {
boolean isValid = false;
if (userName != null) {
isValid = true;
}
return isValid;
}
/**
* Returns true if all property values have valid values
* (they are only set if the value is valid).
*/
public boolean isValid() {
return isBirthDateValid() && isEmailAddrValid() &&
isFoodValid() && isLuckyNumberValid() &&
isGenderValid() && isUserNameValid();
}
/**
* Returns true if the food property includes the specified food
* type
*/
private boolean isFoodTypeSelected(String foodType) {
if (food == null) {
return false;
}
boolean selected = false;
for (int i = 0; i < food.length; i++) {
if (food[i].equals(foodType)) {
selected = true;
break;
}
}
return selected;
}
}
c:set
<%@ taglib prefix="c" uri="http://java.sun.com/jstl/core" %>
<html>
<head>
<title>Counter page</title>
</head>
<body bgcolor="white">
<%-- Increment the counter --%>
<c:set var="sessionCounter" scope="session"
value="${sessionCounter + 1}" />
<h1>Counter page</h1>
This page has been visited <b>
<c:out value="${sessionCounter}" />
</b> times within the current session.
<p>
Click here to load the page through a
<a href="counter2.jsp">regular link</a>.
<p>
Click here to load the page through an
<a href="<c:url value="counter2.jsp" />">encoded link</a>.
</body>
</html>