我的 Java 入门项目
我入门 Java 是在2019年10月入的，当时已经学完了 C语言，因此这个入门项目只用了一个下午
工具：IDEA + MariaDB + Navicat + Tomcat + maven
SQL 文件
CREATE DATABASE `book` DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;
SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;
DROP TABLE IF EXISTS `employees_cn`;
/*!40101 SET @saved_cs_client = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `employees_cn` (
`employee_id` int(11) NOT NULL AUTO_INCREMENT,
`employee_name` varchar(255) COLLATE utf8_bin DEFAULT NULL,
`employee_address` varchar(255) COLLATE utf8_bin DEFAULT NULL,
`employee_price` int(10) DEFAULT NULL,
PRIMARY KEY (`employee_id`) USING BTREE
) ENGINE=InnoDB AUTO_INCREMENT=49 DEFAULT CHARSET=utf8 COLLATE=utf8_bin ROW_FORMAT=DYNAMIC;
INSERT INTO `employees_cn`
VALUES (1,'张伟','北京',20000),
(6,'周通','上海',17500),
(14,'王飞','赣州',28000),
(17,'马超','佛山',20000),
(18,'刘备','抚州',15000),
(20,'李兰','北京',20000),
(21,'李兰妈','株洲',46000),
(22,'周杰','深圳',20000),
(23,'丁宁','天津',1500),
(24,'张飞','上饶',25000),
(25,'周杰','深圳',20000),
(48,'孙红雷','哈尔滨',30000);
创建 JavaWeb 项目
新建工程后，maven会下载一些文件，没多大，大家耐心等待即可。
新建工程成功以后是下面这样的：
首先在 pom.xml 文件中 </build> 上面添加如下代码，添加完成后，等待它自己加载完成即可。
<plugins>
<plugin>
<groupId>org.apache.tomcat.maven</groupId>
<artifactId>tomcat7-maven-plugin</artifactId>
<version>2.2</version>
<configuration>
<hostName>localhost</hostName> <!-- Default: localhost -->
<port>8080</port> <!-- 启动端口 Default:8080 -->
<path>/</path> <!-- 访问应用路径 Default: /${project.artifactId}-->
<uriEncoding>UTF-8</uriEncoding> <!-- uri编码 Default: ISO-8859-1 -->
</configuration>
</plugin>
</plugins>
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编写代码
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.baidu</groupId>
<artifactId>MyBlog</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>
<name>MyBlog Maven Webapp</name>
<!-- FIXME change it to the project's website -->
<url>http://www.example.com</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>1.7</maven.compiler.source>
<maven.compiler.target>1.7</maven.compiler.target>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13.2</version>
<scope>test</scope>
</dependency>
<!-- https://mvnrepository.com/artifact/com.speedment.runtime/runtime-typemapper -->
<dependency>
<groupId>com.speedment.runtime</groupId>
<artifactId>runtime-typemapper</artifactId>
<version>3.2.10</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.teiid.connectors/translator-loopback -->
<dependency>
<groupId>org.teiid.connectors</groupId>
<artifactId>translator-loopback</artifactId>
<version>16.0.0</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.apache.xmlgraphics/batik-css -->
<dependency>
<groupId>org.apache.xmlgraphics</groupId>
<artifactId>batik-css</artifactId>
<version>1.14</version>
</dependency>
<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.25</version>
</dependency>
<!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>4.0.1</version>
<scope>provided</scope>
</dependency>
<!-- https://mvnrepository.com/artifact/javax.servlet.jsp/javax.servlet.jsp-api -->
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>javax.servlet.jsp-api</artifactId>
<version>2.3.3</version>
<scope>provided</scope>
</dependency>
<!-- https://mvnrepository.com/artifact/javax.servlet/jstl -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
</dependencies>
<build>
<finalName>MyBlog</finalName>
<pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
<plugins>
<plugin>
<artifactId>maven-clean-plugin</artifactId>
<version>3.1.0</version>
</plugin>
<!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->
<plugin>
<artifactId>maven-resources-plugin</artifactId>
<version>3.0.2</version>
</plugin>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.0</version>
</plugin>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.22.1</version>
</plugin>
<plugin>
<artifactId>maven-war-plugin</artifactId>
<version>3.2.2</version>
</plugin>
<plugin>
<artifactId>maven-install-plugin</artifactId>
<version>2.5.2</version>
</plugin>
<plugin>
<artifactId>maven-deploy-plugin</artifactId>
<version>2.8.2</version>
</plugin>
</plugins>
</pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.tomcat.maven</groupId>
<artifactId>tomcat7-maven-plugin</artifactId>
<version>2.2</version>
<configuration>
<hostName>localhost</hostName> <!-- Default: localhost -->
<port>8081</port> <!-- 启动端口 Default:8080 -->
<path>/</path> <!-- 访问应用路径 Default: /${project.artifactId}-->
<uriEncoding>UTF-8</uriEncoding> <!-- uri编码 Default: ISO-8859-1 -->
</configuration>
</plugin>
</plugins>
</build>
</project>
DatabaseForBook.java
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
*
* @author colors
* @date 2019/10/26
*/
public class DatabaseForBook {
private final String url = "jdbc:mysql://localhost:3306/book?characterEncoding=UTF8&servertimeZone=GMT%2B8";
private final String driver = "com.mysql.jdbc.Driver";
private final String name = "root";
private final String password = "123456";
private Connection connection = null;
private final List allEmployees = new ArrayList();
public void openDatabase(){
try {
// 加载驱动
Class.forName(driver);
connection = DriverManager.getConnection(url,name,password);
} catch (ClassNotFoundException | SQLException e) {
e.printStackTrace();
}
}
public void addData(String name, String address , float price){
// 打开数据库
openDatabase();
try {
// 操作数据库的一个sql语句
String sql = "INSERT into employees_cn (employee_name,employee_address,employee_price) VALUES (?,?,?)";
// 获取声明
PreparedStatement statement = connection.prepareStatement(sql);
statement.setObject(1,name);
statement.setObject(2,address);
statement.setObject(3,price);
// 执行你的sql
statement.execute();
} catch (SQLException e) {
e.printStackTrace();
}
closeDatabase();
}
public void deleteData(String name){
openDatabase();
String sql = "DELETE FROM employees_cn WHERE employee_name= ?";
try {
PreparedStatement statement = connection.prepareStatement(sql);
statement.setObject(1, name);
statement.execute();
} catch (SQLException e) {
e.printStackTrace();
}
closeDatabase();
}
public void updateData(String addreess, int price, String name){
openDatabase();
String sql = "UPDATE employees_cn set employee_address = ? , employee_price = ? WHERE employee_name = ?";
try {
PreparedStatement statement = connection.prepareStatement(sql);
statement.setObject(1, addreess);
statement.setObject(2, price);
statement.setObject(3, name);
statement.execute();
} catch (SQLException e) {
e.printStackTrace();
}
closeDatabase();
}
public List selectData() {
openDatabase();
String sql = "select * from employees_cn";
try {
PreparedStatement statement = connection.prepareStatement(sql);
ResultSet resultSet = statement.executeQuery();
while (resultSet.next()) {
int id = resultSet.getInt("employee_id");
String name = resultSet.getString("employee_name");
String address = resultSet.getString("employee_address");
int price = resultSet.getInt("employee_price");
// sout
System.out.println(id + " " + name + " " + address + " " + price);
// 集合
Map<String, Object> employee = new HashMap<>();
employee.put("id", id);
employee.put("name", name);
employee.put("address", address);
employee.put("price", price);
allEmployees.add(employee);
}
return allEmployees;
} catch (SQLException e) {
e.printStackTrace();
}
closeDatabase();
return null;
}
public void closeDatabase(){
if (connection !=null){
try {
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
BookServlet.java
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;
/**
*
* @author colors
* @date 2019/10/27
*/
// 接受客户请求
// 返回数据给客户
public class BookServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// 去查数据库
DatabaseForBook databaseForBook = new DatabaseForBook();
List allEmployees = databaseForBook.selectData();
// 将数据放到网页里
req.setAttribute("all", allEmployees);
// 将网页返给用户
req.getRequestDispatcher("employee.jsp").forward(req, resp);
}
}
TestBook.java
import org.junit.Test;
/**
* Created by guoke on 2019/10/30.
*/
public class TestBook {
@Test
public void testBook(){
DatabaseForBook databaseForBook = new DatabaseForBook();
databaseForBook.addData("郭柯柯","九江",30000);
}
@Test
public void testSelect(){
DatabaseForBook databaseForBook = new DatabaseForBook();
databaseForBook.selectData();
}
@Test
public void testDelete(){
DatabaseForBook databaseForBook = new DatabaseForBook();
databaseForBook.deleteData("郭柯柯");
}
@Test
public void testUpdate(){
DatabaseForBook databaseForBook = new DatabaseForBook();
databaseForBook.updateData("北京", 20000, "刘备");
}
}
index.jsp
<html>
<body>
<h2>Hello World!</h2>
</body>
</html>
employee.jsp
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ page isELIgnored="false" %>
<%--
Created by IntelliJ IDEA.
User: colors
Date: 2019/10/27
Time: 15:53
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>部门员工表</title>
</head>
<body>
<%-- jsp + el + jstl --%>
<table border="1" cellspacing="0" align="center" >
<caption><h3>部门员工表</h3></caption>
<thead>
<tr>
<th>工号</th>
<th>姓名</th>
<th>住址</th>
<th>工资</th>
</tr>
</thead>
<c:forEach items="${all}" var="employee">
<tr>
<td>${employee.id}</td>
<td>${employee.name}</td>
<td>${employee.address}</td>
<td>${employee.price}</td>
</tr>
</c:forEach>
</table>
</body>
</html>
web.xml
<!DOCTYPE web-app PUBLIC
"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd" >
<web-app>
<display-name>Archetype Created Web Application</display-name>
<servlet>
<servlet-name>a</servlet-name>
<servlet-class>BookServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>a</servlet-name>
<url-pattern>/all</url-pattern>
</servlet-mapping>
</web-app>
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