http断点续传简单实现（java)

/* pNepC<rY  
**SiteFileFetch.java &"&Z #llb  
*/ =P't(<  
package NetFox;  zv0l,-o  
import java.io.*; a&/#X9/  
import java.net.*; TaKLzd2  
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public class SiteFileFetch extends Thread { TN+iA~kQ  
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SiteInfoBean siteInfoBean = null; //文件信息Bean e2s]{obf  
long[] nStartPos; //开始位置 HK,cJahq  
long[] nEndPos; //结束位置 }wr{W:j  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 X' H[7 ^W  
long nFileLength; //文件长度 RJ 8+h  
boolean bFirst = true; //是否第一次取文件 dCi?SIN  
boolean bStop = false; //停止标志 hYPl&^  
File tmpFile; //文件下载的临时信息 }X)&zenz  
DataOutputStream output; //输出到文件的输出流 ,':fu  
e:fy#,HEj{  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） xS4w5i2  
public SiteFileFetch(SiteInfoBean bean) throws IOException SUC
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{ n.!#P|  
siteInfoBean = bean; *W,]>v0%T  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); .}t~'*D  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ]O+Ma}dxz:  
if(tmpFile.exists ()) !h"Kq>9T  
{ ,J,/."Y  
bFirst = false; ]m g)Q:d,  
read_nPos(); G&D7a
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} `Q|*1  
else 5D\f8L  
{ JjPKR?[>  
nStartPos = new long[bean.getNSplitter()]; PF)jdcX  
nEndPos = new long[bean.getNSplitter()]; K1mPr^3rC  
} `^u>9v-+'  
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} *SU\ABcov  
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public void run() $?Yry.2  
{ ^U `[(kz=  
//获得文件长度 Ixb=L(V  
//分割文件 q)LMm7  
//实例FileSplitterFetch :o0JY= 5  
//启动FileSplitterFetch线程 U 9_9l7&r  
//等待子线程返回 "+kL)]  
try{ fkuLj%R  
if(bFirst) z:8eEq3w  
{ 3h;{!
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nFileLength = getFileSize(); <sWprR  
if(nFileLength == -1) h1B? 8pD
 
{ qaiNz S@q  
System.err.println("File Length is not known!"); E
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} fol,xMc&  
else if(nFileLength == -2) tNO-e|~'  
{ HJLu'KY}  
System.err.println("File is not access!"); "'c A2~  
} X iS1\*  
else G,?hp>lj  
{ U{7w#>V .  
for(int i=0;i<nStartPos.length;i++) ~HTmO;HNf"  
{ xf<at->  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); Bp_$.!Qy  
} tjIl-IQ  
for(int i=0;i<nEndPos.length-1;i++) a|%J=k>>  
{ \w/yF4,3<w  
nEndPos = nStartPos[i+1]; `IP/d  
} +

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nEndPos[nEndPos.length-1] = nFileLength; +]*zlE\N`  
} ozmrw\_}[  
} UJD 0K]s  
[$qyF|/K`n  
v25R_""~  
//启动子线程 7|{}\w(I  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ;nep5!s;<  
for(int i=0;i<nStartPos.length;i++) &~8oQC-eF  
{ N >FKy'.gk  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), !TA

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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), <v)1<*I  
nStartPos,nEndPos,i); DK$X2B"cV  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); JLnH&(O  
fileSplitterFetch.start(); {K+icTL3  
} >"|B9Woc  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), %SX|o-B~.o  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); \n$u)Xj~6^  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", h]Wr [v  
nEndPos = " + nFileLength); 4lr(,nPRD  
// fileSplitterFetch[nPos.length-1].start(); I KqQ>Z-q~  
H\h3TdL  
< vL,*.zd  
//等待子线程结束 1;C+$  
//int count = 0; =Q+;=-1  
//是否结束while循环 @Ws*QTlV  
boolean breakWhile = false; n,jKmA  
hlV=qfc  
Z'4./  
while(!bStop) Wi*.TWz
3  
{ s%qF/70'  
write_nPos(); tX5"UQA  
Utility.sleep(500); wb]%m1H`:  
breakWhile = true; cv?06x{  
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n!NS(.o  
for(int i=0;i<nStartPos.length;i++) tXoWwQD;Y  
{ k[bD\'
  
if(!fileSplitterFetch.bDownOver) @JtM5qB  
{ JW{rA6?
 
breakWhile = false; q)Lu_6 mg  
break; 3Ndq>  
}  8cU}I4|  
} 
k,85Y$`'  
if(breakWhile) M.x=<:upp  
break; gnFr}L&j  
%
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`);AW(Q  
//count++; 6hlc1?  
//if(count>4) "Om=
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// siteStop(); a2dnbfSWa[  
} )[PtaPWeT  
8D>n1b(H  
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System.err.println("文件下载结束！"); W~zbm]  
} TOkp%@9/
 
catch(Exception e){e.printStackTrace ();} le1}0L  
} C69q&S,  
HW=C),*]cR  
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//获得文件长度 ^Y@\1fX 4e  
public long getFileSize() SLkhCR  
{ VRI0W`  
int nFileLength = -1; Jbjmv:db  
try{ j<Bkj/  
URL url = new URL(siteInfoBean.getSSiteURL()); )we}6sE"  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 6%t1bM a  
httpConnection.setRequestProperty("User-Agent","NetFox"); o<[#0T^K   
|_] Q$q[[%  
8kU!8^mH  
int responseCode=httpConnection.getResponseCode(); )CuZDf@  
if(responseCode>=400) { vKLAxc  
{ n&"B0ycF  
processErrorCode(responseCode); P,xKZ{(  
return -2; //-2 represent access is error q?4p)@#   
} -n=^U  
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String sHeader; uW30ep'  
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for(int i=1;;i++) :<hXH^n  
{ F@mQQ  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); r~/  
//Utility.log(in.readLine()); rf>0H^r  
sHeader=httpConnection.getHeaderFieldKey(i); -*$HddD  
if(sHeader!=null) L\@I*QP  
{ UJM1VAJ0  
if(sHeader.equals("Content-Length")) >+JqA7K  
{ n\xX},  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); eO?p*"p"F  
break; oXb;w@:  
} Fx;QU)1l3  
} )6q,>whI]  
else r[BVvX/,F  
break; l8I /0`_  
} q=%RDG+  
} 9;r)#3Q[^  
catch(IOException e){e.printStackTrace ();} [P&7i57  
catch(Exception e){e.printStackTrace ();} mS^tX i5hg  
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Utility.log(nFileLength);  f4Xk,1Is  
;D:9+E<>a  
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return nFileLength; EB2w0
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} |G?htZF  
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//保存下载信息（文件指针位置） 8n'B6hi  
private void write_nPos() :c8&N-`  
{ E^vJ@O  
try{ wN;^[F  
output = new DataOutputStream(new FileOutputStream(tmpFile)); .}OR  
output.writeInt(nStartPos.length); M}yDXJx  
for(int i=0;i<nStartPos.length;i++) r[4tPk  
{ M%ICdIc'  
// output.writeLong(nPos); ` :o4'CG  
output.writeLong(fileSplitterFetch.nStartPos); 77\]B  
output.writeLong(fileSplitterFetch.nEndPos); 8,C*4y~  
} y~q8pH1  
output.close(); lu<xv  
} 0`X]o'RxS  
catch(IOException e){e.printStackTrace ();} $,,op(  
catch(Exception e){e.printStackTrace ();} P*FMwrJj>r  
} IF44F3(V4  
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//读取保存的下载信息（文件指针位置） ~:Ll&29i  
private void read_nPos() j`~Ms>  
{ kQEy#JQmB  
try{ tasUZ#\6  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); BW 4%l  
int nCount = input.readInt(); ^; )8VP6  
nStartPos = new long[nCount]; @\f^0^G  
nEndPos = new long[nCount]; S/9DtXQ  
for(int i=0;i<nStartPos.length;i++) ,n3a gkPO>  
{ @cFJeOC|  
nStartPos = input.readLong(); czS+< w  
nEndPos = input.readLong(); S7/eS)SQR  
}  K i'Fn"  
input.close(); 5@+,Xh,H|t  
} X*{2[+<o  
catch(IOException e){e.printStackTrace ();} _$ +^q-  
catch(Exception e){e.printStackTrace ();} |4B:<x  
} "#{4d),r  
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private void processErrorCode(int nErrorCode) v7iuL6jl  
{ &e#~<Wm82  
System.err.println("Error Code : " + nErrorCode); Jl#%uU/sx  
} vb<oi&X  
Y8-86 *zC  
KG|n  
//停止文件下载 LR".pH13  
public void siteStop() }a/x._[s  
{ J&.{7YF  
bStop = true; L.S;J[a;  
for(int i=0;i<nStartPos.length;i++) " @v <Bk  
fileSplitterFetch.splitterStop(); xI($Uu}S  
/5Oa,NS7  
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} ki?S~'a  
} tjdaaN#,V  
//负责部分文件的抓取 ??M"6k  
**FileSplitterFetch.java ihIVUu-M  
*/ \=:~ki=@B  
package NetFox; )qo {c1X  
<vONmE a  
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import java.io.*; .QZaGw=,z  
import java.net.*; _qw?@478  
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public class FileSplitterFetch extends Thread { a&c6.#E{y  
+l9!Fl{MK\  
3?V_BUoON  
String sURL; //File URL H!5\v
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long nStartPos; //File Snippet Start Position nxWY7hU  
long nEndPos; //File Snippet End Position ]:Nsf|C0  
int nThreadID; //Thread's ID E\as@pqo\p  
boolean bDownOver = false; //Downing is over
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boolean bStop = false; //Stop identical 3%E }JU?MM  
FileAccessI fileAccessI = null; //File Access interface +a^nlW9g  
}o(zj=7  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException _AAaC_q  
{ !g5
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this.sURL = sURL; VUPXO  
this.nStartPos = nStart; "alyfyBu'M  
this.nEndPos = nEnd; p i %<Sy  
nThreadID = id; {^CY..3 A  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 G6/p1xy>o:  
} |iE50,  
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public void run() ==3dEJS  
{ Tn*9lj4  
while(nStartPos < nEndPos && !bStop) >qS9PX  
{ 5-aj2>=7  
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try{ pEBM3r!X  
URL url = new URL(sURL); (tIo:j  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); gy#/D& N[  
httpConnection.setRequestProperty("User-Agent","NetFox"); 3RYpJAH  
String sProperty = "bytes="+nStartPos+"-"; OBOtuu.  
httpConnection.setRequestProperty("RANGE",sProperty); p"n$!ilbm  
Utility.log(sProperty); ,z;cbsV-{  
]P.'>4  
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InputStream input = httpConnection.getInputStream(); W+UfGk}A  
//logResponseHead(httpConnection); 6-z%633DL  
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byte[] b = new byte[1024]; LhOa{1SY  
int nRead; M+U9R@  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) Sdt`i  
{ 6$kqa
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nStartPos += fileAccessI.write(b,0,nRead); qU%/W|LY  
//if(nThreadID == 1) NidIVbT.A  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 3Dng1}  
} oW ::h
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7 n8"/0kc:  
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Utility.log("Thread " + nThreadID + " is over!"); U>]$a71  
bDownOver = true; _I@9HC 4  
//nPos = fileAccessI.write (b,0,nRead); Fv~20G(O  
} <0b)YJb4M  
catch(Exception e){e.printStackTrace ();} c~z82iXNO  
} l`oZ)?ur  
} )bS yB29S  
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//打印回应的头信息 f .Q\Z'S^  
public void logResponseHead(HttpURLConnection con) j[`j9mM8  
{ n^Hm;BiE#  
for(int i=1;;i++) NQBpX  
{ &e @2  
String header=con.getHeaderFieldKey(i); hs^zTZ_  
if(header!=null) tSr8 zAV  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); B2
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Utility.log(header+" : "+con.getHeaderField(header)); ;LcZ`1  
else 3EJj9}#x"'  
break; G<}()+L  
} U{2BVqM  
} J!c)s!`w  
$xzAv{  
#.rdQ,)<  
public void splitterStop() b*a#<K$T_  
{ yA)/Q Yge  
bStop = true; \pPY37l  
} X <f8,n
 
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} zr-*$1eu  
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/* iW$_zgN  
**FileAccess.java d' !]ZWe  
*//文件访问(定位，写) &XIt5<$~R  
package NetFox; E{XH?_xo  
import java.io.*; 3@kf@Vf  
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6a[}'/  
public class FileAccessI implements Serializable{ |:nn>E}ZA/  
cz >V8  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 /)YNs7gR  
RandomAccessFile oSavedFile; 2;k*@k-t  
long nPos; NCiW^#b  
*Fy2BZH%Q  
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public FileAccessI() throws IOException a!a-b~#cx  
{ T-
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this("",0); z>LUH  
} /Lfm&;  
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public FileAccessI(String sName,long nPos) throws IOException r(:5kC8K  
{ wo4;n9@I  
oSavedFile = new RandomAccessFile(sName,"rw"); h{%nC>m;  
this.nPos = nPos; 3x`|  
oSavedFile.seek(nPos); "
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} umjt]Gu[  
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]] !VK  
public synchronized int write(byte[] b,int nStart,int nLen) ). <-X^@  
{ qraSRK5  
int n = -1; WffQ:L?  
try{ &-;4.op  
oSavedFile.write(b,nStart,nLen); zNs55e.rx  
n = nLen; xcd#&  
} S=MEG+Ad  
catch(IOException e) ?:vv50  
{ yQU{zY  
e.printStackTrace (); .CL[_;}  
} QA< Rhv,  
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return n; \K5DOM "#  
} nL5cK:  
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} 5&QJ7B,!  
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/* o*b] p-  
**SiteInfoBean.java SON-Z
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*/ +NeOSQSj  
package NetFox; (uXL^oja  
vq0Vq(V=  
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public class SiteInfoBean { 'H3^e}   
@ju@WY45$^  
rNrxaRQ  
private String sSiteURL; //Site's URL RmI]1S_=  
private String sFilePath; //Saved File's Path <lgYcdJ   
private String sFileName; //Saved File's Name 2a-w% (K  
private int nSplitter; //Count of Splited Downloading File )Lk639r  
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public SiteInfoBean() UxbjA- U[  
{//nSplitter的缺省值为5 6@Y_*4$|  
//default value of nSplitter is 5 8hu<E4]L  
this("","","",5); Dl<bnx;0  
} l}a)ZeR1  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) s(5Y  
{ ]GMe\n  
sSiteURL= sURL; n D0K).=Q  
sFilePath = sPath; *M[?bk~~  
sFileName = sName; aI%g2q0f  
this.nSplitter = nSpiltter; 9eGyyZg  
4qO+_!x{)  
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} ot,jp|N>f~  
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public String getSSiteURL() ?}Z1bH  
{ q]\:P.x!>
 
return sSiteURL; fX(3H1$"  
} {'NZ.  
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public void setSSiteURL(String value) BHIRHmM<Y  
{ Lco~,OE  
sSiteURL = value; ~d o9;8v  
} TCN8a/@z  
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public String getSFilePath() ZXu>,Jy  
{ e|NG"
<  
return sFilePath; L(/e&J@><  
} /1Qr#OJ(]  
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public void setSFilePath(String value) NiNM{[3oS  
{ p?{Xu4(  
sFilePath = value; .sx
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} O)C\vF#  
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public String getSFileName() H~oail{EQ  
{ xj<Rp|7&  
return sFileName; Um}  
} 2n,*Nd`  
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public void setSFileName(String value) OtY`@\hy  
{ kj|6iG  
sFileName = value; P!~MZ+7#&  
} Kc!}`Pm  
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!!qK=V|>  
public int getNSplitter() Vmc5IPd{\  
{ Rh3eLt~|(  
return nSplitter; }elc `jj  
} HpR]q05d  
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public void setNSplitter(int nCount) _f
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{ R]Vt Y7}i,  
nSplitter = nCount; G !<Z.]  
} =Ee&da^MB  
} ~{?_p@&n  
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/* 2{M^,=^>  
**Utility.java A]y`7jJ  
*/ T\:4qETQF]  
package NetFox; 7@C<oy_bb  
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public class Utility { iF*:d  
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public Utility() d]`CxI]  
{ \/E>4)MDy  
B*
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Pih tf4
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} lNNv|YiL  
sD<a+Lw}x  
//线程睡眠 uvg
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public static void sleep(int nSecond) iz5CAxm  
{ '#! gh?  
try{ {Z{75}  
Thread.sleep(nSecond); TH)"wNa  
} hrmut*<|  
catch(Exception e) yhlFFbU  
{ OL5v).Bb  
e.printStackTrace (); T} `x-  
} y@]_+2Vo  
} wWgWWXGT}  
9K/HO!z  
//日志 m2-Sx  
public static void log(String sMsg) =Xm@YVf&ZD  
{ (As#^q\>B  
System.err.println(sMsg); k[0-CB  
} (VS5V31"  
?xK8#  
1m+p;T$  
public static void log(int sMsg) X"MB|Ny  
{ fz;iOjr>  
System.err.println(sMsg); 
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} BW-`t-,E;  
} tv>>l%  
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dL:-Y.?0M  
/* 85lCj-cs  
**TestMethod.java M=.:,wRm  
*/ QpZ:gM_  
package NetFox; :d3bt~b'  
~7Y+2FZ  
V=)_yIS  
public class TestMethod { jNe`;o  
8m5p_\&  
P D4Tz!F  
public TestMethod() NIh:DbE  
{ ///xx/weblogic60b2_win.exe hZ[E7=NTQ^  
try{ -7m:91x  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); !GOM5z,  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); e}mD]O}  
SiteFileFetch fileFetch = new SiteFileFetch(bean); U0=]  
fileFetch.start(); U93}-){m  
} ygOd69  
catch(Exception e){e.printStackTrace ();} l;af~ef)'  
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FE" y\2}  
} - *F(7$  
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 R=.4  
public static void main(String[] args) S2n39 3  
{ yPM3a7-Bm  
new TestMethod(); ]FD'5
p{  
} t'9*R7=  
}
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