一个简单的JavaBean实例，包含属性、构造函数，getter函数、setter函数
package com.runoob;
public class StudentsBean implements java.io.Serializable
{
private String firstName = null;
private String lastName = null;
private int age = 0;
public StudentsBean() {
}
public String getFirstName(){
return firstName;
}
public String getLastName(){
return lastName;
}
public int getAge(){
return age;
}
public void setFirstName(String firstName){
this.firstName = firstName;
}
public void setLastName(String lastName){
this.lastName = lastName;
}
public void setAge(int age) {
this.age = age;
}
}
name属性指的是Bean的id属性。property属性指的是想要调用的getter或setter方法。
一个简单的JSP+JavaBean的实例如下：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<html>
<head>
<title>get 和 set 属性实例</title>
</head>
<body>
<jsp:useBean id="students"
class="com.runoob.StudentsBean">
<jsp:setProperty name="students" property="firstName"
value="小强"/>
<jsp:setProperty name="students" property="lastName"
value="王"/>
<jsp:setProperty name="students" property="age"
value="10"/>
</jsp:useBean>
<p>学生名字:
<jsp:getProperty name="students" property="firstName"/>
</p>
<p>学生姓氏:
<jsp:getProperty name="students" property="lastName"/>
</p>
<p>学生年龄:
<jsp:getProperty name="students" property="age"/>
</p>
</body>
</html>
下面再说明一种JSP+JavaBean的方式
（1）创建conn类来封装对数据库的操作方法
（2）创建index.jsp来使用conn类中封装的方法
package com.gx.bean;
import java.sql.*;
public class conn {
public Connection getConn(){
Connection conn = null;
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost:3308/manage","数据库用户名","数据库密码");
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e){
e.printStackTrace();
}
return conn;
}
public PreparedStatement prepare(Connection conn,String sql){
PreparedStatement pstmt = null;
try{
if (conn != null) {
pstmt = conn.prepareStatement(sql);
}
}catch (SQLException e){
e.printStackTrace();
}
return pstmt;
}
public Statement getStatement(Connection conn){
Statement stmt = null;
try{
if (conn != null) {
stmt = conn.createStatement();
}
}catch (SQLException e){
e.printStackTrace();
}
return stmt;
}
public ResultSet getResultSet(Statement stmt,String sql){
ResultSet rs = null;
if(stmt!=null){
try {
rs = stmt.executeQuery(sql);
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
return rs;
}
public void excuteUpdate(Statement stmt,String sql){
if(stmt!=null){
try {
stmt.executeUpdate(sql);
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
}
public void close(Connection conn){
if(conn!=null){
try {
conn.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
conn=null;
}
}
public void close(ResultSet rs){
if(rs!=null){
try {
rs.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
rs=null;
}
}
public void close(Statement stmt){
if(stmt!=null){
try {
stmt.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
stmt=null;
}
}
}
index.jsp
<%--
Created by IntelliJ IDEA.
User: 12526
Date: 2021/1/13
Time: 13:00
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" import="java.sql.*" %>
<html>
<head>
<title>JSP+JavaBean实例</title>
</head>
<body>
<jsp:useBean id="DB" class="com.gx.bean.conn" />
<%
Connection conn = DB.getConn();
Statement stmt = DB.getStatement(conn);
ResultSet rs = DB.getResultSet(stmt,"select * from users");
try{
while(rs.next()){
out.println("<table>");
out.println("<tr>");
out.println("<tr>"+rs.getInt("id")+"</td>");
out.println("<tr>"+rs.getString("name")+"</td>");
out.println("<tr>"+rs.getString("password")+"</td>");
out.println("</tr>");
out.println("</table>");
}
}catch (SQLException e){
e.printStackTrace();
}finally {
DB.close(conn);
DB.close(stmt);
DB.close(rs);
}
%>
</body>
</html>
写到这里的时候遇到了一个tomcat报500的坑，就是使用out.println()的时候，对
标签和标签忘记写反斜杠结束符了，导致了报500的错误
添加完反斜杠后成功显示页面
可以看到成功将数据库的内容显示了出来
