http断点续传简单实现（java)

/* E1U4v&P  
**SiteFileFetch.java 8osS OOzM  
*/ 5vUz  
package NetFox; |1<]o;:  
import java.io.*; xzMeK
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import java.net.*;
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public class SiteFileFetch extends Thread { lJGqR0:r+  
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SiteInfoBean siteInfoBean = null; //文件信息Bean r{/
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long[] nStartPos; //开始位置 LEn=dU  
long[] nEndPos; //结束位置 O$<%z[  
FileSplitterFetch[] fileSplitterFetch; //子线程对象
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long nFileLength; //文件长度 #TW>'lF  
boolean bFirst = true; //是否第一次取文件 <y\
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boolean bStop = false; //停止标志 Y?&DEKFbD  
File tmpFile; //文件下载的临时信息 &0th1-OP_  
DataOutputStream output; //输出到文件的输出流 4mM2C`I  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 'Tru?y\  
public SiteFileFetch(SiteInfoBean bean) throws IOException @LWxz  
{ oM18aR&  
siteInfoBean = bean; #iRyjD  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); @o3R`ZgC]\  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); +LI*!(T|lm  
if(tmpFile.exists ()) 5E\<r/FeJ  
{ Jm);|#y  
bFirst = false; 9znx1AsN  
read_nPos(); |=^#d\?]j  
} ?5r2j3mqgv  
else C<wj?!v,F[  
{ 4I:JaRT d  
nStartPos = new long[bean.getNSplitter()]; U Qi^udGFD  
nEndPos = new long[bean.getNSplitter()]; @F3-Ugm  
} Qa7S'(  
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} #<tWYE  
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public void run() eUKl Co  
{ $)T
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//获得文件长度 ExOB P  
//分割文件 OnPy8mC  
//实例FileSplitterFetch u7Y'3x,`  
//启动FileSplitterFetch线程 e??{&[  
//等待子线程返回 /|u]Y/ *  
try{ f5=t*9_-[  
if(bFirst) ?D~SHcBaN  
{ c~L6fvS  
nFileLength = getFileSize(); )
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if(nFileLength == -1) s68_o[[E  
{ i9EMi_%  
System.err.println("File Length is not known!"); $?/Xk%d+  
} @)2V"FE4i  
else if(nFileLength == -2) @R OY}CZ{/  
{ ev: !,}]w  
System.err.println("File is not access!"); ,~j$rs`Z  
} &TkbnDuYd~  
else <v7KE*#  
{ -o!,,XYj .  
for(int i=0;i<nStartPos.length;i++) ]}l+ !NV<  
{ D 5r   
nStartPos = (long)(i*(nFileLength/nStartPos.length)); 0Yzb=QMD  
} I>8@=V~  
for(int i=0;i<nEndPos.length-1;i++) "!6 B5Oz  
{ @Z=|$*9  
nEndPos = nStartPos[i+1]; i!d7,>l+Q~  
} @Y&9S)xcE  
nEndPos[nEndPos.length-1] = nFileLength; pv m'pu78  
} P15*VPy  
} %oCjZ"ke  
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//启动子线程 @X6#$ex  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; +&N&D"9A  
for(int i=0;i<nStartPos.length;i++) H+#wj|,+\  
{ @aD~YtL"n  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), wM4g1H%s  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), \]`(xxt1  
nStartPos,nEndPos,i); 6P*)rye  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); +|"n4iZ!)  
fileSplitterFetch.start(); DN8pJa  
} B]KLn?zt5  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), eRx[&-c  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); h%w\O Z7  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", '3u]-GU2_  
nEndPos = " + nFileLength); 3JE;:2O~P  
// fileSplitterFetch[nPos.length-1].start(); 7SY->-H8  
hv:Z%D |S  
ep}
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//等待子线程结束 FTYLMQ i  
//int count = 0; 4TQISu)  
//是否结束while循环 +81+4{*  
boolean breakWhile = false; g/X=#!  
  [aS)<^  
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while(!bStop) ~Yz/t  
{ NdSxWrD`m  
write_nPos(); np\Q&  
Utility.sleep(500); tEX~72v  
breakWhile = true; +heS\I_Mp  
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' bw,K*  
for(int i=0;i<nStartPos.length;i++) wY ;8UN  
{ &N7:k+E
 
if(!fileSplitterFetch.bDownOver) 3F'dT[;  
{ ?a0}^:6  
breakWhile = false; +e]b,9.sR  
break; 8
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} A-wxf91+:  
} pvR& ~g  
if(breakWhile) KZ
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break; >)A  
!6/IKh`J  
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//count++; g+/U^JIc4l  
//if(count>4) GN;XB b]w  
// siteStop(); =i5:*J  
} XK/@!ud"`  
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System.err.println("文件下载结束！"); O/^w! :z'  
} 0?Wf\7  
catch(Exception e){e.printStackTrace ();} QRHm|f9_C  
} LLHOWD C(2  
;)]zv\fC  
:lQjy@J  
//获得文件长度 .z>." `  
public long getFileSize() UO!6&k>
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{ H$z+gbjJ  
int nFileLength = -1; g5|\G%dOt  
try{ rLVc<595  
URL url = new URL(siteInfoBean.getSSiteURL()); !>@V#I  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ;F(01  
httpConnection.setRequestProperty("User-Agent","NetFox"); P"~T*Qq-R  
}0nB'0|y  
_r5Ild@n  
int responseCode=httpConnection.getResponseCode();
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if(responseCode>=400) nJ#@W b@  
{ ,L:)ZZgN  
processErrorCode(responseCode); h_G7T1;L  
return -2; //-2 represent access is error (dipKs?K  
} (l_de)N7  
[}>6n72gNh  
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String sHeader; <r`Jn49  
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for(int i=1;;i++) hJ*E"{xs  
{ gO%i5  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ![!b^:f  
//Utility.log(in.readLine()); *g41"Cl  
sHeader=httpConnection.getHeaderFieldKey(i); L0V

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if(sHeader!=null) ?HyioLO  
{ 2^ZPO4|  
if(sHeader.equals("Content-Length")) "#k(V=y  
{ E=*Q\3G~  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); wEc5{ b5
M  
break; 3M*[a~  
} wP1VQUL  
}
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else ~wg^>!E  
break; BF[?* b  
} S|4/C  
} K y2xWd8  
catch(IOException e){e.printStackTrace ();} wXGFq3`  
catch(Exception e){e.printStackTrace ();} 1WN93SQ=  
LHz<=]?@  
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Utility.log(nFileLength); {-`
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return nFileLength; >qvD39w  
} jeFl+K'1  
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//保存下载信息（文件指针位置） 5o ^=~  
private void write_nPos() qWRMwvN
{  
{ [ =2In;
 
try{ 7Ej#7\TB]  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ^Jc0c)*  
output.writeInt(nStartPos.length); 6b01xu(A[  
for(int i=0;i<nStartPos.length;i++) r3vj o(  
{ XRz6Yf(/  
// output.writeLong(nPos); 2=M!lB *  
output.writeLong(fileSplitterFetch.nStartPos); hD"~ ^  
output.writeLong(fileSplitterFetch.nEndPos); SZD2'UaG  
} h5keYBA  
output.close(); 9d}ny
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} 8J1.(Mwb?  
catch(IOException e){e.printStackTrace ();} J*C*](  
catch(Exception e){e.printStackTrace ();} \bSHBTK  
} IEf^.Z
 
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//读取保存的下载信息（文件指针位置） {/!Gh\i  
private void read_nPos() vkgL"([_  
{ g|_*(=Q  
try{ ClZyQ=UAD  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); ppP?1Il`kb  
int nCount = input.readInt(); .Q)"F /  
nStartPos = new long[nCount]; K+OU~SED%F  
nEndPos = new long[nCount]; P`"DepeD  
for(int i=0;i<nStartPos.length;i++) <F & hfy  
{ 'B6H/d
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nStartPos = input.readLong(); bQjHQ"
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nEndPos = input.readLong(); hzo,.hS's  
} :/l  
input.close(); Bys|i0tb-  
} p'}%pAY  
catch(IOException e){e.printStackTrace ();} 4344PBj  
catch(Exception e){e.printStackTrace ();} M?u)H&kEl  
} Sxu v}y\  
#8OqX*/  
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private void processErrorCode(int nErrorCode) Oh4WYDyT  
{ F[Sat;Sll  
System.err.println("Error Code : " + nErrorCode); dtl<  
} ,jcp"-5#j  
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}TvAjLIS6  
//停止文件下载 QLG,r^  
public void siteStop() Q
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{ }>U03aa
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bStop = true; ]
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for(int i=0;i<nStartPos.length;i++)  B4ze$#  
fileSplitterFetch.splitterStop(); e90z(EF?0  
{ rn~D5R  
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} iL1so+di  
} cEu98nP  
//负责部分文件的抓取 cfS]C_6d  
**FileSplitterFetch.java ^dD?riFAk  
*/ fZgU@!z  
package NetFox; }2o
J  
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import java.io.*; So`"z[5  
import java.net.*; {rLOAewr  
;A!i V|  
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public class FileSplitterFetch extends Thread { Cz)D3Df^  
^yTN(\9  
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String sURL; //File URL kzXW<V9  
long nStartPos; //File Snippet Start Position R FiR)G ,  
long nEndPos; //File Snippet End Position g\'84:*J\  
int nThreadID; //Thread's ID S~Q";C[&  
boolean bDownOver = false; //Downing is over 7RJ
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boolean bStop = false; //Stop identical < *OF  
FileAccessI fileAccessI = null; //File Access interface LL+rdxJO^  
|D:0BATRP  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException Z9I./s9  
{ q'tT)IgD  
this.sURL = sURL; kw'D2692  
this.nStartPos = nStart; B,T.bgp\  
this.nEndPos = nEnd; xE_[=7=  
nThreadID = id; _Tz!~z  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 8w'8n  
} oZtz"B  
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public void run() WcFZRy-erc  
{ \-yi#N  
while(nStartPos < nEndPos && !bStop) 6I0MJpLW  
{ my6T@0R  
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try{ WgB,,L,  
URL url = new URL(sURL); zu%pr95U  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ta(x
4fP_  
httpConnection.setRequestProperty("User-Agent","NetFox"); p4 PFoFo2  
String sProperty = "bytes="+nStartPos+"-"; dD%m=x  
httpConnection.setRequestProperty("RANGE",sProperty); r%i{a  
Utility.log(sProperty); eS
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InputStream input = httpConnection.getInputStream(); jo~vOu  
//logResponseHead(httpConnection); U"]i.J1  
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byte[] b = new byte[1024]; tEj5WEnNE8  
int nRead; <n{9pZ5.  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) l ,.;dw  
{ =@>&kU%$&  
nStartPos += fileAccessI.write(b,0,nRead); w?q"%F;/  
//if(nThreadID == 1) B?'ti{p A9  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); RJSgts "F  
} <T]kpP<lC  
H@:@zD!G[  
76/%Py|  
Utility.log("Thread " + nThreadID + " is over!"); OHw6#N$\  
bDownOver = true; 9'M_tMm5  
//nPos = fileAccessI.write (b,0,nRead); I j /J  
} =
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catch(Exception e){e.printStackTrace ();} jg(A_V  
} X1"nq]chGy  
} zqkmsFH{  
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tJP(eaqZ  
//打印回应的头信息 \!3='~2:=o  
public void logResponseHead(HttpURLConnection con) j3><J  
{ LmE-&  
for(int i=1;;i++) A5b}G
 
{ p:jrqjLp  
String header=con.getHeaderFieldKey(i); mfvQ]tz_+  
if(header!=null) x@=7M'vr%  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ~cjvo?)&e;  
Utility.log(header+" : "+con.getHeaderField(header)); gNeCnf#Xa  
else rgCId@R  
break; eMwf'*#  
} r[x7?cXsW  
} 5tL6R3  
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public void splitterStop() J
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{ (hoqLL\}k  
bStop = true; xjYFTb}!  
} ;z68`P-  
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} 7o<RvM  
;/
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/* 
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**FileAccess.java RjT[y: !  
*//文件访问(定位，写) jv ";?*I6.  
package NetFox; '};Xb|msU  
import java.io.*; g;pFT  
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public class FileAccessI implements Serializable{ dj=n1f+;[  
B06/mKZ7  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 };*5+XY^  
RandomAccessFile oSavedFile; ]%."  
long nPos; &Lw| t_y  
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ZD/!C9:&.0  
public FileAccessI() throws IOException ;p/@tr9  
{ Ud](hp"  
this("",0); >\'yj| U,  
} ~BC5no  
c
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public FileAccessI(String sName,long nPos) throws IOException aF:I]]TfK~  
{ 1\McsX4  
oSavedFile = new RandomAccessFile(sName,"rw"); G9 !1Wz
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this.nPos = nPos; }7V/(K  
oSavedFile.seek(nPos); z)26Ahm TV  
} sYz:(hZS  
xASjw?  
xiI!_0'  
public synchronized int write(byte[] b,int nStart,int nLen) (.c?)_G,  
{ yVL~SH|  
int n = -1; #ua#$&p  
try{ ?@
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oSavedFile.write(b,nStart,nLen); *VH1(E`hl  
n = nLen; e\89;)  
} C8?/$1|RL  
catch(IOException e) +#W5Qb}VR  
{ mU
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e.printStackTrace (); -+L1Hid.7  
} <AVpFy  
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return n; $j:0*Z=>  
} &~j"3G;e  
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* .e^s3q$  
} +RbCa c  
a
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/* olqHa5qn  
**SiteInfoBean.java (HTVSC%=  
*/ T:si?7CR  
package NetFox; 0<Y)yNsV  
+,smjg:O  
' o5,P/6  
public class SiteInfoBean { /ZczfM\  
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GB-=DC6  
private String sSiteURL; //Site's URL ?0.+DB $  
private String sFilePath; //Saved File's Path `);`E_'U k  
private String sFileName; //Saved File's Name D@2Tx  
private int nSplitter; //Count of Splited Downloading File xzy9~))o  
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public SiteInfoBean() `:8
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{//nSplitter的缺省值为5 W>"i0p  
//default value of nSplitter is 5 6)TFb,  
this("","","",5); V3jx{BXs2  
} A81kb  
xTe?*  
Q>.-u6(&  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Y4i-Pp?  
{ 4[6A~iC_  
sSiteURL= sURL; '\9A78NV{;  
sFilePath = sPath; $rdA0%
;  
sFileName = sName; )wKuumet  
this.nSplitter = nSpiltter; TPkm~>zD.  

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} ^,?]]=mE  
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+%FGti$[  
public String getSSiteURL() pdE=9l'  
{ kJ~^ }o  
return sSiteURL; MOj 0"x)  
} %1#5 7-  
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public void setSSiteURL(String value) VQX#P<  
{ [E=
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sSiteURL = value; #Z
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} QutQG  
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n&@\[,B  
public String getSFilePath() Qd@`jwjS  
{ \ Xuu|]  
return sFilePath; j88H3b
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} 7)[4|I  
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public void setSFilePath(String value) -0>@jfP^D  
{ hG3b7!^#g  
sFilePath = value; ]e+S~me  
} ; LTc4t  
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6N]v9uXZ  
public String getSFileName() @$Y`I{Xf  
{ s7=]!7QGS!  
return sFileName; p#3P`I>ZrT  
} k{9s>l~'  
5HmX-+XpK  
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public void setSFileName(String value) c/pT2/y  
{ lqu1H&  
sFileName = value; HmQuRW  
} Y,?rykRj  
@ j'
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public int getNSplitter() n-p|7N  
{ Cgt{5  
return nSplitter; Dtelr=/s  
} Nk]r2^.z[  
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public void setNSplitter(int nCount) V7 c7(G  
{ 2c}>}A4  
nSplitter = nCount; MA"DP7e?v  
} M7En%sBp  
} I,.>tC  
w${=]h*2  
Cvq2UNz(R  
/* U2!9Tl9".  
**Utility.java {ImZ><xe/  
*/
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package NetFox; MLaH("aen  
q S2#=  
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public class Utility { l9#vr  
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public Utility() v dyu=*Y  
{ iYBs )  
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} p ^T0(\1  
u|APx8?"o  
//线程睡眠 =3Y?U*d  
public static void sleep(int nSecond) ]
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{ 03[(dRK>=  
try{ P)ZGNtO9fG  
Thread.sleep(nSecond); K5'@$Km  
} .\qZkk}2l  
catch(Exception e) <
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{ =((#kDrN  
e.printStackTrace (); ABB4(_3E  
} r`VKb  
} z1_\P) M  
BY72fy#e  
//日志 ?< mSEgvu  
public static void log(String sMsg) JT,8/o  
{ \Ua"gS2L  
System.err.println(sMsg); 4
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} ^HQg$}=  
}5FdX3YR  
\A Y7%>  
public static void log(int sMsg) td&W>(
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{ ~M2w&g;1  
System.err.println(sMsg); z^O>'9#
 
} 80LKxA;5N  
} b\F(.8  
Mo0+"`
   
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/* u.gnvdU  
**TestMethod.java OcwD<Xy  
*/ S~/zBFo-  
package NetFox; }LN +V~  
bwS1YGb  
:dLfM)8}  
public class TestMethod { *dL!)+:d  
E_MGejm@  
N)WAzH  
public TestMethod() xm6cn\
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{ ///xx/weblogic60b2_win.exe 8$BZbj%?hx  
try{ `)/G5 fB  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); /T!S)FD\/v  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); $ohIdpZLH2  
SiteFileFetch fileFetch = new SiteFileFetch(bean); e>=P'  
fileFetch.start(); M9[Fx=
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} |ffM6W1:  
catch(Exception e){e.printStackTrace ();} -tlRe12
 
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} 2r^|  
lrPiaSO`I  
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public static void main(String[] args) U5[xW  
{ 0jF~cV  
new TestMethod(); !g-|@W  
} %tT&/F  
} 5^~%10=  
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