python与java对接工具Jython介绍

快速入门

下面我们使用jython来调用自定义jar包中的类。

编辑java文件：Beach.java

public class Beach {

    private String name;
    private String city;

    public Beach(String name, String city){
        this.name = name;
        this.city = city;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }

}

编译成jar包：

# javac Beach.java 
# echo Main-Class: Beach >manifest.txt
# jar cvfm Craps.jar manifest.txt *.class
已添加清单
正在添加: Beach.class(输入 = 795) (输出 = 430)(压缩了 45%)
正在添加: Point.class(输入 = 708) (输出 = 445)(压缩了 37%)

添加Craps.jar到CLASSPATH，修改/etc/profile，修改CLASSPATH

export CLASSPATH=.:$JAVA_HOME/jre/lib/rt.jar:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:/usr/local/jython/Craps.jar

使用. /etc/profile导入变量。然后使用jython调用java代码。

# ./jython 
Jython 2.7.0 (default:9987c746f838, Apr 29 2015, 02:25:11) 
[Java HotSpot(TM) 64-Bit Server VM (Oracle Corporation)] on java1.7.0_79
Type "help", "copyright", "credits" or "license" for more information.
>>> import Beach
>>> beach = Beach("Cocoa Beach","Cocoa Beach")
>>> beach.getName()
u'Cocoa Beach'
>>> print beach.getName()
Cocoa Beach
>>>

基础

Linux安装：

# java -jar jython-installer-2.7.0.jar 
# ./jython 
Jython 2.7.0 (default:9987c746f838, Apr 29 2015, 02:25:11) 
[Java HotSpot(TM) 64-Bit Server VM (Oracle Corporation)] on java1.7.0_79
Type "help", "copyright", "credits" or "license" for more information.
>>>

windows安装：双击jython-installer-2.7.0.jar, 执行jython.exe

变量定义：

java
int x = 0;
jython：
x = 0
x = 'Hello Jython'

是动态类型的。

保留字：

and     assert     break     class     continue
def     del     elif     else     except
exec     finally     for     from     global
or     pass     print     raise     return
try     while     with     yield

编码结构使用缩进。

函数名也可以作为函数的参数。

语句关键字：

if-elif-else     for
while     continue
break     try-except-finally
assert     def
print     del
raise     import

文件名和类名一样可以直接导入。

此部分参考资料：

http://www.jython.org/jythonbook/en/1.0/JythonAndJavaIntegration.html

http://www.skylit.com/javamethods/faqs/createjar.html

参考资料：

http://www.jython.org/jythonbook/en/1.0/

模块和包

查看命名空间

>>> dir()
['__builtins__', '__doc__', '__name__', '__package__']

Jython的导入不像java那样必须在头部。导入java以右边名优先，python以左边名优先。模块查找路径：

>>> import sys
>>> sys.path
['', '/usr/local/jython2.7.0/Lib', '__classpath__', '__pyclasspath__/', '/usr/local/jython2.7.0/Lib/site-packages']

>>> import sys
>>> sys.path
['', '/usr/local/jython2.7.0/Lib', '__classpath__', '__pyclasspath__/', '/usr/local/jython2.7.0/Lib/site-packages']

>>> import sys
>>> sys.path.append("/home/andrew/code/java/mysql-connector-java-5.1.39/mysql-connector-java-5.1.39-bin.jar")
>>> import com.mysql
*sys-package-mgr*: can't write cache file for '/home/andrew/code/java/mysql-connector-java-5.1.39/mysql-connector-java-5.1.39-bin.jar'
*sys-package-mgr*: can't write index file
>>> dir(com.mysql)
['__name__', 'fabric', 'jdbc']

>>> import java.util.zip
>>> dir(java.util.zip)
['Adler32', 'CRC32', 'CheckedInputStream', 'CheckedOutputStream', 'Checksum', 'DataFormatException', 'Deflater', 'DeflaterInputStream', 'DeflaterOutputStream', 'GZIPInputStream', 'GZIPOutputStream', 'Inflater', 'InflaterInputStream', 'InflaterOutputStream', 'ZipEntry', 'ZipError', 'ZipException', 'ZipFile', 'ZipInputStream', 'ZipOutputStream', '__name__']
>>> dir(java.util.zip.ZipInputStream)
['__class__', '__copy__', '__deepcopy__', '__delattr__', '__doc__', '__ensure_finalizer__', '__eq__', '__format__', '__getattribute__', '__hash__', '__init__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__str__', '__subclasshook__', '__unicode__', 'available', 'class', 'close', 'closeEntry', 'equals', 'getClass', 'getNextEntry', 'hashCode', 'mark', 'markSupported', 'nextEntry', 'notify', 'notifyAll', 'read', 'reset', 'skip', 'toString', 'wait']

Jython 查找Jar和类的方法：

python.packages.paths
python.packages.directories

java.class.path
java.ext.dirs

python.cachedir.skip

pycimport把python字节码转换成java字节码。Jython导入java包可能有多个包合并。

>>> import sys
>>> sys.path_hooks
[, ,
]

import pycimport

数据类型

Jython特定的collection，多用于给java传递数据。

# Import and use a Java ArrayList

>>> import java.util.ArrayList as ArrayList

>>> arr = ArrayList()

#  Add method will add an element to the list and return a boolean to signify
successsful addition

>>> arr.add(1)

True

>>> arr.add(2)

True

>>> print arr

[1, 2]

比较老的Jarray，不推荐使用，不过可以创建空数组：

类型：

Character    Java Equivalent
z    boolean
b    byte
c    char
d    Double
f    Float
h    Short
i    Int
l    Long

>>> my_seq = (1,2,3,4,5)

>>> from jarray import array

>>> array(my_seq,'i')

array('i', [1, 2, 3, 4, 5])

>>> myStr = "Hello Jython"

>>> array(myStr,'c')

array('c', 'Hello Jython')

>>> arr = zeros(10,'z')

>>> arr

array('z', [False, False, False, False, False, False, False, False, False, False])

>>> arr2 = zeros(6, 'i')

>>> arr2

array('i', [0, 0, 0, 0, 0, 0])

求素数

`>>> ``nums = range(2, 50) `
`>>> ``for i in range(2, 8): `
`... ``    nums = filter(lambda x: x == i or x % i, nums)`
`... `
`>>> ``print nums`

读取输入：

# Obtain a value from the command line and store it into a variable
>>> import sys
>>> fav_team = sys.stdin.readline()
Cubs
>>> sys.stdout.write("My favorite team is: %s" % fav_team)
My favorite team is: Cubs

函数

协程：

**def** search_file(filename):
    **print** 'Searching file *%s*' % (filename)
    my_file = open(filename, 'r')
    file_content = my_file.read()
    my_file.close()
    **while** True:
        search_text = (**yield**)
        search_result = file_content.count(search_text)
        **print** 'Number of matches: *%d*' % (search_result)

Jython脚本编程基础

os.chdir不会改变jvm的启动目录。

>>> import os
>>> os.getcwd()
'/Users/frank/Desktop/frank/hg/jythonbook~jython-book/src/chapter8'
>>> from java.io import File
>>> f = File(".")
>>> for x in f.list():
... print x
...
args.py
search.py
>>> os.chdir("/Users/frank")
>>> os.getcwd()
'/Users/frank'
>>> os.listdir(".")
['Desktop', 'Documents', 'Downloads', 'Dropbox', 'Library', 'Movies', 'Music', 'Pictures', 'Public', 'Sites']
>>> g = File(".")
>>> for x in g.list():
...     print x
...
args.py
search.py

编译代码
```#!python
#!/usr/local/jython2.7.0/bin/jython

from javax.tools import (ForwardingJavaFileManager, ToolProvider, DiagnosticCollector,)
names = ["/home/andrew/code/python/jythonbook/src/chapter8/HelloWorld.java"]
compiler = ToolProvider.getSystemJavaCompiler()
diagnostics = DiagnosticCollector()
manager = compiler.getStandardFileManager(diagnostics, None, None)
units = manager.getJavaFileObjectsFromStrings(names)
comp_task = compiler.getTask(None, manager, diagnostics, None, None, units)
success = comp_task.call()
manager.close()

**import** **os**
**import** **sys**
**import** **glob**

**from** **javax.tools** **import** (forwardingjavafilemanager, toolprovider,
         diagnosticcollector,)

tasks = {}

**def** task(func):
    tasks[func.func_name] = func

**@task**
**def** clean():
    files = glob.glob("\*.class")
    **for** file **in** files:
        os.unlink(file)

**@task**
**def** compile():
    files = glob.glob("\*.java")
    _log("compiling *%s*" % files)
    **if** **not** _compile(files):
        quit()
    _log("compiled")

**def** _log(message):
    **if** options.verbose:
        **print** message

**def** _compile(names):
    compiler = toolprovider.getsystemjavacompiler()
    diagnostics = diagnosticcollector()
    manager = compiler.getstandardfilemanager(diagnostics, none, none)
    units = manager.getjavafileobjectsfromstrings(names)
    comp_task = compiler.gettask(none, manager, diagnostics, none, none, units)
    success = comp_task.call()
    manager.close()
    **return** success

**if** __name__ == '__main__':
    **from** **optparse** **import** optionparser
    parser = optionparser()
    parser.add_option("-q", "--quiet",
        action="store_false", dest="verbose", default=true,
        help="don't print out task messages.")
    parser.add_option("-p", "--projecthelp",
        action="store_true", dest="projecthelp",
        help="print out list of tasks.")
    (options, args) = parser.parse_args()

    **if** options.projecthelp:
        **for** task **in** tasks:
            **print** task
        sys.exit(0)

    **if** len(args) < 1:
        **print** "usage: jython builder.py [options] task"
        sys.exit(1)

    **try**:
        current = tasks[args[0]]
    **except** KeyError:
        **print** "task *%s* not defined." % args[0]
        sys.exit(1)
    current()

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World");
    }
}

[frank@pacman chapter8]$ jython builder.py --help
Usage: builder.py [options]

Options:
    -h, --help show this help message and exit
    -q, --quiet Don't print out task messages.
    -p, --projecthelp Print out list of tasks.
[frank@pacman chapter8]$ jython builder.py --projecthelp
compile
clean
[frank@pacman chapter8]$ jython builder.py compile
compiling ['HelloWorld.java']
compiled
[frank@pacman chapter8]$ ls
HelloWorld.java HelloWorld.class builder.py
[frank@pacman chapter8]$ jython builder.py clean
[frank@pacman chapter8]$ ls
HelloWorld.java builder.py
[frank@pacman chapter8]$ jython builder.py --quiet compile
[frank@pacman chapter8]$ ls
HelloWorld.class HelloWorld.java builder.py
[frank@pacman chapter8]$