http断点续传简单实现（java)

/* HP|,AmVLl  
**SiteFileFetch.java p9R`hgx  
*/ ]n?a h  
package NetFox;  wJ!  
import java.io.*; S$W *i@x?  
import java.net.*; RL~|Kr<7J  
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public class SiteFileFetch extends Thread { j^KM  
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SiteInfoBean siteInfoBean = null; //文件信息Bean .6!]RA5!=  
long[] nStartPos; //开始位置 J&^r}6D  
long[] nEndPos; //结束位置 :eS7"EG{3  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 FePJ8  
long nFileLength; //文件长度 O8SX#,3^}  
boolean bFirst = true; //是否第一次取文件 8>j+xbw  
boolean bStop = false; //停止标志 ]w%7/N0R  
File tmpFile; //文件下载的临时信息 c}Jy'F7&f  
DataOutputStream output; //输出到文件的输出流 Gcg`Knr  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） \^EjE  
public SiteFileFetch(SiteInfoBean bean) throws IOException 0LoA-c<Ay  
{ M7yJ2u<Ty  
siteInfoBean = bean; meR%);\  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); v|_?qBs"  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); l,h
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if(tmpFile.exists ()) 2t1WbP1  
{ v0X5`VV  
bFirst = false; IaE};8a8  
read_nPos(); OW)8Z60  
} +<:p`%  
else gb@Rx  
{ \yb^%$hZ0  
nStartPos = new long[bean.getNSplitter()]; +x G]
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nEndPos = new long[bean.getNSplitter()]; GY,@jp|R  
} 0VoC|,$U  
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} `]5XY8^kI  
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public void run() 9foQ0#R  
{ g%j z,|  
//获得文件长度 4}580mBc  
//分割文件 f:7Y  
//实例FileSplitterFetch ;}f%bE  
//启动FileSplitterFetch线程 -2> L*"^  
//等待子线程返回 cWFvYF  
try{ (4ow0}1  
if(bFirst) %Tsefs?_  
{ FD|R4 V*3  
nFileLength = getFileSize(); 'P@
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if(nFileLength == -1) n$`Nx\v  
{ 'ZT!a]4  
System.err.println("File Length is not known!"); dq:M!F  
} .%->  
else if(nFileLength == -2) NXeo&+F  
{ V$q%=Sip  
System.err.println("File is not access!"); U{>!`RN  
} >ID 3oi
  
else 5`x9+XvoN  
{ A ,LAA$  
for(int i=0;i<nStartPos.length;i++) C+5^[V  
{ 2"<}9A<Xs  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); uO[4 WZ  
} W\} VZY  
for(int i=0;i<nEndPos.length-1;i++) xR#hU;E}  
{ aE,x>I 7 D  
nEndPos = nStartPos[i+1]; /f%u_ 8pV%  
} P]y2W#Rs  
nEndPos[nEndPos.length-1] = nFileLength; 9D<^)ShY  
} s\7|b:y&  
} F,:F9r?l,H  
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//启动子线程 a$aI%  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; SI;G|uO;/  
for(int i=0;i<nStartPos.length;i++) ~PlwPvWo  
{ 5I&^n0h|&  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Iu1P}R>C  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 9s*Lzi[}  
nStartPos,nEndPos,i); E\V>3rse  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ni%^w(J3Q  
fileSplitterFetch.start(); X/7: *  
} cK-!Evv  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 1>1|>%  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); {'!D2y.7g  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", Do_L  
nEndPos = " + nFileLength); ^f`#8G7(  
// fileSplitterFetch[nPos.length-1].start(); VwC,+B  
jC\R8_  
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//等待子线程结束 i"e)LJz  
//int count = 0; =<e
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//是否结束while循环 ZgXh[UHQy  
boolean breakWhile = false; H}U
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while(!bStop) xE6y9"}!h  
{ s?`)[K'-  
write_nPos(); /`s^.Xh  
Utility.sleep(500); P$pl  
breakWhile = true; P?0b-Qr$a  
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for(int i=0;i<nStartPos.length;i++) Sl$dXB@  
{ pp{);  
if(!fileSplitterFetch.bDownOver) U-lN_?  
{ "lz!'~im  
breakWhile = false; yTDoS|B+)  
break; "(C}Dn#  
} e<C5}#wt  
} n[iil$VKh  
if(breakWhile) 5;|9bWH  
break; oOUVU}H  
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5
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//count++; Me`"@{r|#  
//if(count>4) *|=&MU*+  
// siteStop(); r?[mn^Bo5  
} tICxAp:  
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System.err.println("文件下载结束！"); R]V`t^1  
} jr9ZRHCU  
catch(Exception e){e.printStackTrace ();} 72{kig9c  
} NK4ven7/  
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//获得文件长度 aIfog+Lp  
public long getFileSize()
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{ lo(Ht=d  
int nFileLength = -1; Fza)dJ7  
try{ ,\qo  
URL url = new URL(siteInfoBean.getSSiteURL()); Maxnk3n  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); l+N?:E$5=%  
httpConnection.setRequestProperty("User-Agent","NetFox"); =}q4ked/  
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int responseCode=httpConnection.getResponseCode(); 3] @<.  
if(responseCode>=400) RB\WttI  
{ 7}lZa~/  
processErrorCode(responseCode); NMj`wQ`M+  
return -2; //-2 represent access is error HOUyB's'  
} q?MYX=Y6  
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String sHeader; 9iOlR=-*  
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for(int i=1;;i++) MkYem6  
{ z44uhRh  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 21WqLgT3 4  
//Utility.log(in.readLine()); (dT!u8Oe  
sHeader=httpConnection.getHeaderFieldKey(i); nAX|=qp#  
if(sHeader!=null) pIrAGA;  
{ Zk/NO^1b  
if(sHeader.equals("Content-Length")) &6:,2W&s  
{ H\b5]q%  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); }3*h`(Bv7  
break; .*f;v4!  
} >3kR~:;  
} J`8>QMK^5  
else s<dD>SU  
break; @t2 Q5c  
} P0Jd6"sS"  
} $x)'_o}e  
catch(IOException e){e.printStackTrace ();} $e;!nI;z  
catch(Exception e){e.printStackTrace ();} *.+>ur?t  
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Utility.log(nFileLength); feopO j6~+  
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return nFileLength; (o:CxhV  
} ^GAdl
}  
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//保存下载信息（文件指针位置） Nb8<8O ^  
private void write_nPos() E*I

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{ dSL %%  
try{ S]o  
output = new DataOutputStream(new FileOutputStream(tmpFile)); #wd \&  
output.writeInt(nStartPos.length); .;F+ QP0  
for(int i=0;i<nStartPos.length;i++) N4v)0  
{ 2(rZ@Wl  
// output.writeLong(nPos); ]q3Kd{B  
output.writeLong(fileSplitterFetch.nStartPos); 7E5Dz7  
output.writeLong(fileSplitterFetch.nEndPos); T7T!v  
} [!q&r(-K  
output.close(); qB39\j  
} `%XgGHiE  
catch(IOException e){e.printStackTrace ();} ^kD?0Fm  
catch(Exception e){e.printStackTrace ();} ^VIUXa  
} VoyH:  
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//读取保存的下载信息（文件指针位置） u7C{
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private void read_nPos() 2%qn!+.  
{ Wu4Nq+  
try{ rO`g~>-  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); .apX72's,  
int nCount = input.readInt(); )f!dG(\&#  
nStartPos = new long[nCount]; '=~y'nPG7  
nEndPos = new long[nCount]; Z+dR(9otH3  
for(int i=0;i<nStartPos.length;i++) KVcZ@0[S  
{ CU;nrd"  
nStartPos = input.readLong(); PJYA5"}W  
nEndPos = input.readLong(); OT&E
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} M$W#Q\<*#r  
input.close(); w.Vynb  
} t(Zs*c(  
catch(IOException e){e.printStackTrace ();} Wi5|9  
catch(Exception e){e.printStackTrace ();} JAb?u.,Ns_  
} PM.SEzhm  
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private void processErrorCode(int nErrorCode) Riw7<j  
{ Q kZM(pG  
System.err.println("Error Code : " + nErrorCode); eE{L>u  
} 7 h1"8#X  
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//停止文件下载 :ky<`Jfr`  
public void siteStop() 9$,gTU_a  
{ Tb={g;0@  
bStop = true; M96( Rg  
for(int i=0;i<nStartPos.length;i++) 9i<-\w^$  
fileSplitterFetch.splitterStop(); _o?(t\B9{  
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} z;C=d(|nN  
} .lBY"W&{  
//负责部分文件的抓取 |3,V%>z  
**FileSplitterFetch.java |3s&Y`x-D  
*/ iW}l[g8sw!  
package NetFox; J=X% xb  
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import java.io.*; hcgc =$^  
import java.net.*; p},Fwbl  
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public class FileSplitterFetch extends Thread { e^NEj1  
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String sURL; //File URL klJ[ {p  
long nStartPos; //File Snippet Start Position F!&pENQ  
long nEndPos; //File Snippet End Position ~{vdP=/WP  
int nThreadID; //Thread's ID MgQU6O<  
boolean bDownOver = false; //Downing is over "-n%874IT  
boolean bStop = false; //Stop identical ~J-|,ZMd  
FileAccessI fileAccessI = null; //File Access interface 5; PXF  
b_jZL'en  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException &U~r}=  
{ !Gp3/<"Wy$  
this.sURL = sURL; _`_IUuj$E  
this.nStartPos = nStart; jN%p5nZ^EK  
this.nEndPos = nEnd; 7vaN&%;E%  
nThreadID = id;
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fileAccessI = new FileAccessI(sName,nStartPos);//定位 p$nK@t}  
} fHd!/%iG  
s!'A\nVV1$  
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public void run() %Sn6*\z  
{ :pDY  
while(nStartPos < nEndPos && !bStop) =/g$bZ  
{ Ydh<TF4!  
9V;$v  
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try{ A3$aMCwKd  
URL url = new URL(sURL); %Lp7@  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); _ML~c&9jv  
httpConnection.setRequestProperty("User-Agent","NetFox"); V<vPFxC  
String sProperty = "bytes="+nStartPos+"-"; >yBxa)  
httpConnection.setRequestProperty("RANGE",sProperty); +&7Kk9^  
Utility.log(sProperty); ,=Nw(GI  
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InputStream input = httpConnection.getInputStream(); v]T(zL|  
//logResponseHead(httpConnection); nF<y7XkO  
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byte[] b = new byte[1024]; )J+{oB[>b  
int nRead; %A62xnX  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 5eOj,[?  
{ BY*2yp}7  
nStartPos += fileAccessI.write(b,0,nRead); tP`G]BCbt  
//if(nThreadID == 1) QM ZUt  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); V[Rrst0yo  
} +l
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Utility.log("Thread " + nThreadID + " is over!"); Hs%QEvZl  
bDownOver = true; < m enABN4  
//nPos = fileAccessI.write (b,0,nRead); x_<bK$OU  
} n#>.\F  
catch(Exception e){e.printStackTrace ();} vK6ibl0  
} qB F!b0lr  
} >7nV$.5S  
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//打印回应的头信息 7-d}pgVK  
public void logResponseHead(HttpURLConnection con) {OO*iZ.O  
{ ov`^o25f  
for(int i=1;;i++) ?+n&hHRg  
{ qByNHo7Tb  
String header=con.getHeaderFieldKey(i); 5@czK*5  
if(header!=null) )@]6=*%  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ]
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Utility.log(header+" : "+con.getHeaderField(header)); $_RWd#Q(  
else GsIwY {d  
break; DB`$Ru@  
} tL~,ZCQz  
} E-)VPZ1D  
]
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public void splitterStop() _ktK+8*6`  
{ zb;(?!Bd#  
bStop = true; Q(|PZng  
} o
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} Qj(vBo?D  
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/* DS:>/m>)  
**FileAccess.java uu}`warW  
*//文件访问(定位，写) JF~1'"_f:  
package NetFox; &yxNvyA[u  
import java.io.*; AH2_#\  
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public class FileAccessI implements Serializable{ %G;0T
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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
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RandomAccessFile oSavedFile; BBHK  
long nPos; sm 's-gD  
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public FileAccessI() throws IOException GE1i+.+-.  
{ /g_9m  
this("",0); %#~((m1  
} n*4lz^LR  
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public FileAccessI(String sName,long nPos) throws IOException bIgh@= 2  
{ P$Z}  
oSavedFile = new RandomAccessFile(sName,"rw"); z]kwRWe`j  
this.nPos = nPos; Y3-gUX*w0  
oSavedFile.seek(nPos); lVPOYl%
 
} iI5+P`sE&J  
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public synchronized int write(byte[] b,int nStart,int nLen) &V'519vmoZ  
{ t3PtKgP-6  
int n = -1; 7vn%kW=$  
try{ ~C&*.ZR  
oSavedFile.write(b,nStart,nLen); 9O;cJ)tXY  
n = nLen; qG<7hr@x]  
} t\h$&[[l'z  
catch(IOException e) pSHSgd~&  
{ #j;Tb2&w  
e.printStackTrace (); |% z^N*  
} X1+wX`f  
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return n; ~+yZfOcw  
} _V@WNo%B  
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} @@I7$*  
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/* xJ{_qP  
**SiteInfoBean.java vY6oVjM  
*/ v??TJ^1  
package NetFox; ,LDm8   
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public class SiteInfoBean { vw2`:]Q+  
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private String sSiteURL; //Site's URL x2co>.
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private String sFilePath; //Saved File's Path 7BR8/4gcPu  
private String sFileName; //Saved File's Name cHx%Nd\  
private int nSplitter; //Count of Splited Downloading File JK]R*!{n  
h.)h@$d  
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public SiteInfoBean() j[I`\"  
{//nSplitter的缺省值为5 b_TS<,  
//default value of nSplitter is 5 98RKCc9h  
this("","","",5); ~@T<gA9V  
} IOL L1ar
 
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7p.>\YtoR}  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) ]1D%zKY%$Z  
{ }pVTTs`  
sSiteURL= sURL; F/p,j0S  
sFilePath = sPath; y%S1ZTScO  
sFileName = sName; .%}?b~   
this.nSplitter = nSpiltter; s,6`RI%  
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} |
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public String getSSiteURL() {ox2Tg?  
{ M*sR3SZ  
return sSiteURL; mMSh2B  
} \\06T`  
:w`3cwQ  
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public void setSSiteURL(String value) .~>?*}  
{ 7ER
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sSiteURL = value; K
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} ~ Vw9  
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public String getSFilePath() (@r `$5D.b  
{ iCj2"T4TN  
return sFilePath; MP^ d}FL  
} AH#4wPxF  
:XG;ru%i  
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public void setSFilePath(String value) [kV;[c}  
{ fpWg R4__  
sFilePath = value; oR .cSGh  
} b| M3`  
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public String getSFileName() :O-iykXyI  
{ WOLuw%
  
return sFileName; :i~W }r  
} eS+g|$c
W  
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public void setSFileName(String value)
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{ :#5xA?=* S  
sFileName = value; oVvc?P  
} 2S"Nf8>zp  
D&G"BZx|  

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public int getNSplitter() vI1i,x#i  
{ Ea6 &~"  
return nSplitter; tZyo`[
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} 0'5/K ,  
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public void setNSplitter(int nCount) N8to
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{ KLoE&ds  
nSplitter = nCount; JyLa#\ R  
} O.G'?m<:#  
} O.`Jl%  
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/* );V2?G`/  
**Utility.java S! Rc|6y%  
*/ uhyj5u)  
package NetFox; VhL{'w7f  
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({r*=wAP  
public class Utility { #LlUxHv #  
3_Cp%~Gi-_  
!Ucjax~  
public Utility() fhPkEvJ  
{ mw$r$C
{  
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r3E!dTDWq  
} FBx_c;)9Z  
/1N6X.Zb  
//线程睡眠 uvDzKMw~R  
public static void sleep(int nSecond) &QRE"_g  
{ Q;11N7+  
try{ +gd4\ZG  
Thread.sleep(nSecond); r={c,i  
} ho8`sh>N  
catch(Exception e) l^GP3S  
{ k.<]4iS  
e.printStackTrace (); $`ZzvZ'r  
} 32DbNEk  
} zgx&
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L`f^y;Y.  
//日志 K<?nq0-  
public static void log(String sMsg) o#) {1<0vg  
{ }En  
System.err.println(sMsg); !+>v[(OzM  
} T|J9cgtS  
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public static void log(int sMsg) O[tvR:Nh  
{ Q!- 0xlx  
System.err.println(sMsg); P-F)%T[  
} W} WI; cI  
} A.<H>=Z#O  
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/* r/
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**TestMethod.java Grs]d-xI  
*/ mxor1P#|  
package NetFox; x{D yTtX<  
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public class TestMethod { ^`un'5Vk  
8!.ojdyn  
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public TestMethod() V5+SWXZ  
{ ///xx/weblogic60b2_win.exe HhO".GA  
try{ oFOnjK"|F  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 5F`;yh+e  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); K
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SiteFileFetch fileFetch = new SiteFileFetch(bean); c/c$D;T  
fileFetch.start(); }Zl&]e
 
} 21k5I #U  
catch(Exception e){e.printStackTrace ();} r0p w_j  
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} 8DP+W$  
%$%&m1Y  
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public static void main(String[] args) +`3!I  
{ V_plq6z  
new TestMethod(); P[s8JDqu  
} +P.+_7+:  
} ^C2\`jLMY  
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