http断点续传简单实现（java)

/*  Rqwzh@}  
**SiteFileFetch.java WI]o cF  
*/ ^[%%r3"$C  
package NetFox; =%
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import java.io.*; Zm
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import java.net.*; R52I= a5,*  
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public class SiteFileFetch extends Thread { 3=-4%%[M@  
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SiteInfoBean siteInfoBean = null; //文件信息Bean rkiT1YTY  
long[] nStartPos; //开始位置 )54%HM_$k  
long[] nEndPos; //结束位置 Fnk_\d6Ma  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 v]__%_  
long nFileLength; //文件长度 ?+T^O?r|O  
boolean bFirst = true; //是否第一次取文件 \{Q?^E  
boolean bStop = false; //停止标志 0$7.g!h?  
File tmpFile; //文件下载的临时信息 VqL.iZ-  
DataOutputStream output; //输出到文件的输出流 +[SgO}sF  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） x0d~i!d  
public SiteFileFetch(SiteInfoBean bean) throws IOException 9
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{ cRX~z  
siteInfoBean = bean; >0p$(>N]  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); }j,[ 1@S  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); $gBd <N9|c  
if(tmpFile.exists ()) jxJv.  
{ 0]HYP;E"U  
bFirst = false; (98Nzgxgx}  
read_nPos(); :e
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} Qt]Q:9I[  
else s=?g\oR  
{ ]%Zz \Q  
nStartPos = new long[bean.getNSplitter()]; NEa>\K<\  
nEndPos = new long[bean.getNSplitter()]; FKe,qTqa  
} 2lL,zFAq  
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} ~b{Gz6u>  
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public void run() ,lCgQ0}<  
{ 5U_H>oD  
//获得文件长度 5SkW-+$  
//分割文件 5>AX*]c  
//实例FileSplitterFetch }w4QP+ x  
//启动FileSplitterFetch线程 r-
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//等待子线程返回 gWY"w!f  
try{ 7)h[Zy,A  
if(bFirst) pLv$\MiZ  
{ a<]B B$~  
nFileLength = getFileSize(); :$MG*/Q  
if(nFileLength == -1) *,BzcZ  
{ []s^   
System.err.println("File Length is not known!"); l }XU59  
} Z$J#|  
else if(nFileLength == -2) vM_:&j_?``  
{ 0a"igq9t  
System.err.println("File is not access!"); xC C:BO`pw  
} u4Em%:Xj  
else <3,<\ub  
{
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for(int i=0;i<nStartPos.length;i++) 43V}#DA@  
{ VY)s+Bx  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); q\\gpCgp  
} v
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for(int i=0;i<nEndPos.length-1;i++) /  g 2b  
{ .jMq  
nEndPos = nStartPos[i+1]; A<;SnXm  
} %kgkXc~6|x  
nEndPos[nEndPos.length-1] = nFileLength; +**!@uY  
} .5  
} %,ngRYxT#  
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//启动子线程 ,]b~t0|B  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; h;3cd0  
for(int i=0;i<nStartPos.length;i++) 3j3N!T9  
{ F
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fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), vzmc}y G  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), x`6<m!d`  
nStartPos,nEndPos,i); ]vuwkn+)  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); _ 84ut  
fileSplitterFetch.start(); XV^1tX>f{  
} Ks}Xgc\  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ,-z9 #t  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); KF4PJi;*  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", ^wS5>lf7p  
nEndPos = " + nFileLength); Is+O  
// fileSplitterFetch[nPos.length-1].start(); N!`e}Z6S  
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c&L"N!4z  
//等待子线程结束 `=7j$#6U  
//int count = 0; ;j2vHU#q-  
//是否结束while循环 Qyy.IPTP  
boolean breakWhile = false; kY'T{Sm1^  
]5%/3P,/  
}- Wa`t7U  
while(!bStop) "+unS)M;Y  
{ ;t+ub8  
write_nPos(); jbR0%X2  
Utility.sleep(500); '? jlH0;  
breakWhile = true; jMpD+Mb  
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for(int i=0;i<nStartPos.length;i++) `7H4Y&E  
{ ]n-:Yv5 W  
if(!fileSplitterFetch.bDownOver) VWO9=A*Y|  
{ o: ;"w"G  
breakWhile = false; ;,]P=Ey  
break; zz& ?{vJ  
} cYqfsd# B  
} ,*7d  
if(breakWhile) -ig6w.%lk  
break; _2N$LLbg  
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//count++; 1T[et-  
//if(count>4) Y/7 $1
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// siteStop(); H@l}WihW  
} gynh#&r  
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System.err.println("文件下载结束！"); rylzcN9RM$  
} ciMzf$+G$  
catch(Exception e){e.printStackTrace ();} K#"O a h  
} HF(KN{0.B  
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l<N}!lG|  
//获得文件长度 ."FuwKSJCo  
public long getFileSize() KIWe@e  
{ %dY<=x#b  
int nFileLength = -1; xNbPsoK  
try{ &iV,W4  
URL url = new URL(siteInfoBean.getSSiteURL()); o^ XtU5SVq  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); t]-5 ]oI  
httpConnection.setRequestProperty("User-Agent","NetFox"); [p<w._b i  
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F;]%V%F.X  
int responseCode=httpConnection.getResponseCode(); Phke`3tth  
if(responseCode>=400) @*sWu_-Y%  
{ 4t)/  
processErrorCode(responseCode); A
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return -2; //-2 represent access is error GI&h`X5,e  
} e;(0(rI  
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String sHeader;
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for(int i=1;;i++) qT^I?g"!  
{ Ng_!zrx04  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ,2W8=ON  
//Utility.log(in.readLine()); /3{b%0Aa  
sHeader=httpConnection.getHeaderFieldKey(i); hvaSH69*m  
if(sHeader!=null) (P$H<FtH  
{ hodgDrmO/  
if(sHeader.equals("Content-Length")) &#iTQD  
{ B $mX3B
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nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); eow'K 821A  
break; )vSRHE  
} 5D'\b}*lJ}  
} k`N^Vdr  
else 5s]. @C8  
break; >:b Q  
} aca=yDs2  
} yYfsy?3  
catch(IOException e){e.printStackTrace ();} zOiu5  
catch(Exception e){e.printStackTrace ();} :*KHx|Q  
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Utility.log(nFileLength); [)TRTxFb  
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return nFileLength; Ll4g[8  
} <q@a~'Ai?!  
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7K98#;a)5  
//保存下载信息（文件指针位置） :\o {_  
private void write_nPos() $\U4hHOo  
{ c-0#w=  
try{ 55fC~J<  
output = new DataOutputStream(new FileOutputStream(tmpFile)); %B.yW`,X  
output.writeInt(nStartPos.length); HKUn`ng  
for(int i=0;i<nStartPos.length;i++) b"{'T]"*j  
{ (P:<t6;+  
// output.writeLong(nPos); AQwdw>I-FX  
output.writeLong(fileSplitterFetch.nStartPos); $F5 b  
output.writeLong(fileSplitterFetch.nEndPos); bXNk%W[n  
} ilqy/fL#  
output.close(); (:
>,u*x%  
} m*kl  
catch(IOException e){e.printStackTrace ();} |mw.qI|  
catch(Exception e){e.printStackTrace ();} FFEfI4&SfS  
} W*I(f]8:y`  
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//读取保存的下载信息（文件指针位置） lp^<3o*1  
private void read_nPos() u@cYw:-C  
{ =D<PVGo9  
try{ K42K!8$  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); mrF58Uq;A  
int nCount = input.readInt(); z+n,uHs  
nStartPos = new long[nCount]; ybKWOp:O  
nEndPos = new long[nCount]; "[ZB+-|[0  
for(int i=0;i<nStartPos.length;i++) LHo3 Niy.  
{ g0["^P1tV  
nStartPos = input.readLong(); d\gJ$ ~^K  
nEndPos = input.readLong(); 1 P!Yxeh  
} ~ r438&  
input.close(); 
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} ElW~48  
catch(IOException e){e.printStackTrace ();} ,tu
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catch(Exception e){e.printStackTrace ();} |$ lM#Ua  
} #ZrHsfP  
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private void processErrorCode(int nErrorCode) SSWP~ t  
{ LAS'u"c|  
System.err.println("Error Code : " + nErrorCode); IHv[v*4:  
} 9^#c|
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//停止文件下载 sW'2+|3"  
public void siteStop() +Z!)^j  
{ ;"~ fZ2$U  
bStop = true; ]Hefm?9*^  
for(int i=0;i<nStartPos.length;i++)  :7]Sa`  
fileSplitterFetch.splitterStop(); ?WqT[MnK  
A
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} kr9*,E9cv  
} %|q>pin2  
//负责部分文件的抓取 3@$,s
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**FileSplitterFetch.java VoWNW  
*/ 67G?K;)e  
package NetFox; Zy?Hi`  
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import java.io.*; /YMj-S_b~  
import java.net.*; '6cWS'9"  
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public class FileSplitterFetch extends Thread { b)qo
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Ki$MpA3j  
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String sURL; //File URL )I^7)x  
long nStartPos; //File Snippet Start Position SBfT20z[  
long nEndPos; //File Snippet End Position .yqM7U_  
int nThreadID; //Thread's ID f=r<n
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boolean bDownOver = false; //Downing is over gv-
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boolean bStop = false; //Stop identical %4,O 2\0?&  
FileAccessI fileAccessI = null; //File Access interface _M`--.{\O[  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException "8x8UgG  
{ ~5%W:qw
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this.sURL = sURL; [ 0KlC1=  
this.nStartPos = nStart; xy/`ZS2WPq  
this.nEndPos = nEnd; "!ug_'VW  
nThreadID = id; [6%VRqY  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 %InA+5s`  
} c4^ks&)'  
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C.Kh[V\Ut  
public void run() BW}U%B^.  
{ qG?Qc (  
while(nStartPos < nEndPos && !bStop) !Sh&3uy_qN  
{ >,$_| C  
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try{ r%yvOF\>  
URL url = new URL(sURL); /v1Q4mq  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); CYs,`  
httpConnection.setRequestProperty("User-Agent","NetFox"); fzb29 -  
String sProperty = "bytes="+nStartPos+"-"; 93("oBd[s(  
httpConnection.setRequestProperty("RANGE",sProperty); [65`$x
-  
Utility.log(sProperty); ~962i#&4  
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InputStream input = httpConnection.getInputStream(); mS$j?>m  
//logResponseHead(httpConnection); tl,.fjZn  
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byte[] b = new byte[1024]; Z<1FSk,[  
int nRead; "U>JM@0DNm  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 0WZ_7C?  
{ -Ta9 pxZk  
nStartPos += fileAccessI.write(b,0,nRead); Xqg@ e:g  
//if(nThreadID == 1) Ce9|=Jx!  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); "GMBjT8  
} P;=n9hgHI  
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Utility.log("Thread " + nThreadID + " is over!"); dMf:h"7  
bDownOver = true;
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//nPos = fileAccessI.write (b,0,nRead); ]@j*/IP  
} %Gz0^[+  
catch(Exception e){e.printStackTrace ();} )t0$qd ]  
} ZkRx1S"m  
} rzhWw-GY  
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//打印回应的头信息 TN!j13,  
public void logResponseHead(HttpURLConnection con) U\4g#!qj  
{ M -cTRd-i  
for(int i=1;;i++) ww\CQ6/h  
{ l&O
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String header=con.getHeaderFieldKey(i); 2&:f&"  
if(header!=null) h)ECf?r<  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); QRc{vUR&  
Utility.log(header+" : "+con.getHeaderField(header)); =9y[1t  
else ?26I,:;  
break; A!s`[2 Z  
} Se:.4<  
} 2,$8icM  
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t}"^  
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public void splitterStop() &gVN&  
{ we~[] \  
bStop = true; H*RC@O_hv  
} 0%9 q8M;  
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} lGPUIoUo  
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.0S~872  
/* Uol|9F  
**FileAccess.java B:b5UD  
*//文件访问(定位，写) ZXqSH${Tp  
package NetFox; rn/ /%  
import java.io.*; <r.)hT"0  
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*xx'@e|<;  
public class FileAccessI implements Serializable{ X[*<NN  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 <C1H36p  
RandomAccessFile oSavedFile; C]O(T2l{l  
long nPos; RkH W  
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public FileAccessI() throws IOException Yl4^AR&  
{ M>wYD\oeg  
this("",0); nOt&pq7  
} zvYq@Mhr  
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public FileAccessI(String sName,long nPos) throws IOException 7L`A{L  
{ )
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oSavedFile = new RandomAccessFile(sName,"rw"); 0[RL>;
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this.nPos = nPos; Ed0QQyC@9  
oSavedFile.seek(nPos); _(_a*ml  
} j@W.&- _  
**w!CaqvY  

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public synchronized int write(byte[] b,int nStart,int nLen) ' KWyx  
{ ;+W#5<i  
int n = -1; u!!Y=!y*<  
try{ H{@Yo\J  
oSavedFile.write(b,nStart,nLen); #o=y?(  
n = nLen; j#X
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} s[M
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catch(IOException e) a=1NE
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{ }\
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e.printStackTrace (); nGpXI\K  
} T}Km?d  
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return n; Pj#<K%Bz  
} Gy9$wH@8  
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} Fz3fwLawI  
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/* sT !~J4  
**SiteInfoBean.java 3VsW@SG7N  
*/ WzPTFw[  
package NetFox; q 0$,*[PH  
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public class SiteInfoBean { ; o?-yI&T*  
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private String sSiteURL; //Site's URL &R[ Mc-2  
private String sFilePath; //Saved File's Path *EOdEFsR/  
private String sFileName; //Saved File's Name ?^H `M|S  
private int nSplitter; //Count of Splited Downloading File _g+JA3sIJ  
-l`f)0{  
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public SiteInfoBean() WB?jRYp  
{//nSplitter的缺省值为5 Keuf9u  
//default value of nSplitter is 5 di?K"Z>  
this("","","",5); G^~k)6v=m  
} x^HGVWw_  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) W}3.E "K  
{ "8c@sHk(w  
sSiteURL= sURL; "w^!/  
sFilePath = sPath; xe#FUS 3  
sFileName = sName; yyoqX"v[  
this.nSplitter = nSpiltter; nc~F_i=  
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} aK&b{d  
W,4QzcQR  
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public String getSSiteURL() NiWa7/Hr  
{ ;'?l$ ._  
return sSiteURL; G,$PV e*  
} ZO!
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public void setSSiteURL(String value) R%Qf7Q  
{ :H7D~ n  
sSiteURL = value; "JVkVp[5D+  
} ]=.\-K  
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public String getSFilePath() 0)%YNaskj  
{ P<PJ)>  
return sFilePath; $$D}I*^Dt  
} E4gYemuN  
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public void setSFilePath(String value) ~J5+i9T.)  
{ 1q~+E\x  
sFilePath = value; 0]>u)%  
} +!k&Yje  
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public String getSFileName() 8MK>)P o)  
{ l\BVS)  
return sFileName; kQ4dwF~  
} +J_c'ChN  
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public void setSFileName(String value) b^ L \>3  
{ B||*.`3gN  
sFileName = value; $.C=H[QC  
} :@kGAI  
{n(b{ibl  
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public int getNSplitter() jYx38_5e  
{

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return nSplitter; tna .52*/  
} ]p*l%(dhY  
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public void setNSplitter(int nCount) p%iGc<vHX  
{ 3Dg,GaRk  
nSplitter = nCount; r^h4z`:L  
} x N=i]~  
} ]Gpxhg  
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/* 8j Mk)-  
**Utility.java H]Cy=Zi"  
*/ P6E3-?4j  
package NetFox; &/mA7Vf>eR  
nS/)
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public class Utility { xHoKo  
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public Utility() %F\?R[^5  
{ zBo1P(kek  
f_[<L  

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} t/ +=|*  
-0?~  
//线程睡眠 7P"| J\  
public static void sleep(int nSecond) c#a@n 4  
{ M54j@_81pX  
try{ H:!7:  
Thread.sleep(nSecond); >G);j@Q  
} HuB<k3#sPy  
catch(Exception e) S7=Bd[4  
{ q+P|l5_ t  
e.printStackTrace (); aT_&x@x  
} >fe-d#!{  
} umD!
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AP[|Ta  
//日志 6^uq?  
public static void log(String sMsg) T^:UBjK6t{  
{ &f!z1d-qg?  
System.err.println(sMsg); bx<RV7>0  
} '#s05hr  
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5:O-tgig.  
public static void log(int sMsg)
}~#pEX~j*  
{ xB_!>SqF1U  
System.err.println(sMsg); W`K7
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} ;epV<{e$q4  
} FQT~pfY  
dA@'b5N{"  
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/* Xg<*@4RD8  
**TestMethod.java SeHagKA  
*/ 9l}FU$  
package NetFox; t0z!DOODZP  
*_R]*o!W'  
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public class TestMethod { HH
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XID<(HBA"!  
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public TestMethod() A6GE,FhsG  
{ ///xx/weblogic60b2_win.exe cU ?0(z7  
try{ M(jgd  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); GN
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//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); Wi[~fI8^!  
SiteFileFetch fileFetch = new SiteFileFetch(bean); "J+3w  
fileFetch.start(); ~2<7ZtV=  
} {S,l_d+(  
catch(Exception e){e.printStackTrace ();} 350_CN,  
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} wSb1"a  
3= 
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/V8}eZ97  
public static void main(String[] args) \zieyE  
{ 8#(Q_  
new TestMethod(); V+Cwzc^j  
} 7:9.&W/KE  
} L!
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