JavaBean表单验证

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First Step: write the JavaBean source code.

package register.test;import java.util.Map;import java.util.HashMap;public class RegisterBean {private String name;private String age;private String email;private Map<String,String> errors;public RegisterBean() {this.name="";this.age="";this.email="";this.errors=new HashMap<String,String>();}public boolean isValid() {boolean flag = true ;if(!this.name.matches("\\w{6,15}")){flag = false ;this.name = "" ;this.errors.put("errname","user name must between 6~15 words") ;}if(!this.email.matches("\\w+@\\w+\\.\\w+\\.?\\w*")){flag = false ;this.email = "" ;this.errors.put("erremail","Email doesn't match.") ;}if(!this.age.matches("\\d+")){flag = false ;this.age = "" ;this.errors.put("errage","Age must be a number") ;}return flag ;}public String getError(String key) {String value=this.errors.get(key);return value==null?"":value;}public void setName(String name) {this.name=name;}public void setAge(String age) {this.age=age;}public void setEmail(String email) {this.email=email;}public String getName() {return name;}public String getAge() {return age;}public String getEmail() {return email;}}

Then We should have a register page, here we go:

<html><head><title>Register Page</title></head><jsp:useBean id="user" scope="request" class="register.test.RegisterBean"/><body><form action="check.jsp" method="post">Account ID: <input type="text" name="name" value="<jsp:getProperty name="user" property="name"/>"/><%=user.getError("errname")%><br>Age :       <input type="text" name="age" value="<jsp:getProperty name="user" property="age"/>"/><%=user.getError("errage")%><br>Email:      <input type="text" name="email" value="<jsp:getProperty name="user" property="email"/>"/><%=user.getError("erremail")%><br><input type="submit" value="Submit"></form></body></html>

When we submit this form, we use check.jsp to check the form content.

<html><head><title>Check Page</title></head><body><jsp:useBean id="user" scope="request" class="register.test.RegisterBean"/><jsp:setProperty name="user" property="*"/><% if (user.isValid()) {%><jsp:forward page="show.htm"/><%} else {%><jsp:forward page="index1.jsp"/><%}%></body></html>

Here we omit the show page, it's not important.

*we should notice something here

->we should use the label tosetProperty for the instance of a JavaBean, it will never be done automatically.

->when we need some data from the JavaBean, we usegetProperty and if we need to modify the data, we must use setProperty label manually.