Java之JDBC工具类DBUtils的使用

工程目录结构如下：

自定义工具类-JDBCUtils_03.java：

package com.xiao.utils;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Properties;
/**
* @author 笑笑
* @Date   2018年3月15日下午2:38:39
*
*/
//通过加载properties文件来连接数据库的方式二
public class JDBCUtils_03 {
private static String driver;
private static String url;
private static String username;
private static String password;
/**
* 静态代码块加载配置文件信息
*/
static {
try {
// 1.通过当前类获取类加载器
ClassLoader classLoader = JDBCUtils_03.class.getClassLoader();
// 2.通过类加载器的方法获得一个输入流
InputStream in = classLoader.getResourceAsStream("jdbc.properties");
// 3.创建一个properties对象(集合)
Properties props = new Properties();
// 4.加载输入流
props.load(in);
// 5.获取相关参数的值
driver = props.getProperty("driver");
url = props.getProperty("url");
username = props.getProperty("username");
password = props.getProperty("password");
} catch (IOException e) {
e.printStackTrace();
}

}
//注册并获取数据库连接
public static Connection getConnection() throws Exception{
//1.注册驱动
Class.forName(driver);
//2.获取数据库连接
Connection cn =  DriverManager.getConnection(url, username, password);
return cn;
}
//释放资源
public static void relase(Connection cn,Statement st,ResultSet rs) throws Exception{
if(rs!=null){
rs.close();
}
if(st!=null){
st.close();
}
if(cn!=null){
cn.close();
}
}

}

DButils测试类-QueryRunnerDemo.java：

package com.xiao.DButilsTest;

import java.sql.Connection;
import java.util.List;
import java.util.Map;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.ArrayHandler;
import org.apache.commons.dbutils.handlers.ArrayListHandler;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.ColumnListHandler;
import org.apache.commons.dbutils.handlers.MapHandler;
import org.apache.commons.dbutils.handlers.MapListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;
import org.junit.Test;
import com.xiao.pojo.User;
import com.xiao.utils.JDBCUtils_03;
/**
* @author 笑笑
* @Date   2018年3月16日上午11:54:46
*
*/
public class QueryRunnerDemo {

//添加数据,使用QueryRunner类的update方法
@Test
public void addUser() throws Exception{
//JDBCUtils_03工具类获取数据库连接
Connection cn = JDBCUtils_03.getConnection();
//创建QueryRunner类的对象
QueryRunner qr = new QueryRunner();
//书写SQL语句
String sql = "insert into user_tb values(?,?,?,?,?,?)";
//将？占位符的实际参数写在数组中
Object[] params = {0,"笑笑","123456",23,"男","123@123.com"};
//调用update执行SQL语句
int row = qr.update(cn, sql, params);
if(row > 0){
System.out.println("添加用户成功！");
}else{
System.out.println("添加用户失败！");
}
//释放资源
JDBCUtils_03.relase(cn, null, null);
}

//修改数据
@Test
public void updateUser() throws Exception{
//JDBCUtils_03工具类获取数据库连接
Connection cn = JDBCUtils_03.getConnection();
//创建QueryRunner类的对象
QueryRunner qr = new QueryRunner();
//书写SQL语句
String sql = "update user_tb set username = ? where uid = ?";
//定义参数数组
Object[] params = {"我爱笑笑",1};
//执行SQL语句
int row = qr.update(cn, sql, params);
if(row > 0){
System.out.println("修改成功！");
}else{
System.out.println("修改失败！");
}
//释放资源
JDBCUtils_03.relase(cn, null, null);
}

//删除数据
@Test
public void removeUser() throws Exception{
//JDBCUtils_03工具类获取数据库连接
Connection cn = JDBCUtils_03.getConnection();
//创建QueryRunner类的对象
QueryRunner qr = new QueryRunner();
//书写SQL语句
String sql = "delete from user_tb where uid = ?";
//只有一个参数，可以直接调用update方法执行
int row = qr.update(cn, sql, 1);
if(row > 0){
System.out.println("删除成功！");
}else{
System.out.println("删除失败！");
}
//释放资源
JDBCUtils_03.relase(cn, null, null);
}

//查询数据，使用QueryRunner类的query方法
//ArrayHandler,将结果集的第一条数据存储到一个对象数组中,数组中的每个值对应此条数据的每个字段值
@Test
public void arrayHandler() throws Exception{
//JDBCUtils_03工具类获取数据库连接
Connection cn = JDBCUtils_03.getConnection();
//创建QueryRunner类的对象
QueryRunner qr = new QueryRunner();
//书写SQL语句
String sql = "select * from user_tb";
//调用query方法执行查询
Object[] result = qr.query(cn, sql, new ArrayHandler());
//增强for遍历数组
for (Object object : result) {
System.out.print(object+"\t");
}
//释放资源
JDBCUtils_03.relase(cn, null, null);
}

//ArrayListHandler,将结果集的每一条数据存储到对象数组中，将对象数组存储到List集合中
@Test
public void arrayListHandler() throws Exception{
//JDBCUtils_03工具类获取数据库连接
Connection cn = JDBCUtils_03.getConnection();
//创建QueryRunner类的对象
QueryRunner qr = new QueryRunner();
//书写SQL语句
String sql = "select * from user_tb";
//调用query方法执行查询
List<Object[]> result = qr.query(cn, sql, new ArrayListHandler());
//增强for遍历数组,外层循环遍历集合，内层循环遍历数组
for (Object[] objects : result) {
for (Object object : objects) {
System.out.print(object+"\t");
}
System.out.println();
}
//释放资源
JDBCUtils_03.relase(cn, null, null);
}

//BeanHandler,将结果集的第一条数据封装成JavaBean对象，被封装的对象必须要有空参构造
@Test
public void beanHandler()throws Exception{
//JDBCUtils_03工具类获取数据库连接
Connection cn = JDBCUtils_03.getConnection();
//创建QueryRunner类的对象
QueryRunner qr = new QueryRunner();
//书写SQL语句
String sql = "select * from user_tb where uid = ?";
//执行SQL语句,结果集的第一条数据封装到User对象
User user = qr.query(cn, sql, new BeanHandler<>(User.class),12);
System.out.println(user);
//释放资源
JDBCUtils_03.relase(cn, null, null);
}

//BeanListHandler,将结果集的每一条数据封装成JavaBean对象 ，将JavaBean对象放入List集合中
@Test
public void beanListHandler()throws Exception{
//JDBCUtils_03工具类获取数据库连接
Connection cn = JDBCUtils_03.getConnection();
//创建QueryRunner类的对象
QueryRunner qr = new QueryRunner();
//书写SQL语句
String sql = "select * from user_tb";
//执行SQL语句,结果集的每一条数据封装到User对象
List<User> list = qr.query(cn, sql, new BeanListHandler<>(User.class));
//增强for遍历集合
for (User user : list) {
System.out.println(user);
}
//释放资源
JDBCUtils_03.relase(cn, null, null);
}

//ColumnListHandler,将结果集中指定的列的字段值，封装到List集合中
@Test
public void columnListHandler() throws Exception{
//JDBCUtils_03工具类获取数据库连接
Connection cn = JDBCUtils_03.getConnection();
//创建QueryRunner类的对象
QueryRunner qr = new QueryRunner();
//书写SQL语句
String sql = "select * from user_tb";
//执行SQL语句,用列名做参数
List<Object> list = qr.query(cn, sql, new ColumnListHandler<>("username"));
//遍历集合
for (Object object : list) {
System.out.println(object);
}
//释放资源
JDBCUtils_03.relase(cn, null, null);
}

//ScalarHandler,用于只有一个数据结果的，如聚合函数：count
@Test
public void scalarHandler()throws Exception{
//JDBCUtils_03工具类获取数据库连接
Connection cn = JDBCUtils_03.g
4000
etConnection();
//创建QueryRunner类的对象
QueryRunner qr = new QueryRunner();
//书写SQL语句
String sql = "select count(*) from user_tb";
//执行SQL语句
long count = qr.query(cn, sql, new ScalarHandler<Long>());
System.out.println(count);
//释放资源
JDBCUtils_03.relase(cn, null, null);
}

//MapHandler,将结果集的第一条数据封装到Map集合
@Test
public void mapHandler()throws Exception{
//JDBCUtils_03工具类获取数据库连接
Connection cn = JDBCUtils_03.getConnection();
//创建QueryRunner类的对象
QueryRunner qr = new QueryRunner();
//书写SQL语句
String sql = "select * from user_tb";
//执行SQL语句
Map<String, Object> map = qr.query(cn, sql, new MapHandler());
//遍历Map集合
for(String key:map.keySet()){
System.out.println(key+"  "+map.get(key));
}
//释放资源
JDBCUtils_03.relase(cn, null, null);
}

//MapListHandler,将结果集的每一条数据封装到Map集合中，再将Map集合放入List集合中
@Test
public void mapListHandler()throws Exception{
//JDBCUtils_03工具类获取数据库连接
Connection cn = JDBCUtils_03.getConnection();
//创建QueryRunner类的对象
QueryRunner qr = new QueryRunner();
//书写SQL语句
String sql = "select * from user_tb";
//执行SQL语句
List<Map<String,Object>> list = qr.query(cn, sql, new MapListHandler());
//遍历，外层循环遍历List集合，内层循环遍历Map集合
for(Map<String,Object>map:list){
for(String key:map.keySet()){
System.out.println(key+"  "+map.get(key));
}
System.out.println();
}
//释放资源
JDBCUtils_03.relase(cn, null, null);
}
}

User类：

package com.xiao.pojo;

/**
* @author 笑笑
* @Date   2018年3月15日上午9:20:28
*
*/
public class User {

private int uid = 0;
private String username = null;
private String password = null;
private int age = 0;
private String gender = null;
private String email = null;

//空参构造器
public User() {
}
//有参构造器
public User(int uid, String username, String password, int age, String gender, String email) {
this.uid = uid;
this.username = username;
this.password = password;
this.age = age;
this.gender = gender;
this.email = email;
}
public int getUid() {
return uid;
}
public void setUid(int uid) {
this.uid = uid;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
//重写toString
@Override
public String toString() {
return "User [uid=" + uid + ", username=" + username + ", password=" + password + ", age=" + age + ", gender="
+ gender + ", email=" + email + "]";
}

}

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/all_db?useUnicode=true&characterEncoding=utf8
username=root
password=root