使用IDEA創建Maven JAVA項目,使用Dao層,對數據庫中的表進行增刪改查

題目需求：

使用IDEA 創建 MAVEN  JAVA 項目

根據下圖 在mysql數據庫中創建員工表(T_Employee)

創建實體類 Employee  並創建DAO 層(使用JDBC技術)

以及測試類 對創建的DAO實現類進行增刪改查進行測試

項目結構

1.在數據庫中創建表(我使用的Navicat)

CREATE TABLE eee(
    id INT(11) PRIMARY KEY auto_increment,
    name VARCHAR(30),
    age INT(11),
    birthday date,
    salary DECIMAL(10,0)
)

2.創建實體類Employee

package com.ujiuye.bean;

import lombok.*;

import java.util.Date;

//idea插件:lombok
@Setter
@Getter
@NoArgsConstructor
@AllArgsConstructor
@ToString
public class Employee {
    public int id;
    public String name;
    public int age;
    public Date birthday;
    public int salary;
    
}

3.準備工作

3.1導包/添加依賴----pom.xml

學Maven之前我們需要在項目中創建一個名爲lib的文件夾,把JDBC,C3P0,dbutils所需的jar包放入文件夾下,但是現在我們學了Maven就不需要這樣導包了,只需要在項目的pom.xml文件中添加需要的依賴即可

<?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.ujiuye</groupId>
  <artifactId>employee</artifactId>
  <version>1.0.0</version>

  <name>employee</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>4.11</version>
      <scope>test</scope>
    </dependency>

    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <version>1.16.20</version>
      <scope>provided</scope>
    </dependency>

    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.39</version>
    </dependency>

    <dependency>
      <groupId>com.mchange</groupId>
      <artifactId>c3p0</artifactId>
      <version>0.9.5.2</version>
    </dependency>

    <dependency>
      <groupId>commons-dbutils</groupId>
      <artifactId>commons-dbutils</artifactId>
      <version>1.6</version>
    </dependency>

    <dependency>
      <groupId>org.apache.commons</groupId>
      <artifactId>commons-dbcp2</artifactId>
      <version>2.1.1</version>
    </dependency>
    
  </dependencies>

</project>

3.2c3p0-config.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
   <default-config>
       <!-- 必須項 -->
       <property name="driverClass">com.mysql.jdbc.Driver</property>
       <property name="jdbcUrl">jdbc:mysql:///db3</property>
       <property name="user">root</property>
       <property name="password">1234</property>
  
        <!-- 連接池參數 -->
	    <property name="initialPoolSize">5</property>
	    <property name="maxPoolSize">10</property>
	    <property name="checkoutTimeout">2000</property>
	    <property name="maxIdleTime">1000</property>	
   </default-config>
</c3p0-config>

3.3項目所需的工具類

3.3.1c3p0獲取連接的工具類

package com.ujiuye.utils;

import com.mchange.v2.c3p0.ComboPooledDataSource;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;

public class C3P0Utils {
	
	private static DataSource ds = new ComboPooledDataSource();
   
	public static DataSource getDataSource(){
		
		return ds;
	}
	
	
	public static Connection getConnection(){
		
		Connection conn = null;
		
		try {
			conn = ds.getConnection();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		
		return conn;
	}
}

3.3.2字符串日期互相轉換的工具類

package com.ujiuye.utils;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class DateUtil {
	
	public static Date stringToDate(String str){
		
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
		
		Date date = null;
		try {
			date = sdf.parse(str);
		} catch (ParseException e) {
			e.printStackTrace();
		}
		
		return date;
	}
	
	public static String dateToString(Date date){
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
		return sdf.format(date);
	}

}

3.4EmployeeDao.java文件

package com.ujiuye.dao;


import com.ujiuye.bean.Employee;

import java.util.List;

public interface EmployeeDao {
    public List<Employee> findAllEmployee();
    public int insert(Employee employee);
    public int update(Employee employee);
    public int deleteById(int id);
}

3.5EmployeeImpl.java文件

package com.ujiuye.dao.impl;

import com.ujiuye.bean.Employee;
import com.ujiuye.dao.EmployeeDao;
import com.ujiuye.utils.C3P0Utils;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanListHandler;

import java.sql.SQLException;
import java.util.List;

public class EmployeeDaoImpl implements EmployeeDao{

    @Override
    public List<Employee> findAllEmployee() {
        List<Employee> list = null;

        QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());

        String sql = "select * from employee";

        try {
            list = qr.query(sql,new BeanListHandler<>(Employee.class));
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return list;
    }

    @Override
    public int insert(Employee employee) {
        int result = 0;
        QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
        String sql = "insert into employee values(null,?,?,?,?)";
        try {
            result = qr.update(sql,new Object[]{employee.getName(),employee.getAge(),employee.getBirthday(),employee.getSalary()});
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return result;
    }

    @Override
    public int update(Employee employee) {
        int result = 0;

        QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());

        String sql = "update employee set name=?,age=?,birthday=?,salary=? where id=?";

        try {
            result = qr.update(sql,new Object[]{employee.getName(),employee.getAge(),employee.getBirthday(),employee.getSalary(),employee.getId()});
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return result;
    }

    @Override
    public int deleteById(int id) {
        int result = 0;
        QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());

        String sql = "delete from employee where id = ?";

        try {
            result = qr.update(sql,id);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return result;
    }


}

4.測試類

package com.ujiuye.bean;

import com.ujiuye.dao.EmployeeDao;
import com.ujiuye.dao.impl.EmployeeDaoImpl;
import org.junit.Test;

import java.util.Date;
import java.util.List;

public class TestEmployee {
    EmployeeDao dao = new EmployeeDaoImpl();
    @Test
    public void testFindAllEmployee(){

       List<Employee> list = dao.findAllEmployee();
       for(Employee e : list){
           System.out.println(e);
       }

    }

    @Test
    public void testInsert(){
        Employee e = new Employee(5,"王二小",18,new Date(),1000);
        int result = dao.insert(e);
        System.out.println(result);
    }

    @Test
    public void testUpdate(){
        Employee e = new Employee(5,"tom",18,new Date(),1000);
        int i = dao.update(e);
        System.out.println(i+"更新");
    }

    @Test
    public void testDelete(){
        int i = dao.deleteById(6);
        System.out.println(i+"刪除");
    }
}

Maven主要可以讓我們通過pom.xml文件中添加依賴,如果是一個特別大的項目,所需的jar包很多,使用maven的方式添加依賴就會很方便