DBHelper代码
这一楼的代码非常好。可以制作一个DBHelper类，专门派回数据库连接对象。
建议把这个代码分成两个类，一个类作为“数据库连接对象”，把数据库操作方法做成一个方法类，这样比较灵活。
以下代码为MySQL版本，
String driver = "com.mysql.jdbc.Driver"; // 数据库驱动
如果是SQLite数据库请使用：String driver = "org.sqlite.JDBC"; // 数据库驱动
以下是代码开始：
package com.hebut.util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public final class DBHelper {
// 此方法为获取数据库连接
public static Connection getConnection() {
Connection conn = null;
try {
String driver = "com.mysql.jdbc.Driver"; // 数据库驱动
String url = "jdbc:MySQL://127.0.0.1:3306/school";// 数据库
String user = "root"; // 用户名
String password = "hadoop"; // 密码
Class.forName(driver); // 加载数据库驱动
if (null == conn) {
conn = DriverManager.getConnection(url, user, password);
}
} catch (ClassNotFoundException e) {
System.out.println("Sorry,can't find the Driver!");
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
return conn;
}
/**
* 增删改【Add、Del、Update】
*
* @param sql
* @return int
*/
public static int executeNonQuery(String sql) {
int result = 0;
Connection conn = null;
Statement stmt = null;
try {
conn = getConnection();
stmt = conn.createStatement();
result = stmt.executeUpdate(sql);
} catch (SQLException err) {
err.printStackTrace();
free(null, stmt, conn);
} finally {
free(null, stmt, conn);
}
return result;
}
/**
* 增删改【Add、Delete、Update】
*
* @param sql
* @param obj
* @return int
*/
public static int executeNonQuery(String sql, Object... obj) {
int result = 0;
Connection conn = null;
PreparedStatement pstmt = null;
try {
conn = getConnection();
pstmt = conn.prepareStatement(sql);
for (int i = 0; i < obj.length; i++) {
pstmt.setObject(i + 1, obj);
}
result = pstmt.executeUpdate();
} catch (SQLException err) {
err.printStackTrace();
free(null, pstmt, conn);
} finally {
free(null, pstmt, conn);
}
return result;
}
/**
* 查【Query】
*
* @param sql
* @return ResultSet
*/
public static ResultSet executeQuery(String sql) {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
try {
conn = getConnection();
stmt = conn.createStatement();
rs = stmt.executeQuery(sql);
} catch (SQLException err) {
err.printStackTrace();
free(rs, stmt, conn);
}
return rs;
}
/**
* 查【Query】
*
* @param sql
* @param obj
* @return ResultSet
*/
public static ResultSet executeQuery(String sql, Object... obj) {
Connection conn = null;
PreparedStatement pstmt = null;
ResultSet rs = null;
try {
conn = getConnection();
pstmt = conn.prepareStatement(sql);
for (int i = 0; i < obj.length; i++) {
pstmt.setObject(i + 1, obj);
}
rs = pstmt.executeQuery();
} catch (SQLException err) {
err.printStackTrace();
free(rs, pstmt, conn);
}
return rs;
}
/**
* 判断记录是否存在
*
* @param sql
* @return Boolean
*/
public static Boolean isExist(String sql) {
ResultSet rs = null;
try {
rs = executeQuery(sql);
rs.last();
int count = rs.getRow();
if (count > 0) {
return true;
} else {
return false;
}
} catch (SQLException err) {
err.printStackTrace();
free(rs);
return false;
} finally {
free(rs);
}
}
/**
* 判断记录是否存在
*
* @param sql
* @return Boolean
*/
public static Boolean isExist(String sql, Object... obj) {
ResultSet rs = null;
try {
rs = executeQuery(sql, obj);
rs.last();
int count = rs.getRow();
if (count > 0) {
return true;
} else {
return false;
}
} catch (SQLException err) {
err.printStackTrace();
free(rs);
return false;
} finally {
free(rs);
}
}
/**
* 获取查询记录的总行数
*
* @param sql
* @return int
*/
public static int getCount(String sql) {
int result = 0;
ResultSet rs = null;
try {
rs = executeQuery(sql);
rs.last();
result = rs.getRow();
} catch (SQLException err) {
free(rs);
err.printStackTrace();
} finally {
free(rs);
}
return result;
}
/**
* 获取查询记录的总行数
*
* @param sql
* @param obj
* @return int
*/
public static int getCount(String sql, Object... obj) {
int result = 0;
ResultSet rs = null;
try {
rs = executeQuery(sql, obj);
rs.last();
result = rs.getRow();
} catch (SQLException err) {
err.printStackTrace();
} finally {
free(rs);
}
return result;
}
/**
* 释放【ResultSet】资源
*
* @param rs
*/
public static void free(ResultSet rs) {
try {
if (rs != null) {
rs.close();
}
} catch (SQLException err) {
err.printStackTrace();
}
}
/**
* 释放【Statement】资源
*
* @param st
*/
public static void free(Statement st) {
try {
if (st != null) {
st.close();
}
} catch (SQLException err) {
err.printStackTrace();
}
}
/**
* 释放【Connection】资源
*
* @param conn
*/
public static void free(Connection conn) {
try {
if (conn != null) {
conn.close();
}
} catch (SQLException err) {
err.printStackTrace();
}
}
/**
* 释放所有数据资源
*
* @param rs
* @param st
* @param conn
*/
public static void free(ResultSet rs, Statement st, Connection conn) {
free(rs);
free(st);
free(conn);
}
}
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