JdbcTest.java类
package com.bjsxt;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class JdbcTest {
//向Dpeartment表中添加一条数据
public void insertDepartments(String department_name,int location_id) {
Connection conn= null;
Statement state= null;
try {
/**驱动注册
Class.forName("com.mysql.jdbc.Driver");
//创建链接
conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8", "root", "123456");
*/
conn=JdbcUtil.getConnection();
String sql="insert into departments values(default,'"+department_name+"'"+location_id+")" ;
state = conn.createStatement();
int flag =state.executeUpdate(sql);
System.out.println(flag);
} catch (Exception e) {
e.printStackTrace();
}finally {
//JdbcUtil.closeStatement(state);
//JdbcUtil.closeConnection(conn);
JdbcUtil.closeResource(state, conn,null);
}
}
//更新departments表中department_id为6的数据，将部门名称修改为教学部，location_id为6
public void updateDepartments(String department_name,int location_id,int department_id) {
Connection conn =null;
Statement state=null;
try {
conn=JdbcUtil.getConnection();
state=conn.createStatement();
String sql="update departments d set d.department_name = '"+department_name+"',d.location_id = "+location_id+" where d.department_id ="+department_id;
int flag= state.executeUpdate(sql);
System.out.println(flag);
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}finally {
JdbcUtil.closeResource(state, conn,null);
}
}
//查询departments表中部门ID为6的部门信息
public void selectDepartmentsById(int departmentId) {
Connection conn=null;
Statement state=null;
ResultSet rs=null;
try {
conn=JdbcUtil.getConnection();
state= conn.createStatement();
String sql="select * from departments d where d.department_id = "+departmentId;
//执行返回结果
rs= state.executeQuery(sql);
while(rs.next()) {
System.out.println(rs.getInt("department_id")+" "+rs.getInt("department_name")+" "+rs.getInt(3));
}
}catch(Exception e) {
e.printStackTrace();
}finally {
JdbcUtil.closeResource(state, conn,rs);
}
}
public static void main(String[] args) {
// TODO Auto-generated method stub
JdbcTest test=new JdbcTest();
//test.insertDepartments("研发部", 1);
//test.updateDepartments("xx部", 8,4 );
//test.updateDepartments("啰嗦不", 6, 4);
//test.insertDepartments("干啥不", 10);
test.selectDepartmentsById(6);
}
}JdbcUtil.java类
package com.bjsxt;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ResourceBundle;
import java.sql.Statement;
/**
* Jdbc工具类
* @author wyz
*
*/
public class JdbcUtil {
private static String driver ;
private static String jdbcurl;
private static String username;
private static String password;
static {
//读取Properties文件
ResourceBundle bundle = ResourceBundle.getBundle("jdbc");
driver=bundle.getString(driver);
jdbcurl=bundle.getString(jdbcurl);
username=bundle.getString(username);
password=bundle.getString(password);
try {
Class.forName(driver);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
//获取Connection对象
public static Connection getConnection() {
Connection conn=null;
try {
conn= DriverManager.getConnection(jdbcurl,username,password);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return conn;
}
//关闭statement
public static void closeStatement(Statement state) {
try {
if(state!=null) {
state.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
//关闭Connection
public static void closeConnection(Connection conn) {
try {
if(conn!=null) {
conn.close();
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
//关闭资源
public static void closeResource(Statement state,Connection conn,ResultSet rs) {
closeStatement(state);
closeConnection(conn);
closeResultSet(rs);
}
//关闭ResultSet链接
public static void closeResultSet(ResultSet rs) {
try {
if(rs!= null) {
rs.close();
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}jdbc.properties
driver =com.mysql.jdbc.Driver
jdbcurl =jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8
username =root
password =123456
还是报错跟之前同学们一样的问题，我看不太懂导包啥的我报错就是这样的
这是下面一章了，这章我就一直报错，找了好久没解决问题，学习下面一章的时候还是报错。麻烦老师详细解释一下
老师为什么下面这个类不加static上面的创建对面就会报错，这是为什么
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