完成了ejb后我们需要再来完成使用ejb的客户端程序，我们写一个servlet程序来完成这个工作，代码如下：
package.net.chinacode.web;
import java.io.ioexception;
import java.util.date;
import java.util.properties;
import javax.naming.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.rmi.portableremoteobject;
import.net.chinacode.hello.hello;
import.net.chinacode.hello.hellohome;
public class helloservlet extends httpservlet {
// constructor
public helloservlet() {
super();
trace("
}
// a reference to the remote `hello' object
protected hello _hello;
// initializes this servlet
public void init(servletconfig config) throws servletexception {
super.init(config);
trace("init");
// get the initial jndi context using our settings
context context;
try {
context = new initialcontext();
}
catch (throwable exception) {
throw new servletexception(
"unable to get initial jndi context: " + exception.tostring());
}
// get a reference to the hello home interface
hellohome hellohome;
try {
object boundobject = context.lookup("java:comp/env/ejb/hellohome");
hellohome = (hellohome) portableremoteobject.narrow(boundobject,hellohome.class);
}
catch (throwable exception) {
throw new servletexception(
"unable to get home interface: " + exception.tostring());
}
// get a reference to a hello instance
try {
_ hello = hellohome.create();
}
catch (throwable exception) {
throw new servletexception(
"unable to create hello instance: " + exception.tostring());
}
// insanity check: make sure we have a valid reference
if (_hello == null) {
throw new servletexception(
"unable to create hello instance, create() returned null");
}
}
// handles the http get request
public void doget(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception {
trace("doget");
servletoutputstream out = response.getoutputstream();
response.setcontenttype("text/html");
// get the answer from the bean
string answer;
try {
answer = _hello.sayhello("hd");
}
catch (throwable exception) {
out.println("");
out.println("time stamp: " + new date().tostring());
out.println("
hello type: " + _hello.getclass().getname());
out.println("error calling the hello bean");
out.println(exception.tostring());
out.println("");
out.println("");
return;
}
out.println("");
out.println("time stamp: " + new date().tostring());
out.println("
hello type: " + _hello.getclass().getname());
out.println("
answer: " + answer);
out.println("");
out.println("");
}
// displays a trace message to system.out
private void trace(string methodname) {
system.out.print(methodname);
system.out.println("() called");
}
}
这我们在servlet中先使用context = new initialcontext();来得到环境上下文，通过这句话我们就可以来向jndi数据树中进行查询了，而又使用object boundobject = context.lookup("java:comp/env/ejb/hellohome");来得到了我们在系统的web.xml中设置的参数，这个参数是在jndi目录数中的节点名，再通过一个对以下操作来得到ejb的home接口：hellohome = (hellohome) portableremoteobject.narrow(boundobject,hellohome.class);而home接口的create方法会返回remote接口，这个remote接口可以来直接调用server上的实际方法。
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