在java中如何读取文件

mjs2000 2000-07-27 08:36:00
我在编写Applet中想读取文本文件
报告的错误好象是没有权限,
提示的:
Exception:com.ms.security.SecurityExceptionEx
我如何做才可以呢?(在不降低系统安全性的前提下)
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lvyu 2000-08-10
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数字签名
10 Steps to create a digital certificate and sign an applet
27-jul-00 : 5:17 :irene67
These steps describe the creation of a self-signed applet. This is useful for testing purposes. For use of public reachable applets, there will be needed a "real" certificate issued by an authority like VeriSign or Thawte. (See step 10 - no user will import and trust a self-signed applet from an unkown developer).

The applet needs to run in the plugin, as only the plugin is platform- and browser-independent. And without this indepence, it makes no sense to use java...

1. Create your code for the applet as usual. It is not necessary to set any permissions or use security managers in the code.

2. Install JDK 1.3 Path for use of the following commands: [jdk 1.3 path]\bin\ (commands are keytool, jar, jarsigner) Password for the keystore is *any* password. Only Sun knows why... perhaps ;-)
我装的是jdk1.2,ie5.5,java plugin 1.2,同样可行.
3. Generate key: keytool -genkey -alias tstkey Enter keystore password: ******* What is your first and last name? [Unknown]: Your Name What is the name of your organizational unit? [Unknown]: YourUnit What is the name of your organization? [Unknown]: YourOrg What is the name of your City or Locality? [Unknown]: YourCity What is the name of your State or Province? [Unknown]: YS What is the two-letter country code for this unit? [Unknown]: US Is CN=Your Name, OU=YourUnit, O=YourOrg, L=YourCity, ST=YS, C=US correct? [no]: yes

(wait...)

Enter key password for tstkey (RETURN if same as keystore password):

(press [enter])

4. Export key: keytool -export -alias tstkey -file tstcert.crt

Enter keystore password: ******* Certificate stored in file tstcert.crt

5. Create JAR: jar cvf tst.jar tst.class Add all classes used in your project by typing the classnames in the same line.

added manifest adding: tst.class(in = 849) (out= 536)(deflated 36%)

6. Verify JAR: jar tvf tst.jar

0 Thu Jul 27 12:58:28 GMT+02:00 2000 META-INF/ 68 Thu Jul 27 12:58:28 GMT+02:00 2000 META-INF/MANIFEST.MF 849 Thu Jul 27 12:49:04 GMT+02:00 2000 tst.class

7. Sign JAR: jarsigner tst.jar tstkey Enter Passphrase for keystore: *******

8. Verifiy Signing: jarsigner -verify -verbose -certs tst.jar

130 Thu Jul 27 13:04:12 GMT+02:00 2000 META-INF/MANIFEST.MF 183 Thu Jul 27 13:04:12 GMT+02:00 2000 META-INF/TSTKEY.SF 920 Thu Jul 27 13:04:12 GMT+02:00 2000 META-INF/TSTKEY.RSA 0 Thu Jul 27 12:58:28 GMT+02:00 2000 META-INF/ smk 849 Thu Jul 27 12:49:04 GMT+02:00 2000 tst.class

X.509, CN=Your Name, OU=YourUnit, O=YourOrg, L=YourCity, ST=YS, C=US (tstkey)

s = signature was verified m = entry is listed in manifest k = at least one certificate was found in keystore i = at least one certificate was found in identity scope

jar verified.

9. Create HTML-File for use of the Applet by the Sun Plugin 1.3 (recommended to use HTML Converter Version 1.3)

10. Place a link to the .crt file (created in step 4) in the HTML-File. This .crt file has to be opened by the browser and has to be set to trusted, as the root CA for testing is not known to the browser. For use with "real" certificates, this step should not be necessary.

只有数字签名的applet才可能不在sandbox中运行,从而访问本地资源.
lvyu@sina.com
lvyu 2000-08-08
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javaduke 2000-07-28
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编写方式不对
到www.duekjava.com
的酷毙学堂看一下。

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