我正在使用 Flutter 和 Brother Printer Native SDK 开发一个 Android 应用程序。我使用 MethodChannel 在 FlutterActivity 和 MainActivity 之间进行通信。这是我使用 Brother QL-810W 打印机打印标签的代码：
MainActivity.java
public class MainActivity extends FlutterActivity {
private static final String CHANNEL = "brother/print";
public static Printer printer;
protected PrinterInfo settings;
protected PrinterStatus bit;
@Override
public void configureFlutterEngine (@NonNull FlutterEngine flutterEngine) {
super.configureFlutterEngine(flutterEngine);
GeneratedPluginRegistrant.registerWith(flutterEngine);
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
new MethodChannel(flutterEngine.getDartExecutor().getBinaryMessenger(), CHANNEL)
.setMethodCallHandler(
(call, result) -> {
if (call.method.equals("print")) {
String address = call.argument("address");
String base64 = call.argument("base64");
int lblCount = 1; //call.argument("labels");
// Specify printer
printer = new Printer();
settings = new PrinterInfo();
settings = printer.getPrinterInfo();
settings.workPath = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS) + "/BrotherPrinter";
settings.printerModel = PrinterInfo.Model.QL_810W;
settings.port = PrinterInfo.Port.NET;
settings.ipAddress = address;
// Print Settings
settings.paperSize = PrinterInfo.PaperSize.CUSTOM;
settings.orientation = PrinterInfo.Orientation.LANDSCAPE;
settings.valign = PrinterInfo.VAlign.MIDDLE;
settings.align = PrinterInfo.Align.CENTER;
settings.printMode = PrinterInfo.PrintMode.FIT_TO_PAGE;
settings.numberOfCopies = lblCount;
//settings.labelNameIndex = LabelInfo.QL700.W62.ordinal();
settings.labelNameIndex = LabelInfo.QL700.W62RB.ordinal();
settings.isAutoCut = true;
settings.isCutAtEnd = false;
settings.isHalfCut = false;
settings.isSpecialTape = false;
printer.setPrinterInfo(settings);
if (printer.startCommunication()) {
bit = new PrinterStatus();
bit = printer.printImage(bmpFromBase64(base64));
if (bit.errorCode != PrinterInfo.ErrorCode.ERROR_NONE) {
Log.d("TAG", "ERROR - " + bit.errorCode);
result.error("ERROR",bit.errorCode.toString(),"Error when Printing");
Toast.makeText(this, "Error at printer: " + bit.errorCode.toString(), Toast.LENGTH_SHORT).show();
}
printer.endCommunication();
result.success(0);
}
}else{
result.notImplemented();
}
});
}
public static Bitmap bmpFromBase64(String base64){
try{
byte[] bytes = Base64.decode(base64, Base64.DEFAULT);
InputStream stream = new ByteArrayInputStream(bytes);
return BitmapFactory.decodeStream(stream);
}catch(Exception e){
e.printStackTrace();
return null;
}
}
}
我在测试我的应用程序时收到以下错误。
Build fingerprint: 'Nokia/Onyx_00WW/B2N_sprout:10/QKQ1.190828.002/00WW_4_15N:user/release-keys'
Revision: '0'
ABI: 'arm64'
Timestamp: 2021-10-07 18:28:33+0200
pid: 18121, tid: 18121, name: fhs_date_labels >>> com.abi_selvaraj.fhs_date_labels <<<
uid: 10241
signal 6 (SIGABRT), code -1 (SI_QUEUE), fault addr --------
Abort message: 'JNI DETECTED ERROR IN APPLICATION: GetStringUTFChars received NULL jstring
in call to GetStringUTFChars
from boolean com.brother.ptouch.sdk.JNIWrapper.writeByteInFile(int[], int, java.lang.String, boolean)'
x0 0000000000000000 x1 00000000000046c9 x2 0000000000000006 x3 0000007fcd9c8270
x4 fefeff7213592f97 x5 fefeff7213592f97 x6 fefeff7213592f97 x7 7f7f7f7f7f7f7fff
x8 00000000000000f0 x9 dd7c75978bd06d95 x10 0000000000000001 x11 0000000000000000
x12 fffffff0fffffbdf x13 ffffffffffffffff x14 0000000000000000 x15 ffffffffffffffff
x16 0000007315fe78c0 x17 0000007315fc3900 x18 00000072172da558 x19 00000000000046c9
x20 00000000000046c9 x21 00000000ffffffff x22 00000072825f1760 x23 00000072926ad705
x24 00000072926cf1f5 x25 0000000000000001 x26 00000072925bc258 x27 0000007318a06820
x28 0000007292bd9338 x29 0000007fcd9c8310
sp 0000007fcd9c8250 lr 0000007315f750c4 pc 0000007315f750f0
backtrace:
#00 pc 00000000000830f0 /apex/com.android.runtime/lib64/bionic/libc.so (abort+160) (BuildId: cf739dbc84bcc78f7a1500721bfb3758)
#01 pc 00000000004b99ac /apex/com.android.runtime/lib64/libart.so (art::Runtime::Abort(char const*)+2280) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#02 pc 000000000000b458 /system/lib64/libbase.so (android::base::LogMessage::~LogMessage()+580) (BuildId: 36cd125456a5320dd3dcb8cfbd889a1a)
#03 pc 0000000000377f60 /apex/com.android.runtime/lib64/libart.so (art::JavaVMExt::JniAbort(char const*, char const*)+1584) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#04 pc 0000000000378184 /apex/com.android.runtime/lib64/libart.so (art::JavaVMExt::JniAbortV(char const*, char const*, std::__va_list)+108) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#05 pc 000000000036a5ac /apex/com.android.runtime/lib64/libart.so (art::(anonymous namespace)::ScopedCheck::AbortF(char const*, ...)+136) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#06 pc 0000000000369bfc /apex/com.android.runtime/lib64/libart.so (art::(anonymous namespace)::ScopedCheck::CheckInstance(art::ScopedObjectAccess&, art::(anonymous namespace)::ScopedCheck::InstanceKind, _jobject*, bool)+420) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#07 pc 0000000000368e4c /apex/com.android.runtime/lib64/libart.so (art::(anonymous namespace)::ScopedCheck::CheckPossibleHeapValue(art::ScopedObjectAccess&, char, art::(anonymous namespace)::JniValueType)+580) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#08 pc 0000000000368468 /apex/com.android.runtime/lib64/libart.so (art::(anonymous namespace)::ScopedCheck::Check(art::ScopedObjectAccess&, bool, char const*, art::(anonymous namespace)::JniValueType*)+652) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#09 pc 0000000000371560 /apex/com.android.runtime/lib64/libart.so (art::(anonymous namespace)::CheckJNI::GetStringCharsInternal(char const*, _JNIEnv*, _jstring*, unsigned char*, bool, bool)+676) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#10 pc 000000000003a198 /data/app/com.abi_selvaraj.fhs_date_labels-9UrlxSd-fzffTZQSnIcl_Q==/lib/arm64/libcreatedata.so (Java_com_brother_ptouch_sdk_JNIWrapper_writeByteInFile+108) (BuildId: f8707a015211e716396c82b381288ee73ac39880)
#11 pc 0000000000140350 /apex/com.android.runtime/lib64/libart.so (art_quick_generic_jni_trampoline+144) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#12 pc 00000000001375b8 /apex/com.android.runtime/lib64/libart.so (art_quick_invoke_static_stub+568) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#13 pc 000000000014600c /apex/com.android.runtime/lib64/libart.so (art::ArtMethod::Invoke(art::Thread*, unsigned int*, unsigned int, art::JValue*, char const*)+276) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#14 pc 00000000002e3674 /apex/com.android.runtime/lib64/libart.so (art::interpreter::ArtInterpreterToCompiledCodeBridge(art::Thread*, art::ArtMethod*, art::ShadowFrame*, unsigned short, art::JValue*)+384) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#15 pc 00000000002de8d4 /apex/com.android.runtime/lib64/libart.so (bool art::interpreter::DoCall<false, false>(art::ArtMethod*, art::Thread*, art::ShadowFrame&, art::Instruction const*, unsigned short, art::JValue*)+892) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#16 pc 00000000005a3dd4 /apex/com.android.runtime/lib64/libart.so (MterpInvokeStatic+372) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#17 pc 0000000000131994 /apex/com.android.runtime/lib64/libart.so (mterp_op_invoke_static+20) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#18 pc 00000000001e2684 [anon:dalvik-classes2.dex extracted in memory from /data/app/com.abi_selvaraj.fhs_date_labels-9UrlxSd-fzffTZQSnIcl_Q==/base.apk!classes2.dex] (com.brother.ptouch.sdk.JNIWrapper.byteFileWriteRGB+176)
#19 pc 00000000005a4070 /apex/com.android.runtime/lib64/libart.so (MterpInvokeStatic+1040) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#20 pc 0000000000131994 /apex/com.android.runtime/lib64/libart.so (mterp_op_invoke_static+20) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#21 pc 00000000001e2914 [anon:dalvik-classes2.dex extracted in memory from /data/app/com.abi_selvaraj.fhs_date_labels-9UrlxSd-fzffTZQSnIcl_Q==/base.apk!classes2.dex] (com.brother.ptouch.sdk.JNIWrapper.print+4)
#22 pc 00000000005a4070 /apex/com.android.runtime/lib64/libart.so (MterpInvokeStatic+1040) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#23 pc 0000000000131994 /apex/com.android.runtime/lib64/libart.so (mterp_op_invoke_static+20) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#24 pc 00000000001ea6fc [anon:dalvik-classes2.dex extracted in memory from /data/app/com.abi_selvaraj.fhs_date_labels-9UrlxSd-fzffTZQSnIcl_Q==/base.apk!classes2.dex] (com.brother.ptouch.sdk.Printer.printImage+196)
#25 pc 00000000005a15c0 /apex/com.android.runtime/lib64/libart.so (MterpInvokeVirtual+1352) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#26 pc 0000000000131814 /apex/com.android.runtime/lib64/libart.so (mterp_op_invoke_virtual+20) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#27 pc 00000000001dd7e8 [anon:dalvik-classes2.dex extracted in memory from /data/app/com.abi_selvaraj.fhs_date_labels-9UrlxSd-fzffTZQSnIcl_Q==/base.apk!classes2.dex] (com.abi_selvaraj.fhs_date_labels.MainActivity.lambda$configureFlutterEngine$0$MainActivity+360)
#28 pc 00000000005a15c0 /apex/com.android.runtime/lib64/libart.so (MterpInvokeVirtual+1352) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#29 pc 0000000000131814 /apex/com.android.runtime/lib64/libart.so (mterp_op_invoke_virtual+20) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#30 pc 00000000001dd55c [anon:dalvik-classes2.dex extracted in memory from /data/app/com.abi_selvaraj.fhs_date_labels-9UrlxSd-fzffTZQSnIcl_Q==/base.apk!classes2.dex] (com.abi_selvaraj.fhs_date_labels.-$$Lambda$MainActivity$cnaSj6gUAqIaWfP_TCdFhmQeBEk.onMethodCall+4)
#31 pc 00000000005a2de0 /apex/com.android.runtime/lib64/libart.so (MterpInvokeInterface+1788) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#32 pc 0000000000131a14 /apex/com.android.runtime/lib64/libart.so (mterp_op_invoke_interface+20) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#33 pc 0000000000156d0e [anon:dalvik-classes3.dex extracted in memory from /data/app/com.abi_selvaraj.fhs_date_labels-9UrlxSd-fzffTZQSnIcl_Q==/base.apk!classes3.dex] (io.flutter.plugin.common.MethodChannel$IncomingMethodCallHandler.onMessage+34)
#34 pc 00000000005a2de0 /apex/com.android.runtime/lib64/libart.so (MterpInvokeInterface+1788) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#35 pc 0000000000131a14 /apex/com.android.runtime/lib64/libart.so (mterp_op_invoke_interface+20) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#36 pc 000000000014cce2 [anon:dalvik-classes3.dex extracted in memory from /data/app/com.abi_selvaraj.fhs_date_labels-9UrlxSd-fzffTZQSnIcl_Q==/base.apk!classes3.dex] (io.flutter.embedding.engine.dart.DartMessenger.handleMessageFromDart+98)
#37 pc 00000000005a2de0 /apex/com.android.runtime/lib64/libart.so (MterpInvokeInterface+1788) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#38 pc 0000000000131a14 /apex/com.android.runtime/lib64/libart.so (mterp_op_invoke_interface+20) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#39 pc 000000000014b908 [anon:dalvik-classes3.dex extracted in memory from /data/app/com.abi_selvaraj.fhs_date_labels-9UrlxSd-fzffTZQSnIcl_Q==/base.apk!classes3.dex] (io.flutter.embedding.engine.FlutterJNI.handlePlatformMessage+8)
#40 pc 00000000002b4988 /apex/com.android.runtime/lib64/libart.so (_ZN3art11interpreterL7ExecuteEPNS_6ThreadERKNS_20CodeItemDataAccessorERNS_11ShadowFrameENS_6JValueEbb.llvm.13098898000035350125+240) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#41 pc 0000000000592868 /apex/com.android.runtime/lib64/libart.so (artQuickToInterpreterBridge+1032) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#42 pc 0000000000140468 /apex/com.android.runtime/lib64/libart.so (art_quick_to_interpreter_bridge+88) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#43 pc 0000000000137334 /apex/com.android.runtime/lib64/libart.so (art_quick_invoke_stub+548) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#44 pc 0000000000145fec /apex/com.android.runtime/lib64/libart.so (art::ArtMethod::Invoke(art::Thread*, unsigned int*, unsigned int, art::JValue*, char const*)+244) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#45 pc 00000000004b126c /apex/com.android.runtime/lib64/libart.so (art::(anonymous namespace)::InvokeWithArgArray(art::ScopedObjectAccessAlreadyRunnable const&, art::ArtMethod*, art::(anonymous namespace)::ArgArray*, art::JValue*, char const*)+104) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#46 pc 00000000004b26b8 /apex/com.android.runtime/lib64/libart.so (art::InvokeVirtualOrInterfaceWithVarArgs(art::ScopedObjectAccessAlreadyRunnable const&, _jobject*, _jmethodID*, std::__va_list)+424) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#47 pc 0000000000397f88 /apex/com.android.runtime/lib64/libart.so (art::JNI::CallVoidMethodV(_JNIEnv*, _jobject*, _jmethodID*, std::__va_list)+628) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#48 pc 000000000036ca20 /apex/com.android.runtime/lib64/libart.so (art::(anonymous namespace)::CheckJNI::CallMethodV(char const*, _JNIEnv*, _jobject*, _jclass*, _jmethodID*, std::__va_list, art::Primitive::Type, art::InvokeType)+2368) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#49 pc 000000000035ad00 /apex/com.android.runtime/lib64/libart.so (art::(anonymous namespace)::CheckJNI::CallVoidMethodV(_JNIEnv*, _jobject*, _jmethodID*, std::__va_list)+72) (BuildId: 9e1ab66d67be247f1f43b362accdaf63)
#50 pc 00000000014628c8 /data/app/com.abi_selvaraj.fhs_date_labels-9UrlxSd-fzffTZQSnIcl_Q==/lib/arm64/libflutter.so (BuildId: fb1d4058f3179a6ac8718723ecfdf17c672f1abe)
#51 pc 0000000040000000 <unknown>
我已经尝试了我在网上找到的关于 JNI Detected Error 的解决方案，它们都指向相同的答案：Include External Storage Permission in AndroidManifest.xml 是不够的，runtime permissions must be enabled for Android 6.0 and up。我也为我的设备启用了运行时权限。但错误似乎仍然存在。
请帮助我了解我可能出错的地方，以及我需要检查什么来解决这个问题。让我知道我是否应该再分享我身边的代码，我会这样做。因为这是在将我的应用程序分发给我的客户之前我需要解决的最后一件事。
编辑
错误与 Brother 打印机 SDK 的工作路径有关。我将其修改为以下内容，似乎已经解决了这个问题：
从：
settings.workPath = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS) + "/BrotherPrinter";
至：
settings.workPath = getFilesDir() + "/";