http断点续传简单实现（java)

/* ;b_<5S  
**SiteFileFetch.java u(`7F(R  
*/ ]Rmu+N|  
package NetFox; X{h[   
import java.io.*; qJXfc||Zg  
import java.net.*; +]Z*_?j9{  
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public class SiteFileFetch extends Thread { v6T<K)S  
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SiteInfoBean siteInfoBean = null; //文件信息Bean f>?b2a2HX  
long[] nStartPos; //开始位置 ^4{{ +G)j  
long[] nEndPos; //结束位置 OoZv\"}!_  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 eHyIFoaC/  
long nFileLength; //文件长度 \@6V{y'Zo  
boolean bFirst = true; //是否第一次取文件 C{V,=Fo^  
boolean bStop = false; //停止标志 p
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File tmpFile; //文件下载的临时信息 }7qboUGe  
DataOutputStream output; //输出到文件的输出流 \F7NuG:m,  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） H.[(`wi!I  
public SiteFileFetch(SiteInfoBean bean) throws IOException pJQ_G`E  
{ df$pT?o  
siteInfoBean = bean; \T;(k?28HN  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); :&s8G*  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ]TsmWob  
if(tmpFile.exists ()) `O?j -zR  
{ W{kTM4  
bFirst = false; c>#3{}X|x%  
read_nPos(); 1EliR uJ  
} >V&GL{  
else <?!%dV{z  
{ z,SNJIsx  
nStartPos = new long[bean.getNSplitter()]; IXR%IggJA  
nEndPos = new long[bean.getNSplitter()]; jZqCM{  
} \YH*x`  
}y%mG&KSz  
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} \Iz-<:gA'  
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public void run() QU@CPME  
{ NcIr; }  
//获得文件长度 k,r}X:<6jz  
//分割文件 ZgxpH
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//实例FileSplitterFetch HB}iT1.`  
//启动FileSplitterFetch线程 )79F"ltzh  
//等待子线程返回 "u"?~  
try{ tLGNYW!K  
if(bFirst) YA8ZB&]En/  
{ Qmj%otSg  
nFileLength = getFileSize();  '5P
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if(nFileLength == -1) +Ui%}^ZZ  
{ Mbtk:Gu
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System.err.println("File Length is not known!"); ~fz9PoC  
} m=MM  
else if(nFileLength == -2) z*/}rk4i  
{ f5#VU7=1F2  
System.err.println("File is not access!"); ^<Sy{KY  
} t\-;n:p-  
else [}"m4+  
{ XJ?zP=UK  
for(int i=0;i<nStartPos.length;i++) =o4McV}  
{ hDTM\>.c;s  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); <A] Kg  
} nD{{/_"'  
for(int i=0;i<nEndPos.length-1;i++) ]Q{MF- EKj  
{ 51!#m|  
nEndPos = nStartPos[i+1]; <+ckE2j  
} oD%B'{Zs4  
nEndPos[nEndPos.length-1] = nFileLength; ;VgB!  
} /6#i$\ j  
} =UZm4=T  
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//启动子线程 o 0H.DeP  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; hKN/&P^  
for(int i=0;i<nStartPos.length;i++) ajD/)9S
 
{ VOrBN
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fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ?qczMck_  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), |Q#CQz  
nStartPos,nEndPos,i); 6b h.5|  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); e|.a%,Dcy  
fileSplitterFetch.start(); +Pb@@C&  
} l gTw>r   
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Yr 1k\q  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1);
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// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", bU_P@GKB  
nEndPos = " + nFileLength); Hr=?_Un"  
// fileSplitterFetch[nPos.length-1].start(); x7c#kU2A&Z  
IlMst16q5  
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//等待子线程结束 G8OnNI  
//int count = 0; pt9fOih[  
//是否结束while循环 cu"ge]},  
boolean breakWhile = false; Wvwjj~HP2}  
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vO
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while(!bStop) )<^G]a
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{ gqACIXR  
write_nPos(); 3qwSm<  
Utility.sleep(500); wWB^m@:4  
breakWhile = true; Xe<kd
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sm;\;MP*yH  
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for(int i=0;i<nStartPos.length;i++) *uvE`4V^Jg  
{ ]0myoWpi3  
if(!fileSplitterFetch.bDownOver) !+ ??3-q  
{ :.W</o~\s  
breakWhile = false; 2M?L++i  
break; +ZPn[|  
} >SHW  
} hbTJXP~~?  
if(breakWhile) fBct%M 3  
break; Y j*Y*LB~  
v^(J+d_>   
)W3kBDD  
//count++; 
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//if(count>4) =-n7/  
// siteStop(); 8POLp9>X  
} ,\0>d}eh!  
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System.err.println("文件下载结束！"); zirnur1  
} #^bn~  
catch(Exception e){e.printStackTrace ();} 2p8}6y:}7  
} Oftjm X_  
8DZ OPA  
h>&t
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//获得文件长度 "AHuq%j  
public long getFileSize() 'Rw*WK  
{ ? -`8w _3  
int nFileLength = -1; y_f^ dIK*=  
try{ m7m)BX%O  
URL url = new URL(siteInfoBean.getSSiteURL()); p
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); .oxeo0@~  
httpConnection.setRequestProperty("User-Agent","NetFox"); 9l:vVp7Uk  
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int responseCode=httpConnection.getResponseCode(); 4F?O5&329i  
if(responseCode>=400) 6yXMre)YV  
{ Mg=R**s1x%  
processErrorCode(responseCode); GQ=Pkko  
return -2; //-2 represent access is error 8Z(\iZ5Rgj  
} ~`o%Y"p%rv  
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String sHeader; E#mp
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for(int i=1;;i++) xX2/uxi8  
{ F}=O Mo:.  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); s,;L6nX"  
//Utility.log(in.readLine()); WEk3 4crk  
sHeader=httpConnection.getHeaderFieldKey(i); R(<_p"9(  
if(sHeader!=null) 6gJc?+  
{ gL6.,4q+1  
if(sHeader.equals("Content-Length")) !eGUiE=  
{ Ihg1%.^V\  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); .*g^ 
i`  
break; *|&&3&7  
} .Sjg  
} WO"<s{v  
else V?o%0
V  
break; h9WyQl7  
} L$ ZZ]?7j  
} %2EHYBQjN  
catch(IOException e){e.printStackTrace ();} LFPYnK  
catch(Exception e){e.printStackTrace ();} 1agI/R  
t Ai?Bjo  
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Utility.log(nFileLength); .+dego
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}R2afTn[;  
return nFileLength; H(F9&6}  
} &=hkB9 ;  
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//保存下载信息（文件指针位置） $z'_Hr'  
private void write_nPos() :,Ad1(  
{ L|K^w *\C  
try{ 9:]|TIPi  
output = new DataOutputStream(new FileOutputStream(tmpFile)); _$BH.I  
output.writeInt(nStartPos.length); Ej/P:nB  
for(int i=0;i<nStartPos.length;i++) "c0Nv8_G  
{ ]{PJ  
// output.writeLong(nPos); H5?H{  
output.writeLong(fileSplitterFetch.nStartPos); \:`-"Ou(*  
output.writeLong(fileSplitterFetch.nEndPos); x]<0Kq9K  
} L<H6AzR+  
output.close(); EGJrnz8  
} I<LIw8LI  
catch(IOException e){e.printStackTrace ();} $%0A#&DVh  
catch(Exception e){e.printStackTrace ();} <+)B8I^  
} DYaOlT(rE  
|n+ `t?L^  
$JZ}=\n7  
//读取保存的下载信息（文件指针位置） !t+eJj  
private void read_nPos() RL~]mI!U  
{ 6SN$El 0|G  
try{ :dj=kuUTbu  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); gtw?u b  
int nCount = input.readInt(); e? n8S  
nStartPos = new long[nCount]; &<oDl_^  
nEndPos = new long[nCount]; #i0f}&
 
for(int i=0;i<nStartPos.length;i++) a&s&6Q|Y  
{ Q!v]njCIB7  
nStartPos = input.readLong(); Xe>   
nEndPos = input.readLong(); EK<ly"S.  
} _/)HAw?k  
input.close();  _V_GdQ  
} F@u>5e^6  
catch(IOException e){e.printStackTrace ();} }@Ou]o  
catch(Exception e){e.printStackTrace ();} <CY<-H  
} Nkg^;-CV0  
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private void processErrorCode(int nErrorCode) Y5$VWUrB  
{ cHk ?$  
System.err.println("Error Code : " + nErrorCode); c$52b4=a  
} 40R7@Vaf  
71!'k>]h  
7)37AKw  
//停止文件下载 S7WT`2  
public void siteStop() $J)2E g  
{ O>kM2xw  
bStop = true; x|q|> dPB  
for(int i=0;i<nStartPos.length;i++) T~b6Zu6  
fileSplitterFetch.splitterStop(); ~k780  
%P`w"H,v3#  
|&0zAP"\  
} =%oQIx  
} T@\%h8@~]  
//负责部分文件的抓取 I18<brZJ  
**FileSplitterFetch.java 9Jj:d)E>o  
*/ i
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package NetFox; ".Sa[A;~  
1]]#HTwX  
m.
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import java.io.*; El4SL'E@  
import java.net.*; i.G"21M  
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public class FileSplitterFetch extends Thread { I2^Eo5'  
*ci%c^}V  
dtd}P~  
String sURL; //File URL 5;Q9Z1 `  
long nStartPos; //File Snippet Start Position (|U|>@  
long nEndPos; //File Snippet End Position |tqYRWn0  
int nThreadID; //Thread's ID dPCn6  
boolean bDownOver = false; //Downing is over bbxo!K m"  
boolean bStop = false; //Stop identical J\c\
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FileAccessI fileAccessI = null; //File Access interface 2!;U.+(  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException SQJ }$#=  
{ k~HS_b*]d  
this.sURL = sURL; gtlyQ _V  
this.nStartPos = nStart;  - j_  
this.nEndPos = nEnd; 7o4B1YD  
nThreadID = id; pA?2UZ  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 w~l%xiC  
} @]xHt&j  
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public void run() MZK%IC>  
{ _W^{,*p  
while(nStartPos < nEndPos && !bStop) 0;avWa)Q  
{
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try{ `;\~$^sj}  
URL url = new URL(sURL); ]0@ 06G(y  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); lz88//@gZ  
httpConnection.setRequestProperty("User-Agent","NetFox"); fs;pX/:FR  
String sProperty = "bytes="+nStartPos+"-"; 4NxI:d$&*  
httpConnection.setRequestProperty("RANGE",sProperty); a<d$P*I(cH  
Utility.log(sProperty); n06Jg+  
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6BIr{SY  
InputStream input = httpConnection.getInputStream(); =%ZR0cWPoI  
//logResponseHead(httpConnection); 9G=H
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byte[] b = new byte[1024]; 85 <%L:EC  
int nRead; MMS#Ci=Lj  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) |+r5D4]e  
{ [&h%T;!Qii  
nStartPos += fileAccessI.write(b,0,nRead); g&`[r6B  
//if(nThreadID == 1) :elTqw>pn  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); kQQhZ8Ch  
} /Vy,6:$H3  
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Utility.log("Thread " + nThreadID + " is over!"); h(M
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bDownOver = true; v7@O ,%  
//nPos = fileAccessI.write (b,0,nRead); @1^:V-=  
} IM$I=5ye  
catch(Exception e){e.printStackTrace ();}
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} }j6<S-s~  
} )*T<s  
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//打印回应的头信息 2E_*'RT  
public void logResponseHead(HttpURLConnection con) DX#_0-o  
{ G;Thz  
for(int i=1;;i++) >C
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{ /{HK0fd  
String header=con.getHeaderFieldKey(i); >J>|+W  
if(header!=null) F|{F'UXj|  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 1H]E:Bq  
Utility.log(header+" : "+con.getHeaderField(header)); B#Z-kFn@  
else ]n$&|@  
break; 9_I#{?  
} QLum=YB  
} ![CF >:e  
! tPHT  
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public void splitterStop() gt{$G|bi  
{ ``* !b>)  
bStop = true; -e(,>9Q  
} 6>
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} 6kM'f}t[C  
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/* c3G&)gU4q  
**FileAccess.java ?2$0
aq  
*//文件访问(定位，写) j~VHU89  
package NetFox; `.F+T)
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import java.io.*; SdOE^_@:  
U)y~{E~c34  
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public class FileAccessI implements Serializable{ rm nfyn  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 Zk#?.z}  
RandomAccessFile oSavedFile; >HlQ+bl$xw  
long nPos; ;?'=*+'>  
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public FileAccessI() throws IOException j~:N8(=  
{ lM'yj}:~  
this("",0); RFzMah?Q=j  
} HG)c\b  
$,L,VYN  
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public FileAccessI(String sName,long nPos) throws IOException V|mz]H#|  
{ .7Lv  
oSavedFile = new RandomAccessFile(sName,"rw"); n`af2I2  
this.nPos = nPos; gdVajOAu  
oSavedFile.seek(nPos); GtNGrJU  
} cgvD>V
Uw  
6q]`??g.  
KIfR4,=Q|  
public synchronized int write(byte[] b,int nStart,int nLen) [H8QxJk  
{ I}{Xv#@o  
int n = -1; p-1 \4  
try{ #w:6<$  
oSavedFile.write(b,nStart,nLen); [d~25  
n = nLen;  T24?1  
} J4;Fk  
catch(IOException e) #m<<]L(o8W  
{ (!9ybH;T  
e.printStackTrace (); 0;pOQF  
} z`Cq,Sz/  
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return n; en6oFPG  
} <dA1n:3o  
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} b!ea(D!:  
6bW:&IPQ;  
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/* @JL+xfz  
**SiteInfoBean.java Q4JvFy0'  
*/ &^W91C?<6  
package NetFox; {Z=m5Dy}  
Cw_XLMY%V1  
(~<9\ZJs  
public class SiteInfoBean { / NlT[@T  
aj:B+}1  
&@MiR8  
private String sSiteURL; //Site's URL c#6g[TE@  
private String sFilePath; //Saved File's Path *1[v08?!  
private String sFileName; //Saved File's Name G$"$k=[  
private int nSplitter; //Count of Splited Downloading File '!6Py1i  
L)LW5%.6  
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public SiteInfoBean() 'l}T_7g  
{//nSplitter的缺省值为5
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//default value of nSplitter is 5  `=h`:`  
this("","","",5); _@47h86Q  
} $"/xi `  
3+EAMn  
bf3Njma%  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) UHEn+Tc>  
{ r6Hdp  
sSiteURL= sURL; S^Z[w|1  
sFilePath = sPath; %EooGHGF?  
sFileName = sName; ~KufSt*  
this.nSplitter = nSpiltter; .#] V5g,  
R""P01IZH  
V~uH)IMkh7  
} ]$>O--  
i:ZL0nH-  
jB17]OCN  
public String getSSiteURL() H-sJt:  
{ %dMP}k/  
return sSiteURL; #iOoi9(  
} BF_R8H,<%  
RG)!v6
  
-H3tBEvoI  
public void setSSiteURL(String value) (,gpR4O[  
{ >*PZ&"}M  
sSiteURL = value; \+cU}  
} x)SW1U3TVx  
G Uf[Dz  
(1pxQ%yEA  
public String getSFilePath() UtF8T6PKdW  
{ 7X$[E*kd  
return sFilePath; @k
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} oT4A|M  
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public void setSFilePath(String value) 0z2A!ap  
{ p. eq N  
sFilePath = value; Y?(kE` R  
} K{}U[@_tS  
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ERO'{nT&  
public String getSFileName() swBgV,;  
{ :3s5{s  
return sFileName; cViEvS r  
} Vs-])Q?7J  
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public void setSFileName(String value) xm}9(EJ  
{ b3G4cO;t;  
sFileName = value; (3DjFT3 w  
} Lbka*@  
I
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public int getNSplitter() lw4#xH-?  
{ hlpi-oW`  
return nSplitter; iyF~:[8  
} mTcopyp  
bqHR~4 #IR  
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public void setNSplitter(int nCount) FC:Z9{2!  
{ |0A"3w  
nSplitter = nCount; G[}$s7@k  
} +rw?k/  
} HJVi:;o  
[*<F   
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/* 2NHkK_B1P  
**Utility.java M^c`j#NQ  
*/ U{vt9t  
package NetFox; g]IRv(gDh  
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}Fd4; ]  
public class Utility { tiZ5 :^$b4  
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jN\} l|;q  
public Utility() /DG+8u  
{ >hkmL](^  
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raL!}  
} =.=4P~T&  
V _(L/6  
//线程睡眠 WoVPp*zlX  
public static void sleep(int nSecond) M ABrf`<b  
{ eI8rnp(Ia  
try{
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Thread.sleep(nSecond); '->%b  
} _g|zDi^  
catch(Exception e) WaY_{
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{ yrp5\k*{y  
e.printStackTrace (); hk =nXv2M  
} D#ZzhHHP  
} ;GW[Yw>Rz  
i6L>,^Dg  
//日志 `nAR/Ye  
public static void log(String sMsg) ;JM%O8  
{ b&AGVW
hh  
System.err.println(sMsg);  `mar-r_m  
} <L4.*  
^I=W<  
;D}8acQ  
public static void log(int sMsg) {MP8B'r-6  
{ lSGtbSyDI  
System.err.println(sMsg); toDv~v  
} 3uSj5+@q6  
} td*1  
i3bH^WwE&k  
?b?6/_W~R  
/* ({XB,Rm  
**TestMethod.java h<)YZ
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*/ PtH>I,/  
package NetFox; f{ ;L"*L  
,$"*X-1  
=Q\z*.5j.  
public class TestMethod { Rra3)i`
*  
%49P<vo`?  
%w+"MkH _  
public TestMethod() c/:d$o-  
{ ///xx/weblogic60b2_win.exe ;DQ{6(  
try{ W7bA#p(  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); n}KF)W=  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); &I8Q'  
SiteFileFetch fileFetch = new SiteFileFetch(bean); :<
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fileFetch.start(); RO>3U2  
} uY{zZ4iw  
catch(Exception e){e.printStackTrace ();} }BTK+Tk8  
0;Lt  
,8=`Y9#  
} /WvF}y  
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public static void main(String[] args) iLQFce7d|&  
{ L#t^:%  
new TestMethod(); 0:NCIsIm<  
} RKIBFP8.  
} &hTe-Es  
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