一、开发环境
系统、开发环境:win7、eclipse 32位、jdk 32位、jre 32位
由于这里使用的dll文件是32位的,而我本身的环境是64位的,包括eclipse、jdk、jre都是64位,所以这里需要开发环境共存(32位、64位共存),如果本来就是32位环境就不用重新搭建环境了。从以下连接分别下载32位软件:
Eclipse IDE for Java EE Developers, 247 MB Windows 32 Bit
http://www.eclipse.org/downloads
2.jdk 32位 ,安装目录:D:\Program Files\java\jdk32
Windows x86 123.49MB jdk-7u45-windows-i586.exe
http://www.oracle.com/technetwork/java/javase/downloads/jdk7-downloads-1880260.html
3.jre 32位 ,安装目录:D:\Program Files\java\jre32
Windows Offline(32-bit) fileSize: 27.7MB
http://www.java.com/en/download/manual.jsp
要让32位和64位eclipse共存,需要修改eclipse目录下的文件:eclipse.ini
在原环境变量(JAVA_HOME指向64位目录)不改变的情况下在上面文件内增加两行:
-vm
D:\Program Files\java\jdk32\bin\javaw.exe
以上的作用使32位eclipse指向32位jdk。
4.JNA下载 ,这里是放在百度云里面的,下载两个文件:jna-3.5.1.jar、platform-3.5.1.jar,放到目录:D:\Program Files\java\JNA_3.5.1
http://pan.baidu.com/s/1iWobp
至于JNA是什么,它本身是基于JNI技术的,然后进行封装以方便dll调用。这里不再详述,网上很多。
二、调用方法
1.简单函数调用
关于jar包导入就不提了,创建工程:DemoTools,这里使用的dll是:libSDK.dll,把该文件放到工程目录下。
dll提供的接口函数:
int System_Init (int version, char* encoding);
java代码->声明部分:
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import com.sun.jna.Library;
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import com.sun.jna.Native;
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public class getSDK {
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public interface Function extends Library {
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Function instanceDll = (Function)Native.loadLibrary( "libSDK.dll",Function.class);
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public int System_Init(int version, String encoding);
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}
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}
java代码->调用部分:
result = getSDK.Function.instanceDll.System_Init(1, "");
dll接口函数及回调函数类型:
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typedef void (*Callback_Status)(char *station_id, char *station_ip, int status);
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int Start_Server(char *ip, int port, Callback_Status fun);
java代码->回调函数声明:
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import com.sun.jna.win32.StdCallLibrary.StdCallCallback;
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public class getSDK {
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public interface Callback_Status extends StdCallCallback {
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public void Status(String station_id, String station_ip, int status);
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}
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}
java代码->回调函数实现:
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public class getSDK {
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public static class Status_Realize implements Callback_Status{
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public void Status(String station_id, String station_ip, int status) {
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if (status == 2) {
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GUI.Station_online(station_id, station_ip, 1, 0);
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} else if (status == 3) {
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GUI.Station_online(station_id, station_ip, 2, 0);
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}
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}
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}
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}
java代码->dll接口调用:
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public static getSDK.Callback_Status callback_status = new getSDK.Status_Realize();
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result = getSDK.Function.instanceDll.Start_Server( "0.0.0.0", 1234, callback_status);
3.回调函数含有结构体数组参数
当回调函数其中一个参数是结构体数组时的处理方法:
dll接口函数、
回调函数类型,结构体类型
:
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typedef struct result_data {
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char Station_id[ 3];
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char Label_id[ 7];
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int Signal;
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int Power;
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int Status;
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}Tstatus, *PTstatus;
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typedef void (*Callback_Data)(char *station_id, char *station_ip, Tstatus ret_data[], int count);
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int Start_Server (char *server_ip, int listen_port, Callback_Status callback_status, Callback_Data callback_data);
java代码->回调函数、结构体定义:
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import com.sun.jna.Structure;
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public class getSDK {
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public interface Function extends Library {
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public static class Tstatus extends Structure {
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public byte[] Station_id = new byte[ 3];
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public byte[] Label_id = new byte[ 7];
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public int Signal;
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public int Power;
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public int Status;
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public static class ByReference extends Tstatus implements
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Structure. ByReference {}
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public static class ByValue extends Tstatus implements
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Structure. ByValue {}
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"rawtypes", "unchecked" })({
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protected List getFieldOrder() {
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List a = new ArrayList();
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a.add( "Station_id");
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a.add( "Label_id");
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a.add( "Signal");
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a.add( "Power");
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a.add( "Status");
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return a;
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}
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}
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public int Start_Server(String server_ip, int port, getSDK.Callback_Status Callback_Status,getSDK.Callback_Data Callback_Data);
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}
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public interface Callback_Data extends StdCallCallback {
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public void Data(String station_id, String station_ip, Pointer data, int count);
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}
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}
java代码->回调函数实现:
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public class getSDK {
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public static class Data_Realize implements Callback_Data{
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public void Data(String station_id, String station_ip, Pointer data, int count) {
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int srow, frow;
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srow = 0;
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frow = 0;
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for ( int i = 0; i < count; i++) {
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byte[] stationbuf = new byte[ 2];
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byte[] labelbuf = new byte[ 6];
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int[] signal = new int[ 1];
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int[] power = new int[ 1];
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int[] status = new int[ 1];
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data.read( 0 + i * 24, stationbuf, 0, 2);
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data.read( 3 + i * 24, labelbuf, 0, 6);
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data.read( 12 + i * 24, signal, 0, 1);
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data.read( 16 + i * 24, power, 0, 1);
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data.read( 20 + i * 24, status, 0, 1);
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String labelID = new String(labelbuf);
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String stationID = new String(stationbuf);
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GUI.message.append(String.valueOf(power[ 0]));
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GUI.message.append(String.valueOf(signal[ 0]));
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GUI.message.append(String.valueOf(status[ 0]));
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}
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}
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}
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}
java代码->接口调用:
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public static getSDK.Callback_Status callback_status = new getSDK.Status_Realize();
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public static getSDK.Callback_Data callback_data = new getSDK.Data_Realize();
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result = getSDK.Function.instanceDll.Start_Server( "0.0.0.0", 1234, callback_status, callback_data);
这里的难点就在处理回调函数的结构体数组参数,参数是从dll传出来的,java里面用指针接收,而获取结构体内部的每个值就需要用读内存的方式读取出来,这里就需要对结构体在内存中的存储方式比较了解才行,因为read函数需要指定:内存起始位置、接收数据数组变量、数组变量的第几个元素、取内存大小,4个参数。
上面源码中i*24作用是取到结构体数组的第二、第三、、、个元素。也就是这里的结构体占内存大小为24,看下面:
在32位系统中char占1个字节,int占4个字节,算下来结构体TStatus应该是22个字节,实际上还有一个内存对齐的概念,结构体前两个char数组共10个字节(是连续存储的),而结构体分配内存的大小必须是该结构体中占字节最大类型的倍数,所以应该分配4字节的倍数即12字节,所以前两个char数组实际分配了12个字节,在取数据时,第三个int的偏移量是12,整个结构体的大小为12 + 3*4(三个int变量)= 24字节
4.接口函数参数为结构体数组
当接口函数的参数为结构体数组,并且结构体成员也为结构体数组时,调用方法:
dll接口函数
类型,结构体类型
:
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typedef unsigned int UINT;
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typedef struct code_word {
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char Feild[ 8];
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BOOL Inverse;
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UINT Length;
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CHAR Payload[ 255];
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}Cword, *pCword;
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typedef struct label_data {
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char Label_id[ 7];
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UINT Count;
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Cword NCword[ 50];
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}Ldata, *pLdata;
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int Start_Update (char *station_id, int count, Ldata data[]);
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public class getSDK {
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public interface Function extends Library {
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public static class Cword extends Structure {
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public byte[] Feild = new byte[ 8];
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public boolean Inverse;
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public int length;
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public byte[] Payload = new byte[ 255];
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public static class ByValue extends Cword implements
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Structure. ByValue {}
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"rawtypes", "unchecked" })({
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protected List getFieldOrder() {
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List a = new ArrayList();
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a.add( "Feild");
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a.add( "X_coord");
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a.add( "Y_coord");
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a.add( "Font");
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a.add( "Inverse");
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a.add( "length");
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a.add( "Payload");
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return a;
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}
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}
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public static class Ldata extends Structure {
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public byte[] Label_id = new byte[ 7];
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public int Count;
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public Cword.ByValue[] NCword = new Cword.ByValue[ 50];
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public static class ByReference extends Ldata implements
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Structure. ByReference {
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}
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public static class ByValue extends Ldata implements
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Structure. ByValue {
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}
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"rawtypes", "unchecked" })({
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protected List getFieldOrder() {
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List a = new ArrayList();
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a.add( "Label_id");
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a.add( "Patten");
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a.add( "Count");
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a.add( "NCword");
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return a;
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}
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}
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public int Start_Update(String station_id, int count, Ldata.ByValue[] data);
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}
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}
java代码->接口函数调用:
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public class GUI {
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public static int labelcount = 5;
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public static String[] labellist = new String[]{ "000834", "000835", "041908",
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"041909", "04190A", "04190B", "04190C", "04190D", "04190E", "04190F", "041910",
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"041911", "041912", "041913", "041914", "041915", "041916", "041917", "041918"};
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bsend.addActionListener( new ActionListener() {
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public void actionPerformed(ActionEvent e) {
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int i;
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int result;
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getSDK.Function.Ldata.ByValue tdata = new getSDK.Function.Ldata.ByValue();
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getSDK.Function.Ldata.ByValue[] data = (getSDK.Function.Ldata.ByValue[])tdata.toArray(labelcount);
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for (i = 0; i < labelcount; i++) {
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data[i].Label_id = labellist[i].getBytes();
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}
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for (i = 0; i < labelcount; i++) {
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data[i].Count = 4;
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}
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getSDK.Function.Cword.ByValue cdata = new getSDK.Function.Cword.ByValue();
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getSDK.Function.Cword.ByValue[] ctdata = (getSDK.Function.Cword.ByValue[])cdata.toArray( 50);
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ctdata[ 0].Feild = "Text".getBytes();
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ctdata[ 0].Inverse = false;
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ctdata[ 0].length = "test".getBytes().length;
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ctdata[ 0].Payload = "test".getBytes();
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ctdata[ 1].Feild = "Text".getBytes();
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ctdata[ 1].Inverse = false;
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ctdata[ 1].length = "hello".getBytes().length;
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ctdata[ 1].Payload = "hello".getBytes();
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ctdata[ 2].Feild = "Text".getBytes();
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ctdata[ 2].Inverse = false;
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ctdata[ 2].length = "单位".getBytes().length;
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ctdata[ 2].Payload = "单位".getBytes();
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ctdata[ 3].Feild = "Text".getBytes();
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ctdata[ 3].Inverse = false;
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ctdata[ 3].length = "规格".getBytes().length;
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ctdata[ 3].Payload = "规格".getBytes();
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for (i = 0; i < labelcount; i++) {
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data[i].NCword = ctdata;
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}
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result = getSDK.Function.instanceDll.Start_Update((String)station.getSelectedItem(), labelcount, data);
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}
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});
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}
getSDK.Function.Ldata.ByValue[] tdata = new getSDK.Function.Ldata.ByValue[labelcount];
的方式,得到的内存是不连续的,当你传递这种方式定义的变量给dll时,dll只能取到第一个结构体元素的值,造成数据丢失。