Java通用的数据库增删改查方法
潘俊楚
JdbcUtils
#阿里巴巴Druid数据库连接池配置
username=root
password=root
url=jdbc:mysql://localhost:3306/database?useSSL=true&allowPublicKeyRetrieval=true&serverTimezone=UTC&useUnicode=true&characterEncoding=utf8
driverClassName=com.mysql.cj.jdbc.Driver
initialSize=10
maxActive=10
#自定义数据库连接配置
username=root
password=root
url=jdbc:mysql://localhost:3306/database?useSSL=true&allowPublicKeyRetrieval=true&serverTimezone=UTC&useUnicode=true&characterEncoding=utf8
driver=com.mysql.cj.jdbc.Driver
package utils;
import com.alibaba.druid.pool.DruidDataSourceFactory;
import javax.sql.DataSource;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;
public class JdbcUtils {
/*
static String username;
static String password;
static String url;
static String driver;
*/
private static DataSource source;
//静态代码块中加载配置文件
static {
try {
//阿里巴巴Druid数据库连接池使用
InputStream in = ClassLoader.getSystemClassLoader().getResourceAsStream("druid.properties");
Properties properties = new Properties();
properties.load(in);
source= DruidDataSourceFactory.createDataSource(properties);
/*
//自定义数据库连接使用
InputStream in = JdbcUtils.class.getClassLoader().getResourceAsStream("db.properties");
Properties properties = new Properties();
properties.load(in);
driver = properties.getProperty("driver");
url = properties.getProperty("url");
username = properties.getProperty("username");
password = properties.getProperty("password");
Class.forName(driver);
*/
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 获取连接
*
* @return
* @throws SQLException
*/
public static Connection getConnection() throws SQLException {
// return DriverManager.getConnection(url,username,password);
return source.getConnection();
}
/**
* 释放资源
* @param conn
* @param ps
* @param rs
*/
public static void release(Connection conn, PreparedStatement ps, ResultSet rs) {
if (rs != null) {
try {
rs.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
if (ps != null) {
try {
ps.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
if (conn != null) {
try {
conn.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
}
}
Dao
不考虑事务处理
package dao;
import utils.JdbcUtils;
import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.util.ArrayList;
import java.util.List;
/**
* 封装了对于数据表的通用操作
* 声明为抽象类，不再对其进行更改
*/
public abstract class BaseDao<T> {
private Class<T> clazz = null;
//在静态代码块中利用反射获取父类的泛型
{
Type genericSuperclass = this.getClass().getGenericSuperclass();
ParameterizedType paramType = (ParameterizedType) genericSuperclass;
Type[] TypeArguments = paramType.getActualTypeArguments();
clazz = (Class<T>) TypeArguments[0];
}
/**
* 通用的增删改操作
*/
public int update(String sql, Object... args) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
int x = 0;
try {
conn = JdbcUtils.getConnection();
ps = conn.prepareStatement(sql);
for (int i = 0; i < args.length; i++) {
ps.setString(i + 1, (String) args[i]);
}
x = ps.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
} finally {
JdbcUtils.release(conn, ps, rs);
}
return x;
}
/**
* 通用的查询操作，用于返回数据表中的单条记录
*/
public T getInstance(String sql, Object... args) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = JdbcUtils.getConnection();
ps = conn.prepareStatement(sql);
for (int i = 0; i < args.length; i++) {
ps.setString(i + 1, (String) args[i]);
}
rs = ps.executeQuery();
ResultSetMetaData rsmd = rs.getMetaData();
int columnCount = rsmd.getColumnCount();
if (rs.next()) {
T t = clazz.newInstance();
for (int i = 0; i < columnCount; i++) {
Object columnValue = rs.getObject(i + 1);
String columnLabel = rsmd.getColumnLabel(i + 1);
Field field = clazz.getDeclaredField(columnLabel);
field.setAccessible(true);
field.set(t, columnValue);
}
return t;
}
} catch (Exception e) {
e.printStackTrace();
} finally {
JdbcUtils.release(conn, ps, rs);
}
return null;
}
/**
* 通用的查询操作，用于返回数据表中的多条记录构成的集合
*/
public List<T> getForList(String sql, Object... args) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = JdbcUtils.getConnection();
ps = conn.prepareStatement(sql);
for (int i = 0; i < args.length; i++) {
ps.setString(i + 1, (String) args[i]);
}
rs = ps.executeQuery();
ResultSetMetaData rsmd = rs.getMetaData();
int columnCount = rsmd.getColumnCount();
ArrayList<T> list = new ArrayList<>();
while (rs.next()) {
T t = clazz.newInstance();
for (int i = 0; i < columnCount; i++) {
Object columnValue = rs.getObject(i + 1);
String columnLabel = rsmd.getColumnLabel(i + 1);
Field field = clazz.getDeclaredField(columnLabel);
field.setAccessible(true);
field.set(t, columnValue);
}
list.add(t);
}
return list;
} catch (Exception e) {
e.printStackTrace();
} finally {
JdbcUtils.release(conn, ps, rs);
}
return null;
}
/**
* 查询特殊值的通用方法
*/
public T getValue(String sql, Object... args) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = JdbcUtils.getConnection();
ps = conn.prepareStatement(sql);
for (int i = 0; i < args.length; i++) {
ps.setObject(i + 1, (String) args[i]);
}
rs = ps.executeQuery();
if (rs.next()) {
return (T) rs.getObject(1);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
JdbcUtils.release(conn, ps, rs);
}
return null;
}
}
考虑事务处理
package dao2;
import utils.JdbcUtils;
import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.util.ArrayList;
import java.util.List;
/**
* 封装了对于数据表的通用操作(考虑了事务操作)
* 声明为抽象类，不再对其进行更改
*/
public abstract class BaseDao<T> {
private Class<T> clazz = null;
//在静态代码块中利用反射获取父类的泛型
{
Type genericSuperclass = this.getClass().getGenericSuperclass();
ParameterizedType paramType = (ParameterizedType) genericSuperclass;
Type[] TypeArguments = paramType.getActualTypeArguments();
clazz = (Class<T>) TypeArguments[0];
}
/**
* 通用的增删改操作
*/
public int update(Connection conn, String sql, Object... args) {
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = JdbcUtils.getConnection();
ps = conn.prepareStatement(sql);
for (int i = 0; i < args.length; i++) {
ps.setString(i + 1, (String) args[i]);
}
return ps.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
} finally {
JdbcUtils.release(null, ps, rs);
}
return 0;
}
/**
* 通用的查询操作，用于返回数据表中的单条记录
*/
public T getInstance(Connection conn, String sql, Object... args) {
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = JdbcUtils.getConnection();
ps = conn.prepareStatement(sql);
for (int i = 0; i < args.length; i++) {
ps.setString(i + 1, (String) args[i]);
}
rs = ps.executeQuery();
ResultSetMetaData rsmd = rs.getMetaData();
int columnCount = rsmd.getColumnCount();
if (rs.next()) {
T t = clazz.newInstance();
for (int i = 0; i < columnCount; i++) {
Object columnValue = rs.getObject(i + 1);
String columnLabel = rsmd.getColumnLabel(i + 1);
Field field = clazz.getDeclaredField(columnLabel);
field.setAccessible(true);
field.set(t, columnValue);
}
return t;
}
} catch (Exception e) {
e.printStackTrace();
} finally {
JdbcUtils.release(null, ps, rs);
}
return null;
}
/**
* 通用的查询操作，用于返回数据表中的多条记录构成的集合
*/
public List<T> getForList(Connection conn, String sql, Object... args) {
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = JdbcUtils.getConnection();
ps = conn.prepareStatement(sql);
for (int i = 0; i < args.length; i++) {
ps.setString(i + 1, (String) args[i]);
}
rs = ps.executeQuery();
ResultSetMetaData rsmd = rs.getMetaData();
int columnCount = rsmd.getColumnCount();
ArrayList<T> list = new ArrayList<>();
while (rs.next()) {
T t = clazz.newInstance();
for (int i = 0; i < columnCount; i++) {
Object columnValue = rs.getObject(i + 1);
String columnLabel = rsmd.getColumnLabel(i + 1);
Field field = clazz.getDeclaredField(columnLabel);
field.setAccessible(true);
field.set(t, columnValue);
}
list.add(t);
}
return list;
} catch (Exception e) {
e.printStackTrace();
} finally {
JdbcUtils.release(null, ps, rs);
}
return null;
}
/**
* 查询特殊值的通用方法
*/
public T getValue(Connection conn, String sql, Object... args) {
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = JdbcUtils.getConnection();
ps = conn.prepareStatement(sql);
for (int i = 0; i < args.length; i++) {
ps.setObject(i + 1, (String) args[i]);
}
rs = ps.executeQuery();
if (rs.next()) {
return (T) rs.getObject(1);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
JdbcUtils.release(null, ps, rs);
}
return null;
}
}
DButils工具包是apache写的官方的、封装了对数据库进行增删改查方法的包
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