连接 Java 和 R 有两种不同的方法。
如果你想使用JRI-Djava.library.path
,你必须使用指向包含 JRI 库的文件夹的 JVM 参数来启动你的 java 程序。
例如:
$JAVA_HOME/bin/java -Djava.library.path=/app/vendor/R/lib/R/library/rJava/jri/ -jar target/myapp.jar
如果找不到 JRI 安装目录,请尝试查找 JRI SO 库:
find / -name "libjri.*"
此外,请确保您已在您的环境中创建了 R_HOME 和 LD_LIBRARY_PATH:
- R_HOME:指向您的本地 R 安装(Ej:/Library/Frameworks/R.framework/Resources)
- LD_LIBRARY_PATH:指向 R lib 目录以及 JRI 目录(EJ:$LD_LIBRARY_PATH:/app/vendor/R/lib/R/lib:/app/vendor/R/lib/R/bin)
这是一个例子:
@Test
public void testMeanFunction() {
// just making sure we have the right version of everything
if (!Rengine.versionCheck()) {
System.err.println("** Version mismatch - Java files don't match library version.");
fail(String.format("Invalid versions. Rengine must have the same version of native library. Rengine version: %d. RNI library version: %d", Rengine.getVersion(), Rengine.rniGetVersion()));
}
// Enables debug traces
Rengine.DEBUG = 1;
System.out.println("Creating Rengine (with arguments)");
// 1) we pass the arguments from the command line
// 2) we won't use the main loop at first, we'll start it later
// (that's the "false" as second argument)
// 3) no callback class will be used
engine = REngine.engineForClass("org.rosuda.REngine.JRI.JRIEngine", new String[] { "--no-save" }, null, false);
System.out.println("Rengine created...");
engine.parseAndEval("rVector=c(1,2,3,4,5)");
REXP result = engine.parseAndEval("meanVal=mean(rVector)");
// generic vectors are RVector to accomodate names
assertThat(result.asDouble()).isEqualTo(3.0);
}
另一方面,如果你想使用Rserve,你需要在一个单独的进程中启动 Rserve ,然后从你的 java 进程中创建一个 RConnection 。
例如:
if(LOGGER.isInfoEnabled()) {
LOGGER.info("Starting RServe process...");
}
ProcessBuilder builder = new ProcessBuilder("/bin/sh", "-c", String.format("echo 'library(Rserve);Rserve(FALSE,args=\"--no-save --slave --RS-conf %s\")'|%s --no-save --slave", rserveConf, rexe));
builder.inheritIO();
Process rProcess = builder.start();
if(LOGGER.isInfoEnabled()) {
LOGGER.info("Waiting for Rserve to start...");
}
int execCodeResult = rProcess.waitFor();
if(execCodeResult != SUCCESS_CODE) {
LOGGER.error(String.format("Unexpected error code starting RServe: %d", execCodeResult));
} else {
LOGGER.error("RServe started successfully");
}
if(LOGGER.isInfoEnabled()) {
LOGGER.info("Opening connection to RServe daemon....");
}
REngine engine = new RConnection();
if(LOGGER.isInfoEnabled()) {
LOGGER.info(String.format("Obtaining R server version: %d", ((RConnection)engine).getServerVersion()));
}
//Perform some engine.parseAndEval("....");
rserveConf是 Rserv conf 文件的路径,而rexe是 R 可执行文件的完整路径。
例如,在我的 MacOS 计算机中,我可以启动 Rserve 执行此行:
/bin/sh -c "echo 'library(Rserve);Rserve(FALSE,args=\"--slave --RS-conf /Users/me/Documents/test/rserve.conf\")'|/Library/Frameworks/R.framework/Versions/3.2/Resources/bin/exec/R --no-save --slave"
此命令输出如下内容:
Starting Rserve:
/Library/Frameworks/R.framework/Resources/bin/R CMD /Library/Frameworks/R.framework/Versions/3.2/Resources/library/Rserve/libs//Rserve --slave
Rserv started in daemon mode.
确保在启动 Rserve 时指定“--slave”参数。
如果您想查看更多示例,我的 github 中有一个使用两种方法 JRI 和 RServe 的演示项目:
https://github.com/jfcorugedo/RJavaServer