如何解决错误`java.net.ConnectException:无法连接到localhost/127.0.0.1:8000` [英] How to solve the error `java.net.ConnectException: Failed to connect to localhost/127.0.0.1:8000`

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问题描述

我目前正在开发使用 android-studio 和 Kotlin 的应用程序以及使用 django-rest-framework 的API系统.

I'm currently developing an application using android-studio with Kotlin and an API system using django-rest-framework.

我想使用Android模拟器访问本地服务器 127.0.0.1 ，以从API方法中获取一些价值.

I want to access my local server 127.0.0.1 with an android emulator to get some value from the API method.

我检查了堆栈溢出站点和其他站点中的一些问题，并设置了代码以参考某些文章，例如在 AndroidManifest.xml 中添加一些代码，从而创建了 network_security_config.xml ，更改 Android模拟器的代理，并更改 Django rest framework 项目中的某些代码.

I checked some questions in the stack overflow site and other sites and I set my codes up referring to some articles, like adding some code in an AndroidManifest.xml, making a network_security_config.xml, changing a proxy of Android emulator and changing some code in Django rest framework project.

即使我在本地服务器上命中一个端点，我也会遇到类似以下的错误代码:

even though when I hit an endpoint in my local server I have error codes like below:

2020-10-07 22:37:39.318 7247-7247/com.sample.apitest I/System.out: checked
2020-10-07 22:37:39.358 7247-7280/com.sample.apitest D/NetworkSecurityConfig: Using Network Security Config from resource network_security_config debugBuild: true
2020-10-07 22:37:39.392 7247-7280/com.sample.apitest W/System.err: java.net.ConnectException: Failed to connect to localhost/127.0.0.1:8000
2020-10-07 22:37:39.394 7247-7280/com.sample.apitest W/System.err:     at com.android.okhttp.internal.io.RealConnection.connectSocket(RealConnection.java:143)
2020-10-07 22:37:39.394 7247-7280/com.sample.apitest W/System.err:     at com.android.okhttp.internal.io.RealConnection.connect(RealConnection.java:112)
2020-10-07 22:37:39.394 7247-7280/com.sample.apitest W/System.err:     at com.android.okhttp.internal.http.StreamAllocation.findConnection(StreamAllocation.java:184)
2020-10-07 22:37:39.395 7247-7280/com.sample.apitest W/System.err:     at com.android.okhttp.internal.http.StreamAllocation.findHealthyConnection(StreamAllocation.java:126)
2020-10-07 22:37:39.395 7247-7280/com.sample.apitest W/System.err:     at com.android.okhttp.internal.http.StreamAllocation.newStream(StreamAllocation.java:95)
2020-10-07 22:37:39.395 7247-7280/com.sample.apitest W/System.err:     at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:281)
2020-10-07 22:37:39.396 7247-7280/com.sample.apitest W/System.err:     at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:224)
2020-10-07 22:37:39.396 7247-7280/com.sample.apitest W/System.err:     at com.android.okhttp.internal.huc.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:461)
2020-10-07 22:37:39.396 7247-7280/com.sample.apitest W/System.err:     at com.android.okhttp.internal.huc.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:127)
2020-10-07 22:37:39.397 7247-7280/com.sample.apitest W/System.err:     at com.sample.apitest.MainActivity$HitAPITask.doInBackground(MainActivity.kt:49)
2020-10-07 22:37:39.397 7247-7280/com.sample.apitest W/System.err:     at com.sample.apitest.MainActivity$HitAPITask.doInBackground(MainActivity.kt:39)
2020-10-07 22:37:39.397 7247-7280/com.sample.apitest W/System.err:     at android.os.AsyncTask$2.call(AsyncTask.java:333)
2020-10-07 22:37:39.397 7247-7280/com.sample.apitest W/System.err:     at java.util.concurrent.FutureTask.run(FutureTask.java:266)
2020-10-07 22:37:39.397 7247-7280/com.sample.apitest W/System.err:     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:245)
2020-10-07 22:37:39.397 7247-7280/com.sample.apitest W/System.err:     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
2020-10-07 22:37:39.398 7247-7280/com.sample.apitest W/System.err:     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
2020-10-07 22:37:39.398 7247-7280/com.sample.apitest W/System.err:     at java.lang.Thread.run(Thread.java:764)

我该如何解决此错误?

以下是代码:

Android项目

模拟器设置

AndroidManifest.xml

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
          xmlns:tools="http://schemas.android.com/tools" package="com.sample.apitest">

    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

    <application
            android:networkSecurityConfig="@xml/network_security_config"
            android:usesCleartextTraffic="true"

            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"
            tools:ignore="GoogleAppIndexingWarning"
            tools:targetApi="n">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>

                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
    </application>
</manifest>

network_security_config.xml

network_security_config.xml

<?xml version="1.0" encoding="utf-8"?>
<network-security-config>
    <domain-config cleartextTrafficPermitted="true">
        <domain includeSubdomains="true">localhost</domain>
    </domain-config>
</network-security-config>

MainActivity.kt

MainActivity.kt

package com.sample.apitest

import android.os.AsyncTask
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.TextView
import org.json.JSONException
import org.json.JSONObject
import java.io.BufferedReader
import java.io.IOException
import java.io.InputStreamReader
import java.net.HttpURLConnection
import java.net.MalformedURLException
import java.net.URL

class MainActivity : AppCompatActivity() {

    var name: TextView? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        name = findViewById(R.id.textView)
        val button = findViewById<Button>(R.id.button)

        button.setOnClickListener {
            println("checked")
            HitAPITask().execute("http://localhost:8000/api/name/")

        }
    }

    inner class HitAPITask : AsyncTask<String, String, String>() {

        override fun doInBackground(vararg params: String?): String? {
            var connection: HttpURLConnection? = null
            var reader: BufferedReader? = null
            val buffer: StringBuffer

            try {
                val url = URL(params[0])
                connection = url.openConnection() as HttpURLConnection
                connection.connect()

                val stream = connection.inputStream
                reader = BufferedReader(InputStreamReader(stream))
                buffer = StringBuffer()
                var line: String?
                while (true) {
                    line = reader.readLine()
                    if (line == null) {
                        break
                    }
                    buffer.append(line)
                }

                var jsonText = buffer.toString()

                val jsonObj = JSONObject(jsonText)
                val plant_name: String = jsonObj.getString("name")

                return plant_name
            } catch (e: MalformedURLException) {
                e.printStackTrace()
            } catch (e: IOException) {
                e.printStackTrace()
            } catch (e: JSONException) {
                e.printStackTrace()
            } finally {
                connection?.disconnect()
                try {
                    reader?.close()
                } catch (e: IOException) {
                    e.printStackTrace()
                }
            }
            return null
        }

        override fun onPostExecute(result: String?) {
            super.onPostExecute(result)
            if (result == null) return

            name!!.text = result
        }
    }
}

build.gradle

build.gradle

apply plugin: 'com.android.application'

apply plugin: 'kotlin-android'

apply plugin: 'kotlin-android-extensions'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.sample.apitest"
        minSdkVersion 16
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation"org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:2.0.1'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

Django rest 框架项目

project/settings.py

project/settings.py

    #...      

INSTALLED_APPS = [
    #...
    'corsheaders',
]

MIDDLEWARE = [
    #...
    'corsheaders.middleware.CorsMiddleware',
    'django.middleware.common.CommonMiddleware',
]

CORS_ORIGIN_WHITELIST = [
    'http://10.0.2.2:8000'
]

API端点

[ Method = GET ] http://127.0.0.1:8000/api/name/

    {
      "name": "myName.",
    }

android-studio:3.3.2

android-studio: 3.3.2

python:3.7.5

python: 3.7.5

django-cors-headers:2.4.0

django-cors-headers: 2.4.0

djangorestframework:3.8.2

djangorestframework: 3.8.2

推荐答案

尝试打开cmd，然后在其上写入 ipconfig 之后，您获得了本地IP地址，然后尝试输入您的代码

Try open cmd and then write ipconfig on it after that you got your local ip address then try to put on your code

例如你从你的 cmd 中得到 192.168.1.2 然后像这样把它放到你的代码中:

for example you got 192.168.1.2 from your cmd then put it to your code like this:

HitAPITask().execute("http://192.168.1.2/api/name/")

这篇关于如何解决错误`java.net.ConnectException:无法连接到localhost/127.0.0.1:8000`的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！

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