如果jar文件>一定大小,Applet无法在Windows 7上加载Java 1.7

我们有一个相当复杂的签名小程序,自从我们几年前开发以来,我们一直在为我们工作.在我们关心的所有操作系统/浏览器配置上,Java 1.5和1.6都可以正常运行.

在Windows 7或Vista上的任何浏览器中,它不适用于Java 1.7.我们已经看到它在Windows XP上工作.该小程序正在Apache使用mod_proxy连接到Tomcat 6的站点中运行.

这些都是为了背景信息,因为我将问题减少到一个非常简单的未签名小程序：

package myapplet;
import java.applet.Applet;
import java.awt.Color;
import java.awt.Graphics;

public class MyApplet extends Applet {
    private static final long    serialVersionUID    = 1L;

    public void paint(Graphics g) {
        g.drawRect(0,250,100);
        g.setColor(Color.blue);
        g.drawString("Look at me,I'm a Java Applet!",10,50);
    }
}

如果这个applet类被放入一个jar文件中,另外一个jar文件的大小(压缩大小)大约为18KB,那么applet在本地运行的Tomcat 6(或Apache 2.2)服务时不加载.

我通过添加文本文件到jar文件和更改文本文件的大小来玩.通过在文本文件中添加一个字符,我得到了它从工作到不工作的点.

看着带有跟踪的控制台日志挂在正在尝试下载jar文件的位置.这是我认为挂的线程：

"thread applet-com.bright.assetbank.clientsideedit.myapplet.MyApplet-1" prio=4 tid=0x048d8c00 nid=0x19b8 runnable [0x0700d000]
    java.lang.Thread.State: RUNNABLE
    at java.net.socketInputStream.socketRead0(Native Method)
    at java.net.socketInputStream.read(UnkNown Source)
    at java.net.socketInputStream.read(UnkNown Source)
    at java.io.BufferedInputStream.read1(UnkNown Source)
    at java.io.BufferedInputStream.read(UnkNown Source)
    - locked <0x29fd75b0> (a java.io.BufferedInputStream)
    at sun.net.www.MeteredStream.read(UnkNown Source)
    - locked <0x29fd75d0> (a sun.net.www.http.KeepAliveStream)
    at java.io.FilterInputStream.read(UnkNown Source)
    at sun.net.www.protocol.http.HttpURLConnection$HttpInputStream.read(UnkNown Source)
    at java.io.BufferedInputStream.read1(UnkNown Source)
    at java.io.BufferedInputStream.read(UnkNown Source)
    - locked <0x29fd7630> (a java.io.BufferedInputStream)
    at java.io.FilterInputStream.read(UnkNown Source)
    at sun.plugin.PluginURLJarFileCallBack.downloadJAR(UnkNown Source)
    at sun.plugin.PluginURLJarFileCallBack.access$000(UnkNown Source)
    at sun.plugin.PluginURLJarFileCallBack$1.run(UnkNown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.plugin.PluginURLJarFileCallBack.retrieve(UnkNown Source)
    at sun.net.www.protocol.jar.URLJarFile.retrieve(UnkNown Source)
    at sun.net.www.protocol.jar.URLJarFile.getJarFile(UnkNown Source)
    at sun.net.www.protocol.jar.JarFileFactory.get(UnkNown Source)
    at sun.net.www.protocol.jar.JarURLConnection.connect(UnkNown Source)
    at sun.plugin.net.protocol.jar.CachedJarURLConnection.connect(UnkNown Source)
    at sun.plugin.net.protocol.jar.CachedJarURLConnection.getJarFileInternal(UnkNown Source)
    - locked <0x29f2a938> (a sun.plugin.net.protocol.jar.CachedJarURLConnection)
    at sun.plugin.net.protocol.jar.CachedJarURLConnection.getJarFile(UnkNown Source)
    - locked <0x29f2a938> (a sun.plugin.net.protocol.jar.CachedJarURLConnection)
    at com.sun.deploy.security.DeployURLClasspath$JarLoader.getJarFile(UnkNown Source)
    at com.sun.deploy.security.DeployURLClasspath$JarLoader.access$1000(UnkNown Source)
    at com.sun.deploy.security.DeployURLClasspath$JarLoader$1.run(UnkNown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.deploy.security.DeployURLClasspath$JarLoader.ensureOpen(UnkNown Source)
    at com.sun.deploy.security.DeployURLClasspath$JarLoader.<init>(UnkNown Source)
    at com.sun.deploy.security.DeployURLClasspath$3.run(UnkNown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.deploy.security.DeployURLClasspath.getLoader(UnkNown Source)
    at com.sun.deploy.security.DeployURLClasspath.getLoader(UnkNown Source)
    - locked <0x29dc7e98> (a com.sun.deploy.security.DeployURLClasspath)
    at com.sun.deploy.security.DeployURLClasspath.getResource(UnkNown Source)
    at sun.plugin2.applet.Plugin2ClassLoader$2.run(UnkNown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.plugin2.applet.Plugin2ClassLoader.findClassHelper(UnkNown Source)
    at sun.plugin2.applet.Applet2ClassLoader.findClass(UnkNown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(UnkNown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass(UnkNown Source)
    - locked <0x29dc7ed8> (a sun.plugin2.applet.Applet2ClassLoader)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(UnkNown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass(UnkNown Source)
    - locked <0x29dc7f78> (a sun.plugin2.applet.Applet2ClassLoader)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass(UnkNown Source)
    - locked <0x29dc7f78> (a sun.plugin2.applet.Applet2ClassLoader)
    at java.lang.classLoader.loadClass(UnkNown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadCode(UnkNown Source)
    at sun.plugin2.applet.Plugin2Manager.initAppletAdapter(UnkNown Source)
    at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(UnkNown Source)
    at java.lang.Thread.run(UnkNown Source)

以下是Java控制台中的最后4行：

network: Cache entry not found [url: http://localhost/editor.jar,version: null]
network: Connecting http://localhost/editor.jar with proxy=DIRECT
network: Connecting http://localhost:80/ with proxy=DIRECT
network: Connecting http://localhost/editor.jar with cookie "csrftoken=523154b2e73a76b6f2088464bd4df4f7"

一些额外的信息：

>在浏览器中运行Java 7的Windows Vista中,如果我取消选中“启用黑名单撤销检查”,则会加载我们的主applet(由Apache-> mod_proxy-> tomcat提供).如果这样做,它不会加载.取消选中此功能在Windows 7上没有任何效果(即不使其正常工作).
>我尝试在Tomcat(本地),Apache(本地)和Apache(在通过Internet访问的远程服务器)上托管我的测试小程序.对于每一个都有一个大小的jar文件,小程序不会加载到该文件,但是这个大小在Web服务器之间是不同的.例如,在远程服务器上,jar文件可能会更大 – 在加载之前它必须超过1MB.

有没有人看到这种行为,当试图加载一个applet与Java 7运行在Windows 7或Vista上的浏览器？有解决方案吗？

分步说明如何重现此问题：

>将上面的代码复制到一个名为MyApplet.java的文件中
目录叫做myapplet
>编译代码,即javac MyApplet.java
>创建一个jar文件：cd到myapplet的父目录并键入jar -cvf editor.jar myapplet
>创建一个简单的HTML页面来显示小程序.

例如：

<html>  
    <body>
        <applet code="myapplet.MyApplet" name="MyApplet" width="300" height="300" archive= "editor.jar" ></applet>
    </body>
</html>

将此HTML文件和jar文件放入同一个目录,并从Web服务器提供服务器. Apache或Tomcat.
>在Windows 7操作系统上的Chrome或IE浏览此HTML页面.小程序会加载好！
>重复上述步骤,但这次放一个小文件,例如在创建jar文件之前,将图像(例如< 2KB)放入myapplet目录(MyApplet.class旁边).这也应该起作用.
>重复,但是在创建jar文件之前,这个时候会将一个大的图像(例如> 100KB)放入myapplet目录(MyApplet.class旁边).这个jar文件现在会很大.这将不起作用,即小程序不会加载.如果是这样,而您正在使用Windows 7,那么请让我知道.在测试时,不要忘记applet被缓存,所以按下java控制台中的x键来刷新类加载器缓存和f5刷新浏览器.

-Djava.net.preferIPv4Stack=true

<html>  
    <body>
        <applet code="myapplet.MyApplet" name="MyApplet" width="300" height="300" archive= "editor.jar" >
        <param name="java_arguments" value="-Djava.net.preferIPv4Stack=true">
    </applet>
    </body>
</html>