kk Blog —— 通用基础

date [-d @int|str] [+%s|"+%F %T"]

jsp 环境初始化

jdk

https://www.oracle.com/java/technologies/javase-jdk15-downloads.html

linux 环境变量

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vim ~/.bashrc
export JAVA_HOME=/usr/lib/jvm/jdk-15.0.1/
export PATH=$PATH:/usr/lib/jvm/jdk-15.0.1/bin

win 环境变量

右键点击我的电脑,选择属性。点击左边高级系统设置,在弹出的窗口中切换至高级,点击最下面有一个环境变量,进入环境变量设置。

此处需要配置三个系统环境变量:JAVA_HOME 、CLASSPATH、Path;

首先配置点击JAVA_HOME,点击系统变量下的新建,变量名为JAVA_HOME,变量值为安装的jdk所在的路径,我的为:c:\java\jdk-15.0.1,点击确定

然后配置CLASSPATH,与上一步相同,点击新建,变量名为CLASSPATH,变量值为 .;%JAVA_HOME%\lib\dt.jar;%JAVA_HOME%\lib\tools.jar; ,注意最前面有个点不能省去,最后面要有英文的分号,点击确定

最后配置Path,在系统变量中找到Path并双击它,在变量值的最后加上:%JAVA_HOME%\bin;%JAVA_HOME%\jre\bin;最后点击确定

mysql

win

https://dl.pconline.com.cn/download/2260891.html

选择 server only

系统可能需要依赖 .NET Framework 4.5.2 https://www.microsoft.com/en-us/download/confirmation.aspx?id=42642

mysql如何修改root用户的密码

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格式:mysql> set password for 用户名@localhost = password('新密码'); 
例子:mysql> set password for root@localhost = password('123'); 

增加内容

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create database test;
use test
create table info(id integer primary key, name varchar(30), val integer);
alter table info modify id integer auto_increment;
insert into info(name, val) values ('kk', 123);
insert into info(name, val) values ('ll', 456);
select * from info;
quit

tomcat

https://tomcat.apache.org/download-90.cgi

将 mysql-connector-java-5.1.47.jar 放到 lib/ 下

vim webapps/examples/db.jsp

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<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@ page import="java.sql.*"%>

<html>
<head>
<title>通过JSP打开数据表</title>
</head>
<body>
<%
	try {
		Class.forName("com.mysql.jdbc.Driver");  //驱动程序名
		String url = "jdbc:mysql://localhost:3306/test"; //数据库名
		String username = "root";  //数据库用户名
		String password = "123";  //数据库用户密码
		Connection conn = DriverManager.getConnection(url, username, password);  //连接状态

		if (conn != null) {
			out.print("数据库连接成功!");
			out.print("<br />");
			Statement stmt = null;
			ResultSet rs = null;
			String sql = "SELECT * FROM info;";  //查询语句
			stmt = conn.createStatement();
			rs = stmt.executeQuery(sql);
			out.print("查询结果:");
			out.print("<br />");
			out.println("姓名"+"  "+"性别 "+"  "+"年龄");
			out.print("<br />");
			while (rs.next()) {
				out.println(rs.getString("id")+"      "+rs.getString("name")+"    "+rs.getInt("val")); //将查询结果输出
				out.print("<br />");
			}
		} else {
			out.print("连接失败!");
		}
	} catch (Exception e) {
		out.print("数据库连接异常!");
	}
%>
</body>
</html>

直接运行 bin/startup.sh

打开 127.0.0.1:8080/examples/db.jsp 即可看到数据库内容

log 乱码

打开Tomcat安装源码conf文件夹下的logging.properties文件,将UTF-8改成GBK