错误：java.lang.NullPointerException：尝试调用虚拟方法’android.content.res.XmlResourceParser

概述我收到此错误.我是androidstudio的新手,我需要创建此插件以统一在运行时安装apk错误-尝试在空对象引用上调用虚拟方法’android.content.ContextAndroid.content.Context.getApplicationContext()’插件类-packagecom.example.unitypluginappinstall;importandroid.app.A

我收到此错误.我是android studio的新手,我需要创建此插件以统一在运行时安装apk

错误-尝试在空对象引用上调用虚拟方法’androID.content.Context Android.content.Context.getApplicationContext()’

插件类-

package com.example.unitypluginappinstall;import androID.app.Activity;import androID.content.Context;import androID.content.Intent;import androID.net.Uri;import androID.support.v4.content.fileProvIDer;import java.io.file;public class PluginClass extends Activity  {static String errMessage;public static String InstallApp(String ApkPath){ try {     errMessage = "test";     file toInstall = new file(ApkPath);     Uri apkUri = fileProvIDer.getUriForfile(ContextClass.context(), ContextClass.context().getApplicationContext().getPackagename() + ".fileprovIDer", toInstall);     Intent intent = new Intent(Intent.ACTION_INSTALL_PACKAGE);     intent.setData(apkUri);     intent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);     ContextClass.context().startActivity(intent); } catch (Exception e){    errMessage = e.getMessage(); }    return errMessage;}}

ContextClass-

package com.example.unitypluginappinstall;import androID.app.Application;import androID.content.Context;public class ContextClass extends Application {private  static ContextClass instance;public ContextClass(){    instance = this;}public static ContextClass instance(){    return instance;}public static Context context() {    return instance.getApplicationContext();}}

清单文件-

<manifest xmlns:androID="http://schemas.androID.com/apk/res/androID"package="com.example.unitypluginappinstall"><application androID:allowBackup="true" androID:label="@string/app_name"    androID:supportsRtl="true">    <provIDer        androID:name="androID.support.v4.content.fileProvIDer"        androID:authoritIEs="${applicationID}.fileprovIDer"        androID:exported="false"        androID:grantUriPermissions="true">        <Meta-data androID:name="androID.support.file_PROVIDER_PATHS"            androID:resource="@xml/filepaths"></Meta-data>    </provIDer>    androID:name=".ContextClass"></application>

PluginWrapper：

public class PluginWrapper : MonoBehavIoUr {string savePath;voID Start () {    savePath = Path.Combine(Application.persistentDataPath, "data");    savePath = Path.Combine(savePath, "applaunchtest.apk");    Install();}voID Install(){try    {        //Install APK        GameObject.Find("TextDeBUG").GetComponent<Text().text"Installing...";        var plugin = new    AndroIDJavaClass("com.example.unitypluginappinstall.PluginClass");        GameObject.Find("TextDeBUG").GetComponent<Text>().text =    plugin.CallStatic<string>("InstallApp", savePath);    }    catch(Exception e)    {        GameObject.Find("TextDeBUG").GetComponent<Text>().text = e.Message;    }}}

编辑-
插件类

package com.example.unitypluginappinstall;import androID.app.Activity;import androID.content.Context;import androID.content.Intent;import androID.net.Uri;import androID.support.v4.content.fileProvIDer;import java.io.file;public class PluginClass extends Activity  {static String errMessage;public static String InstallApp(Context context, String ApkPath){ try {     errMessage = "test";     file toInstall = new file(ApkPath);     Uri apkUri = fileProvIDer.getUriForfile(context,             context.getApplicationContext().getPackagename() +                     ".fileprovIDer", toInstall);     Intent intent = new Intent(Intent.ACTION_INSTALL_PACKAGE);     intent.setData(apkUri);     intent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);     context.startActivity(intent); } catch (Exception e){    errMessage = e.getMessage(); }    return errMessage;}}

插件包装器-

public class PluginWrapper : MonoBehavIoUr {string savePath;voID Start () {    savePath = Path.Combine(Application.persistentDataPath, "data");    savePath = Path.Combine(savePath, "applaunchtest.apk");    Install();}voID Install(){try    {        //Install APKAndroIDJavaClass unityClass = new AndroIDJavaClass("com.unity3d.player.UnityPlayer");        AndroIDJavaObject unityActivity = unityClass.GetStatic<AndroIDJavaObject>("currentActivity");        AndroIDJavaObject unityContext = unityActivity.Call<AndroIDJavaObject>("getApplicationContext");        GameObject.Find("TextDeBUG").GetComponent<Text().text"Installing...";        var plugin = new    AndroIDJavaClass("com.example.unitypluginappinstall.PluginClass");        GameObject.Find("TextDeBUG").GetComponent<Text>().text =    plugin.CallStatic<string>("InstallApp",unityContext, savePath);    }    catch(Exception e)    {        GameObject.Find("TextDeBUG").GetComponent<Text>().text = e.Message;    }}}

编辑

解决方法:

来自Java的Contect插件为null.如果需要,您必须将Unity的上下文发送到Java插件.

添加另一个接收上下文的参数,然后使用该参数中的该上下文而不是AndroID.content.Context.getApplicationContext()中的那个.

Java的：

public static String InstallApp(Context context, String ApkPath){ try {     errMessage = "test";     file toInstall = new file(ApkPath);     Uri apkUri = fileProvIDer.getUriForfile(context, context.getPackagename() + ".fileprovIDer", toInstall);     Intent intent = new Intent(Intent.ACTION_INSTALL_PACKAGE);     intent.setData(apkUri);     intent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);     context.startActivity(intent); } catch (Exception e){    errMessage = e.getMessage(); }    return errMessage;}

C#：

发送Unity上下文和要传递给函数的路径.

voID Install(){    try    {        GameObject.Find("TextDeBUG").GetComponent<Text>().text = "Installing...";        //Get Unity Context        AndroIDJavaClass unityClass = new AndroIDJavaClass("com.unity3d.player.UnityPlayer");        AndroIDJavaObject unityActivity = unityClass.GetStatic<AndroIDJavaObject>("currentActivity");        AndroIDJavaObject unityContext = unityActivity.Call<AndroIDJavaObject>("getApplicationContext");        AndroIDJavaClass plugin = new AndroIDJavaClass("com.example.unitypluginappinstall.PluginClass");        string result = plugin.CallStatic<string>("InstallApp", unityContext, savePath);    }    catch (Exception e)    {        GameObject.Find("TextDeBUG").GetComponent<Text>().text = e.Message;    }}

您可能有其他不相关的错误,但是Context null问题应该消失了.

编辑：

如果收到异常：

Attempt to invoke virtual method
‘androID.content.res.XmlResourceParser
androID.content.pm.packageItemInfo.loadXmlMetaData(androID.c‌​ontent.pm.PackageMan‌​ager.java.lang.Strin‌​g)’

您只需要做几件事.

1.将“ .jar”插件插入UnityProject / Assets / Plugins / AndroID目录.

2.从“ AndroIDSDK / extras / androID / support / v4 / androID-support-v4.jar”中复制“ androID-support-v4.jar”
 目录到您的“ UnityProject / Assets / Plugins / AndroID”目录.

3.在UnityProject / Assets / Plugins / AndroID目录中创建一个名为“ AndroIDManifest.xml”的文件,并将下面的代码放入其中.

确保用您自己的包名称替换“ com.company.product”.有2种情况出现.您必须同时替换它们：

这些可以在package =“ com.company.product”和androID：authoritIEs =“ com.company.product.fileprovIDer”中找到.不要更改或删除“文件提供程序”,也不要更改其他任何内容.

这是“ AndroIDManifest.xml”文件：

<?xml version="1.0" enCoding="utf-8"?><manifest xmlns:androID="http://schemas.androID.com/apk/res/androID" package="com.company.product" xmlns:tools="http://schemas.androID.com/tools" androID:installLocation="preferExternal" androID:versionname="1.0" androID:versionCode="1">  <supports-screens androID:smallScreens="true" androID:normalScreens="true" androID:largeScreens="true" androID:xlargeScreens="true" androID:anyDensity="true" />  <application androID:theme="@style/UnitythemeSelector" androID:icon="@drawable/app_icon" androID:label="@string/app_name" androID:deBUGgable="true">    <activity androID:name="com.unity3d.player.UnityPlayerActivity" androID:label="@string/app_name">      <intent-filter>        <action androID:name="androID.intent.action.MAIN" />        <category androID:name="androID.intent.category.LAUNCHER" />      </intent-filter>      <Meta-data androID:name="unityplayer.UnityActivity" androID:value="true" />    </activity>    <provIDer          androID:name="androID.support.v4.content.fileProvIDer"          androID:authoritIEs="com.company.product.fileprovIDer"          androID:exported="false"          androID:grantUriPermissions="true">      <Meta-data          androID:name="androID.support.file_PROVIDER_PATHS"          androID:resource="@xml/provIDer_paths"/>    </provIDer>  </application>  <uses-sdk androID:minSdkVersion="16" androID:targetSdkVersion="23" /></manifest>

4.在“ UnityProject / Assets / Plugins / AndroID / res / xml”目录中创建一个名为“ provIDer_paths.xml”的新文件,并将代码放在下面.如您所见,您必须创建一个res,然后创建一个xml文件夹.

确保用您自己的包名称替换“ com.company.product”.
它只出现一次.

这是您应该放入此“ provIDer_paths.xml”文件的内容：

<?xml version="1.0" enCoding="utf-8"?><paths xmlns:androID="http://schemas.androID.com/apk/res/androID">  <!--<external-path name="external_files" path="."/>-->  <external-path path="AndroID/data/com.company.product" name="files_root" />  <external-path path="." name="external_storage_root" /></paths>

而已.

总结

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