错误是：“make: *** No rule to make target `SpecProj_scd.mk'. Stop.”导致我的应用程序崩溃？

Question

我的第一次清理和构建出现此错误：

make: *** No rule to make target `SpecProj_scd.mk'.  Stop.

第二次构建，错误被删除。 请注意，ndk-build，构建良好。

所以我在我的实际设备（平板电脑）上运行该项目，但应用程序崩溃了。

LogCat：

01-29 16:48:48.081: E/Trace(3766): error opening trace file: No such file or directory (2)
01-29 16:48:48.081: D/jdwp(3766): sendBufferedRequest : len=0x39
01-29 16:48:48.110: D/dalvikvm(3766): open_cached_dex_file : /data/app/com.dece.specproj-2.apk /data/dalvik-cache/data@app@com.dece.specproj-2.apk@classes.dex
01-29 16:48:48.117: D/ActivityThread(3766): BIND_APPLICATION handled : 0 / AppBindData{appInfo=ApplicationInfo{42436e88 com.dece.specproj}}
01-29 16:48:48.128: W/dalvikvm(3766): Exception Ljava/lang/UnsatisfiedLinkError; thrown while initializing Lcom/dece/specproj/MainActivity;
01-29 16:48:48.128: W/dalvikvm(3766): Class init failed in newInstance call (Lcom/dece/specproj/MainActivity;)
01-29 16:48:48.128: D/AndroidRuntime(3766): Shutting down VM
01-29 16:48:48.128: W/dalvikvm(3766): threadid=1: thread exiting with uncaught exception (group=0x41e17908)
01-29 16:48:48.137: E/AndroidRuntime(3766): FATAL EXCEPTION: main
01-29 16:48:48.137: E/AndroidRuntime(3766): java.lang.ExceptionInInitializerError
01-29 16:48:48.137: E/AndroidRuntime(3766):     at java.lang.Class.newInstanceImpl(Native Method)
01-29 16:48:48.137: E/AndroidRuntime(3766):     at java.lang.Class.newInstance(Class.java:1319)
01-29 16:48:48.137: E/AndroidRuntime(3766):     at android.app.Instrumentation.newActivity(Instrumentation.java:1053)
01-29 16:48:48.137: E/AndroidRuntime(3766):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2099)
01-29 16:48:48.137: E/AndroidRuntime(3766):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2211)
01-29 16:48:48.137: E/AndroidRuntime(3766):     at android.app.ActivityThread.access$600(ActivityThread.java:149)
01-29 16:48:48.137: E/AndroidRuntime(3766):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1300)
01-29 16:48:48.137: E/AndroidRuntime(3766):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-29 16:48:48.137: E/AndroidRuntime(3766):     at android.os.Looper.loop(Looper.java:153)
01-29 16:48:48.137: E/AndroidRuntime(3766):     at android.app.ActivityThread.main(ActivityThread.java:4987)
01-29 16:48:48.137: E/AndroidRuntime(3766):     at java.lang.reflect.Method.invokeNative(Native Method)
01-29 16:48:48.137: E/AndroidRuntime(3766):     at java.lang.reflect.Method.invoke(Method.java:511)
01-29 16:48:48.137: E/AndroidRuntime(3766):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:821)
01-29 16:48:48.137: E/AndroidRuntime(3766):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:584)
01-29 16:48:48.137: E/AndroidRuntime(3766):     at dalvik.system.NativeStart.main(Native Method)
01-29 16:48:48.137: E/AndroidRuntime(3766): Caused by: java.lang.UnsatisfiedLinkError: Couldn't load hellojni: findLibrary returned null
01-29 16:48:48.137: E/AndroidRuntime(3766):     at java.lang.Runtime.loadLibrary(Runtime.java:365)
01-29 16:48:48.137: E/AndroidRuntime(3766):     at java.lang.System.loadLibrary(System.java:535)
01-29 16:48:48.137: E/AndroidRuntime(3766):     at com.dece.specproj.MainActivity.<clinit>(MainActivity.java:13)
01-29 16:48:48.137: E/AndroidRuntime(3766):     ... 15 more

所以我确保我的所有目录都正确添加到环境变量 PATH 以及 Eclipse 中的 PATH，即我的 MinGW bin、MinGW msys bin、cygwin bin、android-ndk 以及 android- sdk ...我认为它们都添加正确，所以错误仍然出现。

我不确定是什么导致了这些问题，因为我是 Android NDK 的新手，所以我会发布我认为可能在其中起作用的内容。

Android.mk

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE    := SpecProj
LOCAL_SRC_FILES := hellojni.c

include $(BUILD_SHARED_LIBRARY)

hellojni.c

#include <string.h>
#include <jni.h>

jstring Java_com_dece_MainActivity_stringFromJNI(JNIEnv* env,jobject thiz)
{
    return (*env)->NewStringUTF(env, "Hello from JNI !");
}

主要活动

package com.dece.specproj;

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;

public class MainActivity extends ActionBarActivity {

    public native String stringFromJNI();
      static
      {
         System.loadLibrary("hellojni");
          }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

activity_main

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.dece.specproj.MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />

</RelativeLayout>

AndroidManifest

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.dece.specproj"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="21" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme">
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

</manifest>

Answer 1

问题的核心是这样的：

01-29 16:48:48.137: E/AndroidRuntime(3766): Caused by: java.lang.UnsatisfiedLinkError: Couldn't load hellojni: findLibrary returned null

找不到名为 libhellojni.so 的库（您尝试使用 System.loadLibrary("hellojni"); 将其加载到您的 java 文件中。您的共享库名称在此行中的 Android.mk 中设置：LOCAL_MODULE := SpecProj（导致文件名为libSpecProj.so)。

要使事情正常进行，请将 java 文件中的行更改为 System.loadLibrary("SpecProj");。

我看不出问题标题中引用的错误来自哪里，但它至少与您在运行时看到的错误没有直接关联。这可能表明在您的项目构建中奇怪地设置了其他东西（但您在代码 sn-ps 中引用的任何内容都没有表明这一点，所以它会是之外的东西）。