RMI文件上传例子(转)
使用RMI技术共有6个步骤要走:
(1) 定义和实现远端接口中的参数
(2) 定义和实现远端接口
(3) 编写服务端代码
(4) 编写客户端代码
(5) 生成stub和skeltion ,并将stub打包到客户端jar中,将skeltion打包到服务端jar中
(6) 启动rmiregistry , 并将服务注册到rmiregistry中,然后运行代码。
下面就这六个方面说明rmi技术。
==定义远端接口中的参数==
(1)定义远端接口中的参数
每一个远端接口中的参数都必须是可序列化的。那么,如何定义一个序列化的接口呢,
很简单,只需从java.io.Serializable继承即可,如下所示:
import java.io.Serializable; public interface FileInformation extends Serializable { String getName(); byte[] getContent(); void setInformation(String name , byte[] content); };
(2)实现远端接口中的参数。
实现远端接口中的参数的接口跟与实现其他任何接口没什么不一样的地方,如下所示
public class FileInformationSev implements FileInformation { private String name = null ; private byte[] content = null ; public String getName() { return name ; } public byte[] getContent() { return content; } public void setInformation(String name, byte[] content) { this.name = name ; this.content = content ; } }
那么,为什么要序列化远端接口中的参数(返回值) ?这是因为需要将客户端的对象(参数)转化成byte stream,通过网络协议传输到服务端,再还原成服务端的对象进行调用。或者是需要将服务端的对象(返回值)转化成byte stream,通过网络协议传输到服务端,再还原成客户端的对象进行调用。
在 jdk中, java.lang包和java.util包下的类都已经实现了序列化,直接可以用在远程接口中作参数或返回值;所有的基本类型也可以直接用在远程接口中作参数或返回值;
==定义和实现远端接口==
(1)定义远端接口
远端接口必须从java.rmi.Remote继承;远端接口中的方法如果要throw异常,这个异常必须是 java.rmi.RemoteException(或java.rmi.RemoteException的子类),否则,这个异常就不能被返回到客户 端。Example如下:
import java.rmi.Remote; import java.rmi.RemoteException; public interface LoadFile extends Remote { void upLoadFile(FileInformation fileInof) throws RemoteException; FileInformation downLoadFile(String filename) throws RemoteException ; }
(2)实现远端接口
实现远端接口比较容易,跟其他接口的实现没有什么区别,如下所示:
import java.rmi.Remote; import java.rmi.RemoteException; import java.io.IOException; import java.io.File; import java.io.BufferedInputStream; import java.io.FileInputStream; import java.io.BufferedOutputStream; import java.io.FileOutputStream; import java.rmi.server.UnicastRemoteObject; public class LoadFileService extends UnicastRemoteObject implements LoadFile { private String currentDir= null ; // this contruction is needed public LoadFileService() throws RemoteException { super(); } public void setCurrentDir(String currentDir){ this.currentDir = currentDir ; } public void upLoadFile(FileInformation fileInfo) throws RemoteException{ BufferedOutputStream output = null ; try{ // check paramter if(fileInfo == null ){ throw new RemoteException("the paramter is null "); } //check fileName and content String fileName = fileInfo.getName() ; byte [] content = fileInfo.getContent() ; if(fileName == null || content == null ){ throw new RemoteException("the file or the content is null "); } //create file String filePath = this.currentDir + "\\" + fileName ; File file = new File(filePath); if(!file.exists()){ file.createNewFile(); } //save the content to the file output = new BufferedOutputStream(new FileOutputStream(file)); output.write(content); }catch(RemoteException ex){ throw ex ; }catch(Exception ex){ throw new RemoteException(ex.getLocalizedMessage()); }finally{ if(output != null ){ try{ output.close(); output = null ; }catch(Exception ex){ } } } } public FileInformation downLoadFile(String fileName) throws RemoteException { FileInformation fileInfo = null ; BufferedInputStream input = null ; try{ // check paramter if(fileName == null){ throw new RemoteException("the paramter is null "); } // get path String filePath = this.currentDir + "\\" + fileName ; File file = new File(filePath); if(!file.exists()){ throw new RemoteException("the file whose name is " + fileName + " not existed "); } // get content byte[] content = new byte[(int)file.length()]; input = new BufferedInputStream(new FileInputStream(file)); input.read(content); // set file name and content to fileInfo fileInfo = new FileInformationSev(); fileInfo.setInformation(fileName , content); }catch(RemoteException ex){ throw ex ; }catch(Exception ex){ throw new RemoteException(ex.getLocalizedMessage()); }finally{ if(input != null ){ try{ input.close(); input = null ; }catch(Exception ex){ } } } return fileInfo ; } }
==编写服务端代码==
服务端代码主要有3个步骤:
(1)加载安全管理器
(2)创建一个服务对象
(3)将这个服务对象注册到命名服务上
import java.rmi.RMISecurityManager; import java.rmi.Naming; public class RMIServer { public static void main(String[] args) { try{ //加载安全管理器 System.setSecurityManager(new RMISecurityManager() ); //创建一个服务对象 LoadFileService server = new LoadFileService(); server.setCurrentDir("c:\\rmiexample"); //将服务对象注册到rmi注册服务器上,而不是其他服务器 //(因为LoadFileService extends UnicastRemoteObject) Naming.rebind("//127.0.0.1:2000/LoadFileServer", server); }catch(Exception ex){ System.out.println(ex.getLocalizedMessage()); ex.printStackTrace(); } } }
注意:将对象注册以后,不可关闭服务对象。
==编写客户端代码==
客户端代码需要两个步骤:
(1)根据服务的名称,查找服务对象
(2)调用服务服务对象对应的方法完成工作
在这个例子中,我们从客户端上传一个文件到服务器,并将服务器的一个文件下载下来。
代码如下:
import java.io.IOException; import java.io.File; import java.io.BufferedInputStream; import java.io.FileInputStream; import java.io.BufferedOutputStream; import java.io.FileOutputStream; import java.rmi.Naming; public class RMIClient { private static String getNameByPath(String path){ StringBuffer strBuffer = new StringBuffer(path); int index = strBuffer.lastIndexOf("\\"); String name = strBuffer.substring(index+1); return name ; } public static void uploadFile(LoadFile load){ BufferedInputStream input = null ; FileInformation fileInfo = null ; try{ byte[] buffer = new byte[100]; System.out.println("please given the uploadfile path, just like c:\\rmiexample\\test.xml"); System.in.read(buffer); String uploadPath = new String(buffer) ; uploadPath = uploadPath.trim(); File file = new File(uploadPath); byte[] content = new byte[(int)file.length()]; input = new BufferedInputStream(new FileInputStream(file)); input.read(content); fileInfo = new FileInformationSev(); fileInfo.setInformation(getNameByPath(uploadPath), content ); load.upLoadFile(fileInfo); }catch(Exception ex){ System.out.println(ex.getLocalizedMessage()); ex.printStackTrace(); }finally{ try{ if( input != null ){ input.close(); input = null ; } }catch(Exception ex){ } } } public static void downLoadFile(LoadFile load){ BufferedOutputStream output = null ; FileInformation fileInfo = null ; try{ byte [] fileBuffer = new byte[100]; System.out.println("please given the file's name that need download, format just like test.xml"); System.in.read(fileBuffer); String downFileName = new String(fileBuffer) ; downFileName = downFileName.trim(); byte[] pathBuffer = new byte[100]; System.out.println("please given the local position , format just like c:\\rmiexample"); System.in.read(pathBuffer); String localPath = new String(pathBuffer) ; localPath = localPath.trim(); fileInfo= load.downLoadFile(downFileName); File file = new File(localPath+"\\"+downFileName ); if(!file.exists()){ file.createNewFile(); } output = new BufferedOutputStream(new FileOutputStream(file)); output.write(fileInfo.getContent()); output.flush(); }catch(Exception ex){ System.out.println(ex.getLocalizedMessage()); ex.printStackTrace(); }finally{ try{ if( output != null ){ output.close(); output = null ; } }catch(Exception ex){ } } } public static void main(String[] args) { try{ String serverName = "//192.168.39.168:2000/LoadFileServer"; //2 get the server LoadFile load = (LoadFile)Naming.lookup(serverName); //3 upload file RMIClient.uploadFile(load); //4 download file RMIClient.downLoadFile(load); }catch(Exception ex){ System.out.println(ex.getLocalizedMessage()); ex.printStackTrace(); } } }
==根据服务端的实现生成stub和skeltion , 并将stub打包到客户端jar中,将sub和skeltion打包到服务端jar中==
* 调用如下命令生成stub和skeltion
rmic LoadFileService
生成的文件名如下:
LoadFileService_Skel.class
LoadFileService_Stub.class
* 调用如下命令将LoadFileService_Stub.class和其他客户端文件到客户端jar中
jar cvf Client.jar FileInformation.class
jar uvf Client.jar FileInformationSev.class
jar uvf Client.jar LoadFile.class
jar uvf Client.jar RMIClient.class
jar uvf Client.jar LoadFileService_Stub.class
调用如下命令将LoadFileService_ Skel.class和其他服务端文件到服务端jar中
jar cvf Server.jar FileInformation.class
jar uvf Server.jar FileInformationSev.class
jar uvf Server.jar LoadFile.class
jar uvf Server.jar LoadFileService.class
jar uvf Server.jar LoadFileService_Skel.class
jar uvf Client.jar LoadFileService_Stub.class
jar uvf Server.jar RMIServer.class
==启动rmiregistry , 并将服务注册到rmiregistry中,然后运行代码==
(1)使用rmiregistry [port] 启动rmi服务
rmiregistry 2000
(2)编写授权代码如下所示,并存为c:\rmiexample\grant.txt
grant {
permission java.net.SocketPermission "*", "accept, connect, listen, resolve";
permission java.io.FilePermission "<<ALL FILES>>", "read, write, delete, execute";
};
(3)启动服务器,
set CLASSPATH=%CLASSPATH%;C:\rmiexample\Server.jar
java -Djava.security.policy=C:\rmiexample\grant.txt RMIServer
(4) 启动客户端
set CLASSPATH=%CLASSPATH%;C:\rmiexample\Client.jar
java -Djava.security.policy=C:\rmiexample\grant.txt RMIClient
java security