http断点续传简单实现（java)

/* XP Iu]F  
**SiteFileFetch.java ]|\>O5eeu  
*/ 3=eGS  
package NetFox; My43\p  
import java.io.*; xQ(KmP2hl  
import java.net.*; dpOL1rrE  
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public class SiteFileFetch extends Thread { H
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SiteInfoBean siteInfoBean = null; //文件信息Bean %RR|QY*  
long[] nStartPos; //开始位置 oqU#I~ -  
long[] nEndPos; //结束位置 -|iA!w#31  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 =S7C
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long nFileLength; //文件长度 EKJc)|8  
boolean bFirst = true; //是否第一次取文件 8~L.6c5U  
boolean bStop = false; //停止标志 =dw*B
 
File tmpFile; //文件下载的临时信息 ;@;
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DataOutputStream output; //输出到文件的输出流 W0,"V'C  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） Ia>th\_&  
public SiteFileFetch(SiteInfoBean bean) throws IOException 9!/1F !  
{ l`w|o  
siteInfoBean = bean; tS.b5$Q  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); DB?PS^-2  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); j9 &AMg  
if(tmpFile.exists ()) whp\*]8  
{ !gH.st  
bFirst = false; e+[J[<8  
read_nPos(); :^.87>V7  
} ,Z\,IRn  
else FYE9&{]h  
{ *V<2\-  
nStartPos = new long[bean.getNSplitter()]; 6'lT`E|  
nEndPos = new long[bean.getNSplitter()]; [q|Q]O0  
} #mFAl|O  
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} ,%DAh  
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public void run() B qi
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{ ]KPg=@Q/  
//获得文件长度 KVe'2Q<  
//分割文件 cLk+( dn  
//实例FileSplitterFetch Tee3U%Y  
//启动FileSplitterFetch线程 ^ cd5Zl  
//等待子线程返回 \\pyu]z  
try{ (Y@|h%1W  
if(bFirst) MM)/B>cQt  
{ ykl=KR  
nFileLength = getFileSize(); K{|dt W&  
if(nFileLength == -1) `Q_ R/9~  
{ HC, 0"W  
System.err.println("File Length is not known!"); @^jLYu|W  
} 4]Nr$FY  
else if(nFileLength == -2) 3ncvM>~g  
{ vM;dPE7  
System.err.println("File is not access!"); Dve5m=  
} T%#P??k  
else V<I${i$]0  
{ L|Gk}n  
for(int i=0;i<nStartPos.length;i++) / {bK*A!  
{ (ZR"O8  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); hl~F1"q)  
} 3 AF]en  
for(int i=0;i<nEndPos.length-1;i++) |>V>6%>vK6  
{ J0z0%p   
nEndPos = nStartPos[i+1]; 1s\hJATfz  
} xb_:9  
nEndPos[nEndPos.length-1] = nFileLength; DG FvRB  
} <^Nj~+G'  
} xE[tD? M{  
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//启动子线程 xR%a
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; )Ea_:
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for(int i=0;i<nStartPos.length;i++) M!i5StGC  
{ -H;y_^2  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), h>Pg:*N,(  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), $ T_EsnN  
nStartPos,nEndPos,i); u(a&x|WY
 
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 6?x{-Zj^?  
fileSplitterFetch.start(); vrDRSc6_  
} < tq9  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), -k{R<L  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); uk/+ i`=  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", DfFPGFv  
nEndPos = " + nFileLength); ]>i0;RME  
// fileSplitterFetch[nPos.length-1].start(); />7/S^  
2= mD  
vw6FvE`lC  
//等待子线程结束 #al^Uqd  
//int count = 0; #9"_|d=l  
//是否结束while循环 nx]b\A  
boolean breakWhile = false; R?Q-@N>wE  
?LFSR  
i(kK!7W35  
while(!bStop) <LZvh8  
{ mR@X
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write_nPos(); n?tAa|_  
Utility.sleep(500); ZEJadR  
breakWhile = true; D/`E!6Fk=  
K
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for(int i=0;i<nStartPos.length;i++) x)5v8kgf  
{ H)+kN'J  
if(!fileSplitterFetch.bDownOver) m%\[1|N  
{ JH;DVPX9z  
breakWhile = false; Q^Z}Y~.  
break; [SvwJIJJ  
} ]}l!L;  
} _q$fw&  
if(breakWhile) `roSOX1f  
break; Oei2,3l,?  
jG :R\D}0  
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//count++; 3dphS ^X  
//if(count>4) 7T Bo*-!  
// siteStop(); PSE|4{'  
} *xC '  
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System.err.println("文件下载结束！"); r8.v0b"1  
} :W.(,65c  
catch(Exception e){e.printStackTrace ();} :wAB"TCt0  
} 1w^[Eno$$  
^)pY2t<^  
+60;z4y}w  
//获得文件长度 .>&fwG  
public long getFileSize() [{*#cr f  
{ uoHhp4>^  
int nFileLength = -1; vsR ^aVwVZ  
try{ LeCU"~  
URL url = new URL(siteInfoBean.getSSiteURL()); U:e9Vq'N m  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); b2%[9)"I.  
httpConnection.setRequestProperty("User-Agent","NetFox"); KJfyh=AD(  
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int responseCode=httpConnection.getResponseCode(); mio'm  
if(responseCode>=400) XQ+hTtP  
{ -9"Ls?Cu  
processErrorCode(responseCode); (?[cDw/{J:  
return -2; //-2 represent access is error '3->G/Pu  
} )O Cr6UR  
|_*1/Wz@  
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String sHeader; Nj\WvKG  
IW
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for(int i=1;;i++) tPHiz%  
{ 4+gA/<  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); Wg1WY}zG  
//Utility.log(in.readLine()); Y<XDR:]A,  
sHeader=httpConnection.getHeaderFieldKey(i); |93%,  
if(sHeader!=null) wP9C\W;  
{ 91XHz14  
if(sHeader.equals("Content-Length")) '5--eYG  
{ 5KSsRq/8"  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); -(G2@NG  
break; !c7Od )]  
} D>Z_N?iR  
} QPEv@laM  
else BKEB,K=K@  
break; =Yk$Q\c
 
} 0*/~9n-Vl  
} z-j\S7F  
catch(IOException e){e.printStackTrace ();} `39U I7  
catch(Exception e){e.printStackTrace ();} O.dNhd$  
*79<ypKG$  
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Utility.log(nFileLength);
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return nFileLength; m.*+0NG  
} Q~kwUZ  
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//保存下载信息（文件指针位置） >Z%^|S9  
private void write_nPos() oSoG&4  
{ K\q/JuDfc  
try{ #a&Vx&7L  
output = new DataOutputStream(new FileOutputStream(tmpFile)); +!(hd  
output.writeInt(nStartPos.length); |7-tUHMo[  
for(int i=0;i<nStartPos.length;i++) HNPr| (  
{ ^ytd~iK8  
// output.writeLong(nPos); $j/F7.S  
output.writeLong(fileSplitterFetch.nStartPos); V1G]LM  
output.writeLong(fileSplitterFetch.nEndPos); !QovpO">z  
} )94R\f  
output.close(); r%m2$vx#  
} ln.~>FO  
catch(IOException e){e.printStackTrace ();} Mx }(w\\T  
catch(Exception e){e.printStackTrace ();} :Us-^zVr  
} Ow I?(ruL'  
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//读取保存的下载信息（文件指针位置） ".u?-xcbJ  
private void read_nPos() 9maw+c!~  
{ gyK"#-/_d  
try{ K*<n<;W  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 9=SZL~#CE  
int nCount = input.readInt(); L!Ro`6|7;  
nStartPos = new long[nCount]; D-.>Dw:  
nEndPos = new long[nCount]; O\w%E@9Fh  
for(int i=0;i<nStartPos.length;i++) 82vx:*Ip!}  
{ UgP5^3F2  
nStartPos = input.readLong(); i@RjG
 
nEndPos = input.readLong(); -1R~3j1_  
} SZPu"O\  
input.close(); tv2dyC&a  
} [Dhc9  
catch(IOException e){e.printStackTrace ();} SYL$?kl  
catch(Exception e){e.printStackTrace ();} UnPSJ]VW  
}  P/Zo  
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private void processErrorCode(int nErrorCode) OL>/FOH:Fx  
{ '54@-}D  
System.err.println("Error Code : " + nErrorCode); uFqH_04  
} BSz\9 eT  
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-=RXhE_{  
//停止文件下载 rtpjx%  
public void siteStop() &}FYz8w 2/  
{ gLH(Wr~(a  
bStop = true; z 4-wvn<*  
for(int i=0;i<nStartPos.length;i++) t^'1Ebg  
fileSplitterFetch.splitterStop(); [{ pc1U-  
J L3A/^  
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} 7mN?;X33  
} ft7wMi  
//负责部分文件的抓取 ZFzOW  
**FileSplitterFetch.java Nl+2m4  
*/ b?$3jOtW  
package NetFox; g#AA.@/Z  
~AO0(Lp  
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import java.io.*; (xTHin$  
import java.net.*; $Z j.  
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public class FileSplitterFetch extends Thread { LF0~H}S;6B  
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String sURL; //File URL 5HU>o|.  
long nStartPos; //File Snippet Start Position "*
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long nEndPos; //File Snippet End Position $=bN=hE  
int nThreadID; //Thread's ID f,1rmX1  
boolean bDownOver = false; //Downing is over 5Z:HCp-aG  
boolean bStop = false; //Stop identical >|s=l`"Xz  
FileAccessI fileAccessI = null; //File Access interface j@Dy
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException @dXf_2Tv=  
{ Cfj*[i4  
this.sURL = sURL; `{/=i|6  
this.nStartPos = nStart; z23KSPo  
this.nEndPos = nEnd; +k>v^sz  
nThreadID = id; 84{<]
y  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 N 8OPeY  
} __9673y  
8,R]R=  
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public void run() ,9rT|:N  
{
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while(nStartPos < nEndPos && !bStop) 'L,rJ =M3  
{ yZ 9 *oDs  
}PXWRv.gW  
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try{ YGHWO#!Gp  
URL url = new URL(sURL); Cn"N5(i  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); gk&?h7P"<  
httpConnection.setRequestProperty("User-Agent","NetFox"); *~vRbD$q  
String sProperty = "bytes="+nStartPos+"-"; 0Zq"-  
httpConnection.setRequestProperty("RANGE",sProperty); UJZa1p@L  
Utility.log(sProperty); _CZ*z  
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InputStream input = httpConnection.getInputStream(); ]
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//logResponseHead(httpConnection); k\
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byte[] b = new byte[1024]; <7zpHSFBq  
int nRead; V_~wWuZ-  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) l>G#+#{  
{ t.w?OyO  
nStartPos += fileAccessI.write(b,0,nRead); kA3kh`l  
//if(nThreadID == 1) O$$N{  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); '!0CwZ 7  
} jIl-}/2  
(=X16}n:>  
-P?} qy^j(  
Utility.log("Thread " + nThreadID + " is over!"); Z+}SM]m  
bDownOver = true; KGJB.<Be  
//nPos = fileAccessI.write (b,0,nRead); lz(9pz  
} wEp/bR1=  
catch(Exception e){e.printStackTrace ();} 6Q`ce!~$  
} \-B>']:R4  
} JdAjKN  
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//打印回应的头信息 E|6|m8  
public void logResponseHead(HttpURLConnection con) 81g&WQ'  
{ jm?mO9p~  
for(int i=1;;i++) MG<~{Y84}  
{ X6;aF;"5  
String header=con.getHeaderFieldKey(i); Y~CS2%j  
if(header!=null) QQ
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//responseHeaders.put(header,httpConnection.getHeaderField(header)); vi2xonq^  
Utility.log(header+" : "+con.getHeaderField(header)); LgaJp_d>9*  
else c:iMbJOn#  
break; v6rw.  
} <s:Xj  
} HP8pEo0Y  
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public void splitterStop()  2O  
{ itvwmI,m\  
bStop = true; L`!sV-.  
} I@\{6
hw  
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-  
} 7%<jZ=  
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/* /t/q$X  
**FileAccess.java E,X,RM~ +D  
*//文件访问(定位，写) p-}:7CXP  
package NetFox; 4S=lO?\"A  
import java.io.*; #Z.J
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public class FileAccessI implements Serializable{ c;e,)$)-|  
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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 v:>P;\]r9M  
RandomAccessFile oSavedFile; 7-LeJRB
 
long nPos; KV6S-  
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public FileAccessI() throws IOException HT]ubw]rJ  
{ M(BZ<,9V  
this("",0); $@xkKe"  
} oHYD6qJX{  
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public FileAccessI(String sName,long nPos) throws IOException vfm-K;,#  
{ 
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oSavedFile = new RandomAccessFile(sName,"rw"); bcYz?o
6  
this.nPos = nPos; |(V3  
oSavedFile.seek(nPos); -bE|FFU  
} I,[EL{fz  
n>Ei1  
fP|\1Y?CS  
public synchronized int write(byte[] b,int nStart,int nLen) dO@iq^9-  
{ 8ah]D  
int n = -1; r:IU+3  
try{ n&fV3[m`2  
oSavedFile.write(b,nStart,nLen); a$GKrc,z  
n = nLen; cwroG#jGT  
} m|k,8guG  
catch(IOException e) 7Av]f3Zr  
{ lO *Hv9#  
e.printStackTrace (); 4L0LT>'M\  
} :uEp7Y4  
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return n; _e'mG'P(  
} V6k9L*VP  
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} :wZZ 1qa  
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/* hqBRh+[  
**SiteInfoBean.java 8n)Q^z+ K  
*/ J3]m*i5A  
package NetFox; 4Y!v$r  
;w>B}v;RE  

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public class SiteInfoBean { .phQ7":`  
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private String sSiteURL; //Site's URL PG!vn@b6  
private String sFilePath; //Saved File's Path _X[c19q  
private String sFileName; //Saved File's Name J\V(MN,  
private int nSplitter; //Count of Splited Downloading File [OcD#~drO  
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public SiteInfoBean() [xPE?OD  
{//nSplitter的缺省值为5 | QA8"&r  
//default value of nSplitter is 5 N[-)c,O  
this("","","",5); Fo#*_y5\  
} b~gF,^w  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) hd~rC*I  
{ 7L*`nU|h  
sSiteURL= sURL; 3fPv71NVtt  
sFilePath = sPath; A=K1T]o  
sFileName = sName; St`m52V(5X  
this.nSplitter = nSpiltter; Q)>'fZ)  
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} R 6Em^A/>  
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public String getSSiteURL() w.f[
)  
{ 9YABr> ?  
return sSiteURL; $b} +5  
} #pfosC[  
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7%"7Rb^@  
public void setSSiteURL(String value) sXxO{aeev  
{ 3:Wr)>l}#  
sSiteURL = value; gwJu&HA/  
} I>aa'em  
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public String getSFilePath() P{18crC[1  
{ DF2&j!  
return sFilePath; Ysu/7o4  
} 5ov%(QI  
d}_c(  
7w,FA  
public void setSFilePath(String value) L ]c9
 
{ S)yV51^B  
sFilePath = value; ]||=<!^kn  
} 'QF>e  
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:8rCCop Uv  
public String getSFileName() OWsYE?  
{ `@7tWX0  
return sFileName; 03
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} t;Om9  
Z >=Y  
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public void setSFileName(String value) _+iz?|U  
{ K8Zk{on  
sFileName = value; %SCu29km  
} Q%^bA,$&D  
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public int getNSplitter() ?` i/  
{ 3:1 c_  
return nSplitter; u7WM6X  
} 4sjr\9IDC  
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public void setNSplitter(int nCount) 8[;oUVb
5  
{ (B<AK4G  
nSplitter = nCount; KTt$Pt/.  
} 79H+~1Az  
} (14kR  
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/* x35s6  
**Utility.java [dlH t;S  
*/ .N&}<T[  
package NetFox; _9|@nUD  
7G/|e24  
Ws)X5C=A  
public class Utility { A'iF'<%  
30+l0\1  
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public Utility() 4uAafQ`@H  
{ "B3:m-'  
f*{;\n(.t  
Ba|}C(Ws?  
} i0Q _f!j  
Eu.qA9,@U  
//线程睡眠 @H0%N
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public static void sleep(int nSecond) #l#[\6  
{ MmH_gR  
try{ \N+Ta:U1P  
Thread.sleep(nSecond); ID#qKFFW  
} ?^ezEpW  
catch(Exception e) ^jjJM|a  
{ !r obau7  
e.printStackTrace (); /(ju  
} O)%kl  
} [.xk
 
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//日志 oV>AFs6  
public static void log(String sMsg) zy6(S_j  
{ a<jE25t  
System.err.println(sMsg); ^
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} I7z/GA\x  
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public static void log(int sMsg) jI`To%^Y  
{ Kx185Q'W  
System.err.println(sMsg); 0nq}SH  
} p6Dv;@)Yn
 
} Dh(T)yc  
!riMIl1  
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/* [j]J_S9jJ  
**TestMethod.java ec4%Wk2  
*/ ]!G>8Rc  
package NetFox; bSR+yr'?  
_JJKbi  
_% 9+U[@  
public class TestMethod { ) v5n "W  
7h9[-d6  
4O_+4yS  
public TestMethod() [S&O-b8A  
{ ///xx/weblogic60b2_win.exe fwv T2G4  
try{ <&s)k  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); eOPCYyN  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); k.xv+^b9Q  
SiteFileFetch fileFetch = new SiteFileFetch(bean); @*O{*2  
fileFetch.start(); yX.5Y|A<  
} (<R\  
catch(Exception e){e.printStackTrace ();} ]n]uN~)9  
%>9+1lUhV  
+bc#GzVF  
} !QR?\9`  
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3^R][;  
public static void main(String[] args) tZu*Asx7  
{ `Ivw`}L  
new TestMethod(); Z++Z@J"  
} 5*wApu{2A  
} ?WQd  
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