APIM manage workflow with multiple roles APIM 3.0.0 per API based subscription workflow Logging internal HTTP requests Log APIM analytics events to a file Monetization and sample with WSO2 API Manager 2.6.0 Share application and subscription among a set of specific groups or roles WSO2 APIM Correlating analytics event with correlationID APIM analytics distinguish production and sandbox traffic APIM 2.x.x analytics internal and analytics tuneup Configure APIM(Next release) Key Manager User stores APIM(Next release) working with key manager DAS 3.x Parse system variables to Spark Context Revoke OAuth application In APIM 2.1.0 Next WSO2 APIM powered by WSO2 Ballerina Configure WSO2 APIM Analytics on Cluster environment Configure WSO2 DAS 3.1.0 for WSO2 APIM 2.0.0 Analytics WSO2 APIM publishing custom statistics WSO2 APIM Error codes Working with WSO2 message tracer Use DAS admin service to query using Spark SQL Configure WSO2 APIM Analytics using XML WSO2 APIM Generating and Retrieving Custom Statistics Understanding WSO2 APIM Statistics Model Publishing WSO2 APIM 1.10.x Runtime Statistics to DAS with RDBMS Publishing_APIM_1100_Runtime_Statistics_to_DAS Aggregate functions with WSO2 DAS REST API Create a cApp for WSO2 DAS Debugging WSO2 Products using OSGI console. Publishing APIM Runtime Statistics to DAS Deploy cApp on WSO2 DAS How to configure and start the Accumulo minicluster How to setup DNS server on Ubuntu and Ubuntu server How to use Java Reflection how to install apache web server on ubuntu and ubuntu server How to install Mail server on Ubuntu and Ubuntu server How to install squirrelmail webmail client on Ubuntu and Ubuntu Server Pass and return String value to JNI method Pass and return numeric value to JNI method Calling a C Function from the Java Programming Language using JNI AXIS 2 Sample web service Client with maven and eclipse How to setup AXIS 2 with Apache Tomcat AXIS 2 Sample web service with maven and eclipse Robot framework Sample with Selenium Robot framework Custom Library Sample Behaviour-Driven Development with JBehave and Eclipse Play Audio with Netbeans and linking with LibVLC Implement LibVLC based player with QT-part2 Simple Audio playing sample with LibVLC How to install LibVLC on Ubuntu Implement LibVLC based player with QT-part1
Pass and return String value to JNI method
  • If you didn't know how to write sample JNI please follow previous blog.
  • Java and C represent String as diffrent way.
  • In Java language String are sequence of UTF-16 code and in C it is bytes.
  • Thus in JNI it has two two functions to convert String to UTF-8 and one to convert it back to UTF-16
  • Let's implement simple Greeting Class which is get person's name and return String greeting
  • Define the Greeting.java class as below.
    class Greeting {
    
    	public static native String sayHello(String name);
    
    	static
    	{
    		System.loadLibrary("Greeting");
    	}
    }
    
  • Compile and generate corresponding header definition
    javac Greeting.java
    javah Greeting
    
  • Then implement the Greeting.c as below
  • unlike before we use GetStringUTFChars to convert utf-8 chars and NewStringUTF to get UTF-16 Sequence
    #include "Greeting.h"
    #include 
    #include 
    
    JNIEXPORT jstring JNICALL Java_Greeting_sayHello (JNIEnv *env, jclass cl, jstring name)
    {
    	jstring jstr;
    	char greeting[] = "Hello, ";
    
    	char* cname;
    	cname = (*env)->GetStringUTFChars(env, name, NULL);
    
    	strcat(greeting,cname);
    
    	jstr = (*env)->NewStringUTF(env, greeting);
    
    	return jstr;
    }
    
    
  • Generate the dynamic library according to the environment
    //on Cygwin programming environment in windows
    gcc -mno-cygwin -D __int64="long long" -I JAVA_HOME/include/ -I JAVA_HOME/include/win32 -shared -Wl,--add-stdcall-alias -o Greeting.dll Greeting.c
    
    // Gnu C compiler on Linux
    gcc -fPIC -I JAVA_HOME/include -I JAVA_HOME/include/linux -shared -o libGreeting.so Greeting.c
    
    
    //With tSun compiler under the Solaris Operating System
    cc -G -I JAVA_HOME/include -I JAVA_HOME/include/solaris -o libGreeting.so Greeting.c
    
    //in Microsoft C++ compiler on Windows
    cl -I JAVA_HOME\include -I JAVA_HOME\include\win32 -LD Greeting.c -FeGreeting.dll
    
    
  • Create GreetingTest class
    class GreetingTest
     {
        public static void main(String[] args)
        {
    	   System.out.println(Greeting.sayHello("Rukshan"));
        }
     }
    
  • Run the GreetingTest class
    javac GreetingTest.java
    java GreetingTest
    
  • download the sample code here.

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