《文件读写到SQLite数据库的方法》博客中，介绍了文件读写到SQLite数据库的方法，例子使用的Python语言，本文是使用 C# 将文件读写到 SQLite 数据库的几种方法的具体示例，如果有些概念模糊可参考作者以前博客。
1. 使用 BLOB 存储文件
示例代码：
cs
using System;
using System.Data.SQLite;
using System.IO;
class Program
{
static void Main(string[] args)
{
string databasePath = "example.db";
string connectionString = $"Data Source={databasePath};Version=3;";
// 创建数据库和表
using (var connection = new SQLiteConnection(connectionString))
{
connection.Open();
string createTableQuery = @"
CREATE TABLE IF NOT EXISTS Files (
id INTEGER PRIMARY KEY AUTOINCREMENT,
name TEXT NOT NULL,
data BLOB NOT NULL
);";
using (var command = new SQLiteCommand(createTableQuery, connection))
{
command.ExecuteNonQuery();
}
}
// 插入文件到数据库
string filePath = "example.pdf"; // 替换为你的文件路径
InsertFile(filePath, connectionString);
// 从数据库读取文件
ReadFile(1, connectionString); // 假设读取 ID 为 1 的文件
}
static void InsertFile(string filePath, string connectionString)
{
byte[] fileData = File.ReadAllBytes(filePath);
string fileName = Path.GetFileName(filePath);
using (var connection = new SQLiteConnection(connectionString))
{
connection.Open();
string insertQuery = "INSERT INTO Files (name, data) VALUES (@name, @data)";
using (var command = new SQLiteCommand(insertQuery, connection))
{
command.Parameters.AddWithValue("@name", fileName);
command.Parameters.AddWithValue("@data", fileData);
command.ExecuteNonQuery();
}
}
Console.WriteLine($"File '{fileName}' has been saved to the database.");
}
static void ReadFile(int fileId, string connectionString)
{
using (var connection = new SQLiteConnection(connectionString))
{
connection.Open();
string selectQuery = "SELECT name, data FROM Files WHERE id = @id";
using (var command = new SQLiteCommand(selectQuery, connection))
{
command.Parameters.AddWithValue("@id", fileId);
using (var reader = command.ExecuteReader())
{
if (reader.Read())
{
string fileName = reader.GetString(0);
byte[] fileData = (byte[])reader["data"];
File.WriteAllBytes(fileName, fileData);
Console.WriteLine($"File '{fileName}' has been restored from the database.");
}
}
}
}
}
}2. 存储文件路径
示例代码：
cs
using System;
using System.Data.SQLite;
class Program
{
static void Main(string[] args)
{
string databasePath = "example.db";
string connectionString = $"Data Source={databasePath};Version=3;";
// 创建数据库和表
using (var connection = new SQLiteConnection(connectionString))
{
connection.Open();
string createTableQuery = @"
CREATE TABLE IF NOT EXISTS FilePaths (
id INTEGER PRIMARY KEY AUTOINCREMENT,
name TEXT NOT NULL,
path TEXT NOT NULL
);";
using (var command = new SQLiteCommand(createTableQuery, connection))
{
command.ExecuteNonQuery();
}
}
// 插入文件路径
string filePath = "example.pdf"; // 替换为你的文件路径
InsertFilePath(filePath, connectionString);
// 从数据库读取文件路径
GetFilePath(1, connectionString); // 假设读取 ID 为 1 的文件路径
}
static void InsertFilePath(string filePath, string connectionString)
{
string fileName = System.IO.Path.GetFileName(filePath);
using (var connection = new SQLiteConnection(connectionString))
{
connection.Open();
string insertQuery = "INSERT INTO FilePaths (name, path) VALUES (@name, @path)";
using (var command = new SQLiteCommand(insertQuery, connection))
{
command.Parameters.AddWithValue("@name", fileName);
command.Parameters.AddWithValue("@path", filePath);
command.ExecuteNonQuery();
}
}
Console.WriteLine($"File path '{filePath}' has been saved to the database.");
}
static void GetFilePath(int fileId, string connectionString)
{
using (var connection = new SQLiteConnection(connectionString))
{
connection.Open();
string selectQuery = "SELECT name, path FROM FilePaths WHERE id = @id";
using (var command = new SQLiteCommand(selectQuery, connection))
{
command.Parameters.AddWithValue("@id", fileId);
using (var reader = command.ExecuteReader())
{
if (reader.Read())
{
string fileName = reader.GetString(0);
string filePath = reader.GetString(1);
Console.WriteLine($"File '{fileName}' is located at '{filePath}'.");
}
}
}
}
}
}3. 分块存储文件
示例代码：
cs
using System;
using System.Data.SQLite;
using System.IO;
class Program
{
static void Main(string[] args)
{
string databasePath = "example.db";
string connectionString = $"Data Source={databasePath};Version=3;";
// 创建数据库和表
using (var connection = new SQLiteConnection(connectionString))
{
connection.Open();
string createTableQuery = @"
CREATE TABLE IF NOT EXISTS FileChunks (
id INTEGER PRIMARY KEY AUTOINCREMENT,
file_id INTEGER NOT NULL,
chunk_index INTEGER NOT NULL,
chunk_data BLOB NOT NULL
);";
using (var command = new SQLiteCommand(createTableQuery, connection))
{
command.ExecuteNonQuery();
}
}
// 插入文件分块
string filePath = "example.pdf"; // 替换为你的文件路径
InsertFileChunks(filePath, 1, connectionString); // 假设文件 ID 为 1
// 重新组装文件
ReassembleFile(1, "output.pdf", connectionString); // 输出为 output.pdf
}
static void InsertFileChunks(string filePath, int fileId, string connectionString)
{
int chunkSize = 1024 * 1024; // 每块大小为 1MB
byte[] buffer = new byte[chunkSize];
int chunkIndex = 0;
using (var fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read))
using (var connection = new SQLiteConnection(connectionString))
{
connection.Open();
string insertQuery = "INSERT INTO FileChunks (file_id, chunk_index, chunk_data) VALUES (@file_id, @chunk_index, @chunk_data)";
using (var command = new SQLiteCommand(insertQuery, connection))
{
int bytesRead;
while ((bytesRead = fileStream.Read(buffer, 0, chunkSize)) > 0)
{
byte[] chunkData = new byte[bytesRead];
Array.Copy(buffer, chunkData, bytesRead);
command.Parameters.Clear();
command.Parameters.AddWithValue("@file_id", fileId);
command.Parameters.AddWithValue("@chunk_index", chunkIndex++);
command.Parameters.AddWithValue("@chunk_data", chunkData);
command.ExecuteNonQuery();
}
}
}
Console.WriteLine($"File '{filePath}' has been stored in chunks.");
}
static void ReassembleFile(int fileId, string outputPath, string connectionString)
{
using (var connection = new SQLiteConnection(connectionString))
{
connection.Open();
string selectQuery = "SELECT chunk_data FROM FileChunks WHERE file_id = @file_id ORDER BY chunk_index";
using (var command = new SQLiteCommand(selectQuery, connection))
{
command.Parameters.AddWithValue("@file_id", fileId);
using (var reader = command.ExecuteReader())
using (var outputFile = new FileStream(outputPath, FileMode.Create, FileAccess.Write))
{
while (reader.Read())
{
byte[] chunkData = (byte[])reader["chunk_data"];
outputFile.Write(chunkData, 0, chunkData.Length);
}
}
}
}
Console.WriteLine($"File has been reassembled to '{outputPath}'.");
}
}