java - Android 上的 TCP 套接字连接被拒绝

Question

在一个简单的客户端-服务器 TCP 套接字中，当我尝试在 Android Studio 中创建客户端套接字时遇到问题。导致错误的指令是Socket s=new Socket(hostname,port);

我使用的端口是 1993，我尝试了 hostname 变量的一些值:

1. 主机名=“127.0.0.1”
2. 主机名=“localhost”
3. 主机名=""
4. hostname=InetAddress.getByName([with-前 2 个值])

在每种情况下，应用程序都会因为此错误而停止，下面的错误属于第一点，其他错误都会出现类似的错误。

    W/System.err: Couldn't get I/O for the connection to 127.0.0.1    W/System.err: java.net.ConnectException: failed to connect to /127.0.0.1 (port 1993): connect failed: ECONNREFUSED (Connection refused)            at libcore.io.IoBridge.connect(IoBridge.java:124)            at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:183)            at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:163)            at java.net.Socket.startupSocket(Socket.java:592)            at java.net.Socket.tryAllAddresses(Socket.java:128)            at java.net.Socket.(Socket.java:178)            at java.net.Socket.(Socket.java:150)    W/System.err:     at com.example.davide.beachapp.model.ClientSocket$MyThread.run(ClientSocket.java:92)        Caused by: android.system.ErrnoException: connect failed: ECONNREFUSED (Connection refused)            at libcore.io.Posix.connect(Native Method)            at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:111)            at libcore.io.IoBridge.connectErrno(IoBridge.java:137)            at libcore.io.IoBridge.connect(IoBridge.java:122)            ... 7 more

The same instruction in Eclipse works, I tested it with a server "nc -l 1993" on the command-line and everything works on Eclipse.

Maybe it's some configuration problem with the manifest?

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
  package="com.example.davide.beachapp">
  <uses-permission android:name="android.permission.INTERNET" />
  <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
  <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
  <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>                
  <application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity
      android:name=".MainActivity"
      android:label="@string/app_name"
      android:theme="@style/AppTheme.NoActionBar">
      <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" >
      </intent-filter>
    </activity>
  </application>
</manifest>

Answer 1

如果您使用的是模拟器，请尝试使用 10.0.2.2 而不是 127.0.0.1。

有关更多信息，请访问此页面:

Set up Android Emulator networking