文件上传的步骤: 打开websocket--连接websocket服务器--在浏览器里选择文件--将文件读入到内存中(以arraybuffer的形式)--在socket里发送文件--完毕!
服务器端:
先配置好websocket的服务器, 这里用一个java的开源websocket服务器: Java-WebSocket
根据该项目的快速教程可以建立一个websocket服务器, 就是里面的一个ChatServer.java文件. 一个聊天室服务器.
客户端(html):
1.建立连接
ws = new WebSocket($("#uri").val());
//连接成功建立后响应
ws.onopen = function() {
}
//收到服务器消息后响应
ws.onmessage = function(e) {
}
//连接关闭后响应
ws.onclose = function() {
ws = null;
}
2.读取并发送文件
var inputElement = document.getElementById("file");
var file = inputElement.files;
var reader = new FileReader();
//以二进制形式读取文件
reader.readAsArrayBuffer(file);
//文件读取完毕后该函数响应
reader.onload = function loaded(evt) {
var binaryString = evt.target.result;
//发送文件
ws.send(binaryString);
}
3. 服务端响应:
public void onMessage(WebSocket conn, byte[] message) {
//saveFileFromBytes
System.out.println("收到2进制流");
}
在服务端响应并保存文件, 文件传送完毕!
未完善的地方:
1. 多个文件读取, file标签中加入"multiple"属性可以选择多个文件.
2. FileRead是将文件读入到内存的, 文件太大的话需要分段读取.
要注意的地方:
1. 读取文件时要用使用"readAsArrayBuffer"方法, 更多FileRead的用法参见 w3c的file API
2. 如果是用Chrome的话，必须把网页放在服务器上或插件里，file协议下会失败。FileRead的onload函数不会响应!
参考资料:
用JavaScript读取和保存文件
FileReader详解与实例---读取并显示图像文件
完整代码:
websocket.html(有用到Jquery):
<!DOCTYPE html>
<html>
<head>
<title>WebSocket Chat Client</title>
<meta charset="utf-8" />
<script type="text/javascript" src="jquery-1.6.4.min.js"></script>
<script type="text/javascript" >
//判读浏览器是否支持websocket
$().ready(function() {
if ( !window.WebSocket ) {
alert("童鞋, 你的浏览器不支持该功能啊");
}
});
//在消息框中打印内容
function log(text) {
$("#log").append(text+"\n");
}
//全局的websocket变量
var ws;
//创建连接
$(function() {
$("#uriForm").submit(function() {
log("准备连接到" + $("#uri").val());
ws = new WebSocket($("#uri").val());
//连接成功建立后响应
ws.onopen = function() {
log("成功连接到" + $("#uri").val());
}
//收到服务器消息后响应
ws.onmessage = function(e) {
log("收到服务器消息:" + e.data + "'\n");
}
//连接关闭后响应
ws.onclose = function() {
log("关闭连接");
$("#disconnect").attr({"disabled":"disabled"});
$("#uri").removeAttr("disabled");
$("#connect").removeAttr("disabled");
ws = null;
}
$("#uri").attr({"disabled":"disabled"});
$("#connect").attr({"disabled":"disabled"});
$("#disconnect").removeAttr("disabled");
return false;
});
});
//发送字符串消息
$(function() {
$("#sendForm").submit(function() {
if (ws) {
var textField = $("#textField");
ws.send(textField.val());
log("我说:" + textField.val());
textField.val("");
textField.focus();
}
return false;
});
});
//发送arraybuffer(二进制文件)
$(function() {
$("#sendFileForm").submit(function() {
var inputElement = document.getElementById("file");
var fileList = inputElement.files;
for ( var i = 0; i < fileList.length; i++) {
console.log(fileList[i]);
log(fileList[i].name);
//发送文件名
ws.send(fileList[i].name);
// reader.readAsBinaryString(fileList[i]);
//读取文件
var reader = new FileReader();
reader.readAsArrayBuffer(fileList[i]);
// reader.readAsText(fileList[i]);
//文件读取完毕后该函数响应
reader.onload = function loaded(evt) {
var binaryString = evt.target.result;
// Handle UTF-16 file dump
log("\n开始发送文件");
ws.send(binaryString);
}
}
return false;
});
});
$(function() {
$("#disconnect").click(function() {
if (ws) {
$("#log").empty();
ws.close();
ws = null;
}
return false;
});
});
$(function() {
$("#reset").click(function() {
$("#log").empty();
return false;
});
});
</script>
</head>
<body>
<form id="uriForm">
<input type="text" id="uri" value="ws://localhost:8887"
style=" 200px;"> <input type="submit" id="connect"
value="Connect"><input type="button" id="disconnect"
value="Disconnect" disabled="disabled">
</form>
<br>
<form id="sendFileForm">
<input id="file" type="file" multiple />
<input type="submit" value="Send" />
<input type="button" id="reset" value="清空消息框"/>
</form>
<br>
<form id="sendForm">
<input type="text" id="textField" value="" style=" 200px;">
<input type="submit" value="Send">
</form>
<br>
<form>
<textarea id="log" rows="30" cols="100"
style="font-family: monospace; color: red;"></textarea>
</form>
<br>
</body>
</html>
ChatServer.java(需要导入WebSocket.jar):
package jyu.webserver;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.UnknownHostException;
import org.java_websocket.WebSocket;
import org.java_websocket.WebSocketServer;
import org.java_websocket.handshake.ClientHandshake;
/**
* A simple WebSocketServer implementation. Keeps track of a "chatroom".
*/
public class ChatServer extends WebSocketServer {
private String fileName = null;
public ChatServer( int port ) throws UnknownHostException {
super( new InetSocketAddress( InetAddress.getByName( "localhost" ), port ) );
}
public ChatServer( InetSocketAddress address ) {
super( address );
}
public ChatServer( String address ,int port) throws UnknownHostException {
super( new InetSocketAddress( InetAddress.getByName( address ), port ) );
}
@Override
public void onOpen( WebSocket conn, ClientHandshake handshake ) {
try {
this.sendToAll( conn + " entered the room!" );
} catch ( InterruptedException ex ) {
ex.printStackTrace();
}
System.out.println( conn + " entered the room!" );
}
@Override
public void onClose( WebSocket conn, int code, String reason, boolean remote ) {
try {
this.sendToAll( conn + " has left the room!" );
} catch ( InterruptedException ex ) {
ex.printStackTrace();
}
System.out.println( conn + " has left the room!" );
}
@Override
public void onMessage( WebSocket conn, String message ) {
conn.getRemoteSocketAddress().getAddress().getAddress();
try {
this.sendToAll( conn + "说: " + message );
} catch ( InterruptedException ex ) {
ex.printStackTrace();
}
// System.out.println( conn + ": " + message );
// byte[] fileBanary = message.getBytes();
// saveFileFromBytes(fileBanary, "src/test.png");
fileName = message;
System.out.println("收到字符串流");
}
@Override
public void onMessage(WebSocket conn, byte[] message) {
saveFileFromBytes(message, "src/" + fileName);
System.out.println("收到2进制流");
}
public static void main( String[] args ) throws InterruptedException , IOException {
WebSocket.DEBUG = false;
int port = 8887;
try {
port = Integer.parseInt( args[ 0 ] );
} catch ( Exception ex ) {
}
ChatServer s = new ChatServer("localhost", port );
s.start();
System.out.println( "ChatServer started on port: " + s.getPort() );
BufferedReader sysin = new BufferedReader( new InputStreamReader( System.in ) );
while ( true ) {
String in = sysin.readLine();
s.sendToAll( in );
}
}
@Override
public void onError( WebSocket conn, Exception ex ) {
ex.printStackTrace();
}
/**
* Sends <var>text</var> to all currently connected WebSocket clients.
*
* @param text
* The String to send across the network.
* @throws InterruptedException
* When socket related I/O errors occur.
*/
public void sendToAll( String text ) throws InterruptedException {
for( WebSocket c : connections() ) {
c.send( text );
}
}
public static boolean saveFileFromBytes(byte[] b, String outputFile)
{
BufferedOutputStream stream = null;
File file = null;
try
{
file = new File(outputFile);
FileOutputStream fstream = new FileOutputStream(file);
stream = new BufferedOutputStream(fstream);
stream.write(b);
}
catch (Exception e)
{
e.printStackTrace();
return false;
}
finally
{
if (stream != null)
{
try
{
stream.close();
}
catch (IOException e1)
{
e1.printStackTrace();
}
}
}
return true;
}
}