mysql与myeclipse连接
2017-07-03 21:29
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工程中的包
1.包的命名规则
com.公司名.(项目名.具体模块的名称)实现分类的名称
1.po包:存放的是javabean类,每个Javabean类对应数据库中一张表。类名和表名一致
2.dao包:存放的是操作数据的类,即对数据库中的表进行增删查改操作的类,每个dao类对应数据库中的一张表。类
名为一表名+Dao
3.util包:存放的是公用的类和常量类
4.test包:存放的是测试类
javabean类:储存数据的类。只包括属性、构造器、setter和getter方法
数据库客服端操作数据库的步骤:
1.连接数据库(ip地址,端口号,用户名,密码,数据库名)
2.打开发送和执行sql语句的窗口
3.发送和执行sql语句
4.根据返回结果,判断是否正确操作了数据库
5.关闭打开的所有的东西
JDBC操作数据库的步骤:
1.连接到数据库:
(1)加载数据库驱动:会抛出一个ClassNotFoundException异常
mysql:Class.forName("com.mysql.jdbc.Driver")
oracle:Class.forName("");
(2)利用驱动和三个参数(url,user,password)获得连接:会抛出一个SQLException异常
java.sql.Connection con = java.sql.DriverManager.getConnection(url,user,password);
mysql:String url = "jdbc:mysql://127.0.0.1:端口号/databaseName".
oracle:String url = "";
3.通过连接获得操作数据库的对象:会抛出一个SQLException异常
java.sql.Statement st = con.createStatement();
4.使用java.sql.Statement对象执行sql语句:会抛出一个SQLException异常
执行更新sql语句:int rows = st.executeUpdate(sql);
执行查询sql语句:java.sql.ResultSet re = st.executeQuery(sql);
5.根据返回的rows/re,判断SQL语句是否正确执行:
rows!=0 SQL语句正常执行
re.next()==true 表示查出了字表
6.关闭,先打开后关闭
关闭re:re.close():会抛出一个SQLException异常
关闭st:st.close():会抛出一个SQLException异常
关闭con:con.close()会抛出一个SQLException异常
第一个jar 包:数据库的驱动
Web工程的jar包都是放在WebRoot/WEB-INF/lib文件夹里(放在里面,自动导入)
几个接口:
java.sql.Connection是一个接口
java.sql.Statement是一个接口
java.sql.ResultSet是一个接口
java.sql.PreparedStatement是一个接口
数据库连接配置文件:database.properties只加载一次,放在src文件夹下面
properties文件以键(name)值(value)方式保存数据
从properties文件中解析出value值:
InputStream is = null;
is = DBConnectionUtil.class.getClassLoader().getResourceAsStream("jdbc.properties");
Properties p = new Properties();
p.load(is);
String value = p.getProperty("name");
java.sql.Statement和java.sql.PreparedStatement比较
代码比较
1.SQL的写法:
Satement:String sql = "selete id from user where email =' "+email+" ' ";
PreparedStatement:String sql = "selete id from user where email = ?"
2.st/ps的获取:
Statement:st = con.createStatement();
PreparedStatement:ps = con.preparedStatement(sql);
3.参数的设置:
Statement:在SQL中给出
PreparedStatement:ps.setType(1,value); ps.setType(2,value);
4.执行SQL:
Statement:int rows = st.executeUpdate(sql); re = st.executeQuery(sql);
PreparedStatement:int rows = ps.executeUpdate(); re = ps.executeQuery();
PreparedStatement的优势:
1.防止SQL的注入,提高安全性
2.对参数实现类型的自动转换,代码的可读性,可维护性提高
3,.对于批处理:PreparedStatement效率更高一些(oracle明显,MySQL区别不大)
package com.yy.jdbc.dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import com.yy.jdbc.po.User;
import com.yy.jdbc.util.DBconnectionUitl;
/**
* @author kouyang
*
*/
public class UserDao {
//单例模式
public UserDao(){
}
private static UserDao userDao = new UserDao();
public static UserDao getInstance(){
return userDao;
}
/**
* @param user
*
* @return true保存成功,false保存失败
*/
public boolean saveUser(User user){
boolean flag = false;
Connection conn = null;
Statement st = null;
String sql = "";
try {
//获取连接
conn = DBconnectionUitl.getConnection();
//产生执行sql语句的对象
st = conn.createStatement();
//拼凑sql语句
sql = "insert into user(username,sex,password) values ('"
+ user.getUsername() + "',"
+ user.getSex() + ",'"
+ user.getPassword() + "'"
+ ")";
System.out.println(sql);
//执行sql语句
int rows = st.executeUpdate(sql);
if(rows != 0)
flag = true;
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBconnectionUitl.closeAll(null, st, conn);
}
return flag;
}
/**
* 通过userId删除user对象
* @param userId
* @return
*/
public boolean deleteUserByUserId(int userId){
boolean flag = false;
Connection conn = null;
Statement st = null;
String sql = "delete from user where userId = " + userId;
try {
conn = DBconnectionUitl.getConnection();
st = conn.createStatement();
int rows = st.executeUpdate(sql);
if(rows != 0)
flag = true;
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBconnectionUitl.closeAll(null, st, conn);
}
return flag;
}
/**
* 通过username修改user对象
* @param username
* @return
*/
public boolean updateUserByUsername(String username,String password){
boolean flag = false;
Connection conn = null;
Statement st = null;
String sql = "update user set password='"+password+"' where username = '" + username+"'";
System.out.println(sql);
try {
conn = DBconnectionUitl.getConnection();
st = conn.createStatement();
int rows = st.executeUpdate(sql);
if(rows != 0)
flag = true;
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBconnectionUitl.closeAll(null, st, conn);
}
return flag;
}
public List<User> getAllUserList(){
List<User> userList = new ArrayList<User>();
Connection conn = null;
Statement st = null;
String sql = "select * from user";
ResultSet rs = null;
try {
conn = DBconnectionUitl.getConnection();
st = conn.createStatement();
rs = st.executeQuery(sql);
while(rs.next()){
User user = new User();
user.setUserId(rs.getInt("userId"));
user.setUsername(rs.getString("username"));
user.setSex(rs.getInt("sex"));
user.setPassword(rs.getString("password"));
user.setFlag(rs.getInt("flag"));
userList.add(user);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBconnectionUitl.closeAll(rs, st, conn);
}
return userList;
}
public List<User> getUserListPage(int start,int pageNo){
List<User> userList = new ArrayList<User>();
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs =
4000
null;
String sql = "select * from user order by userId asc limit ?,?";
try {
conn = DBconnectionUitl.getConnection();
ps = conn.prepareStatement(sql);
ps.setInt(1, start);
ps.setInt(2, pageNo);
rs = ps.executeQuery();
while(rs.next()){
User user = new User();
user.setUserId(rs.getInt("userId"));
user.setUsername(rs.getString("username"));
user.setSex(rs.getInt("sex"));
user.setPassword(rs.getString("password"));
user.setFlag(rs.getInt("flag"));
userList.add(user);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBconnectionUitl.closeAll(rs, ps, conn);
}
return userList;
}
}
package com.yy.jdbc.po;
public class User {
private int userId;
private String username;
private int sex;
private String password;
private int flag;
public int getUserId() {
return userId;
}
public void setUserId(int userId) {
this.userId = userId;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public int getSex() {
return sex;
}
public void setSex(int sex) {
this.sex = sex;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public int getFlag() {
return flag;
}
public void setFlag(int flag) {
this.flag = flag;
}
}
工程中的包
1.包的命名规则
com.公司名.(项目名.具体模块的名称)实现分类的名称
1.po包:存放的是javabean类,每个Javabean类对应数据库中一张表。类名和表名一致
2.dao包:存放的是操作数据的类,即对数据库中的表进行增删查改操作的类,每个dao类对应数据库中的一张表。类
名为一表名+Dao
3.util包:存放的是公用的类和常量类
4.test包:存放的是测试类
javabean类:储存数据的类。只包括属性、构造器、setter和getter方法
数据库客服端操作数据库的步骤:
1.连接数据库(ip地址,端口号,用户名,密码,数据库名)
2.打开发送和执行sql语句的窗口
3.发送和执行sql语句
4.根据返回结果,判断是否正确操作了数据库
5.关闭打开的所有的东西
JDBC操作数据库的步骤:
1.连接到数据库:
(1)加载数据库驱动:会抛出一个ClassNotFoundException异常
mysql:Class.forName("com.mysql.jdbc.Driver")
oracle:Class.forName("");
(2)利用驱动和三个参数(url,user,password)获得连接:会抛出一个SQLException异常
java.sql.Connection con = java.sql.DriverManager.getConnection(url,user,password);
mysql:String url = "jdbc:mysql://127.0.0.1:端口号/databaseName".
oracle:String url = "";
3.通过连接获得操作数据库的对象:会抛出一个SQLException异常
java.sql.Statement st = con.createStatement();
4.使用java.sql.Statement对象执行sql语句:会抛出一个SQLException异常
执行更新sql语句:int rows = st.executeUpdate(sql);
执行查询sql语句:java.sql.ResultSet re = st.executeQuery(sql);
5.根据返回的rows/re,判断SQL语句是否正确执行:
rows!=0 SQL语句正常执行
re.next()==true 表示查出了字表
6.关闭,先打开后关闭
关闭re:re.close():会抛出一个SQLException异常
关闭st:st.close():会抛出一个SQLException异常
关闭con:con.close()会抛出一个SQLException异常
第一个jar 包:数据库的驱动
Web工程的jar包都是放在WebRoot/WEB-INF/lib文件夹里(放在里面,自动导入)
几个接口:
java.sql.Connection是一个接口
java.sql.Statement是一个接口
java.sql.ResultSet是一个接口
java.sql.PreparedStatement是一个接口
数据库连接配置文件:database.properties只加载一次,放在src文件夹下面
properties文件以键(name)值(value)方式保存数据
从properties文件中解析出value值:
InputStream is = null;
is = DBConnectionUtil.class.getClassLoader().getResourceAsStream("jdbc.properties");
Properties p = new Properties();
p.load(is);
String value = p.getProperty("name");
java.sql.Statement和java.sql.PreparedStatement比较
代码比较
1.SQL的写法:
Satement:String sql = "selete id from user where email =' "+email+" ' ";
PreparedStatement:String sql = "selete id from user where email = ?"
2.st/ps的获取:
Statement:st = con.createStatement();
PreparedStatement:ps = con.preparedStatement(sql);
3.参数的设置:
Statement:在SQL中给出
PreparedStatement:ps.setType(1,value); ps.setType(2,value);
4.执行SQL:
Statement:int rows = st.executeUpdate(sql); re = st.executeQuery(sql);
PreparedStatement:int rows = ps.executeUpdate(); re = ps.executeQuery();
PreparedStatement的优势:
1.防止SQL的注入,提高安全性
2.对参数实现类型的自动转换,代码的可读性,可维护性提高
3,.对于批处理:PreparedStatement效率更高一些(oracle明显,MySQL区别不大)
package com.yy.jdbc.dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import com.yy.jdbc.po.User;
import com.yy.jdbc.util.DBconnectionUitl;
/**
* @author kouyang
*
*/
public class UserDao {
//单例模式
public UserDao(){
}
private static UserDao userDao = new UserDao();
public static UserDao getInstance(){
return userDao;
}
/**
* @param user
*
* @return true保存成功,false保存失败
*/
public boolean saveUser(User user){
boolean flag = false;
Connection conn = null;
Statement st = null;
String sql = "";
try {
//获取连接
conn = DBconnectionUitl.getConnection();
//产生执行sql语句的对象
st = conn.createStatement();
//拼凑sql语句
sql = "insert into user(username,sex,password) values ('"
+ user.getUsername() + "',"
+ user.getSex() + ",'"
+ user.getPassword() + "'"
+ ")";
System.out.println(sql);
//执行sql语句
int rows = st.executeUpdate(sql);
if(rows != 0)
flag = true;
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBconnectionUitl.closeAll(null, st, conn);
}
return flag;
}
/**
* 通过userId删除user对象
* @param userId
* @return
*/
public boolean deleteUserByUserId(int userId){
boolean flag = false;
Connection conn = null;
Statement st = null;
String sql = "delete from user where userId = " + userId;
try {
conn = DBconnectionUitl.getConnection();
st = conn.createStatement();
int rows = st.executeUpdate(sql);
if(rows != 0)
flag = true;
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBconnectionUitl.closeAll(null, st, conn);
}
return flag;
}
/**
* 通过username修改user对象
* @param username
* @return
*/
public boolean updateUserByUsername(String username,String password){
boolean flag = false;
Connection conn = null;
Statement st = null;
String sql = "update user set password='"+password+"' where username = '" + username+"'";
System.out.println(sql);
try {
conn = DBconnectionUitl.getConnection();
st = conn.createStatement();
int rows = st.executeUpdate(sql);
if(rows != 0)
flag = true;
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBconnectionUitl.closeAll(null, st, conn);
}
return flag;
}
public List<User> getAllUserList(){
List<User> userList = new ArrayList<User>();
Connection conn = null;
Statement st = null;
String sql = "select * from user";
ResultSet rs = null;
try {
conn = DBconnectionUitl.getConnection();
st = conn.createStatement();
rs = st.executeQuery(sql);
while(rs.next()){
User user = new User();
user.setUserId(rs.getInt("userId"));
user.setUsername(rs.getString("username"));
user.setSex(rs.getInt("sex"));
user.setPassword(rs.getString("password"));
user.setFlag(rs.getInt("flag"));
userList.add(user);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBconnectionUitl.closeAll(rs, st, conn);
}
return userList;
}
public List<User> getUserListPage(int start,int pageNo){
List<User> userList = new ArrayList<User>();
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs =
4000
null;
String sql = "select * from user order by userId asc limit ?,?";
try {
conn = DBconnectionUitl.getConnection();
ps = conn.prepareStatement(sql);
ps.setInt(1, start);
ps.setInt(2, pageNo);
rs = ps.executeQuery();
while(rs.next()){
User user = new User();
user.setUserId(rs.getInt("userId"));
user.setUsername(rs.getString("username"));
user.setSex(rs.getInt("sex"));
user.setPassword(rs.getString("password"));
user.setFlag(rs.getInt("flag"));
userList.add(user);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBconnectionUitl.closeAll(rs, ps, conn);
}
return userList;
}
}
package com.yy.jdbc.po;
public class User {
private int userId;
private String username;
private int sex;
private String password;
private int flag;
public int getUserId() {
return userId;
}
public void setUserId(int userId) {
this.userId = userId;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public int getSex() {
return sex;
}
public void setSex(int sex) {
this.sex = sex;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public int getFlag() {
return flag;
}
public void setFlag(int flag) {
this.flag = flag;
}
}
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