如何调用Java方法＆amp;从Haskell轻松实例化Java对象？

时间：2015-12-28 10:45:14

标签： java haskell

我找到了这个图书馆：https://hackage.haskell.org/package/java-bridge

根据作者的说法，支持Haskell对Java的3级绑定。正如所宣传的那样，mid level interface效果很好。但是，正如我正在使用它时，编写粘合代码开始变得重复和无聊，因为它只是以特定方式匹配类，方法和类型名称。 Here are some examples of using the mid level interface

据我了解，high level interface应该通过自动编写粘合代码来工作。 所以我试图让这项工作取得很大成功：

import Foreign.Java
import Foreign.Java.Bindings
import Data.Map as Map

main = runJava $ do
  jClasses <- reflectJavaClasses ["java.sql.DriverManager"]
  let info = Map.fromList [("java.sql.DriverManager", jClasses !! 0)]
  io $ putStrLn $ printJavaClassModule (jClasses !! 0) "DriverManager" info
  io $ putStrLn $ printJavaPackageModule "DriverManager" "DriverManager" info jClasses
  io $ putStrLn $ printJavaClassBootfile (jClasses !! 0) "DriverManager" info

其中输出以下内容：

Preprocessing executable 'exp-java' for exp-java-0.1.0.0...
[1 of 1] Compiling Main             ( main.hs, dist/build/exp-java/exp-java-tmp/Main.o )
Linking dist/build/exp-java/exp-java ...
{-# LANGUAGE Haskell2010 #-}
-- | Class @java.sql.DriverManager@
module DriverManager (
    -- * Methods
deregisterDriver,    
equals,    
getClass,    
getConnection,    
getConnection',    
getConnection'',    
getDriver,    
getDrivers,    
getLogStream,    
getLogWriter,    
getLoginTimeout,    
hashCode,    
notify,    
notifyAll,    
println,    
registerDriver,    
setLogStream,    
setLogWriter,    
setLoginTimeout,    
toString,    
wait,    
wait',    
wait'',    
    -- * Information about this class.
    info'
) where
import qualified Foreign.Java as JNI
import Foreign.Java ((-->))
import qualified Prelude as Prelude
import Prelude ((.), ($), (>>=), (>>), return)
import qualified Foreign.Java.Bindings.Support as JNIS
import Data.Functor ((<$>))


exp-java: classModImports in Foreign.Java.Bindings.Java2Haskell - class definition not found

问题

  1. 任何可能导致此问题的想法classModImports in Foreign.Java.Bindings.Java2Haskell - class definition not found？请参阅下面的编辑。似乎需要使用findJavaClasses来解决此错误。

  2. 我使用的方式与预期不同吗？

  3. 我可以查看高级API的预期和工作用法示例吗？

  4. 有没有其他方法（例如不同的库）我可以（也/更容易）实现从Haskell到Java的易于使用的接口？

    5. 编辑（2015-12-28 11:42 UTC）

    我设法得到了进一步的发展，但还没有完全发挥作用：

    import Foreign.Java
import Foreign.Java.Bindings
import Data.Map as Map

main = runJava $ do
  let target = "java.sql.DriverManager"
  deps <- findJavaClasses 21 [target]
  jClasses <- reflectJavaClasses deps
  let jClassesMap = Map.fromList $ zip deps jClasses
  let l = flip Map.lookup
  let (Just targetJClass) = jClassesMap `l` target
  io $ putStrLn $ printJavaClassModule targetJClass "DriverManager" jClassesMap

    哪个输出：

    {-# LANGUAGE Haskell2010 #-}
-- | Class @java.sql.DriverManager@
module DriverManager (
    -- * Methods
deregisterDriver,
equals,
getClass,
getConnection,
getConnection',
getConnection'',
getDriver,
getDrivers,
getLogStream,
getLogWriter,
getLoginTimeout,
hashCode,
notify,
notifyAll,
println,
registerDriver,
setLogStream,
setLogWriter,
setLoginTimeout,
toString,
wait,
wait',
wait'',
    -- * Information about this class.
    info'
) where
import qualified Foreign.Java as JNI
import Foreign.Java ((-->))
import qualified Prelude as Prelude
import Prelude ((.), ($), (>>=), (>>), return)
import qualified Foreign.Java.Bindings.Support as JNIS
import Data.Functor ((<$>))


import qualified

info' = "DriverManager"

-- | @static synchronized deregisterDriver(java.sql.Driver) -> void@
deregisterDriver :: ( v1, JNIS.VoidResult void) => v1 -> JNI.Java void
deregisterDriver a1 = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getStaticMethod` "deregisterDriver" JNI.::= JNI.object "java.sql.Driver" --> JNI.void
    a1' <- Prelude.Just <$> JNI.asObject a1
    result <- JNI.callStaticMethodE method a1'
    JNIS.toVoidResult result
-- | @virtual equals(java.lang.Object) -> boolean@
equals :: (JNIS.BooleanResult boolean,  this,  v1) => this -> v1 -> JNI.Java boolean
equals this a1 = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getMethod` "equals" JNI.::= JNI.object "java.lang.Object" --> JNI.boolean
    this' <- JNI.asObject this
    a1' <- Prelude.Just <$> JNI.asObject a1
    result <- JNI.callMethodE method this' a1'
    JNIS.toBooleanResult result
-- | @virtual native final getClass() -> java.lang.Class@
getClass :: ( this, JNIS.ObjectResult (object (' v2))) => this -> JNI.Java (object (' v2))
getClass this = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getMethod` "getClass" JNI.::= JNI.object "java.lang.Class"
    this' <- JNI.asObject this
    result <- JNI.callMethodE method this'
    JNIS.toObjectResult result
-- | @static getConnection(java.lang.String, java.lang.String, java.lang.String) -> java.sql.Connection@
getConnection :: ( v1,  v2,  v3, JNIS.ObjectResult (object ')) => v1 -> v2 -> v3 -> JNI.Java (object ')
getConnection a1 a2 a3 = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getStaticMethod` "getConnection" JNI.::= JNI.object "java.lang.String" --> JNI.object "java.lang.String" --> JNI.object "java.lang.String" --> JNI.object "java.sql.Connection"
    a1' <- Prelude.Just <$> JNI.asObject a1
    a2' <- Prelude.Just <$> JNI.asObject a2
    a3' <- Prelude.Just <$> JNI.asObject a3
    result <- JNI.callStaticMethodE method a1' a2' a3'
    JNIS.toObjectResult result
-- | @static getConnection(java.lang.String, java.util.Properties) -> java.sql.Connection@
getConnection' :: ( v1,  v2, JNIS.ObjectResult (object ')) => v1 -> v2 -> JNI.Java (object ')
getConnection' a1 a2 = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getStaticMethod` "getConnection" JNI.::= JNI.object "java.lang.String" --> JNI.object "java.util.Properties" --> JNI.object "java.sql.Connection"
    a1' <- Prelude.Just <$> JNI.asObject a1
    a2' <- Prelude.Just <$> JNI.asObject a2
    result <- JNI.callStaticMethodE method a1' a2'
    JNIS.toObjectResult result
-- | @static getConnection(java.lang.String) -> java.sql.Connection@
getConnection'' :: ( v1, JNIS.ObjectResult (object ')) => v1 -> JNI.Java (object ')
getConnection'' a1 = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getStaticMethod` "getConnection" JNI.::= JNI.object "java.lang.String" --> JNI.object "java.sql.Connection"
    a1' <- Prelude.Just <$> JNI.asObject a1
    result <- JNI.callStaticMethodE method a1'
    JNIS.toObjectResult result
-- | @static getDriver(java.lang.String) -> java.sql.Driver@
getDriver :: ( v1, JNIS.ObjectResult (object ')) => v1 -> JNI.Java (object ')
getDriver a1 = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getStaticMethod` "getDriver" JNI.::= JNI.object "java.lang.String" --> JNI.object "java.sql.Driver"
    a1' <- Prelude.Just <$> JNI.asObject a1
    result <- JNI.callStaticMethodE method a1'
    JNIS.toObjectResult result
-- | @static getDrivers() -> java.util.Enumeration@
getDrivers :: (JNIS.ObjectResult (object (' v2))) => JNI.Java (object (' v2))
getDrivers = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getStaticMethod` "getDrivers" JNI.::= JNI.object "java.util.Enumeration"
    result <- JNI.callStaticMethodE method
    JNIS.toObjectResult result
-- | @static getLogStream() -> java.io.PrintStream@
getLogStream :: (JNIS.ObjectResult (object ')) => JNI.Java (object ')
getLogStream = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getStaticMethod` "getLogStream" JNI.::= JNI.object "java.io.PrintStream"
    result <- JNI.callStaticMethodE method
    JNIS.toObjectResult result
-- | @static getLogWriter() -> java.io.PrintWriter@
getLogWriter :: (JNIS.ObjectResult (object ')) => JNI.Java (object ')
getLogWriter = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getStaticMethod` "getLogWriter" JNI.::= JNI.object "java.io.PrintWriter"
    result <- JNI.callStaticMethodE method
    JNIS.toObjectResult result
-- | @static getLoginTimeout() -> int@
getLoginTimeout :: (JNIS.IntResult int) => JNI.Java int
getLoginTimeout = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getStaticMethod` "getLoginTimeout" JNI.::= JNI.int
    result <- JNI.callStaticMethodE method
    JNIS.toIntResult result
-- | @virtual native hashCode() -> int@
hashCode :: (JNIS.IntResult int,  this) => this -> JNI.Java int
hashCode this = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getMethod` "hashCode" JNI.::= JNI.int
    this' <- JNI.asObject this
    result <- JNI.callMethodE method this'
    JNIS.toIntResult result
-- | @virtual native final notify() -> void@
notify :: ( this, JNIS.VoidResult void) => this -> JNI.Java void
notify this = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getMethod` "notify" JNI.::= JNI.void
    this' <- JNI.asObject this
    result <- JNI.callMethodE method this'
    JNIS.toVoidResult result
-- | @virtual native final notifyAll() -> void@
notifyAll :: ( this, JNIS.VoidResult void) => this -> JNI.Java void
notifyAll this = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getMethod` "notifyAll" JNI.::= JNI.void
    this' <- JNI.asObject this
    result <- JNI.callMethodE method this'
    JNIS.toVoidResult result
-- | @static println(java.lang.String) -> void@
println :: ( v1, JNIS.VoidResult void) => v1 -> JNI.Java void
println a1 = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getStaticMethod` "println" JNI.::= JNI.object "java.lang.String" --> JNI.void
    a1' <- Prelude.Just <$> JNI.asObject a1
    result <- JNI.callStaticMethodE method a1'
    JNIS.toVoidResult result
-- | @static synchronized registerDriver(java.sql.Driver) -> void@
registerDriver :: ( v1, JNIS.VoidResult void) => v1 -> JNI.Java void
registerDriver a1 = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getStaticMethod` "registerDriver" JNI.::= JNI.object "java.sql.Driver" --> JNI.void
    a1' <- Prelude.Just <$> JNI.asObject a1
    result <- JNI.callStaticMethodE method a1'
    JNIS.toVoidResult result
-- | @static setLogStream(java.io.PrintStream) -> void@
setLogStream :: ( v1, JNIS.VoidResult void) => v1 -> JNI.Java void
setLogStream a1 = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getStaticMethod` "setLogStream" JNI.::= JNI.object "java.io.PrintStream" --> JNI.void
    a1' <- Prelude.Just <$> JNI.asObject a1
    result <- JNI.callStaticMethodE method a1'
    JNIS.toVoidResult result
-- | @static setLogWriter(java.io.PrintWriter) -> void@
setLogWriter :: ( v1, JNIS.VoidResult void) => v1 -> JNI.Java void
setLogWriter a1 = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getStaticMethod` "setLogWriter" JNI.::= JNI.object "java.io.PrintWriter" --> JNI.void
    a1' <- Prelude.Just <$> JNI.asObject a1
    result <- JNI.callStaticMethodE method a1'
    JNIS.toVoidResult result
-- | @static setLoginTimeout(int) -> void@
setLoginTimeout :: (JNIS.JInt v1, JNIS.VoidResult void) => v1 -> JNI.Java void
setLoginTimeout a1 = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getStaticMethod` "setLoginTimeout" JNI.::= JNI.int --> JNI.void
    a1' <- JNIS.toInt a1
    result <- JNI.callStaticMethodE method a1'
    JNIS.toVoidResult result
-- | @virtual toString() -> java.lang.String@
toString :: ( this, JNIS.ObjectResult (object ')) => this -> JNI.Java (object ')
toString this = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getMethod` "toString" JNI.::= JNI.object "java.lang.String"
    this' <- JNI.asObject this
    result <- JNI.callMethodE method this'
    JNIS.toObjectResult result
-- | @virtual final wait(long, int) -> void@
wait :: ( this, JNIS.JLong v1, JNIS.JInt v2, JNIS.VoidResult void) => this -> v1 -> v2 -> JNI.Java void
wait this a1 a2 = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getMethod` "wait" JNI.::= JNI.long --> JNI.int --> JNI.void
    this' <- JNI.asObject this
    a1' <- JNIS.toLong a1
    a2' <- JNIS.toInt a2
    result <- JNI.callMethodE method this' a1' a2'
    JNIS.toVoidResult result
-- | @virtual native final wait(long) -> void@
wait' :: ( this, JNIS.JLong v1, JNIS.VoidResult void) => this -> v1 -> JNI.Java void
wait' this a1 = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getMethod` "wait" JNI.::= JNI.long --> JNI.void
    this' <- JNI.asObject this
    a1' <- JNIS.toLong a1
    result <- JNI.callMethodE method this' a1'
    JNIS.toVoidResult result
-- | @virtual final wait() -> void@
wait'' :: ( this, JNIS.VoidResult void) => this -> JNI.Java void
wait'' this = do
    (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager"
    (Prelude.Just method) <- clazz `JNI.getMethod` "wait" JNI.::= JNI.void
    this' <- JNI.asObject this
    result <- JNI.callMethodE method this'
    JNIS.toVoidResult result

    现在这已经相当接近，但是即使我尝试手动修补输出源，我也不会用GHC 7.8.4进行编译。

    1. 顶部有一个空的import qualified，导致语法错误。所以我试着通过评论来禁用它。

    2. 然后有很多错误消息指向类型声明的各个部分，所以我也对它们进行了评论，希望GHC可能会推断出一些明智的东西。至少在我试图让它发挥作用之前。

    3. 然后我收到此错误：

      Preprocessing executable 'exp-java' for exp-java-0.1.0.0...
[1 of 2] Compiling DriverManager    ( DriverManager.hs, dist/build/exp-java/exp-java-tmp/DriverManager.o )

DriverManager.hs:109:5:
    No instance for (JNIS.ObjectResult b3)
      arising from a use of ‘JNIS.toObjectResult’
    The type variable ‘b3’ is ambiguous
    Relevant bindings include
      getDrivers :: JNI.Java b3 (bound at DriverManager.hs:105:1)
    Note: there are several potential instances:
      instance JNIS.UnsafeCast a =>
               JNIS.ObjectResult (Prelude.Either JNI.JThrowable (Prelude.Maybe a))
        -- Defined in ‘Foreign.Java.Bindings.Support’
      instance JNIS.UnsafeCast a =>
               JNIS.ObjectResult (Prelude.Either (Prelude.Maybe JNI.JThrowable) a)
        -- Defined in ‘Foreign.Java.Bindings.Support’
      instance JNIS.UnsafeCast a => JNIS.ObjectResult (Prelude.Maybe a)
        -- Defined in ‘Foreign.Java.Bindings.Support’
      ...plus two others
    In a stmt of a 'do' block: JNIS.toObjectResult result
    In the expression:
      do { (Prelude.Just clazz) <- JNI.getClass "java.sql.DriverManager";
           (Prelude.Just method) <- clazz
                                    `JNI.getStaticMethod`
                                      "getDrivers" JNI.::= JNI.object "java.util.Enumeration";
           result <- JNI.callStaticMethodE method;
           JNIS.toObjectResult result }
    In an equation for ‘getDrivers’:
        getDrivers
          = do { (Prelude.Just clazz) <- JNI.getClass
                                           "java.sql.DriverManager";
                 (Prelude.Just method) <- clazz
                                          `JNI.getStaticMethod`
                                            "getDrivers" JNI.::= JNI.object "java.util.Enumeration";
                 result <- JNI.callStaticMethodE method;
                 .... }

      4. 我还不确定如何解决。有什么想法吗？

      我的问题2..4在原始问题的最后，就在编辑之前，仍然有效。

0 个答案:

没有答案
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