我正在研究Getting started with the Digital Asset Ledger API。我小心翼翼地按照指示Configure Maven to work with the Digital Asset Repository行进 创建ping-pong-java项目，并使用'maven'进行编译并运行'sandbox'确实没有问题。但是，输入：
mvn exec:java
导致以下输出：
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building example-ping-pong-grpc-java 0.0.1-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- exec-maven-plugin:1.6.0:java (default-cli) @ example-ping-pong-grpc-java ---
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
[WARNING]
java.lang.RuntimeException: Module PingPong is not available on the ledger
at examples.pingpong.PingPongMain.detectPingPongPackageId (PingPongMain.java:194)
at examples.pingpong.PingPongMain.main (PingPongMain.java:63)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke (Method.java:564)
at org.codehaus.mojo.exec.ExecJavaMojo$1.run (ExecJavaMojo.java:282)
at java.lang.Thread.run (Thread.java:844)
[WARNING] thread Thread[grpc-default-worker-ELG-1-1,5,examples.pingpong.PingPongMain] was interrupted but is still alive after waiting at least 15000msecs
[WARNING] thread Thread[grpc-default-worker-ELG-1-1,5,examples.pingpong.PingPongMain] will linger despite being asked to die via interruption
[WARNING] thread Thread[grpc-default-executor-0,5,examples.pingpong.PingPongMain] will linger despite being asked to die via interruption
[WARNING] thread Thread[ObjectCleanerThread,1,examples.pingpong.PingPongMain] will linger despite being asked to die via interruption
[WARNING] thread Thread[grpc-default-worker-ELG-1-2,5,examples.pingpong.PingPongMain] will linger despite being asked to die via interruption
[WARNING] thread Thread[grpc-default-worker-ELG-1-3,5,examples.pingpong.PingPongMain] will linger despite being asked to die via interruption
[WARNING] thread Thread[grpc-default-worker-ELG-1-4,5,examples.pingpong.PingPongMain] will linger despite being asked to die via interruption
[WARNING] thread Thread[grpc-default-worker-ELG-1-5,5,examples.pingpong.PingPongMain] will linger despite being asked to die via interruption
[WARNING] thread Thread[grpc-default-worker-ELG-1-6,5,examples.pingpong.PingPongMain] will linger despite being asked to die via interruption
[WARNING] thread Thread[grpc-default-worker-ELG-1-7,5,examples.pingpong.PingPongMain] will linger despite being asked to die via interruption
[WARNING] NOTE: 9 thread(s) did not finish despite being asked to via interruption. This is not a problem with exec:java, it is a problem with the running code. Although not serious, it should be remedied.
[WARNING] Couldn't destroy threadgroup org.codehaus.mojo.exec.ExecJavaMojo$IsolatedThreadGroup[name=examples.pingpong.PingPongMain,maxpri=10]
java.lang.IllegalThreadStateException
at java.lang.ThreadGroup.destroy (ThreadGroup.java:776)
at org.codehaus.mojo.exec.ExecJavaMojo.execute (ExecJavaMojo.java:321)
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:134)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:208)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:154)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:146)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:51)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:309)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:194)
at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:107)
at org.apache.maven.cli.MavenCli.execute (MavenCli.java:955)
at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:290)
at org.apache.maven.cli.MavenCli.main (MavenCli.java:194)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke (Method.java:564)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:289)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:229)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:415)
at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:356)
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 18.860 s
[INFO] Finished at: 2019-02-25T15:45:02-05:00
[INFO] Final Memory: 12M/57M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.6.0:java (default-cli) on project example-ping-pong-grpc-java: An exception occured while executing the Java class. Module PingPong is not available on the ledger -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
我点击了错误消息http://www.slf4j.org/codes.html#StaticLoggerBinder中的链接，内容如下：
Failed to load class org.slf4j.impl.StaticLoggerBinder
This warning message is reported when the org.slf4j.impl.StaticLoggerBinder class could not be loaded into memory. This happens when no appropriate SLF4J binding could be found on the class path. Placing one (and only one) of slf4j-nop.jar slf4j-simple.jar, slf4j-log4j12.jar, slf4j-jdk14.jar or logback-classic.jar on the class path should solve the problem.
SINCE 1.6.0 As of SLF4J version 1.6, in the absence of a binding, SLF4J will default to a no-operation (NOP) logger implementation.
If you are responsible for packaging an application and do not care about logging, then placing slf4j-nop.jar on the class path of your application will get rid of this warning message. Note that embedded components such as libraries or frameworks should not declare a dependency on any SLF4J binding but only depend on slf4j-api. When a library declares a compile-time dependency on a SLF4J binding, it imposes that binding on the end-user, thus negating SLF4J's purpose.
我不知道该怎么做。我只想按照本教程来了解API分类帐。我没有Java或Maven的经验，我也不打算学习它们，因为我的Ledger应用程序需要用PHP编写。我该怎么办才能解决此错误？
答案 0 :(得分：1)
我认为红色堆栈跟踪有点像红色鲱鱼，重要的消息是从examples.pingpong.PingPongMain.detectPingPongPackageId (PingPongMain.java:194)抛出的RuntimeException-这表明Java代码找不到应加载的DAML模型代码进入分类帐（沙箱）。您是否运行过da sandbox？再试一次，确保沙箱正在运行。另外，请检查您的da.yaml以确保它在那里，并且看起来像这样：
project:
sdk-version: 0.11.3
name: PingPongExample
source: daml/PingPong.daml
parties:
- Alice
- Bob
version: 2
如果您的分类帐服务器（沙盒）正常运行，您应该会在终端上看到它：
paul:ping-pong-java$ da sandbox
[Info] Starting:
Sandbox ledger server /Users/paul/dev/ping-pong-java/daml/PingPong.daml
with no scenario and binding to port 7600
2019-02-26 14:14:50.09 [DEBUG] [package] [] [DA.Service.Daml.Compiler.Impl.Handle:245]
Creating dar: /Users/paul/dev/ping-pong-java/daml/PingPong.daml
2019-02-26 14:14:50.09 [DEBUG] [package] [] [DA.Service.Daml.Compiler.Impl.Handle:171]
Setting files of interest to: [AbsoluteFilePath {getRawFilePath = "/Users/paul/dev/ping-pong-java/daml/PingPong.daml"}]
2019-02-26 14:14:50.09 [INFO] [package] []
Starting shakeRun (aborting the previous one took 0.00s)
2019-02-26 14:14:50.09 [DEBUG] [package] [] [DA.Service.Daml.Compiler.Impl.Handle:217]
Compiling: /Users/paul/dev/ping-pong-java/daml/PingPong.daml
2019-02-26 14:14:50.09 [INFO] [package] []
Finishing shakeRun (took 0.00s, exception)
2019-02-26 14:14:50.09 [INFO] [package] []
Starting shakeRun (aborting the previous one took 0.00s)
2019-02-26 14:14:51.17 [INFO] [package] []
Finishing shakeRun (took 1.08s, completed)
2019-02-26 14:14:51.17 [INFO] [package] []
Starting shakeRun (aborting the previous one took 0.00s)
2019-02-26 14:14:51.17 [INFO] [package] []
Finishing shakeRun (took 0.00s, completed)
Created /Users/paul/dev/ping-pong-java/target/PingPongExample.dar.
Created /Users/paul/dev/ping-pong-java/target/ghc-prim.dalf.
Waiting for Sandbox.......ok
我假设您正在运行最新版本的SDK（0.11.3）。如果不是，请升级。