学步园

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Security.Cryptography;
using System.IO;
using System.Threading;

namespace FileMD5 {
public partial class MainForm : Form {
public MainForm() {
InitializeComponent();
}

private void button_file_Click(object sender, EventArgs e) {
OpenFileDialog fileDialog = new OpenFileDialog();
fileDialog.Title = "请选择文件";
fileDialog.RestoreDirectory = true;

if (fileDialog.ShowDialog() == DialogResult.OK) {
textBox_file.Text = fileDialog.FileName;
textBox_result.Text = "";
FileInfo file = new FileInfo(fileDialog.FileName);
fileSzie = file.Length;
showFilesize(fileSzie);
}

}

private void button_exit_Click(object sender, EventArgs e) {
this.Close();
this.Dispose();
}

private void button_check_Click(object sender, EventArgs e) {
checkResult();
}

MD5 md5 = (MD5)CryptoConfig.CreateFromName("MD5");
long fileSzie = 0;

private void button_calc_Click(object sender, EventArgs e) {
string file = textBox_file.Text;

if (file.Length == 0) {
textBox_result.Text = "请先重新选择文件!";
return;
}

FileStream fs = null;
try {
fs = new FileStream(file, FileMode.Open, FileAccess.Read);
} catch (SystemException) {
textBox_result.Text = "文件打开错误,请重新选择文件!";
return;
}

//对于大于 100M 的文件启用多线程
if (fs.Length > 100L * 1024 * 1024) {

string message = "文件已经超过 100M ，需要较长的计算时间。\n软件将启动后台线程进行处理。是否继续？";
string caption = "文件较大";
MessageBoxButtons buttons = MessageBoxButtons.YesNo;

if (MessageBox.Show(message, caption, buttons) == System.Windows.Forms.DialogResult.No) {
fs.Close();
textBox_result.Text = "文件较大，未计算。";
return;
}
textBox_result.Text = "正在计算中，请稍候......";
button_calc.Enabled = false;
button_file.Enabled = false;

Thread thread = new Thread(new ParameterizedThreadStart(calcMD5));
thread.Start(fs);

} else {
calcMD5(fs);
}
}

//建立一个 object 参数的函数，是为了处理线程调用中，使用参数的问题。
private void calcMD5(object fs) {
calcMD5((FileStream)fs);
}

// Invoke 函数需要使用的委托
delegate void updateWindows(byte[] result);

private void calcMD5(FileStream fs) {
byte[] md5byte = md5.ComputeHash(fs);

if (this.InvokeRequired) {
this.Invoke(new updateWindows(showResult), md5byte);
} else {
showResult(md5byte);
}
fs.Close();
}

private void showResult(byte[] md5byte) {
int i, j;
StringBuilder sb = new StringBuilder(32);
foreach (byte b in md5byte) {
i = Convert.ToInt32(b);
j = i >> 4;
sb.Append(Convert.ToString(j, 16));
j = ((i << 4) & 0x00ff) >> 4;
sb.Append(Convert.ToString(j, 16));
}

String result = sb.ToString().ToUpper();

textBox_result.Text = result;
button_calc.Enabled = true;
button_file.Enabled = true;
checkResult();

}

private void checkResult() {

string result = textBox_result.Text;

if (textBox_md5.Text.Length == 0) {
textBox_compare.Text = "";
textBox_compare.Visible = false;
return;
}

if(result.Length != 32 ) {
textBox_compare.Visible = true;
textBox_compare.BackColor = Color.Pink;
textBox_compare.Text = "计算结果框中不是MD5码，请先进行计算！";
return;
}

if (textBox_md5.Text.Trim().ToUpper().Equals(result.ToUpper())) {
textBox_compare.Visible = true;
textBox_compare.BackColor = Color.LightGreen;
textBox_compare.Text = "MD5码 已匹配，文件未被修改，可放心使用！";
} else {
textBox_compare.Visible = true;
textBox_compare.BackColor = Color.Red;
textBox_compare.Text = "MD5码 不匹配，文件已被修改，请小心！";
}
}

private void showFilesize(long size) {

float d_size;
string unit = "Byte";

if (size > 1024 * 1024 * 1024) { //大于 1G 的显示
d_size = size / (float)(1024 * 1024 * 1024);
unit = "GB";
} else {
if (size > 1024 * 1024) { //大于 1M 的显示
d_size = size / (float)(1024 * 1024);
unit = "MB";
} else {
if (size > 1024) { //大于 1K 的显示
d_size = size / (float)(1024);
unit = "KB";
} else {
d_size = size;
}
}
}
textBox_filesize.Text = string.Format(" {0:F} {1} ( {2:N0}字节 )", d_size, unit, size);
}
}
}