Javascript 使用WebSocket从Java端点发送图像
Javascript 使用WebSocket从Java端点发送图像,javascript,jakarta-ee,websocket,Javascript,Jakarta Ee,Websocket,我试图在JavaEE7中创建一个Websocket端点,它接收一个文件名作为输入,并返回图像的二进制数据。以下是Websocket的Java端: @ServerEndpoint(value = "/hellobinary") public class HelloWorldBinaryEndpoint { @OnMessage public void hello(String img, Session session) { File fi = new File("C:\\Use
我试图在JavaEE7中创建一个Websocket端点,它接收一个文件名作为输入,并返回图像的二进制数据。以下是Websocket的Java端:
@ServerEndpoint(value = "/hellobinary")
public class HelloWorldBinaryEndpoint {
@OnMessage
public void hello(String img, Session session) {
File fi = new File("C:\\Users\\\images\\"+img);
byte[] fileContent=null;
try {
fileContent = Files.readAllBytes(fi.toPath());
ByteBuffer buf = ByteBuffer.wrap(fileContent);
session.getBasicRemote().sendBinary(buf);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
这是Javascript的一面:
var wsUri = "ws://localhost:8080/websocket/hellobinary";
function init() {
output = document.getElementById("output");
}
function send_message() {
websocket = new WebSocket(wsUri);
websocket.onopen = function(evt) {
onOpen(evt)
};
websocket.onmessage = function(evt) {
onMessage(evt)
};
websocket.onerror = function(evt) {
onError(evt)
};
}
function onOpen(evt) {
writeToScreen("Connected to Endpoint!");
doSend(textID.value);
}
function onMessage(evt) {
drawImageBinary(evt.data);
}
function onError(evt) {
writeToScreen('<span style="color: red;">ERROR:</span> ' + evt.data);
}
function doSend(message) {
writeToScreen("Message Sent: " + message);
websocket.send(message);
}
function writeToScreen(message) {
var pre = document.createElement("p");
pre.style.wordWrap = "break-word";
pre.innerHTML = message;
output.appendChild(pre);
}
function drawImageBinary(blob) {
var bytes = new Uint8Array(blob);
alert('received '+ bytes.length);
var imageData = context.createImageData(canvas.width, canvas.height);
for (var i=8; i<imageData.data.length; i++) {
imageData.data[i] = bytes[i];
}
context.putImageData(imageData, 0, 0);
var img = document.createElement('img');
img.height = canvas.height;
img.width = canvas.width;
img.src = canvas.toDataURL();
}
window.addEventListener("load", init, false);
var wsUri=“ws://localhost:8080/websocket/hellobinary”;
函数init(){
输出=document.getElementById(“输出”);
}
函数send_message(){
websocket=新的websocket(wsUri);
websocket.onopen=函数(evt){
onOpen(evt)
};
websocket.onmessage=函数(evt){
onMessage(evt)
};
websocket.onerror=函数(evt){
onError(evt)
};
}
功能开启(evt){
writeToScreen(“已连接到端点!”);
doSend(textID.value);
}
消息函数(evt){
drawImageBinary(evt.data);
}
函数onError(evt){
writeToScreen('错误:'+evt.data);
}
函数doSend(消息){
writeToScreen(“已发送消息:+消息”);
发送(消息);
}
功能写入屏幕(消息){
var pre=document.createElement(“p”);
pre.style.wordWrap=“断开单词”;
pre.innerHTML=消息;
输出.appendChild(pre);
}
函数drawImageBinary(blob){
var字节=新的Uint8Array(blob);
警报('接收'+字节.长度);
var imageData=context.createImageData(canvas.width、canvas.height);
对于(var i=8;i客户端缺少您:
websocket.binaryType=“arraybuffer”Ok!现在Javascript端也会收到字节数。但是屏幕上仍然没有打印任何内容。因此,在Javascript中呈现字节时一定存在问题。