工具类 JDBCUtils
package com.hspedu.jdbc.utils;
import java.io.FileInputStream;
import java.io.IOException;
import java.sql.*;
import java.util.Properties;
/**
* 这是一个工具类,完成 mysql 的连接和关闭资源
*/
public class JDBCUtils {
//定义相关的属性(4 个), 因为只需要一份,因此,我们做出 static
private static String user; //用户名
private static String password; //密码
private static String url; //url
private static String driver; //驱动名
//在 static 代码块去初始化
static {
try {
Properties properties = new Properties();
properties.load(new FileInputStream("src\\mysql.properties"));
//读取相关的属性值
user = properties.getProperty("user");
password = properties.getProperty("password");
url = properties.getProperty("url");
driver = properties.getProperty("driver");
} catch (IOException e) {
//在实际开发中,我们可以这样处理
//1. 将编译异常转成 运行异常
//2. 调用者,可以选择捕获该异常,也可以选择默认处理该异常,比较方便.
throw new RuntimeException(e);
}
}
//连接数据库, 返回 Connection
public static Connection getConnection() {
try {
return DriverManager.getConnection(url, user, password);
} catch (SQLException e) {
//1. 将编译异常转成 运行异常
//2. 调用者,可以选择捕获该异常,也可以选择默认处理该异常,比较方便. throw new RuntimeException(e);
}
}
//关闭相关资源
/*
1. ResultSet 结果集
2. Statement 或者 PreparedStatement
3. Connection
4. 如果需要关闭资源,就传入对象,否则传入 null
*/
public static void close(ResultSet set, Statement statement, Connection connection) {
//判断是否为 null
try {
if (set != null) {
set.close();
}
if (statement != null) {
statement.close();
}
if (connection != null) {
connection.close();
}
} catch (SQLException e) {
//将编译异常转成运行异常抛出
throw new RuntimeException(e);
}
}
}
测试类
package com.hspedu.jdbc.utils;
import org.junit.jupiter.api.Test;
import java.sql.*;
/**
* 该类演示如何使用 JDBCUtils 工具类,完成 dml 和 select
*/
public class JDBCUtils_Use {
@Test
public void testSelect() {
//1. 得到连接
Connection connection = null;
//2. 组织一个 sql
String sql = "select * from actor where id = ?";
PreparedStatement preparedStatement = null;
ResultSet set = null;
//3. 创建 PreparedStatement 对象
try {
connection = JDBCUtils.getConnection();
System.out.println(connection.getClass()); //com.mysql.jdbc.JDBC4Connection
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setInt(1, 5);//给?号赋值
//执行, 得到结果集
set = preparedStatement.executeQuery();
//遍历该结果集
while (set.next()) {
int id = set.getInt("id");
String name = set.getString("name");
String sex = set.getString("sex");
Date borndate = set.getDate("borndate");
String phone = set.getString("phone");
System.out.println(id + "\t" + name + "\t" + sex + "\t" + borndate + "\t" + phone);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
//关闭资源
JDBCUtils.close(set, preparedStatement, connection);
}
}
@Test
public void testDML() {//insert , update, delete
//1. 得到连接
Connection connection = null;
//2. 组织一个 sql
String sql = "update actor set name = ? where id = ?";
// 测试 delete 和 insert ,自己玩. PreparedStatement preparedStatement = null;
//3. 创建 PreparedStatement 对象
try {
connection = JDBCUtils.getConnection();
preparedStatement = connection.prepareStatement(sql);
//给占位符赋值
preparedStatement.setString(1, "周星驰");
preparedStatement.setInt(2, 4);
//执行
preparedStatement.executeUpdate();
} catch (SQLException e) {
e.printStackTrace();
} finally {
//关闭资源
JDBCUtils.close(null, preparedStatement, connection);
}
}
}
//没有使用事务.
@Test
public void noTransaction() {
//操作转账的业务
//1. 得到连接
Connection connection = null;
//2. 组织一个 sql
String sql = "update account set balance = balance - 100 where id = 1";
String sql2 = "update account set balance = balance + 100 where id = 2";
PreparedStatement preparedStatement = null;
//3. 创建 PreparedStatement 对象
try {
connection = JDBCUtils.getConnection(); // 在默认情况下,connection 是默认自动提交
preparedStatement = connection.prepareStatement(sql);
preparedStatement.executeUpdate(); // 执行第 1 条 sql
int i = 1 / 0; //抛出异常
preparedStatement = connection.prepareStatement(sql2);
preparedStatement.executeUpdate(); // 执行第 3 条 sql
} catch (SQLException e) {
e.printStackTrace();
} finally {
//关闭资源
JDBCUtils.close(null, preparedStatement, connection);
}
}
//事务来解决
@Test
public void useTransaction() {
//操作转账的业务
//1. 得到连接
Connection connection = null;
//2. 组织一个 sql
String sql = "update account set balance = balance - 100 where id = 1";
String sql2 = "update account set balance = balance + 100 where id = 2";
PreparedStatement preparedStatement = null;
//3. 创建 PreparedStatement 对象
try {
connection = JDBCUtils.getConnection(); // 在默认情况下,connection 是默认自动提交
//将 connection 设置为不自动提交
connection.setAutoCommit(false); //开启了事务
preparedStatement = connection.prepareStatement(sql);
preparedStatement.executeUpdate(); // 执行第 1 条 sql
int i = 1 / 0; //抛出异常
preparedStatement = connection.prepareStatement(sql2);
preparedStatement.executeUpdate(); // 执行第 3 条 sql
//这里提交事务
connection.commit();
} catch (SQLException e) {
//这里我们可以进行回滚,即撤销执行的 SQL
//默认回滚到事务开始的状态. System.out.println("执行发生了异常,撤销执行的 sql");
try {
connection.rollback();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
e.printStackTrace();
} finally {
//关闭资源
JDBCUtils.close(null, preparedStatement, connection);
}
}
特别注意:
1.注意修改配置文件
2.记得关闭事物自动提交(巨坑)
package com.hspedu.jdbc.batch_;
import com.hspedu.jdbc.utils.JDBCUtils;
import org.junit.jupiter.api.Test;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
/**
* 演示 java 的批处理
*/
public class Batch_ {
//传统方法,添加 5000 条数据到 admin2
@Test
public void noBatch() throws Exception {
Connection connection = JDBCUtils.getConnection();
String sql = "insert into admin2 values(null, ?, ?)";
PreparedStatement preparedStatement = connection.prepareStatement(sql);
System.out.println("开始执行");
long start = System.currentTimeMillis();//开始时间
for (int i = 0; i < 5000; i++) { //5000 执行
preparedStatement.setString(1, "jack" + i);
preparedStatement.setString(2, "666");
preparedStatement.executeUpdate();
}
long end = System.currentTimeMillis();
System.out.println("传统的方式 耗时=" + (end - start));//传统的方式 耗时=10702
//关闭连接
JDBCUtils.close(null, preparedStatement, connection);
}
//使用批量方式添加数据
@Test
public void batch() throws Exception {
Connection connection = JDBCUtils.getConnection();
connection.setAutoCommit(false);
String sql = "insert into admin2 values(null, ?, ?)";
PreparedStatement preparedStatement = connection.prepareStatement(sql);
System.out.println("开始执行");
long start = System.currentTimeMillis();//开始时间
for (int i = 0; i < 5000; i++) {//5000 执行
preparedStatement.setString(1, "jack" + i);
preparedStatement.setString(2, "666");
//将 sql 语句加入到批处理包中 -> 看源码
/*
//1. //第一就创建 ArrayList - elementData => Object[]
//2. elementData => Object[] 就会存放我们预处理的 sql 语句
//3. 当 elementData 满后,就按照 1.5 扩容
//4. 当添加到指定的值后,就 executeBatch
//5. 批量处理会减少我们发送 sql 语句的网络开销,而且减少编译次数,因此效率提高
public void addBatch() throws SQLException {
synchronized(this.checkClosed().getConnectionMutex()) {
if (this.batchedArgs == null) {
this.batchedArgs = new ArrayList();
}
for(int i = 0; i < this.parameterValues.length; ++i) {
this.checkAllParametersSet(this.parameterValues[i], this.parameterStreams[i], i);
}
this.batchedArgs.add(new PreparedStatement.BatchParams(this.parameterValues, this.parameterStreams, this.isStream, this.streamLengths, this.isNull));
}
}
*/
preparedStatement.addBatch();
//当有 1000 条记录时,在批量执行
if((i + 1) % 1000 == 0) {//满 1000 条 sql
preparedStatement.executeBatch();
//清空一把
preparedStatement.clearBatch();
}
}
long end = System.currentTimeMillis();
connection.commit();
System.out.println("批量方式 耗时=" + (end - start));//批量方式 耗时=108
//关闭连接
JDBCUtils.close(null, preparedStatement, connection);
}
}
package com.hspedu.jdbc.datasource;
import com.hspedu.jdbc.utils.JDBCUtils;
import org.junit.jupiter.api.Test;
import java.sql.Connection;
public class ConQuestion {
//代码 连接 mysql 5000 次
@Test
public void testCon() {
//看看连接-关闭 connection 会耗用多久
long start = System.currentTimeMillis();
System.out.println("开始连接.....");
for (int i = 0; i < 5000; i++) {
//使用传统的 jdbc 方式,得到连接
Connection connection = JDBCUtils.getConnection();
//做一些工作,比如得到 PreparedStatement ,发送 sql
//.......... //关闭
JDBCUtils.close(null, null, connection);
}
long end = System.currentTimeMillis();
System.out.println("传统方式 5000 次 耗时=" + (end - start));//传统方式 5000 次 耗时=7099
}
}
厂家必须实现该接口
package com.hspedu.jdbc.datasource;
import com.mchange.v2.c3p0.ComboPooledDataSource;
import org.junit.jupiter.api.Test;
import java.io.FileInputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;
/**
* 演示 c3p0 的使用
*/
//方式 1: 相关参数,在程序中指定 user, url , password 等
@Test
public void testC3P0_01() throws Exception {
//1. 创建一个数据源对象(相当于连接池)
ComboPooledDataSource comboPooledDataSource = new ComboPooledDataSource();
//2. 通过配置文件 mysql.properties 获取相关连接的信息
Properties properties = new Properties();
properties.load(new FileInputStream("src\\mysql.properties"));
//读取相关的属性值
String user = properties.getProperty("user");
String password = properties.getProperty("password");
String url = properties.getProperty("url");
String driver = properties.getProperty("driver");
//给数据源 comboPooledDataSource 设置相关的参数
//注意:连接管理是由 comboPooledDataSource 来管理
comboPooledDataSource.setDriverClass(driver);
comboPooledDataSource.setJdbcUrl(url);
comboPooledDataSource.setUser(user);
comboPooledDataSource.setPassword(password);
//设置初始化连接数
comboPooledDataSource.setInitialPoolSize(10);
//最大连接数 区别如上图
comboPooledDataSource.setMaxPoolSize(50);
//测试连接池的效率, 测试对 mysql 5000 次操作
long start = System.currentTimeMillis();
for (int i = 0; i < 5000; i++) {
Connection connection = comboPooledDataSource.getConnection(); //这个方法就是从 DataSource 接口实现的
//System.out.println("连接 OK");
connection.close();
}
long end = System.currentTimeMillis();
//c3p0 5000 连接 mysql 耗时=391
System.out.println("c3p0 5000 连接 mysql 耗时=" + (end - start));
}
2)方式2
需要先添加配置文件:c3p0-config.xml
<c3p0-config>
<named-config name="my_c3p0">
<property name="driverClass">com.mysql.jdbc.Driverproperty>
<property name="jdbcUrl">jdbc:mysql://127.0.0.1:3306/t1property>
<property name="user">rootproperty>
<property name="password">rootproperty>
<property name="acquireIncrement">5property>
<property name="initialPoolSize">10property>
<property name="minPoolSize">5property>
<property name="maxPoolSize">50property>
<property name="maxStatements">5property>
<property name="maxStatementsPerConnection">2property>
named-config>
c3p0-config>
//第二种方式 使用配置文件模板来完成
//1. 将 c3p0 提供的 c3p0.config.xml 拷贝到 src 目录下
//2. 该文件指定了连接数据库和连接池的相关参数
@Test
public void testC3P0_02() throws SQLException {
ComboPooledDataSource comboPooledDataSource = new ComboPooledDataSource("hsp_edu");
//测试 5000 次连接 mysql
long start = System.currentTimeMillis();
System.out.println("开始执行....");
for (int i = 0; i < 500000; i++) {
Connection connection = comboPooledDataSource.getConnection();
//System.out.println("连接 OK~");
connection.close();
}
long end = System.currentTimeMillis();
//c3p0 的第二种方式 耗时=413
System.out.println("c3p0 的第二种方式(500000) 耗时=" + (end - start));//1917
}
#key=value
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/t1?rewriteBatchedStatements=true
#url=jdbc:mysql://localhost:3306/girls
username=root
password=root
#initial connection Size
initialSize=10
#min idle connecton size 类似最小连接数
minIdle=5
#max active connection size
maxActive=20
#max wait time (5000 mil seconds) 等待最大时长为5秒
maxWait=5000
@Test
public void testDruid() throws Exception {
//1. 加入 Druid jar 包
//2. 加入 配置文件 druid.properties , 将该文件拷贝项目的 src 目录
//3. 创建 Properties 对象, 读取配置文件
Properties properties = new Properties();
properties.load(new FileInputStream("src\\druid.properties"));
//4. 创建一个指定参数的数据库连接池, Druid 连接池
DataSource dataSource = DruidDataSourceFactory.createDataSource(properties);
long start = System.currentTimeMillis();
for (int i = 0; i < 500000; i++) {
Connection connection = dataSource.getConnection();
System.out.println(connection.getClass());
//System.out.println("连接成功!");
connection.close();
}
long end = System.currentTimeMillis();
//druid 连接池 操作 5000 耗时=412
System.out.println("druid 连接池 操作 500000 耗时=" + (end - start));//539
}
/**
* 基于 druid 数据库连接池的工具类
*/
public class JDBCUtilsByDruid {
private static DataSource ds;
//在静态代码块完成 ds 初始化
static {
Properties properties = new Properties();
try {
properties.load(new FileInputStream("src\\druid.properties"));
ds = DruidDataSourceFactory.createDataSource(properties);
} catch (Exception e) {
e.printStackTrace();
}
}
//编写 getConnection 方法
public static Connection getConnection() throws SQLException {
return ds.getConnection();
}
//关闭连接, 老师再次强调: 在数据库连接池技术中,close 不是真的断掉连接
//而是把使用的 Connection 对象放回连接池
public static void close(ResultSet resultSet, Statement statement, Connection connection) {
try {
if (resultSet != null) {
resultSet.close();
}
if (statement != null) {
statement.close();
}
if (connection != null) {
connection.close();
}
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
}
测试类
@SuppressWarnings({"all"})
public class JDBCUtilsByDruid_USE {
@Test
public void testSelect() {
System.out.println("使用 druid 方式完成");
//1. 得到连接
Connection connection = null;
//2. 组织一个 sql
String sql = "select * from actor where id >= ?";
PreparedStatement preparedStatement = null;
ResultSet set = null;
//3. 创建 PreparedStatement 对象
try {
connection = JDBCUtilsByDruid.getConnection();
System.out.println(connection.getClass());//运行类型 com.alibaba.druid.pool.DruidPooledConnection
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setInt(1, 1);//给?号赋值
//执行, 得到结果集
set = preparedStatement.executeQuery();
//遍历该结果集
while (set.next()) {
int id = set.getInt("id");
String name = set.getString("name");//getName()
String sex = set.getString("sex");//getSex()
Date borndate = set.getDate("borndate");
String phone = set.getString("phone");
System.out.println(id + "\t" + name + "\t" + sex + "\t" + borndate + "\t" + phone);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
//关闭资源
JDBCUtilsByDruid.close(set, preparedStatement, connection);
}
}
}
1)先创建一个类,用于映射
package com.pojo;
/**
* 该类用于和数据库数据进行绑定
*/
public class Actor {
private int id;
private String name;
private String sex;
private String borndate;
private String phone;
public Actor() {//一定要提供,将来反射要用
}
public Actor(int id, String name, String sex, String borndate, String phone) {
this.id = id;
this.name = name;
this.sex = sex;
this.borndate = borndate;
this.phone = phone;
}
public int getId() {
return id;
}
public String getName() {
return name;
}
public String getSex() {
return sex;
}
public String getBorndate() {
return borndate;
}
public String getPhone() {
return phone;
}
@Override
public String toString() {
return "Actor{" +
"id=" + id +
", name='" + name + '\'' +
", sex='" + sex + '\'' +
", borndate='" + borndate + '\'' +
", phone='" + phone + '\'' +
'}';
}
public void setId(int id) {
this.id = id;
}
public void setName(String name) {
this.name = name;
}
public void setSex(String sex) {
this.sex = sex;
}
public void setBorndate(String borndate) {
this.borndate = borndate;
}
public void setPhone(String phone) {
this.phone = phone;
}
}
注意事项:
1.必须提供无参构造和set方法,DBUtil框架使用反射时需要使用
2)测试方法
//使用老师的土方法来解决 ResultSet =封装=> Arraylist
@Test
public ArrayList<Actor> testSelectToArrayList() {
System.out.println("使用 druid 方式完成");
//1. 得到连接
Connection connection = null;
//2. 组织一个 sql
String sql = "select * from actor where id >= ?";
PreparedStatement preparedStatement = null;
ResultSet set = null;
ArrayList<Actor> list = new ArrayList<>();//创建 ArrayList 对象,存放 actor 对象
//3. 创建 PreparedStatement 对象
try {
connection = JDBCUtilsByDruid.getConnection();
System.out.println(connection.getClass());//运行类型 com.alibaba.druid.pool.DruidPooledConnection
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setInt(1, 1);//给?号赋值
//执行, 得到结果集
set = preparedStatement.executeQuery();
//遍历该结果集
while (set.next()) {
int id = set.getInt("id");
String name = set.getString("name");//getName()
String sex = set.getString("sex");//getSex()
Date borndate = set.getDate("borndate");
String phone = set.getString("phone");
//把得到的 resultset 的记录,封装到 Actor 对象,放入到 list 集合
list.add(new Actor(id, name, sex, borndate, phone));
}
System.out.println("list 集合数据=" + list);
for(Actor actor : list) {
System.out.println("id=" + actor.getId() + "\t" + actor.getName());
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
//关闭资源
JDBCUtilsByDruid.close(set, preparedStatement, connection);
}
//因为 ArrayList 和 connection 没有任何关联,所以该集合可以复用.
return list;
}
//使用 apache-DBUtils 工具类 + druid 完成对表的 crud 操作
@Test
public void testQueryMany() throws SQLException { //返回结果是多行的情况
//1. 得到 连接 (druid)
Connection connection = JDBCUtilsByDruid.getConnection();
//2. 使用 DBUtils 类和接口 , 先引入 DBUtils 相关的 jar , 加入到本 Project
//3. 创建 QueryRunner
QueryRunner queryRunner = new QueryRunner();
//4. 就可以执行相关的方法,返回 ArrayList 结果集
//String sql = "select * from actor where id >= ?";
// 注意: sql 语句也可以查询部分列
String sql = "select id, name from actor where id >= ?";
// 解读
//(1) query 方法就是执行 sql 语句,得到 resultset ---封装到 --> ArrayList 集合中
//(2) 返回集合
//(3) connection: 连接
//(4) sql : 执行的 sql 语句
//(5) new BeanListHandler<>(Actor.class): 在将 resultset -> Actor 对象 -> 封装到 ArrayList
// 底层使用反射机制 去获取 Actor 类的属性,然后进行封装
//(6) 1 就是给 sql 语句中的? 赋值,可以有多个值,因为是可变参数 Object... params
//(7) 底层得到的 resultset ,会在 query 关闭, 关闭 PreparedStatment
/**
* 分析 queryRunner.query 方法:
* public T query(Connection conn, String sql, ResultSetHandler rsh, Object... params) throws SQLException {
* PreparedStatement stmt = null;//定义 PreparedStatement
* ResultSet rs = null;//接收返回的 ResultSet
* Object result = null;//返回 ArrayList
*
* try {
* stmt = this.prepareStatement(conn, sql);//创建 PreparedStatement
* this.fillStatement(stmt, params);//对 sql 进行 ? 赋值
* rs = this.wrap(stmt.executeQuery());//执行 sql,返回 resultset
* result = rsh.handle(rs);//返回的 resultset --> arrayList[result] [使用到反射,对传入 class 对象处理]
* } catch (SQLException var33) {
* this.rethrow(var33, sql, params);
* } finally {
* try {
* this.close(rs);//关闭 resultset
* } finally {
* this.close((Statement)stmt);//关闭 preparedstatement 对象
* }
* }
* return result;
* }
*/
List<Actor> list =
queryRunner.query(connection, sql, new BeanListHandler<>(Actor.class), 1);
System.out.println("输出集合的信息");
for (Actor actor : list) {
System.out.print(actor);
}
//释放资源
JDBCUtilsByDruid.close(null, null, connection);
}
1)返回的结果是单行记录(单个对象)
//演示 apache-dbutils + druid
//完成 返回的结果是单行记录(单个对象)
@Test
public void testQuerySingle() throws SQLException {
//1. 得到 连接 (druid)
Connection connection = JDBCUtilsByDruid.getConnection();
//2. 使用 DBUtils 类和接口 , 先引入 DBUtils 相关的 jar , 加入到本 Project
//3. 创建 QueryRunner
QueryRunner queryRunner = new QueryRunner();
//4. 就可以执行相关的方法,返回单个对象
String sql = "select * from actor where id = ?";
// 解读
// 因为我们返回的单行记录<--->单个对象 , 使用的 Hander 是 BeanHandler
Actor actor = queryRunner.query(connection, sql, new BeanHandler<>(Actor.class), 10);
System.out.println(actor);
// 释放资源
JDBCUtilsByDruid.close(null, null, connection);
}
2)完成查询结果是单行单列-返回的就是 object
//演示 apache-dbutils + druid
//完成查询结果是单行单列-返回的就是 object
@Test
public void testScalar() throws SQLException {
//1. 得到 连接 (druid)
Connection connection = JDBCUtilsByDruid.getConnection();
//2. 使用 DBUtils 类和接口 , 先引入 DBUtils 相关的 jar , 加入到本 Project
//3. 创建 QueryRunner
QueryRunner queryRunner = new QueryRunner();
//4. 就可以执行相关的方法,返回单行单列 , 返回的就是 Object
String sql = "select name from actor where id = ?";
//解读: 因为返回的是一个对象, 使用的 handler 就是 ScalarHandler
Object obj = queryRunner.query(connection, sql, new ScalarHandler(), 4);
System.out.println(obj);
// 释放资源
JDBCUtilsByDruid.close(null, null, connection);
}
//演示 apache-dbutils + druid
//完成 dml (update, insert ,delete)
@Test
public void testDML() throws SQLException {
//1. 得到 连接 (druid)
Connection connection = JDBCUtilsByDruid.getConnection();
//2. 使用 DBUtils 类和接口 , 先引入 DBUtils 相关的 jar , 加入到本 Project
//3. 创建 QueryRunner
QueryRunner queryRunner = new QueryRunner();
//4. 这里组织 sql 完成 update, insert delete
//String sql = "update actor set name = ? where id = ?";
//String sql = "insert into actor values(null, ?, ?, ?, ?)";
String sql = "delete from actor where id = ?";
//解读
//(1) 执行 dml 操作是 queryRunner.update()
//(2) 返回的值是受影响的行数 (affected: 受影响)
//int affectedRow = queryRunner.update(connection, sql, "林青霞", "女", "1966-10-10", "116");
int affectedRow = queryRunner.update(connection, sql, 1000 );
System.out.println(affectedRow > 0 ? "执行成功" : "执行没有影响到表");
// 释放资源
JDBCUtilsByDruid.close(null, null, connection);
}
/**
* Actor 对象和 actor 表的记录对应
*/
public class Actor { //Javabean, POJO, Domain 对象
private Integer id;
private String name;
private String sex;
private Date borndate;
private String phone;
public Actor() { //一定要给一个无参构造器[反射需要]
}
public Actor(Integer id, String name, String sex, Date borndate, String phone) {
this.id = id;
this.name = name;
this.sex = sex;
this.borndate = borndate;
this.phone = phone;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public Date getBorndate() {
return borndate;
}
public void setBorndate(Date borndate) {
this.borndate = borndate;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
@Override
public String toString() {
return "\nActor{" +
"id=" + id +
", name='" + name + '\'' +
", sex='" + sex + '\'' +
", borndate=" + borndate +
", phone='" + phone + '\'' +
'}';
}
}
utils:工具类
/**
* 基于 druid 数据库连接池的工具类
*/
public class JDBCUtilsByDruid {
private static DataSource ds;
//在静态代码块完成 ds 初始化
static {
Properties properties = new Properties();
try {
properties.load(new FileInputStream("src\\druid.properties"));
ds = DruidDataSourceFactory.createDataSource(properties);
} catch (Exception e) {
e.printStackTrace();
}
}
//编写 getConnection 方法
public static Connection getConnection() throws SQLException {
return ds.getConnection();
}
//关闭连接, 老师再次强调: 在数据库连接池技术中,close 不是真的断掉连接
//而是把使用的 Connection 对象放回连接池
public static void close(ResultSet resultSet, Statement statement, Connection connection) {
try {
if (resultSet != null) {
resultSet.close();
}
if (statement != null) {
statement.close();
}
if (connection != null) {
connection.close();
}
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
}
BasicDAO
/**
* 开发 BasicDAO , 是其他 DAO 的父类, 使用到 apache-dbutils
*/
public class BasicDAO<T> { //泛型指定具体类型
private QueryRunner qr = new QueryRunner();
//开发通用的 dml 方法, 针对任意的表
public int update(String sql, Object... parameters) {
Connection connection = null;
try {
connection = JDBCUtilsByDruid.getConnection();
int update = qr.update(connection, sql, parameters);
return update;
} catch (SQLException e) {
throw new RuntimeException(e); //将编译异常->运行异常 ,抛出
} finally {
JDBCUtilsByDruid.close(null, null, connection);
}
}
//返回多个对象(即查询的结果是多行), 针对任意表
/**
*
* @param sql sql 语句,可以有 ?
* @param clazz 传入一个类的 Class 对象 比如 Actor.class
* @param parameters 传入 ? 的具体的值,可以是多个
* @return 根据 Actor.class 返回对应的 ArrayList 集合
*/
public List<T> queryMulti(String sql, Class<T> clazz, Object... parameters) {
Connection connection = null;
try {
connection = JDBCUtilsByDruid.getConnection();
return qr.query(connection, sql, new BeanListHandler<T>(clazz), parameters);
} catch (SQLException e) {
throw new RuntimeException(e); //将编译异常->运行异常 ,抛出
} finally {
JDBCUtilsByDruid.close(null, null, connection);
}
}
//查询单行结果 的通用方法
public T querySingle(String sql, Class<T> clazz, Object... parameters) {
Connection connection = null;
try {
connection = JDBCUtilsByDruid.getConnection();
return qr.query(connection, sql, new BeanHandler<T>(clazz), parameters);
} catch (SQLException e) {
throw new RuntimeException(e); //将编译异常->运行异常 ,抛出
} finally {
JDBCUtilsByDruid.close(null, null, connection);
}
}
//查询单行单列的方法,即返回单值的方法
public Object queryScalar(String sql, Object... parameters) {
Connection connection = null;
try {
connection = JDBCUtilsByDruid.getConnection();
return qr.query(connection, sql, new ScalarHandler(), parameters);
} catch (SQLException e) {
throw new RuntimeException(e); //将编译异常->运行异常 ,抛出
} finally {
JDBCUtilsByDruid.close(null, null, connection);
}
}
}
ActorDAO
public class ActorDAO extends BasicDAO<Actor> {
//1. 就有 BasicDAO 的方法
//2. 根据业务需求,可以编写特有的方法.
}
测试类
//测试 ActorDAO 对 actor 表 crud 操作
@Test
public void testActorDAO() {
ActorDAO actorDAO = new ActorDAO();
//1. 查询
List<Actor> actors = actorDAO.queryMulti("select * from actor where id >= ?", Actor.class, 1);
System.out.println("===查询结果===");
for (Actor actor : actors) {
System.out.println(actor);
}
//2. 查询单行记录
Actor actor = actorDAO.querySingle("select * from actor where id = ?", Actor.class, 6);
System.out.println("====查询单行结果====");
System.out.println(actor);
//3. 查询单行单列
Object o = actorDAO.queryScalar("select name from actor where id = ?", 6);
System.out.println("====查询单行单列值===");
System.out.println(o);
//4. dml 操作 insert ,update, delete
int update = actorDAO.update("insert into actor values(null, ?, ?, ?, ?)", "张无忌", "男", "2000-11-11", "999");
System.out.println(update > 0 ? "执行成功" : "执行没有影响表");
}