java增删改查代码

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class DBTools {
// 定义一个方法，用来得到一个"新的"连接对象
public static Connection getConnection()
{
Connection conn = null;
String driverName = "oracle.jdbc.driver.OracleDriver";
String url = "jdbc:oracle:thin:@localhost:1521:ora9i";
String userName = "scott";
String passWord = "tiger";
try {
Class.forName(driverName);
conn = DriverManager.getConnection(url,userName,passWord );
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return conn;
}

public static void closeConn(Connection conn)
{
try {
if(conn != null)
{
conn.close();
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

public static void closeState(Statement state)
{
try {
if(state != null)
{
state.close();
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

public static void closeRs(ResultSet rs)
{
try {
if(rs != null)
{
rs.close();
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}



import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;

import https://www.doczj.com/doc/9b6388450.html,erPO;
import com.tianyitime.notebook.support.util.DBTools;


public class UserDAO {

// 新增user
public void saveUserInfo(UserPO upo)
{
Connection conn = null;
Statement state = null;
try {
conn = DBTools.getConnection();
state = conn.createStatement();
String sql = "insert into notebook_user values ("+getMaxId()+",'"+upo.getYhm()+"','"+upo.getEmail()+"','"+upo.getContent()+"')";
//System.out.println(sql);
state.executeUpdate(sql);

} catch (Exception ex) {
// TODO Auto-generated catch block
ex.printStackTrace();
}
finally
{
DBTools.closeState(state);
DBTools.closeConn(conn);
}
}

//得到一个数据库中当前Id的最大值
private int getMaxId()
{
Connection conn = null;
Statement state = null;
ResultSet rs = null;
int maxId = 0;
try {
conn = DBTools.getConnection();
state = conn.createStatement();
String sql = "select max(id) maxId from notebook_user";
rs = state.executeQuery(sql);
//从resultset对象中将数据取出
if(rs.next())
{
maxId = rs.getInt("maxId");
}
} catch (Exception ex) {
// TODO Auto-generated catch block
ex.printStackTrace();
}

return ++maxId;
}

// 得到所有的记录
public ArrayList getUserInfo()
{
Connection conn = null;
Statement state = null;
ResultSet rs = null;
UserPO upo = null;
ArrayList al = new ArrayList();
try {
conn = DBTools.getConnection();
state = conn.createStatement();
String sql = "select * from notebook_user";
rs = state.executeQuery(sql);
//从resultset对象中将数据取出

while(rs.next())
{
upo = new UserPO();
int id = rs.getInt("id");
String yhm = rs.getString

("yhm");
String email = rs.getString("email");
String content = rs.getString("content");

upo.setId(id);
upo.setYhm(yhm);
upo.setEmail(email);
upo.setContent(content);

//将改对象放入已经创建好的集合类对象ArrauyList
al.add(upo);
}
} catch (Exception ex) {
// TODO Auto-generated catch block
ex.printStackTrace();
}
finally
{
DBTools.closeRs(rs);
DBTools.closeState(state);
DBTools.closeConn(conn);
}
return al;
}

// 删除一条user记录
public void deleteUserInfo(int id)
{
Connection conn = null;
Statement state = null;
try {
conn = DBTools.getConnection();
state = conn.createStatement();
String sql = "delete from notebook_user where id="+id;
//System.out.println(sql);
state.executeUpdate(sql);

} catch (Exception ex) {
// TODO Auto-generated catch block
ex.printStackTrace();
}
finally
{
DBTools.closeState(state);
DBTools.closeConn(conn);
}
}

// 根据给定的信息得到记录
public ArrayList getUserInfoByInfo(String name,String email,String content)
{
Connection conn = null;
Statement state = null;
ResultSet rs = null;
UserPO upo = null;
ArrayList al = new ArrayList();
try {
conn = DBTools.getConnection();
state = conn.createStatement();
String sql = "select * from notebook_user where 1=1 ";
if(!"".equals(name) && name != null)
{
sql += " and yhm like '%"+name+"%'";
}
if(!"".equals(email) && email != null)
{
sql += " and email = '"+email+"'";
}
if(!"".equals(content) && content != null)
{
sql += " and content like '%"+content+"%'";
}
sql+=" order by id desc";
rs = state.executeQuery(sql);
//从resultset对象中将数据取出

while(rs.next())
{
upo = new UserPO();
int id = rs.getInt("id");
String yhm = rs.getString("yhm");
String femail = rs.getString("email");
String fcontent = rs.getString("content");

upo.setId(id);
upo.setYhm(yhm);
upo.setEmail(femail);
upo.setContent(fcontent);

//将改对象放入已经创建好的集合类对象ArrauyList
al.add(upo);
}
} catch (Exception ex) {
// TODO Auto-generated catch block
ex.printStackTrace();
}
finally
{
DBTools.closeRs(rs);
DBTools.closeState(state);
DBTools.closeConn(conn);
}
return al;
}

}