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SpringBoot整合Redis
1、导入jar包<!-- 操作redis --><dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-redis</artifactId></dependency><!-- lombok --> <dependency> <gr原创 2021-02-01 11:49:43 · 276 阅读 · 0 评论 -
Mybatis一对多查询处理
student实体类：import lombok.Data;@Datapublic class Student { private int id; private String name; private String tid;}teacher实体类：import lombok.Data;import java.util.List;@Datapublic class Teacher { private int id; private Strin原创 2021-01-09 21:01:52 · 407 阅读 · 0 评论 -
Mybatis多对一查询处理
1、子查询 <select id="getStudent" resultMap="StudentTeacher"> select * from mybatis.student </select> <resultMap id="StudentTeacher" type="Student"> <result property="id" column="id"/> <result proper原创 2021-01-09 19:58:03 · 163 阅读 · 0 评论 -
Mybatis使用注解实现简单增删改查
1、UserMapper.javaimport com.wjj.pojo.User;import org.apache.ibatis.annotations.Delete;import org.apache.ibatis.annotations.Insert;import org.apache.ibatis.annotations.Select;import org.apache.ibatis.annotations.Update;import java.util.List;import j原创 2021-01-09 14:56:22 · 480 阅读 · 0 评论 -
Mybatis实现分页
1、UserMapper.javaList<User> getUserByLimit(Map<String, Integer> map);2、Usermapper.xml<select id="getUserByLimit" parameterType="map" resultType="com.wjj.pojo.User"> select * from mybatis.user limit #{startIndex}, #{pageSize}</原创 2021-01-09 14:25:33 · 92 阅读 · 0 评论 -
Mybatis配置LOG4J
1、 导包：<dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1.2.17</version> </dependency>2、在配置文件目录下新建一个log4j.properties，内容如下：#将等级为DEBUG的日志信息输出到console和file这两个目的地，conso原创 2021-01-09 13:37:16 · 448 阅读 · 1 评论 -
Mybatis实现增删改查
1、配置pom文件，导入jar包<!-- 导入驱动 --> <dependencies> <!-- mysql驱动 --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <v原创 2021-01-08 18:19:31 · 131 阅读 · 0 评论 -
自定义RedisTemplate
@Bean @SuppressWarnings("all") public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory factory) throws UnknownHostException { RedisTemplate<String, Object> template = new RedisTemplate<String, Ob原创 2020-12-27 16:07:45 · 294 阅读 · 0 评论 -
Java文件下载
public class UrlDown { public static void main(String[] args) throws Exception { // 下载地址 URL url = new URL("https://m10.music.126.net/20201123142926/6c82578eccd898653a0fdd99de9f24c0/yyaac/0708/0652/0508/0b9b6827b718aa223af92bd52aa2424f原创 2020-12-11 18:07:46 · 362 阅读 · 1 评论 -
Jdbc事务的简单使用
public class JdbcTest3 { public static void main(String[] args) { String url = "jdbc:mysql://47.105.167.226:3306/jdbc?useUnicode=true&characterEncoding=utf-8"; String username = "root"; String password = "Wjj811971...";原创 2020-12-09 15:51:25 · 122 阅读 · 0 评论 -
Jdbc连接数据库的两种方式
1、Statementpublic class JdbcTest { public static void main(String[] args) throws Exception { String url = "jdbc:mysql://ip:3306/jdbc?useUnicode=true&characterEncoding=utf-8"; String username = "root"; String password = "密码"原创 2020-12-09 15:15:52 · 216 阅读 · 0 评论 -
Jdbc连接mysql
public class JdbcTest { public static void main(String[] args) throws Exception { String url = "jdbc:mysql://47.105.167.226:3306/jdbc?useUnicode=true&characterEncoding=utf-8"; String username = "root"; String password = "Wjj原创 2020-12-09 14:27:21 · 97 阅读 · 0 评论 -
用户登录检查实现
1、登录页面Java代码public class login extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { String username = req.getParameter("username"); String pa原创 2020-12-09 13:39:30 · 417 阅读 · 0 评论 -
Java中Filter过滤器的配置
1、Java代码public class CharacterEncodingFilter implements Filter { // 初始化 public void init(FilterConfig filterConfig) throws ServletException { System.out.println("已经初始化了..."); } public void doFilter(ServletRequest servletRequest,原创 2020-12-09 11:58:46 · 369 阅读 · 0 评论 -
Session和Cookie的区别
Session使用场景：原创 2020-12-03 22:02:22 · 132 阅读 · 0 评论 -
Session注销方式
1、手动注销（模拟用户注销） HttpSession session = req.getSession(); session.removeAttribute("user"); // 注销session session.invalidate();2、服务器自动注销（模拟服务器超时注销） <!-- 设置session的默认的失效时间 --> <session-config> <!-- 1分钟后失效，默认单位为分钟 --原创 2020-12-03 21:58:26 · 2825 阅读 · 0 评论 -
Session实战
1、pojo类public class User { private String name; private int id; public User(String name, int id, int age) { this.name = name; this.id = id; this.age = age; } private int age; public String getName() {原创 2020-12-03 21:55:51 · 182 阅读 · 0 评论 -
Cookie实战
public class Cookie01 extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { req.setCharacterEncoding("utf-8"); resp.setCharacterEncoding("utf-8"原创 2020-12-03 21:54:12 · 135 阅读 · 0 评论 -
Jsp登录验证
1、Jsp代码：<html><body><h2>你好，请输入用户名和密码！</h2><%--${pageContext.request.contextPath} 代表当前项目--%><form action="${pageContext.request.contextPath}/login" method="get" pageEncoding:<%@ page pageEncoding="UTF-8"%>>原创 2020-12-01 21:36:32 · 430 阅读 · 0 评论 -
Ajax的四部操作
1.创建XmlHttpRequest对象function createXMLHttpRequest(){ try{ return new XmlHttpRequest(); }catch(e){ try{ return new ActiveXObject(Msxm12.XMLHTTP)； }catch(e){ try{ return new Acti原创 2020-12-01 20:39:30 · 227 阅读 · 0 评论 -
用Ajax做检测用户名项目是否被注册常见的问题
JSP源码：<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equ原创 2020-12-01 20:37:48 · 176 阅读 · 0 评论 -
Java中int、String和Chat之间的相互转换
int 转换为string：String.valueOf(x)；string转换为int：Integer.parseInt(str)；chat装换为int：intNum = numChar - ‘0’;int转换为char：一种是自动转换，如char c = 97,会自动的将int类型的96转换成char的‘a’ ； 另一种是强制类型转换，如int i = 97,char c = (char)i ,这样做了之后，char的值也是‘a’；string转换为c原创 2020-12-01 20:35:08 · 1838 阅读 · 0 评论 -
Java实现文件下载
public class FileServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { String realPath = "E:\\Java\\IdeaProjects\\javeweb-01-servlet\\response\原创 2020-12-01 20:31:35 · 364 阅读 · 0 评论 -
Java后端实现验证码
public class ImageServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { resp.setHeader("refresh", "3"); // 在内存中创建一个图片 Buffered原创 2020-12-01 20:20:45 · 591 阅读 · 0 评论