jnlp 与java web start

1,什么是jnlp:

java network launch protocol(java网络发布协议)。是保留applet的优点的前提下，通过一个jnlp程序，你可以在客户机上下载和安装单机版的java应用程序。

jnlp应用程序可以在运行时从因特网上动态下载资源，并且能够在用户连接到因特网的情况下，自动检查程序的版本。

 

2，FileChooser Test .java:

 

//: gui/jnlp/JnlpFileChooser.java
// Opening files on a local machine with JNLP.
// {Requires: javax.jnlp.FileOpenService;
// You must have javaws.jar in your classpath}
// To create the jnlpfilechooser.jar file, do this:
// cd ..
// cd ..
// ut
package gui.jnlp;
import javax.jnlp.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;

public class JnlpFileChooser extends JFrame {
  private JTextField fileName = new JTextField();
  private JButton
    open = new JButton("Open"),
    save = new JButton("Save");
  private JEditorPane ep = new JEditorPane();
  private JScrollPane jsp = new JScrollPane();
  private FileContents fileContents;
  public JnlpFileChooser() {
    JPanel p = new JPanel();
    open.addActionListener(new OpenL());
    p.add(open);
    save.addActionListener(new SaveL());
    p.add(save);
    jsp.getViewport().add(ep);
    add(jsp, BorderLayout.CENTER);
    add(p, BorderLayout.SOUTH);
    fileName.setEditable(false);
    p = new JPanel();
    p.setLayout(new GridLayout(2,1));
    p.add(fileName);
    add(p, BorderLayout.NORTH);
    ep.setContentType("text");
    save.setEnabled(false);
  }
  class OpenL implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      FileOpenService fs = null;
      try {
        fs = (FileOpenService)ServiceManager.lookup(
          "javax.jnlp.FileOpenService");
      } catch(UnavailableServiceException use) {
        throw new RuntimeException(use);
      }
      if(fs != null) {
        try {
          fileContents = fs.openFileDialog(".",
            new String[]{"txt", "*"});
          if(fileContents == null)
            return;
          fileName.setText(fileContents.getName());
          ep.read(fileContents.getInputStream(), null);
        } catch(Exception exc) {
          throw new RuntimeException(exc);
        }
        save.setEnabled(true);
      }
    }
  }
  class SaveL implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      FileSaveService fs = null;
      try {
        fs = (FileSaveService)ServiceManager.lookup(
          "javax.jnlp.FileSaveService");
      } catch(UnavailableServiceException use) {
        throw new RuntimeException(use);
      }
      if(fs != null) {
        try {
          fileContents = fs.saveFileDialog(".",
            new String[]{"txt"},
            new ByteArrayInputStream(
              ep.getText().getBytes()),
            fileContents.getName());
          if(fileContents == null)
            return;
          fileName.setText(fileContents.getName());
        } catch(Exception exc) {
          throw new RuntimeException(exc);
        }
      }
    }
  }
  public static void main(String[] args) {
    JnlpFileChooser fc = new JnlpFileChooser();
    fc.setSize(400, 300);
    fc.setVisible(true);
  }
} ///:~

 

 

3,用于启动的jnlp文件：

 

<?xml version="1.0" encoding="UTF-8"?>
<jnlp spec = "1.0+"
  codebase="file:E:/myeclpse6.0/thinkingjava/bin/gui/jnlp"
  href="filechooser.jnlp">
  <information>
    <title>FileChooser demo application</title>
    <vendor>Mindview Inc.</vendor>
    <description>
      Jnlp File chooser Application
    </description>
    <description kind="short">
      Demonstrates opening, reading and writing a text file
    </description>
    <icon href="mindview.gif"/>
    <offline-allowed/>
  </information>
  <resources>
    <j2se version="1.3+"
      href="http://java.sun.com/products/autodl/j2se"/>
    <jar href="jnlpfilechooser.jar" download="eager"/>
  </resources>
  <application-desc
    main-class="gui.jnlp.JnlpFileChooser"/>
    <security><all-permisssion><security>
</jnlp>

4，文件需要通过以下命令打成jar包：jar cvf gui/jnlp/jnlpfilechooser.jar gui/jnlp/*.class

 

配置文件的 codebase指明jar文件和jnlp文件的目录本地或服务器的目录。

 

 

5，使用introspector(内省器)抽取beaninfo

 

java的设计者希望能提供一个标准的工具，不仅要使用bean用起来简单，而且对于创建复杂的bean也能提供一个标准的

方法。这个工具就是IntroSpector类，这个类最重要的就是静态的getBeanInfo()方法，向这个方法传递一个Class对象引用，它能够完全侦测这个类，然后返回一个BeanInfo对象，通过这个对象得到Bean的属性、方法、事件。

 

//: gui/BeanDumper.java
// Introspecting a Bean.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.beans.*;
import java.lang.reflect.*;
import static net.mindview.util.SwingConsole.*;

public class BeanDumper extends JFrame {
  private JTextField query = new JTextField(20);
  private JTextArea results = new JTextArea();
  public void print(String s) { results.append(s + "\n"); }
  public void dump(Class<?> bean) {
    results.setText("");
    BeanInfo bi = null;
    try {
      bi = Introspector.getBeanInfo(bean, Object.class);
    } catch(IntrospectionException e) {
      print("Couldn't introspect " +  bean.getName());
      return;
    }
    for(PropertyDescriptor d: bi.getPropertyDescriptors()){
      Class<?> p = d.getPropertyType();
      if(p == null) continue;
      print("Property type:\n  " + p.getName() +
        "Property name:\n  " + d.getName());
      Method readMethod = d.getReadMethod();
      if(readMethod != null)
        print("Read method:\n  " + readMethod);
      Method writeMethod = d.getWriteMethod();
      if(writeMethod != null)
        print("Write method:\n  " + writeMethod);
      print("====================");
    }
    print("Public methods:");
    for(MethodDescriptor m : bi.getMethodDescriptors())
      print(m.getMethod().toString());
    print("======================");
    print("Event support:");
    for(EventSetDescriptor e: bi.getEventSetDescriptors()){
      print("Listener type:\n  " +
        e.getListenerType().getName());
      for(Method lm : e.getListenerMethods())
        print("Listener method:\n  " + lm.getName());
      for(MethodDescriptor lmd :
          e.getListenerMethodDescriptors() )
        print("Method descriptor:\n  " + lmd.getMethod());
      Method addListener= e.getAddListenerMethod();
      print("Add Listener Method:\n  " + addListener);
      Method removeListener = e.getRemoveListenerMethod();
      print("Remove Listener Method:\n  "+ removeListener);
      print("====================");
    }
  }
  class Dumper implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      String name = query.getText();
      Class<?> c = null;
      try {
        c = Class.forName(name);
      } catch(ClassNotFoundException ex) {
        results.setText("Couldn't find " + name);
        return;
      }
      dump(c);
    }
  }
  public BeanDumper() {
    JPanel p = new JPanel();
    p.setLayout(new FlowLayout());
    p.add(new JLabel("Qualified bean name:"));
    p.add(query);
    add(BorderLayout.NORTH, p);
    add(new JScrollPane(results));
    Dumper dmpr = new Dumper();
    query.addActionListener(dmpr);
    query.setText("frogbean.Frog");
    // Force evaluation
    dmpr.actionPerformed(new ActionEvent(dmpr, 0, ""));
  }
  public static void main(String[] args) {
    run(new BeanDumper(), 600, 500);
  }
} ///:~