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package jdbc;
import jdbc.domain.Emp;
import jdbc.util.JDBCUtils;
import java.sql.DriverManager;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Date;
/**
* @author ： CodeWater
* @create ：2022-03-09-10:48
* @Function Description ：
* 定义一个方法，查询emp表的数据将其封装为对象，然后装载集合，返回。
*/
public class JdbcDemo08 {
public static void main(String[] args) {
List<Emp> list = new JdbcDemo08().findAll2();
System.out.println(list);
System.out.println(list.size());
}
/*查询所有的Emp对象,普通
* */
public List<Emp> findAll() {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
List<Emp> list = null;
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql:///db3", "root", "root");
String sql = "select * from emp";
stmt = conn.createStatement();
rs = stmt.executeQuery(sql);
Emp emp = null;
list = new ArrayList<Emp>();
while (rs.next()) {
int id = rs.getInt("id");
String ename = rs.getString("ename");
int job_id = rs.getInt("job_id");
int mgr = rs.getInt("mgr");
Date joindate = rs.getDate("joindate");
double salary = rs.getDouble("salary");
double bonus = rs.getDouble("bonuse");
int dept_id = rs.getInt("dept_id");
//创建emp对象，并赋值
emp = new Emp();
emp.setId(id);
emp.setEname(ename);
emp.setJob_id(job_id);
emp.setMgr(mgr);
emp.setJoindate(joindate);
emp.setSalary(salary);
emp.setBonus(bonus);
emp.setDept_id(dept_id);
//装载集合
list.add(emp);
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally {
if (rs != null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (stmt != null) {
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
return list;
}
/*演示JDBC工具类
* */
public List<Emp> findAll2() {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
List<Emp> list = null;
try {
// Class.forName( "com.mysql.jdbc.Driver" );
// conn = DriverManager.getConnection( "jdbc:mysql:///db3" , "root" , "root" );
conn = JDBCUtils.getConnection();
String sql = "select * from emp";
stmt = conn.createStatement();
rs = stmt.executeQuery(sql);
Emp emp = null;
list = new ArrayList<Emp>();
while (rs.next()) {
int id = rs.getInt("id");
String ename = rs.getString("ename");
int job_id = rs.getInt("job_id");
int mgr = rs.getInt("mgr");
Date joindate = rs.getDate("joindate");
double salary = rs.getDouble("salary");
double bonus = rs.getDouble("bonus");
int dept_id = rs.getInt("dept_id");
// 创建emp对象,并赋值
emp = new Emp();
emp.setId(id);
emp.setEname(ename);
emp.setJob_id(job_id);
emp.setMgr(mgr);
emp.setJoindate(joindate);
emp.setSalary(salary);
emp.setBonus(bonus);
emp.setDept_id(dept_id);
list.add(emp);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
//原来使用三个if释放资源
JDBCUtils.close(rs, stmt, conn);
}
return list;
}
}