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Birdshover — Wed, 28 Apr 2010 10:11:00 GMT

�q�个问题比较急，借用首页发一下，谢谢�Q?/span>

最�q�需要对一个C++库进行封装，为简单�v见决定��用JAVA对其��装。但是一直调用不成功�Q�于是写了一�D�|��试代码测试一下。�ؓ(f��)��单�v见，��׃��用默认包了�?/div>

public class TestDLL {
    public native String Test(String put);

    static{
        System.loadLibrary("testdll");
    }

    public static void main(String[] args) {
        TestDLL test = new TestDLL();
        System.out.println(test.Test(new Date().toString()));
    }
}

然后生成了C++头文�?br />

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class TestDLL */

#ifndef _Included_TestDLL
#define _Included_TestDLL
#ifdef __cplusplus
extern "C" {
#endif
/*
* Class:     TestDLL
* Method:    Test
* Signature: (Ljava/lang/String;)Ljava/lang/String;
*/
JNIEXPORT jstring JNICALL Java_TestDLL_Test
  (JNIEnv *, jobject, jstring);

#ifdef __cplusplus
}
#endif
#endif

下面是简单的实现

#include "TestDLL.h"

JNIEXPORT jstring JNICALL Java_TestDLL_Test
(JNIEnv *, jobject, jstring put){
return put;
}

在linux下通过gcc�~�译后，java调用�Q?br /> java -Djava.library.path=/home/xp -cp . TestDLL

一直报错：(x��)

Exception in thread "main" java.lang.UnsatisfiedLinkError: no testdll in java.library.path
        at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1734)
        at java.lang.Runtime.loadLibrary0(Runtime.java:823)
        at java.lang.System.loadLibrary(System.java:1028)
        at TestDLL.main(TestDLL.java:27)

但是我在windows下编译了testdll.dll后，能够调用正常�?br />
接着我改写�ؓ(f��)System.load("/home/xp/testdll.so");�l�果可以在linux使用了，希望有经验的朋友可以解答我的疑问�?br />

Birdshover 2010-04-28 18:11 发表评论

重读Thinking in java

Birdshover — Sat, 31 Oct 2009 03:51:00 GMT

重读Thinking in java对��承和�l�合又有了新的认识。对使用用例和��用用例�P代也有了更深的感�(zh��n)�，记录一下�?/span>

Birdshover 2009-10-31 11:51 发表评论

Birdshover — Thu, 13 Aug 2009 04:48:00 GMT

接口型模式（Interface Pattern�Q�，有的书上也叫�l�构型模�?Structural Pattern)。适配器模式是其中的一�U��?br />
一、对接口�q�行适配

�?.1

如图1.1�Q�已�l�存在了ExistsClass实现了想要的功能�Q�但是，在��用时可能无法使用�Q�因此，把��用的条�g抽象为Adapter接口�Q�用AdapterClass�l�承自ExistsClass同时实现接口�Q�完成工作�?br />

package Interface.Adapter;

public interface Adapter {
void NewWork();
}

package Interface.Adapter;

public class ExistsClass {
    public void Work(){
        System.out.println("do work!");
    }
}

package Interface.Adapter;

public class AdapterClass extends ExistsClass implements Adapter {

    @Override
    public void NewWork() {
        // TODO Auto-generated method stub
        super.Work();
    }
}

package UTest;
import junit.framework.TestCase;

import Interface.Adapter.Adapter;
import Interface.Adapter.AdapterClass;

public class TestAdapter extends TestCase {
    public void testNewWork(){
        Adapter ada = new AdapterClass();
        ada.NewWork();
    }
}

二、对�c�d��象进行适配

�?.1

和接口匹配差不多�Q�但对已存在�c�M��是��承关�p�，而是一�U�关联或依赖�?br />

Birdshover 2009-08-13 12:48 发表评论

详解JavaBean

Birdshover — Fri, 22 May 2009 05:49:00 GMT

本文通过实验的方法，�ȝ��出JavaBean在各�U�情况下实例的状态�?br />
先定义一个类

package yurow.jstore;

import java.util.Random;

public class TestClass {
    private int showCount;

    public TestClass(){
        random = new Random().nextInt();
    }

    private int random;

    public String Show(){
        showCount++;
        String str = "random : " + random;
        str+="
showCount : " + showCount;
        return str;
    }
}

然后在Default.jsp中调用�?br />
<%= test1.Show() %>

<%= test2.Show() %>
在test.jsp同样使用�q�样的调用方式�?br />
而scope一共有"application","page","session","request"四个倹{�?br />
一、page
现在的情冉|��scope="page" 。其��面��h��。test1和test2的random不一��_��q�且两个��面中的也不一致。由此断定：(x��)
scope="page"情况下，一个userBean��是一�ơ实例化的过�E��?br />
二、request
scope="request"的情况与scope="page" 的一栗��?br />
三、session
scope="session"的情况，同一个页面中�Q�test1与test2的random不一��_��可以断定�Q�这是两个实例。而showCount �?x��)不断篏加，因此�q�两个实例�ƈ不随��面的刷新而重新创建。两个不同页面中�Q�test1的状态完全一��_��test2的状态完全一致。这表明�Q�scope="session"的状态，创徏实例是与id相关的。打开不同��览器或者清�I�Cookies�Q�将��D��实例的重新创建。这表明�Q�当前状态下�Q�创建实例与session相关�Q�有个过期的旉��?br />
四、application
scope="application"是全局的表�C�。打开不同��览器浏览不同的��面�Q�test1与test2仍然不一��_��但是不同��面的test1已经一��_��q�且不同��览器中数量仍然累加。所以，实例的创��Z��否，只与id有关�?

Birdshover 2009-05-22 13:49 发表评论

Birdshover — Fri, 16 Jan 2009 03:38:00 GMT

定义一个js的数�l?br /> var arr = [
                    ["1"],
                    ["2"]
                ];
�l�过java引擎解析后，得到的对象是sun.org......NativeArray
在我的eclipse中找不到�q�个�c�R��也��没办法直接转换成java数组对象了�?br />
现在换成在js中��用java的数�l?br /> var result = new java.awt.List();
result.add("aasdasd");
result.add("123123");

java解析�Q?br />   ScriptEngineManager m = new ScriptEngineManager();
  ScriptEngine engine = m.getEngineByExtension("js");
  try {
   engine.eval(file.getContent());
  } catch (ScriptException e) {
   System.out.println("执行脚本错误:" + file.getFileName());
   return;
  }
  List o = (List)engine.get(resultKey);
  System.out.print(o.getItem(0));

�q�样��没有问题了�?

Birdshover 2009-01-16 11:38 发表评论

java 调用javascript脚本(jre6)

Birdshover — Tue, 13 Jan 2009 09:41:00 GMT

必须jre6才行�Q�要不需要用开源库�?/p>

package script;

import javax.script.*;
/**
* Java调用JavaScript�C�Z��
*
* @author Birdshover
*
*/
public final class scriptMaster {
    /**
     * �q�行指定脚本
     * @return �q�回脚本�?br />      */
    public int run() {
        ScriptEngineManager m = new ScriptEngineManager();
        ScriptEngine engine = m.getEngineByExtension("js");
        try{
            engine.eval("var t=1;t++;");
            engine.eval("t++;");
        }catch(ScriptException ex){
            return -1;
        }
        Float val = Float.parseFloat(engine.get("t").toString());
        return val.intValue();
    }
}

java调用javascript,而javascript内部又调用了java的类库�?br />

    public String now(){
        ScriptEngineManager m = new ScriptEngineManager();
        ScriptEngine engine = m.getEngineByExtension("js");
        try{
            engine.eval("var t= new java.util.Date();");
        }catch(ScriptException ex){
            return (new Date()).toString();
        }
        return engine.get("t").toString();
    }

Birdshover 2009-01-13 17:41 发表评论

Birdshover — Tue, 09 Dec 2008 07:18:00 GMT

关于�c�d��转换�Q�C#与JAVA最大的不同在于C#有struct�Q�而JAVA则没有这玩意。于是乎在C#中泛型类型�{换就有一下代�?仅限struct�l�构)。另外一个较?y��u)��的差异呢则是在C#中各struct�c�d��都带有TryParse�Ҏ(gu��)��Q�当�Ӟ��2.0以后�Q�包�?.0�Q�才有�?br />

namespace DObject.DType
{
///

/// �c�d��转换帮助�c�，静态方法实现。加入了�~�存机制�Q�减��反��次数�?br /> ///

    public static class StaticConvertor
    {
        private const string CONVERTMETHOD = "TryParse";
        private static Dictionary<System.Type, MethodInfo> map = new Dictionary<System.Type, MethodInfo>(20);

        private static MethodInfo prepareMethod(System.Type type)
        {
            lock (map)
            {
                if (!map.ContainsKey(type))
                {
                    System.Type[] typeArray = new System.Type[2];
                    typeArray.SetValue(typeof(string), 0);
                    typeArray.SetValue(type.GetType().MakeByRefType(), 1);
                    MethodInfo method = type.GetType().GetMethod(CONVERTMETHOD, typeArray);
                    if (method != null)
                    {
                        map.Add(type, method);
                    }
                    else
                        return null;
                }
                return map[type];
            }
        }    //end prepareMethod

        ///

/// 转换�Ҏ(gu��)��
///

        /// 转换后类�?/span>
        /// 原始对象
        /// 默认�?/span>
        /// 是否转换成功
        /// �q�回�?/span>
        public static T Convert<T>(object raw, T defaultValue, out bool convertSuccessful) where T : struct
        {
            convertSuccessful = false;
            if (raw == null) //��p�|
                return defaultValue;
            else if (raw is T) //成功
            {
                convertSuccessful = true;
                return (T)raw;
            }
            else
            {
                try
                {
                    object[] parms = new object[2];
                    parms[0] = raw.ToString();
                    parms[1] = 0;
                    bool isparser = (bool)prepareMethod(typeof(T)).Invoke(null, parms);
                    if (isparser) //成功
                    {
                        convertSuccessful = true;
                        return (T)parms[1];
                    }
                }
                catch
                {
                }
                return defaultValue;
            }
        } //end Convert
    }
}

以上代码的写法，适合DateTime,Int32,Int64,Int16,byte,bool�{�。只有是struct�l�构�Q��ƈ且有TryParse�Ҏ(gu��)��可以��用。而��用�v来呢也很��单，如以下代�?br />

namespace DObject.DType
{
///

/// Int32�c�d��保证
///

    public class DInt32 : DObject, IValuetable<Int32>, IConvertSuccess
    {
        private int target;
        private int defaultValue = -1;
        ///

/// 构造函敎ͼ�对象初始化时�Q�就执行转换
///

        ///
        public DInt32(object o)
            : base(o)
        {
            target = StaticConvertor.Convert<int>(base.raw, defaultValue, out convertSuccessful);
        }

        public static implicit operator DInt32(DType type)
        {
            return new DInt32(type.RawObject);
        }

        private bool convertSuccessful;
        ///

/// �q�回转换�?br /> ///

        /// �q�回转换��|��如果转换成功则返回��|��转换��p�|�q�回默认�?nbsp;-1
        public int Value()
        {
            return Value(defaultValue);
        }
        ///

/// �q�回转换�?br /> ///

        /// 默认�?/span>
        /// �q�回转换��|��如果转换成功则返回��|��转换��p�|�q�回默认�?/span>
        public int Value(int defaultValue)
        {
            if (convertSuccessful)
                return target;
            return defaultValue;
        }
        ///

/// 是否转换成功
///

        public bool ConvertSuccess
        {
            get { return convertSuccessful; }
        }
    }
}

///

    /// 构造类型，为内�|�类型提供构造参数�?br />     ///
    ///        DInt32 int32 = DType.Default("123");
    ///
    ///

    public class DType
    {
        private object o;

        private DType(object o)
        {
            this.o = o;
        }
        ///

/// 提供对象构造参�?br /> ///

        ///
        ///
        public static DType Default(object o)
        {
            return new DType(o);
        }
        ///

/// 原始对象
///

        public object RawObject
        {
            get { return o; }
        }
    }

使用��h��也是��单：(x��)
DInt32 int32 = DType.Default("123");
int val = int32.Value();

Java里就没这��L(f��ng)��了，使用try捕获错误�q��惌��的。java里没有struct�Q�但是有个类型Number��是可以使用。当�Ӟ��q�就不能像C#一样将�׃��八糟的东襉K��整一块了�Q�要分开来处理了�?br />

/**
*
* @author yurow
*/
public class DNumber extends DObject {

    /**
     * Create new instance of DNumber
     */
    protected DNumber() {
        super();
    }

    protected DNumber(Object obj)
    {
        super(obj);
    }

    protected Boolean isconvert;

    public Number Convert(Number defaultValue) {
        isconvert = false;
        if (obj == null) {
            return defaultValue;
        } else if (obj instanceof Number) {
            isconvert = true;
            return Number.class.cast(obj);
        } else {
            return defaultValue;
        }
    }
}

/**
*
* @author yurow
*/
public class DInt32 extends DNumber {

    /**
     * Create new instance of DInt32
     */
    protected DInt32() {
        super();
    }

    protected DInt32(Object obj) {
        super(obj);
    }

    public static DInt32 newInt32(Object obj) {
        return new DInt32(obj);
    }

    public int Convert()
    {
        return super.Convert(-1).intValue();
    }
}

可以看出�Q�JAVA的类型逻辑层次划分比C#要细��_��处理��h��当然要复杂一些。可见粒度�ƈ非越�l�越好。��道看来JAVA們֐�于按逻辑划分�Q�而C#們֐�于按内存布局划分�?

Birdshover 2008-12-09 15:18 发表评论

Birdshover — Mon, 08 Dec 2008 09:55:00 GMT

    @Override
    public String toString() {
        StringBuffer buffer = new StringBuffer();
        //�q�回所有字�D?/span>
        Field[] fields = this.getClass().getDeclaredFields();
        for (int i = 0; i < fields.length; i++) {
            //当前字段名称
            String name = fields[i].getName();
            buffer.append(name);
            buffer.append(":");
            try {
                //当前实例该字�D��?/span>
                buffer.append(fields[i].get(this));
            } catch (Exception ex) {
                System.out.println("err:" + ex.getMessage());
            }
            buffer.append("\n");
        }
        return buffer.toString();
    }

Birdshover 2008-12-08 17:55 发表评论

Birdshover — Fri, 05 Dec 2008 06:55:00 GMT

public class testclass {
    public static void main(String[] args) throws IOException
    {
        byte[] buffer = new byte[1024];
        int count = System.in.read(buffer);
        System.out.print(new String(buffer,0,count,"gbk"));
    }
}

�q�样一�D�代码，在输入中文时�Q�如果输�?#8220;ces”然后敲空��|��得到“��试”�q�两个字�Q�enter�Q�然后输�?br /> “ces��试”�?br />
要是用Console�q�行�Q�java testclass 则没有这�U�问�?

Birdshover 2008-12-05 14:55 发表评论

Hibernate ,Serverlet POST查询

Birdshover — Wed, 26 Nov 2008 14:18:00 GMT

        try {
            String username = request.getParameter("username");
            String password = request.getParameter("password");
            SessionFactory sf = DefaultDataUtil.getSessionFactory();
            Session s = sf.openSession();
            Query query = s.createQuery("from Users where username=:name");
            query.setParameter("name", username);
            List list = query.list();
            if(list.size() == 1)
            {
                Object o = list.get(0);
                Users user = (Users)o;
                if(user.getPassword().equals(password) )
                {
                    out.print("验证成功�?/span>");
                }
                else
                {
                    out.print("密码错误�?/span>");
                }
            }
            else
            {
                out.print("用户名错误�?/span>");
            }
        }
        catch(Exception ex){
            out.print(ex.getMessage());
        }
        finally {
            out.close();
        }

HQL语句对于表名有大��写匚w��的关�p�，匚w��的映��过来的�c�d��。否则会(x��)报xxx not mapped....错误。其它的�q�是很简单的�?

Birdshover 2008-11-26 22:18 发表评论