WebSocket EndPoint 未得到解决：错误代码：404

Question

我正在尝试创建一个非常基本的网络套接字应用程序。 步骤如下：

创建 EchoServer java 类

    import javax.websocket.OnMessage;
    import javax.websocket.server.ServerEndpoint;
    
    @ServerEndpoint("/echo")
    public class EchoServer {
    
        @OnMessage
        public String echo(String incomingMessage) {
            return "I got this (" + incomingMessage + ") so I am sending it back";
        }
    }

使用 javascript 调用上述端点创建 html

 <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Web Socket JavaScript Echo Client</title> <script language="javascript" type="text/javascript"> var echo_websocket; function init() { output = document.getElementById("output"); } function send_echo() { var wsUri = "ws://localhost:7003/wspractice/echo"; writeToScreen("Connecting to " + wsUri); echo_websocket = new WebSocket(wsUri); echo_websocket.onopen = function (evt) { writeToScreen("Connected !"); doSend(textID.value); }; echo_websocket.onmessage = function (evt) { writeToScreen("Received message: " + evt.data); echo_websocket.close(); }; echo_websocket.onerror = function (evt) { writeToScreen('<span style="color: red;">ERROR:</span> ' + evt.data); echo_websocket.close(); }; } function doSend(message) { echo_websocket.send(message); writeToScreen("Sent message: " + message); } function writeToScreen(message) { var pre = document.createElement("p"); pre.style.wordWrap = "break-word"; pre.innerHTML = message; output.appendChild(pre); } window.addEventListener("load", init, false); </script> </head> <body> <h1>Echo Server</h1> <div style="text-align: left;"> <form action=""> <input onclick="send_echo()" value="Press to send" type="button"> <input id="textID" name="message" value="Hello Web Sockets" type="text"> <br> </form> </div> <div id="output"></div> </body> </html>

在 WebLogic Server 版本：14.1.1.0.0 服务器中将上述项目部署为 war 文件（上下文路径：wspractice）。
weblogic 上的命名服务器配置（侦听端口 7003）
部署在命名服务器上的应用程序

尝试上述 html 时，出现“WebSocket connection to 'ws://localhost:7003/wspractice/echo' failed: Error during WebSocket handshake: Unexpected response code: 404”错误。

当我尝试在 WEB-INF 中访问另一个普通的 jsp 时，它得到了正确的解析，但只有 web-socket 没有得到解析。 结果如下图所示。

我理解 404 发生在服务器无法找到服务（在这种情况下是回声）时，但我不明白为什么会在这种情况下发生，即使“回声”端点可用。

结果在浏览器中。
在 chrome、firefox 中尝试过，但结果相同。 请帮助我理解为什么会发生这种情况。

Answer 1

我试图对您的代码进行尽可能少的更改。 将其用作参考。

EchoServer.java 方法 onMessage 应该有不同的签名。

import java.io.IOException;
import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;

@ServerEndpoint(value = "/echo")
public class EchoServer {
    @OnMessage
    public void onMessage(final Session session, String msg) {
        System.out.println("Msg: " + msg);
        try {
            session.getBasicRemote().sendText(msg);
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }
}

html 中有错别字

<html>
    <head>
        <meta charset="UTF-8">
        <title>Web Socket JavaScript Echo Client</title>
        <script language="javascript" type="text/javascript">
            var echo_websocket;
            function init() {
                output = document.getElementById("output");
            }
            function send_echo() {
                var wsUri = "ws://localhost:8080/test1/echo";
                writeToScreen("Connecting to " + wsUri);
                echo_websocket = new WebSocket(wsUri);
                echo_websocket.onopen = function (evt) {
                    writeToScreen("Connected !");
                    doSend(document.getElementById("textID").value);
                };
                echo_websocket.onmessage = function (evt) {
                    writeToScreen("Received message: " + evt.data);
                    echo_websocket.close();
                };
                echo_websocket.onerror = function (evt) {
                    writeToScreen('<span style="color: red;">ERROR:</span> ' + evt);
                    console.log(evt)
                    echo_websocket.close();
                };
            }
            function doSend(message) {
                echo_websocket.send(message);
                writeToScreen("Sent message: " + message);
            }
            function writeToScreen(message) {
                var pre = document.createElement("p");
                pre.style.wordWrap = "break-word";
                pre.innerHTML = message;
                output.appendChild(pre);
            }
            window.addEventListener("load", init, false);
        </script>
    </head>
    <body>
        <div style="text-align: left;">
            <form action="">
                <input onclick="send_echo()" value="Press to send" type="button">
                <input id="textID" name="message" value="Hello Web Sockets" type="text">
                <br>
            </form>
        </div>
        <div id="output"></div>
    </body>
</html>

以下 pom 引用了 glassfish 嵌入式服务器，因此您可以通过运行以下命令来测试代码段

mvn package embedded-glassfish:run

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.smirnov</groupId>
    <artifactId>test1</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <name>test1</name>

    <properties>
        <endorsed.dir>${project.build.directory}/endorsed</endorsed.dir>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    
    <dependencies>
        <dependency>
            <groupId>javax</groupId>
            <artifactId>javaee-web-api</artifactId>
            <version>7.0</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                    <compilerArguments>
                        <endorseddirs>${endorsed.dir}</endorseddirs>
                    </compilerArguments>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>2.3</version>
                <configuration>
                    <failOnMissingWebXml>false</failOnMissingWebXml>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-dependency-plugin</artifactId>
                <version>2.6</version>
                <executions>
                    <execution>
                        <phase>validate</phase>
                        <goals>
                            <goal>copy</goal>
                        </goals>
                        <configuration>
                            <outputDirectory>${endorsed.dir}</outputDirectory>
                            <silent>true</silent>
                            <artifactItems>
                                <artifactItem>
                                    <groupId>javax</groupId>
                                    <artifactId>javaee-endorsed-api</artifactId>
                                    <version>7.0</version>
                                    <type>jar</type>
                                </artifactItem>
                            </artifactItems>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.glassfish.embedded</groupId>
                <artifactId>maven-embedded-glassfish-plugin</artifactId>
                <version>4.0</version>
                <configuration>
                    <goalPrefix>embedded-glassfish</goalPrefix>
                    <app>${basedir}/target/${project.artifactId}-${project.version}.war</app>
                    <autoDelete>true</autoDelete>
                    <port>8080</port>
                    <name>test1</name>
                    <contextRoot>test1</contextRoot>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>deploy</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

你可以在这里看到这个小项目。

WebSocket EndPoint 未得到解决：错误代码：404

问题描述

1 个解决方案

解决方案1
0 2020-10-01 17:07:49

WebSocket EndPoint 未得到解决：错误代码：404

问题描述

1 个解决方案

解决方案1 0 2020-10-01 17:07:49

解决方案1
0 2020-10-01 17:07:49