一、相关概念
1.什么是JDBC
JDBC(Java Data Base Connectivity,java数据库连接)是一种用于执行SQL语句的Java API,可以为多种关系数据库提供统一访问,它由一组用Java语言编写的类和接口组成。JDBC提供了一种基准,据此可以构建更高级的工具和接口,使数据库开发人员能够编写数据库应用程序。
2.数据库驱动
我们安装好数据库之后,我们的应用程序也是不能直接使用数据库的,必须要通过相应的数据库驱动程序,通过驱动程序去和数据库打交道。其实也就是数据库厂商的JDBC接口实现,即对Connection等接口的实现类的jar文件。
二、常用接口
1.Driver接口
Driver接口由数据库厂家提供,作为java开发人员,只需要使用Driver接口就可以了。在编程中要连接数据库,必须先装载特定厂商的数据库驱动程序,不同的数据库有不同的装载方法。如:
装载MySql驱动:Class.forName("com.mysql.jdbc.Driver");
装载Oracle驱动:Class.forName("oracle.jdbc.driver.OracleDriver");
2.Connection接口
Connection与特定数据库的连接(会话),在连接上下文中执行sql语句并返回结果。DriverManager.getConnection(url, user, password)方法建立在JDBC URL中定义的数据库Connection连接上。
连接MySql数据库:Connection conn = DriverManager.getConnection("jdbc:mysql://host:port/database", "user", "password");
连接Oracle数据库:Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@host:port:database", "user", "password");
连接SqlServer数据库:Connection conn = DriverManager.getConnection("jdbc:microsoft:sqlserver://host:port; DatabaseName=database", "user", "password");
常用方法:
- createStatement():创建向数据库发送sql的statement对象。
- prepareStatement(sql) :创建向数据库发送预编译sql的PrepareSatement对象。
- prepareCall(sql):创建执行存储过程的callableStatement对象。
- setAutoCommit(boolean autoCommit):设置事务是否自动提交。
- commit() :在链接上提交事务。
- rollback() :在此链接上回滚事务。
3.Statement接口
用于执行静态SQL语句并返回它所生成结果的对象。
三种Statement类:
- Statement:由createStatement创建,用于发送简单的SQL语句(不带参数)。
- PreparedStatement :继承自Statement接口,由preparedStatement创建,用于发送含有一个或多个参数的SQL语句。PreparedStatement对象比Statement对象的效率更高,并且可以防止SQL注入,所以我们一般都使用PreparedStatement。
- CallableStatement:继承自PreparedStatement接口,由方法prepareCall创建,用于调用存储过程。
常用Statement方法:
- execute(String sql):运行语句,返回是否有结果集
- executeQuery(String sql):运行select语句,返回ResultSet结果集。
- executeUpdate(String sql):运行insert/update/delete操作,返回更新的行数。
- addBatch(String sql) :把多条sql语句放到一个批处理中。
- executeBatch():向数据库发送一批sql语句执行。
4.ResultSet接口
ResultSet提供检索不同类型字段的方法,常用的有:
- getString(int index)、getString(String columnName):获得在数据库里是varchar、char等类型的数据对象。
- getFloat(int index)、getFloat(String columnName):获得在数据库里是Float类型的数据对象。
- getDate(int index)、getDate(String columnName):获得在数据库里是Date类型的数据。
- getBoolean(int index)、getBoolean(String columnName):获得在数据库里是Boolean类型的数据。
- getObject(int index)、getObject(String columnName):获取在数据库里任意类型的数据。
ResultSet还提供了对结果集进行滚动的方法:
- next():移动到下一行
- Previous():移动到前一行
- absolute(int row):移动到指定行
- beforeFirst():移动resultSet的最前面。
- afterLast() :移动到resultSet的最后面。
使用后依次关闭对象及连接:ResultSet → Statement → Connection
三、使用JDBC的步骤
加载JDBC驱动程序 → 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.注册驱动 (只做一次)
方式一:Class.forName(“com.MySQL.jdbc.Driver”);
推荐这种方式,不会对具体的驱动类产生依赖。
方式二:DriverManager.registerDriver(com.mysql.jdbc.Driver);
会造成DriverManager中产生两个一样的驱动,并会对具体的驱动类产生依赖。
2.建立连接
Connection conn = DriverManager.getConnection(url, user, password);
URL用于标识数据库的位置,通过URL地址告诉JDBC程序连接哪个数据库,URL的写法为:
aaarticlea/png;base64,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" alt="" />
其他参数如:useUnicode=true&characterEncoding=utf8
3.创建执行SQL语句的statement
1 //Statement
2 String id = "5";
3 String sql = "delete from table where id=" + id;
4 Statement st = conn.createStatement();
5 st.executeQuery(sql);
6 //存在sql注入的危险
7 //如果用户传入的id为“5 or 1=1”,那么将删除表中的所有记录
1 //PreparedStatement 有效的防止sql注入(SQL语句在程序运行前已经进行了预编译,当运行时动态地把参数传给PreprareStatement时,即使参数里有敏感字符如 or '1=1'也数据库会作为一个参数一个字段的属性值来处理而不会作为一个SQL指令)
2 String sql = “insert into user (name,pwd) values(?,?)”;
3 PreparedStatement ps = conn.preparedStatement(sql);
4 ps.setString(1, “col_value”); //占位符顺序从1开始
5 ps.setString(2, “123456”); //也可以使用setObject
6 ps.executeQuery();
4.处理执行结果(ResultSet)
1 ResultSet rs = ps.executeQuery();
2 While(rs.next()){
3 rs.getString(“col_name”);
4 rs.getInt(1);
5 //…
6 }
5.释放资源
//数据库连接(Connection)非常耗资源,尽量晚创建,尽量早的释放
//都要加try catch 以防前面关闭出错,后面的就不执行了
1 try {
2 if (rs != null) {
3 rs.close();
4 }
5 } catch (SQLException e) {
6 e.printStackTrace();
7 } finally {
8 try {
9 if (st != null) {
10 st.close();
11 }
12 } catch (SQLException e) {
13 e.printStackTrace();
14 } finally {
15 try {
16 if (conn != null) {
17 conn.close();
18 }
19 } catch (SQLException e) {
20 e.printStackTrace();
21 }
22 }
23 }
四、事务(ACID特点、隔离级别、提交commit、回滚rollback)
1.批处理Batch
package com.test.jdbc;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
/**
* 测试ResultSet结果集的基本用法
*/
public class Demo05 {
public static void main(String[] args) {
Connection conn = null;
Statement stmt = null;
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/testjdbc","root","mysql");
conn.setAutoCommit(false); //设为手动提交
long start = System.currentTimeMillis();
stmt = conn.createStatement();
for (int i = 0; i < 20000; i++) {
stmt.addBatch("insert into t_user (userName,pwd,regTime) values ('hao" + i + "',666666,now())");
}
stmt.executeBatch();
conn.commit(); //提交事务
long end = System.currentTimeMillis();
System.out.println("插入200000条数据,耗时(ms):" + (end - start));
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally{
try {
if (stmt!=null) {
stmt.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (conn!=null) {
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
插入2万条数据的测试
2.测试事务的基本概念和用法
package com.test.jdbc;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
/**
* 测试事务的基本概念和用法
*/
public class Demo06 {
public static void main(String[] args) {
Connection conn = null;
PreparedStatement ps1 = null;
PreparedStatement ps2 = null;
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/testjdbc","root","mysql");
conn.setAutoCommit(false); //JDBC中默认是true,自动提交事务
ps1 = conn.prepareStatement("insert into t_user(userName,pwd)values(?,?)"); //事务开始
ps1.setObject(1, "小高");
ps1.setObject(2, "123");
ps1.execute();
System.out.println("第一次插入");
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
ps2 = conn.prepareStatement("insert into t_user(userName,pwd)values(?,?,?)"); //模拟执行失败(values的参数写成三个了)
//insert时出现异常,执行conn.rollback
ps2.setObject(1, "小张");
ps2.setObject(2, "678");
ps2.execute();
System.out.println("第二次插入");
conn.commit();
} catch (ClassNotFoundException e) {
e.printStackTrace();
try {
conn.rollback();
} catch (SQLException e1) {
e1.printStackTrace();
}
} catch (SQLException e) {
e.printStackTrace();
} finally{
try {
if (ps1!=null) {
ps1.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (ps2!=null) {
ps2.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (conn!=null) {
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
测试事务的基本概念和用法
第一次插入
java.sql.SQLException: No value specified for parameter 3
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1078)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:989)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:975)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:920)
at com.mysql.jdbc.PreparedStatement.checkAllParametersSet(PreparedStatement.java:2611)
at com.mysql.jdbc.PreparedStatement.fillSendPacket(PreparedStatement.java:2586)
at com.mysql.jdbc.PreparedStatement.fillSendPacket(PreparedStatement.java:2510)
at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:1316)
at com.test.jdbc.Demo06.main(Demo06.java:39)
控制台输出
五、时间处理(Date和Time以及Timestamp区别、随机日期生成)
java.util.Date
- 子类:java.sql.Date
- 子类:java.sql.Time
- 子类:java.sql.Timestamp
package com.test.jdbc;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Timestamp;
import java.util.Random;
/**
* 测试时间处理(java.sql.Date,Time,Timestamp)
*/
public class Demo07 {
public static void main(String[] args) {
Connection conn = null;
PreparedStatement ps = null;
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/testjdbc","root","mysql");
for (int i = 0; i < 1000; i++) {
ps = conn.prepareStatement("insert into t_user(userName,pwd,regTime,lastLoginTime)values(?,?,?,?)");
ps.setObject(1, "小高" + i);
ps.setObject(2, "123");
//
int random = 1000000000 + new Random().nextInt(1000000000); //随机时间
java.sql.Date date = new java.sql.Date(System.currentTimeMillis() - random); //插入随机时间
java.sql.Timestamp stamp = new Timestamp(System.currentTimeMillis()); //如果需要插入指定时间,可以使用Calendar、DateFormat
ps.setDate(3, date);
ps.setTimestamp(4, stamp);
//
ps.execute();
}
System.out.println("插入");
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally{
try {
if (ps!=null) {
ps.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (conn!=null) {
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
测试时间处理(java.sql.Date,Time,Timestamp)
package com.test.jdbc;
import java.sql.Connection;
import java.sql.Date;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
/**
* 测试时间处理(java.sql.Date,Time,Timestamp),取出指定时间段的数据
*/
public class Demo08 {
/**
* 将字符串代表的时间转为long数字(格式:yyyy-MM-dd hh:mm:ss)
* @param dateStr
* @return
*/
public static long str2DateTime(String dateStr){
DateFormat format = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
try {
return format.parse(dateStr).getTime();
} catch (ParseException e) {
e.printStackTrace();
return 0;
}
}
public static void main(String[] args) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/testjdbc","root","mysql");
//
ps = conn.prepareStatement("select * from t_user where regTime > ? and regTime < ?");
java.sql.Date start = new java.sql.Date(str2DateTime("2016-06-20 00:00:00"));
java.sql.Date end = new java.sql.Date(str2DateTime("2016-06-24 00:00:00"));
ps.setObject(1, start);
ps.setObject(2, end);
rs = ps.executeQuery();
while(rs.next()){
System.out.println(rs.getInt("id") + "--" + rs.getString("userName")+"--"+rs.getDate("regTime"));
}
//
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally{
try {
if (ps!=null) {
ps.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (conn!=null) {
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
测试时间处理(java.sql.Date,Time,Timestamp),取出指定时间段的数据
六、CLOB文本大对象操作
package com.test.jdbc;
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileReader;
import java.io.InputStreamReader;
import java.io.Reader;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
/**
* 测试CLOB 文本大对象的使用
* 包含:将字符串、文件内容插入数据库中的CLOB字段和将CLOB字段值取出来的操作。
*/
public class Demo09 {
public static void main(String[] args) {
Connection conn = null;
PreparedStatement ps = null;
PreparedStatement ps2 = null;
ResultSet rs = null;
Reader r = null;
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/testjdbc","root","mysql");
//插入//
ps = conn.prepareStatement("insert into t_user(userName,myInfo)values(?,?)");
ps.setString(1, "小高");
//将文本文件内容直接输入到数据库中
// ps.setClob(2, new FileReader(new File("G:/JAVA/test/a.txt")));
//将程序中的字符串输入到数据库中的CLOB字段中
ps.setClob(2, new BufferedReader(new InputStreamReader(new ByteArrayInputStream("aaaa".getBytes()))));
ps.executeUpdate();
System.out.println("插入");
//
//查询//
ps2 = conn.prepareStatement("select * from t_user where id=?");
ps2.setObject(1, 223021);
rs = ps2.executeQuery();
System.out.println("查询");
while (rs.next()) {
Clob c = rs.getClob("myInfo");
r = c.getCharacterStream();
int temp = 0;
while ((temp=r.read())!=-1) {
System.out.print((char)temp);
}
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
} finally{
try {
if (r!=null) {
r.close();
}
} catch (Exception e) {
e.printStackTrace();
}
try {
if (rs!=null) {
rs.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (ps2!=null) {
ps2.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (ps!=null) {
ps.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (conn!=null) {
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
测试CLOB 文本大对象的使用
七、BLOB二进制大对象的使用
package com.test.jdbc;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Blob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
/**
* 测试BLOB 二进制大对象的使用
*/
public class Demo10 {
public static void main(String[] args) {
Connection conn = null;
PreparedStatement ps = null;
PreparedStatement ps2 = null;
ResultSet rs = null;
InputStream is = null;
OutputStream os = null;
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/testjdbc","root","mysql");
//插入//
ps = conn.prepareStatement("insert into t_user(userName,headImg)values(?,?)");
ps.setString(1, "小高");
ps.setBlob(2, new FileInputStream("G:/JAVA/test/d.jpg"));
ps.execute();
//
//查询//
ps2 = conn.prepareStatement("select * from t_user where id=?");
ps2.setObject(1, 223024);
rs = ps2.executeQuery();
System.out.println("查询");
while (rs.next()) {
Blob b = rs.getBlob("headImg");
is = b.getBinaryStream();
os = new FileOutputStream("G:/JAVA/test/h.jpg");
int temp = 0;
while ((temp=is.read())!=-1) {
os.write(temp);
}
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
} finally{
try {
if (os!=null) {
os.close();
}
} catch (Exception e) {
e.printStackTrace();
}
try {
if (is!=null) {
is.close();
}
} catch (Exception e) {
e.printStackTrace();
}
try {
if (rs!=null) {
rs.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (ps2!=null) {
ps2.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (ps!=null) {
ps.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (conn!=null) {
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
测试BLOB二进制大对象的使用
八、总结(简单封装、资源文件properties处理连接信息)
#右击该properties文件--properties--Resource--Text file encoding,选中other,选择其它编码方式。
#如UTF-8或GBK,这样就能在properties里面输入中文,而不会自动转成Unicode了。
#java中的properties文件是一种配置文件,主要用于表达配置信息。
#文件类型为*.properties,格式为文本文件,文件内容是"键=值"的格式。
#在properties文件中,可以用"#"来作注释
#MySQL连接配置
mysqlDriver=com.mysql.jdbc.Driver
mysqlURL=jdbc:mysql://localhost:3306/testjdbc
mysqlUser=root
mysqlPwd=mysql
#Oracle连接配置
#...
db.properties
package com.test.jdbc;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
public class JDBCUtil {
static Properties pros = null; //可以帮助读取和处理资源文件中的信息
static { //加载JDBCUtil类的时候调用
pros = new Properties();
try {
pros.load(Thread.currentThread().getContextClassLoader().getResourceAsStream("db.properties"));
} catch (IOException e) {
e.printStackTrace();
}
}
public static Connection getMysqlConn(){
try {
Class.forName(pros.getProperty("mysqlDriver"));
return DriverManager.getConnection(pros.getProperty("mysqlURL"),
pros.getProperty("mysqlUser"),pros.getProperty("mysqlPwd"));
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
//可以重载多个,这里就懒得写了
public static void close(ResultSet rs,Statement st,Connection conn){
try {
if (rs!=null) {
rs.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (st!=null) {
st.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (conn!=null) {
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
JDBCUtil工具类
package com.test.jdbc;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
/**
* 测试使用JDBCUtil工具类来简化JDBC开发
*/
public class Demo11 {
public static void main(String[] args) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = JDBCUtil.getMysqlConn();
ps = conn.prepareStatement("insert into t_user (userName) values (?)");
ps.setString(1, "小高高");
ps.execute();
} catch (Exception e) {
e.printStackTrace();
} finally{
JDBCUtil.close(rs, ps, conn);
}
}
}
测试使用JDBCUtil工具类来简化JDBC开发