sap目前是世界上最大的也是使用最多的ERP系統，很多大型系統都將自己的業務資料放到了SAP系統來進行管理，那麼當別的系統需要這些資料時，就需要從SAP中獲取這些資料。SAP中有各種不同型別的介面，RFC，PI等等。下面記錄的是java如何呼叫RFC的介面。網上可以找到很多類似的文章，程式碼也是以前的老手寫的，也比較易懂，這裡再記下來主要是為了以後找起來方便。

java呼叫RFC介面需要用到sapjco3.jar，windows下還需要將檔案sapjco3.dll檔案放到system32的目錄下，linux下同樣需要把sapjco3.so放入專案的執行目錄下。程式碼如下：

JOCTest：

package jco;

import com.sap.conn.jco.JCoFunction;
import com.sap.conn.jco.JCoParameterList;
import com.sap.conn.jco.JCoTable;

import java.util.ArrayList;
import java.util.List;

public class JCOTest {

    public static void main(String[] args)
    {
        getUser();
    }
    public static List<User> getUser() {

        JCoFunction function = RfcManager.getFunction("FUNCION_USER");

        RfcManager.execute(function);
        JCoParameterList outputParam = function.getTableParameterList();
        JCoTable bt = outputParam.getTable("TABLEOUT");
        List<User> list = new ArrayList<User>();
        for (int i = 0; i < bt.getNumRows(); i++) {
            bt.setRow(i);

            User user = new User();
            user.setUserName(bt.getString("USER_NAME"));
            list.add(user);
        }
        return list;
    }
}
 

package jco;

import com.sap.conn.jco.*;
import com.sap.conn.jco.ext.Environment;

import java.io.IOException;
import java.util.Properties;

public final class RfcManager {
    private static final String ABAP_AS_POOLED = "ABAP_AS_POOL";
    private static JCOProvider provider;
    private static JCoDestination destination;
    static {
    	Properties properties = loadProperties();
		// catch IllegalStateException if an instance is already registered
        try {
            provider = new JCOProvider();
            Environment.registerDestinationDataProvider(provider);
            provider.changePropertiesForABAP_AS(ABAP_AS_POOLED, properties);
        } catch (IllegalStateException e) {
            System.out.println(e.getMessage());
        }
    }

    public static Properties loadProperties() {
        Properties props=new Properties();
        props.setProperty("jco.client.user","value");
        props.setProperty("jco.client.passwd","value");
        props.setProperty("jco.client.lang", "value");
        props.setProperty("jco.client.client","value");
        props.setProperty("jco.client.sysnr","value");
        props.setProperty("jco.client.ashost","value");
        props.setProperty("jco.destination.peak_limit","value");
        props.setProperty("jco.destination.pool_capacity","value");
        return props;
    }

    public static JCoDestination getDestination() throws JCoException {
        if (destination == null) {
            destination = JCoDestinationManager.getDestination(ABAP_AS_POOLED);
        }
        return destination;
    }

    public static void execute(JCoFunction function) {
         System.out.println("SAP Function Name : " + function.getName());
        try {
            function.execute(getDestination());
        } catch (JCoException e) {
            e.printStackTrace();
        }
    }

	public static JCoFunction getFunction(String functionName) {
        JCoFunction function = null;
        try {
            function = getDestination().getRepository().getFunctionTemplate(functionName).getFunction();
        } catch (JCoException e) {
        	e.printStackTrace();
        } catch (NullPointerException e) {
        	e.printStackTrace();
        }
        return function;
    }
}

 

package jco;

import com.sap.conn.jco.ext.*;
import java.util.HashMap;
import java.util.Properties;

public class JCOProvider implements DestinationDataProvider,SessionReferenceProvider {

    private HashMap<String, Properties> secureDBStorage = new HashMap<String, Properties>();
    private DestinationDataEventListener eL;

    @Override
    public Properties getDestinationProperties(String destinationName) {
        try
        {
            //read the destination from DB
            Properties p = secureDBStorage.get(destinationName);
            if(p!=null)
            {
                //check if all is correct, for example
                if(p.isEmpty()){
                    System.out.println("destination configuration is incorrect!");
                }
                return p;
            }
            System.out.println("properties is null ...");
            return null;
        }
        catch(RuntimeException re)
        {
            System.out.println("internal error!");
            return null;
        }
    }

    @Override
    public void setDestinationDataEventListener(
            DestinationDataEventListener eventListener) {
        this.eL = eventListener;
        System.out.println("eventListener assigned ! ");
    }

    @Override
    public boolean supportsEvents() {
        return true;
    }

    //implementation that saves the properties in a very secure way
    public void changePropertiesForABAP_AS(String destName, Properties properties) {
        synchronized(secureDBStorage)
        {
            if(properties==null)
            {
                if(secureDBStorage.remove(destName)!=null)
                    eL.deleted(destName);
            }
            else
            {
                secureDBStorage.put(destName, properties);
                eL.updated(destName); // create or updated
            }
        }
    }

    public JCoSessionReference getCurrentSessionReference(String scopeType) {

        RfcSessionReference sesRef = JcoMutiThread.localSessionReference.get();
        if (sesRef != null)
            return sesRef;
        throw new RuntimeException("Unknown thread:" + Thread.currentThread().getId());
    }

    public boolean isSessionAlive(String sessionId) {
        return false;
    }

    public void jcoServerSessionContinued(String sessionID)
            throws SessionException {
    }

    public void jcoServerSessionFinished(String sessionID) {

    }

    public void jcoServerSessionPassivated(String sessionID)
            throws SessionException {
    }

    public JCoSessionReference jcoServerSessionStarted() throws SessionException {
        return null;
    }
}

package jco;

import com.sap.conn.jco.ext.JCoSessionReference;

import java.util.concurrent.atomic.AtomicInteger;

public class RfcSessionReference implements JCoSessionReference {
	static AtomicInteger atomicInt = new AtomicInteger(0);
	private String id = "session-" + String.valueOf(atomicInt.addAndGet(1));;

	public void contextFinished() {
	}

	public void contextStarted() {
	}

	public String getID() {
		return id;
	}

}

package jco;

public interface IMultiStepJob {
	public boolean runNextStep();

	String getName();

	public void cleanUp();
}

package jco;

import java.util.Hashtable;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;

public class JcoMutiThread extends Thread {

	public static Hashtable<IMultiStepJob, RfcSessionReference> sessions = new Hashtable<IMultiStepJob, RfcSessionReference>();
	public static ThreadLocal<RfcSessionReference> localSessionReference = new ThreadLocal<RfcSessionReference>();
	private BlockingQueue<IMultiStepJob> queue ;
	private CountDownLatch doneSignal;
	private boolean isSapBusy = false;

	public JcoMutiThread(CountDownLatch doneSignal, BlockingQueue<IMultiStepJob> queue) {
		this.doneSignal = doneSignal;
		this.queue = queue;
	}

	@Override
	public void run() {
		try {
			for (;;) {
				IMultiStepJob job = queue.poll(10, TimeUnit.SECONDS);

				// stop if nothing to do
				if (job == null){
					break;
				}

				if(isSapBusy){
					Thread.sleep(5000);
				}
				RfcSessionReference sesRef = sessions.get(job);
				if (sesRef == null) {
					sesRef = new RfcSessionReference();
					sessions.put(job, sesRef);
				}
				localSessionReference.set(sesRef);

				//Thread Started ("Task " + job.getName() + " is started.");
				try {
					isSapBusy = job.runNextStep();
				} catch (Throwable th) {
					th.printStackTrace();
				}
				
				if(isSapBusy){
					//sap system busy, try again later("Task " + job.getName() + " is passivated.");
					queue.add(job);
				}else{
					//" call sap finished, Task " + job.getName() ;
					sessions.remove(job);
					job.cleanUp();
				}
				localSessionReference.set(null);
			}
		} catch (InterruptedException e) {
			// just leave
		} finally {
			doneSignal.countDown();
		}
	}
}