JDBC—02—JDBC的使用；

清疚 2023-10-09 10:29 40阅读 0赞

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# **一、** **JDBC** **的使用**  #

加载数据库驱动程序 → 使用DriverManager建立数据库连接 Connection → 创建执行SQL的语句Statement → 处理执行结果 ResultSet → 释放资源

## **1.****下载数据库驱动**  ##

1.1MySQL 驱动

https://dev.mysql.com/downloads/connector/j/

由于我的MySQL是8.0.17的,所以要安装8.0的JDBC;

![1734761-20190924180301202-1406457256.png][]

我们选择platform independent(独立于平台),  然后选择.ZIP Archive格式即可;

![1734761-20190924180346080-2034842023.png][]

下载完成后, 我们把jar包提取出来,  放到eclipse的项目中的lib文件夹,  然后build path就可以使用JDBC了!

![1734761-20190924180941153-1744140790.png][]

## **2.****创建项目添加驱动** ##

## **3.****通过** **Statement** **向表中插入数据**  ##

**　　//****注册驱动(通过反射，调用数据库驱动类；)**

**　　//****获取连接**

**　　 "jdbc:数据库类型://数据库存储位置:数据库端口号/连接哪一个数据库?数据库编码格式", "用户名", "密码"**

**   "jdbc:mysql://localhost:3306/test2?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone =GMT","root"."root"**

**　　//****执行** **SQL**

//**释放资源**

**![1734761-20190924181821341-1248485518.png][]**

**4.Statement** **对象修改表中的数据**

**![1734761-20190924202026996-593108926.png][]**

## **5** **封装** **JDBC** **工具类**  ##

**5.1****普通版**

**5.1.1****工具类代码**

/\*\*

\* jdbc 工具类

\* **@author** Administrator

\*/

**public class** JdbcUtil \{

**private static** String *driver* =

"com.mysql.jdbc.Driver";

**private static** String

*jdbcUrl*="jdbc:mysql://localhost:3306/bjsxt?useUnicode

=true&characterEncoding=utf-8";

**private static** String *username* ="root";

**private static** String *userpassword*="root";

**static**\{

**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*, *userpassword*);

\} **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) \{

e.printStackTrace();

//關閉資源

**public static void** closeResource(Statement

state,Connection conn)\{

*closeStatement*(state);

*closeConnection*(conn);

\}\}

**5.2****升级版**

**5.2.1****工模具类代码**

/\*\*

\* jdbc 工具类

\* **@author** Administrator

\*/

**public class** JdbcUtil \{

**private static** String *driver*;

**private static** String *jdbcUrl*;

**private static** String *username*;

**private static** String *userpassword*;

**static**\{

//读取 Properties 文件

ResourceBundle bundle =

ResourceBundle.*getBundle*("jdbc");

*driver* = bundle.getString("driver");

*jdbcUrl*= bundle.getString("jdbcUrl");

*username* = bundle.getString("username");

*userpassword* =bundle.getString("userpassword");

**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*, *userpassword*);

\} **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) \{

e.printStackTrace();

//關閉資源**public static void** closeResource(Statement

state,Connection conn)\{

*closeStatement*(state);

*closeConnection*(conn);

**6** **通过** **Statement** **对象查询数据**

**6.1****代码**

//查询 Departmetns 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;

//执行查询返回结果

rs=state.executeQuery(sql);**while**(rs.next())\{

System.***out***.println(rs.getInt("department\_id")+"

"+rs.getString("department\_name")+" "+rs.getInt(3));

\}**catch**(Exception e)\{

e.printStackTrace();

\}**finally**\{

JdbcUtil.*closeResource*(state, conn,rs);

**7 ResultSet** **讲解**

注意 ResultSet 中封装的并不是我们查询到的所有的结果集，而是返回了查询到的结果

集的数据库游标。通过 ResultSet 中的 next()方法操作游标的位置获取结果集。

**8** **通过** **ResultSet** **实现逻辑分页**

**8.1****代码**

//查询 departments 表中的所有的数据，并且通过 ResultSet 实现逻辑分

页

**public void** selectDeptPage(**int** currentPage,**int** pageRows)\{

Connection conn = **null**;

Statement state = **null**;

ResultSet rs = **null**;

**try**\{

conn = JdbcUtil.*getConnection*();

state = conn.createStatement();

String sql = "select \* from departments";

rs = state.executeQuery(sql);//开始位置与结束位置

**int** begin = (currentPage -1)\*pageRows;

**int** end = currentPage \* pageRows;

//当前位置的计数器

**int** currentNum = 0;

**while**(rs.next())\{

//什么情况下获取结果集中的数据

**if**(currentNum >= begin && currentNum < end)\{

System.***out***.println(rs.getInt("department\_id")+"

"+rs.getString("department\_name"));

//结束操作 ResultSet 的边界条件

**if**(currentNum == end -1)\{

**break**;

currentNum++;

\}**catch**(Exception e)\{

e.printStackTrace();

\}**finally**\{

JdbcUtil.*closeResource*(state, conn, rs);

转载于:https://www.cnblogs.com/EricShen/p/11573724.html

[1734761-20190924180301202-1406457256.png]: https://img2018.cnblogs.com/blog/1734761/201909/1734761-20190924180301202-1406457256.png
[1734761-20190924180346080-2034842023.png]: https://img2018.cnblogs.com/blog/1734761/201909/1734761-20190924180346080-2034842023.png
[1734761-20190924180941153-1744140790.png]: https://img2018.cnblogs.com/blog/1734761/201909/1734761-20190924180941153-1744140790.png
[1734761-20190924181821341-1248485518.png]: https://img2018.cnblogs.com/blog/1734761/201909/1734761-20190924181821341-1248485518.png
[1734761-20190924202026996-593108926.png]: https://img2018.cnblogs.com/blog/1734761/201909/1734761-20190924202026996-593108926.png