Develop Reference

Why is the CLASSPATH failing for Python but working for RazorSQL?

On Windows Server 2016, we are trying to connect over JDBC with a Jython script but it is giving following error:
java.lang.ClassNotFoundException: java.lang.ClassNotFoundException:
com.microsoft.sqlserver.jdbc.SQLServerDriver
RazorSQL, on the same machine, connects without error using these settings:
Driver Class: com.microsoft.sqlserver.jdbc.SQLServerDriver
Driver Location: \Program Files (x86)\RazorSQL\drivers\sqlserver\sqljdbc.jar
As a result, we set the CLASSPATH to same location with this command:
set CLASSPATH=C:\Program Files (x86)\RazorSQL\drivers\sqlserver\sqljdbc.jar
...but when running the code below - we still get the same ClassNotFound error.
This is our Python code:
jclassname = "com.microsoft.sqlserver.jdbc.SQLServerDriver"
database = "our_database_name"
db_elem = ";databaseName={}".format(database) if database else ""
host = "###.##.###.###" # ip address
port = "1433"
user = "user_name"
password = "password"
url = (
 jdbc:sqlserver://{host}:{port}{db_elem}"
 ";user={user};password={password}".format(
host=host, port=port, db_elem=db_elem,
 er=user, password=password)
 )
print url
 
driver_args = [url]
jars = None
libs = None
db = jaydebeapi.connect(jclassname, driver_args, jars=jars,
libs=libs)
This is how we are running our Python script:
C:\jython2.7.0\bin\jython.exe C:\path_to_our_script.py
How is that RazorSQL is connecting fine - but somehow Python cannot? How do we remove this CLASSPATH error?

You have to load the JARs at runtime using the system Classloader.
Please refer to this answer.
The following code snippet has been taken from this Gist.
def loadJar(jarFile):
'''load a jar at runtime using the system Classloader (needed for JDBC)
adapted from http://forum.java.sun.com/thread.jspa?threadID=300557
Author: Steve (SG) Langer Jan 2007 translated the above Java to Jython
Reference: https://wiki.python.org/jython/JythonMonthly/Articles/January2007/3
Author: seansummers#gmail.com simplified and updated for jython-2.5.3b3+
>>> loadJar('jtds-1.3.1.jar')
>>> from java import lang, sql
>>> lang.Class.forName('net.sourceforge.jtds.jdbc.Driver')
<type 'net.sourceforge.jtds.jdbc.Driver'>
>>> sql.DriverManager.getDriver('jdbc:jtds://server')
jTDS 1.3.1
'''
from java import io, net, lang
u = io.File(jarFile).toURL() if type(jarFile) <> net.URL else jarFile
m = net.URLClassLoader.getDeclaredMethod('addURL', [net.URL])
m.accessible = 1
m.invoke(lang.ClassLoader.getSystemClassLoader(), [u])
if __name__ == '__main__':
import doctest
doctest.testmod()
Also look at - https://wiki.python.org/jython/JythonMonthly/Articles/January2007/3

Find JRE installation path in Inno Setup

Followings are my requirement:
Check if the Java is installed
Check if it's installed in a custom directory
if it's, then save the directory path in a variable
Otherwise detect the version and save the standard path in a variable
Below is the code that detects the version and save the standard path to a variable
Problems with my code:
If both 32 and 64 bit is installed it detects the both ..My aim is to detect only 64 bit in case both is installed.
if DirExists(ExpandConstant('{pf32}\java\')) then Is this what i can use to detect custom directory?
I don't think the above code is the right way to find custom directory of java. if the user installed in a different folder other than Java. the other problem is if we uninstall java it doesn't delete the folder java/JRE.
I'm using #TLama's code from Need help on Inno Setup script - issue in check the jre install
[Code]
#define MinJRE "1.7.0"
#define WebJRE "http://www.oracle.com/technetwork/java/javase/downloads/jre6downloads-1902815.html"
function IsJREInstalled: Boolean;
var
JREVersion: string;
JREPath:string
begin
{ read JRE version }
Result := RegQueryStringValue(HKLM32, 'Software\JavaSoft\Java Runtime Environment',
'CurrentVersion', JREVersion);
MsgBox('JAVA 32 bit detected.', mbInformation, MB_OK);
JREPath := 'C:\Program Files (x86)\Java'
{ if the previous reading failed and we're on 64-bit Windows, try to read }
{ the JRE version from WOW node }
if not Result and IsWin64 then
Result := RegQueryStringValue(HKLM64, 'Software\JavaSoft\Java Runtime Environment',
'CurrentVersion', JREVersion);
MsgBox('JAVA 64 bit detected.', mbInformation, MB_OK);
JREPath := 'C:\Program Files\Java'
{ if the JRE version was read, check if it's at least the minimum one }
if Result then
Result := CompareStr(JREVersion, '{#MinJRE}') >= 0;
end;
function InitializeSetup: Boolean;
var
ErrorCode: Integer;
begin
Result := True;
{ check if JRE is installed; if not, then... }
if not IsJREInstalled then
begin
{ show a message box and let user to choose if they want to download JRE; }
{ if so, go to its download site and exit setup; continue otherwise }
if MsgBox('Java is required. Do you want to download it now ?',
mbConfirmation, MB_YESNO) = IDYES then
begin
Result := False;
ShellExec('', '{#WebJRE}', '', '', SW_SHOWNORMAL, ewNoWait, ErrorCode);
end;
end;
end;

JRE installation path is stored in registry like this:
[HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Runtime Environment]
"CurrentVersion"="1.8"
[HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Runtime Environment\1.8]
"JavaHome"="C:\\Program Files\\Java\\jre1.8.0_172"
You can retrieve the installation path of the latest version (with 64-bit preference) using a code like this:
const
JavaKey = 'SOFTWARE\JavaSoft\Java Runtime Environment';
function GetJavaVersionAndPath(
RootKey: Integer; var JavaVersion: string; var JavaPath: string): Boolean;
var
JREVersion: string;
begin
Result :=
RegQueryStringValue(RootKey, JavaKey, 'CurrentVersion', JavaVersion) and
RegQueryStringValue(RootKey, JavaKey + '\' + JavaVersion, 'JavaHome', JavaPath);
end;
{ ... }
var
JavaVersion: string;
JavaPath: string;
begin
if GetJavaVersionAndPath(HKLM64, JavaVersion, JavaPath) then
begin
Log(Format('Java %s 64-bit found in "%s"', [JavaVersion, JavaPath]));
end
else
if GetJavaVersionAndPath(HKLM32, JavaVersion, JavaPath) then
begin
Log(Format('Java %s 32-bit found in "%s"', [JavaVersion, JavaPath]));
end
else
begin
Log('No Java found');
end;
end;

Depending on which JRE you have installed, that registry data may not be there. A more generic solution is probably preferable.
I wanted something I could use across multiple Inno Setup projects, so I wrote a DLL for detecting Java details (home directory, etc.):
https://github.com/Bill-Stewart/JavaInfo
Download from here: https://github.com/Bill-Stewart/JavaInfo/releases
The download includes a sample Inno Setup .iss script that demonstrates how to use the DLL functions.

How to use different bootclasspaths in Bazel workspace?

I'm currently trying to build a Bazel 0.11.1 workspace with projects that use different Java language levels. The actual application uses Java 7, but for some code that won't ship, I want to settle with a more recent Java version to be able to use the new language features.
I can solve this to some extent by using --javacopt in .bazelrc, setting -source 1.7 -target 1.7 and override the defaults on a project level with the javacopts attribute, but this is not enough to ensure proper Java 7 compatibility when compiling with a more recent Java version. For this I really need to compile Java 7 projects against a Java 7 classpath as well.
The only way to use a custom bootclasspath seems to be via java_toolchain. It works. But I could not found a way to use different bootclasspaths for different projects, because the toolchain affects all projects and unlike with javacopts cannot be overridden at the project level.
Is this a usecase that is simply not (yet?) possible with Bazel? Or is there some trickery to make it work?

It turns out there is a way: write a custom rule that performs compilation.
The java_common module provides an interface to the compiler.
library.bzl
def _impl(ctx):
deps = []
for dep in ctx.attr.deps:
if java_common.provider in dep:
deps.append(dep[java_common.provider])
output_jar = ctx.new_file("lib{0}.jar".format(ctx.label.name))
runtime = java_common.JavaRuntimeInfo
compilation_provider = java_common.compile(
ctx,
source_jars = ctx.files.srcs_jars,
source_files = ctx.files.srcs,
output = output_jar,
javac_opts = ctx.attr.javac_opts,
deps = deps,
strict_deps = ctx.attr.strict_deps,
java_toolchain = ctx.attr.toolchain,
host_javabase = ctx.attr._host_javabase,
resources = ctx.files.resources,
neverlink = ctx.attr.neverlink,
)
return struct(
files = depset([output_jar]),
providers = [compilation_provider],
)
library = rule(
implementation = _impl,
attrs = {
"srcs_jars": attr.label_list(allow_files=True),
"srcs": attr.label_list(allow_files=True),
"javac_opts": attr.string_list(default=[]),
"deps": attr.label_list(),
"strict_deps": attr.string(default="ERROR"),
"toolchain": attr.label(default=Label("#bazel_tools//tools/jdk:toolchain")),
"sourcepath": attr.label_list(),
"resources": attr.label_list(),
"neverlink": attr.bool(default=False),
"_host_javabase": attr.label(default=Label("#local_jdk//:jdk")),
},
fragments = ["java"],
)
This rule I can now use to set a different toolchain for compilation.
BUILD
load('//build/jdk:library.bzl', 'library')
library(
name = "test",
srcs = glob(["src/main/java/**/*.java"]),
# data = glob(["src/main/resources/**"]),
toolchain = "//build/jdk:jdk8",
deps = ["..."],
)
Unfortunately I'm not 100% there yet. java_common.compile does not seem to have an equivalent for the data attribute of java_library, but for the most part the toolchain problem is solved.

Can Java be installed as non-root user with Chef?

Chef supports execution as non-root user:
https://docs.chef.io/ctl_chef_client.html#run-as-non-root-user
But if the Chef recipe requires action with root access, then it will not work.
Does one of the Chef recipe to install Java support non-root installation? I didn't find reply in their documentation.

https://supermarket.chef.io/cookbooks/java, with java_home attribute value set to user accessible directory then it should be good.

In general most community cookbooks expect to run as root, so you'll likely have to write your own.

I've been able to install java as non-root user by using following code in recipes / default.rb:
arch = node['java']['arch']
jdk_version = node['java']['jdk_version']
tarball_url = node['java']['jdk'][jdk_version][arch]['url']
tarball_checksum = node['java']['jdk'][jdk_version][arch]['checksum']
bin_cmds = []
java_home = node['java']['java_home']
java_ark 'jdk' do
url tarball_url
checksum tarball_checksum
bin_cmds bin_cmds
app_home java_home
owner node['current_user']
action :install
end
And in attributes / default.rb file:
set['java']['jdk_version'] = '7'
set['java']['java_home'] = "/home/jpmat/jdk#{node['java']['jdk_version']}"
set['java']['oracle']['accept_oracle_download_terms'] = 'true'

Using vSphere VI Java API to get annotation notes

Anyone have a snippet of how to use the vSphere VI Java API to extract the values in the 'Annotations' section of the 'Summary' tab for a VM? I have looked around a lot as well as combed through the API docs but haven't seen it anywhere.

Have a look at the API Documentation of VirtualMachineConfigSpec first .
Then you can do this from java
VirtualMachineConfigSpec configSpec = new VirtualMachineConfigSpec();
configSpec.setAnnotation = "Your annotation string here"
reconfigVM_Task(vmMOR, configSpec);

I did this in Perl SDK, but re-doing it to use Java API should be easy.
You get the annotations from Virtual Machine object which has property named summary of class VirtualMachineSummary which has config of class VirtualMachineConfigSummary which has a annotation field of type string which is what you need.
my $vmname = "vmname you are looking for";
# Get all VMs
my $vms = Vim::find_entity_views(
view_type => 'VirtualMachine',
filter => {"config.name" => qr/^$vmname$/i},
);
# Iterate over the VMs, getting their annotations
foreach my $vm (#{ $vms }) {
my $notes = $vm->summary->config->annotation;
my $name = $vm->summary->config->name;
if (not defined $notes) {
print " - VM: $name has no notes\n";
}
elsif ($notes =~ m/^\$*/) {
print " - VM: $name has empty notes\n";
}
else {
print " - VM: $name notes: '$notes'\n";
}
}
Here is the full code: https://communities.vmware.com/message/2613855#2613855