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jdbc是java连接数据库的一套API,完成如何将数据库中表的数据和内存中对象数据的转换。

package cn;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.List;import org.gjt.mm.mysql.Driver;public class TeacherDao {	/**	 * 从对象中取出属性值，变成数据库中的一条记录	 * 	 * @param t	 */	public void add(Teacher t) {		try {			// 加载驱动			Driver d = new Driver();			// 建立连接			// localhost连接数据库的IP地址，localhost表示本机			// mydata 需要连接数据库名			// root mysql的用户名			// lovo mysql 的密码			Connection con = DriverManager					.getConnection(							"jdbc:mysql://localhost:3306/mydata?characterEncoding=utf-8",							"root", "lovo");			System.out.println(con);			// 执行SQL语句			PreparedStatement ps = con					.prepareStatement("insert into t_teacher(teacherName,edu,job) values(?,?,?)");			// 设置占位符,从t所指向的对象中取出属性值，用来填充?(占位符)			ps.setString(1, t.getName());			ps.setString(2, t.getEdu());			ps.setString(3, t.getJob());			// 更新数据库，将数据写入数据库			ps.executeUpdate();			// 关闭数据库			ps.close();			con.close();		} catch (Exception e) {			// 显示出错信息			e.printStackTrace();		}	}	/**	 * 按主键删除	 * 	 * @param id	 */	public void del(int id) {		try {			Driver d = new Driver();			Connection con = DriverManager					.getConnection(							"jdbc:mysql://localhost:3306/mydata?characterEncoding=utf-8",							"root", "lovo");			PreparedStatement ps = con					.prepareStatement("delete from t_teacher where id=?");			ps.setInt(1, id);			ps.execute();			ps.close();			con.close();		} catch (Exception e) {			e.printStackTrace();		}	}	/**	 * 按照id修改学历，职称	 * 	 * @param id	 * @param edu	 *            学历	 * @param job	 *            职称	 */	public void update(int id, String edu, String job) {		try {			Driver d = new Driver();			Connection con = DriverManager					.getConnection(							"jdbc:mysql://localhost:3306/mydata?characterEncoding=utf-8",							"root", "lovo");			PreparedStatement ps = con					.prepareStatement("update t_teacher set edu=?,job=? where id=?");			ps.setInt(3, id);			ps.setString(1, edu);			ps.setString(2, job);			ps.execute();			ps.close();			con.close();		} catch (Exception e) {			e.printStackTrace();		}	}	/**	 * 根据主键查找对象	 * 	 * @param id	 * @return	 */	public Teacher findById(int id) {		Teacher t = new Teacher();		try {			Driver d = new Driver();			Connection con = DriverManager					.getConnection(							"jdbc:mysql://localhost:3306/mydata?characterEncoding=utf-8",							"root", "lovo");			PreparedStatement ps = con					.prepareStatement("select * from t_teacher where id=?");			ps.setInt(1, id);			// 得到结果集，结果集中就是查询所得的数据			ResultSet rs = ps.executeQuery();			// 将结果集指针移动到下一条记录。如果有下一条记录返回true，否则返回false			boolean isNext = rs.next();			if (isNext == true) {// 判断结果集中是否有数据				// 从数据库表中的id列中取出数据，设置在对象中的id属性中				t.setId(rs.getInt("id"));				t.setName(rs.getString("teacherName"));				t.setEdu(rs.getString("edu"));				t.setJob(rs.getString("job"));			}			rs.close();			ps.close();			con.close();		} catch (Exception e) {			e.printStackTrace();		}		return t;	}	/**	 * 查询所有	 * 	 * @return	 */	public List
   
     findAll() {		List
    
      list = new ArrayList
     
      ();		try {			Driver d = new Driver();			Connection con = DriverManager					.getConnection(							"jdbc:mysql://localhost:3306/mydata?characterEncoding=utf-8",							"root", "lovo");			PreparedStatement ps = con					.prepareStatement("select * from t_teacher");			ResultSet rs = ps.executeQuery();			// 判断是否下一条记录，如果有则循环，没有则退出循环			while (rs.next()) {				// 将数据库记录数据取出，变成对象的属性值				Teacher t = new Teacher();				t.setId(rs.getInt("id"));				t.setName(rs.getString("teacherName"));				t.setEdu(rs.getString("edu"));				t.setJob(rs.getString("job"));				// 将封装好的数据库数据的对象加入集合				list.add(t);			}			rs.close();			ps.close();			con.close();		} catch (Exception e) {			e.printStackTrace();		}		return list;	}	/**	 * 按姓名模糊查询	 * 	 * @param name	 * @return	 */	public List
      
        findByName(String name) {		List
       
         list = new ArrayList
        
         (); try { Driver d = new Driver(); Connection con = DriverManager .getConnection( "jdbc:mysql://localhost:3306/mydata?characterEncoding=utf-8", "root", "lovo"); PreparedStatement ps = con .prepareStatement("select * from t_teacher where teacherName like ?"); ps.setString(1, "%" + name + "%"); ResultSet rs = ps.executeQuery(); while (rs.next()) { Teacher t = new Teacher(); t.setId(rs.getInt("id")); t.setName(rs.getString("teacherName")); t.setEdu(rs.getString("edu")); t.setJob(rs.getString("job")); list.add(t); } rs.close(); ps.close(); con.close(); } catch (Exception e) { e.printStackTrace(); } return list; } public static void main(String[] args) { TeacherDao dao = new TeacherDao(); dao.add(new Teacher("方正", "大专", "教授"));// 测试新增 dao.del(8);// 测试删除 dao.update(4, "本科", "大和尚");// 测试修改 Teacher t = dao.findById(1);// 测试根据id查找 System.out.println(t.getId() + " " + t.getName() + " " + t.getEdu() + " " + t.getJob()); List
         
           list = dao.findAll();// 测试查找全部数据 for (Teacher t2 : list) { System.out.println(t2.getId() + " " + t2.getName() + " " + t2.getEdu() + " " + t2.getJob()); } List
          
            list1 = dao.findByName("方");// 测试按姓名模糊查询 for (Teacher t1 : list) { System.out.println(t1.getId() + " " + t1.getName() + " " + t1.getEdu() + " " + t1.getJob()); } }}class Teacher { /** id */ private int id; /** 老师姓名 */ private String name; /** 学历 */ private String edu; /** 职称 */ private String job; public Teacher( String name, String edu, String job) { super(); this.name = name; this.edu = edu; this.job = job; } public Teacher() { super(); } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getEdu() { return edu; } public void setEdu(String edu) { this.edu = edu; } public String getJob() { return job; } public void setJob(String job) { this.job = job; }}
          
         
        
       
      
     
    
   

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