http断点续传简单实现（java)

/* 0`Qs=R`OM  
**SiteFileFetch.java r ($t.iS  
*/ iQR})=Q  
package NetFox; F
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import java.io.*; jM@I"JZb  
import java.net.*; 2"K~:Tm#w  
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public class SiteFileFetch extends Thread { (c7{dYV  
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SiteInfoBean siteInfoBean = null; //文件信息Bean p2?+[d  
long[] nStartPos; //开始位置 zi 14]FWo  
long[] nEndPos; //结束位置 uUB%I 8  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 8[p6C Jl)  
long nFileLength; //文件长度 !8M'ms>s=  
boolean bFirst = true; //是否第一次取文件 'WgwLE_  
boolean bStop = false; //停止标志 ,>%r|YSJ)  
File tmpFile; //文件下载的临时信息 *iN]#)3>  
DataOutputStream output; //输出到文件的输出流 /9#jv]C:  
I:7,CV  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） ^/YAokj  
public SiteFileFetch(SiteInfoBean bean) throws IOException 6Z}))*3 9  
{ QlXF:Gx"=  
siteInfoBean = bean; ]b$,.t5  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); gV>\lMc[-%  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); i-W2!;G  
if(tmpFile.exists ()) $1 \!Oe[i  
{ 'bO? =+c  
bFirst = false; 8LKZ3Y|  
read_nPos(); !|QeYGnq6  
} [uV/ Ra*g  
else No|{rYYKK  
{ *zht(~%  
nStartPos = new long[bean.getNSplitter()]; %NoZf^?  
nEndPos = new long[bean.getNSplitter()]; zNs8\  
} X~4:sJ\P=  
8jx1W9=`9[  
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} DKCy h`  
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public void run() gJv^v`X  
{ {vlh,0~  
//获得文件长度 Oz7v hOU  
//分割文件 8TvPCZ$x  
//实例FileSplitterFetch ikiy>W8  
//启动FileSplitterFetch线程 A84HaRlkF5  
//等待子线程返回 aN3{\^  
try{ {q4"x5|  
if(bFirst) &zy9}4w,  
{ 6K0*?j{;"  
nFileLength = getFileSize(); A1;t60z+q>  
if(nFileLength == -1) nClU5  
{ =Z
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System.err.println("File Length is not known!"); >D aS*r  
} zvj >KF|y  
else if(nFileLength == -2) Vs{sB*:
 
{ V(0[QA  
System.err.println("File is not access!"); Or|LyQU  
} )Ggx  
else gJ7puN  
{ ;zG|llX  
for(int i=0;i<nStartPos.length;i++) o(qmI/h  
{ "j>0A Hem  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); \H(,'w7H  
} +w5?{J  
for(int i=0;i<nEndPos.length-1;i++) 2>s;xZ@/'R  
{ }@4*0_g"Aw  
nEndPos = nStartPos[i+1]; ?[">%^  
} 5gEK$7Vp  
nEndPos[nEndPos.length-1] = nFileLength; vX%gcs/@  
} ZQ/5]]}3y  
} $!@f{9+
 
7 #N @B  
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//启动子线程 O}V2>W$  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; h]$zub
 
for(int i=0;i<nStartPos.length;i++) WI3!?>d  
{ "bH ~CG:Y  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), q<7n5kJ~  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 2{N0. |5  
nStartPos,nEndPos,i); `rV,<  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); |<$O5b'  
fileSplitterFetch.start(); kA0^~  
} Lf9h;z>#  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), +\Q@7Lj
 
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); f*Bc`+G  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", Ek0.r)Nw  
nEndPos = " + nFileLength); {n'}S(  
// fileSplitterFetch[nPos.length-1].start(); bE"CSK#  
/2q%'"x(  
3]P=co@  
//等待子线程结束 ?`$4ZDM  
//int count = 0; z_)$g=9$  
//是否结束while循环 +L6$Xm5DAv  
boolean breakWhile = false; ly@CX((W
  
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while(!bStop) #96a7K  
{ Y*f<\z(4  
write_nPos(); LTHS&3%2  
Utility.sleep(500); S;~_9i]upe  
breakWhile = true; I%Z&i-33y  
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for(int i=0;i<nStartPos.length;i++) vvCGzOv  
{ B7;MY6h#  
if(!fileSplitterFetch.bDownOver) " B1' K8  
{ )uP= o  
breakWhile = false; b3H;Ea?^^<  
break; *:(t.iL  
} $fKWB5p|()  
} kQ+5pFo3  
if(breakWhile) HZNX1aQ|Q#  
break; gqG"t@Y+  
!O*n6}nPE  
<V{BRRx  
//count++; QHK$  
//if(count>4) YeVhWPn@  
// siteStop(); \JchcQ  
} n$QFj'  
(TPD!=  
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System.err.println("文件下载结束！"); w&H7S{
 
} ,ic}   
catch(Exception e){e.printStackTrace ();} .1;?#t]ZV  
} )I@iW\`7  
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NNX/2  
//获得文件长度 _>.%X45xi  
public long getFileSize() (,>`\\  
{ bc-"If Z&  
int nFileLength = -1; H;8(y4;  
try{ Q
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URL url = new URL(siteInfoBean.getSSiteURL()); W+vm!7wX0  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); iBQftq7  
httpConnection.setRequestProperty("User-Agent","NetFox"); /e}k7U,^  
 2B#WWb  
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int responseCode=httpConnection.getResponseCode(); (@ Bw@9  
if(responseCode>=400) Wo&i)S<i0F  
{ %zGPF  
processErrorCode(responseCode); h!MT5B)r.  
return -2; //-2 represent access is error ETtR*5Y 5  
} w[XW>4xK  
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!u"Hf7/  
String sHeader; t
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for(int i=1;;i++) V+Z22  
{ Uvp?HZ\Z  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); `&o|=  
//Utility.log(in.readLine()); 'EQAG' YV  
sHeader=httpConnection.getHeaderFieldKey(i); =vWnqF:  
if(sHeader!=null) ^U1;5+2G+~  
{ shD$,! k  
if(sHeader.equals("Content-Length")) >z2{D7  
{ -v:Y\=[\  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); *m7e>]-  
break; ZISR]xay  
} UCQL~  
} ,AJd2ix  
else @U}UCG7+  
break; ny}?+&K  
} wGB'c's*  
} ^m~=<4eX  
catch(IOException e){e.printStackTrace ();} C]k\GlhB  
catch(Exception e){e.printStackTrace ();} >U17BGJ.  
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w v1R
]3}  
Utility.log(nFileLength); 8n56rOW!  
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return nFileLength; @{bf]Oc  
} ,yC~{H  
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//保存下载信息（文件指针位置） _*+M'3&=  
private void write_nPos() pG (8VteH  
{ vO\CPb %/  
try{ FIuKX"XR  
output = new DataOutputStream(new FileOutputStream(tmpFile)); Gce![<|ph  
output.writeInt(nStartPos.length); :%0Z
  
for(int i=0;i<nStartPos.length;i++) U_:/>8})d  
{  d00r&Mc  
// output.writeLong(nPos); 9O|m#&wa]  
output.writeLong(fileSplitterFetch.nStartPos);  z\\MLyS  
output.writeLong(fileSplitterFetch.nEndPos); b_B4  
} Aam2Y,B  
output.close(); v>,XJ7P  
} % $J^dF_0
 
catch(IOException e){e.printStackTrace ();} -v]7}[
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catch(Exception e){e.printStackTrace ();} Q>|<R[.7  
} Dd*C?6  
x[_+U4-/  
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//读取保存的下载信息（文件指针位置） %rf<YZ.\  
private void read_nPos() ^*ZO@GNL  
{ 0_ ;-QA
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try{ J^
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DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); H.YntFtD'  
int nCount = input.readInt(); [[Z*n/tr  
nStartPos = new long[nCount]; $+Xohtt  
nEndPos = new long[nCount]; J~~WV<6  
for(int i=0;i<nStartPos.length;i++) Alrk3I3{  
{ zfS`@{;F`|  
nStartPos = input.readLong(); H#f FU  
nEndPos = input.readLong(); ,i'>+Ix<  
} ?O28Q DUI  
input.close(); |d{4_o90  
} ZN. #g_  
catch(IOException e){e.printStackTrace ();} (u~@@d"  
catch(Exception e){e.printStackTrace ();} +] Fdg
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} N^O.P  
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private void processErrorCode(int nErrorCode) gI[xOK#  
{ .(! $j-B  
System.err.println("Error Code : " + nErrorCode); Ygg+*z  
} ?8`b  
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//停止文件下载 -(Yq$5Zc&  
public void siteStop() aC;OFINK  
{ y3d`$'7H>  
bStop = true; C}7Sh6  
for(int i=0;i<nStartPos.length;i++) @xmL?wz  
fileSplitterFetch.splitterStop(); 7%C6gU!r  
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} B lD  
} ?xIwQd0  
//负责部分文件的抓取 aCQAh[T  
**FileSplitterFetch.java "I u3&mc  
*/ -_B*~M/vV`  
package NetFox; &kh-2#E  
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,  
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import java.io.*; K1jE_]@Z  
import java.net.*; iOw'NxmY  
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public class FileSplitterFetch extends Thread { L_Z>*s&  
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String sURL; //File URL L)kwMk  
long nStartPos; //File Snippet Start Position ?nE<Aig  
long nEndPos; //File Snippet End Position uq'T:
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int nThreadID; //Thread's ID A3MVNz$wo"  
boolean bDownOver = false; //Downing is over 86oa>#opU  
boolean bStop = false; //Stop identical ?m0|>[j  
FileAccessI fileAccessI = null; //File Access interface N
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException CnN PziB  
{ "luMz;B  
this.sURL = sURL; uvi+#4~G  
this.nStartPos = nStart; ,-D3tleu`  
this.nEndPos = nEnd; `StlG=TB8  
nThreadID = id; T=%,^  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 it \3-  
} oUoDj'JN{  
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public void run() |<gYzb
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{ V_^p?Fi#  
while(nStartPos < nEndPos && !bStop) M] 7#  
{ /GRkQ",  
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try{ ^z)p@sk#  
URL url = new URL(sURL); t[VA|1gG  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); '| WY 2>/(  
httpConnection.setRequestProperty("User-Agent","NetFox"); ,#m:U5#h  
String sProperty = "bytes="+nStartPos+"-"; {W,&jC  
httpConnection.setRequestProperty("RANGE",sProperty); *d b,N'rK  
Utility.log(sProperty); fgdqp8~  
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InputStream input = httpConnection.getInputStream(); \xR1|M  
//logResponseHead(httpConnection); /6
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*> LA30R*v  
l$ ^LY)i  
byte[] b = new byte[1024]; $bOiP  
int nRead; 3RJsH:u8  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) vq/3
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{ (l}W\iB'd  
nStartPos += fileAccessI.write(b,0,nRead); /fv;`?~d*  
//if(nThreadID == 1) #TS:|
=  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); \SKobO?qI  
} @L0xU??"|  
vY)5<z&  
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Utility.log("Thread " + nThreadID + " is over!"); *MC+
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bDownOver = true; RzhAXI=  
//nPos = fileAccessI.write (b,0,nRead); wNl{,aH@  
} wwaw|$  
catch(Exception e){e.printStackTrace ();} mBN+c9n/  
} :J6 xYy$  
} $raq,SP  
%^Zu^uu  
$\Oc]%  
//打印回应的头信息 RqB8g  
public void logResponseHead(HttpURLConnection con) A{|^_1  
{ 17la/7l<  
for(int i=1;;i++) ]-g9dV_[>j  
{ e|> 5 R  
String header=con.getHeaderFieldKey(i); &
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if(header!=null) bY&!d.  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 8n??/VDRl  
Utility.log(header+" : "+con.getHeaderField(header)); X)Zc*9XA  
else |r['"6  
break; XCvL`  
} _3%eIyk4T  
} uHeKttR-  
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public void splitterStop() AdD,94/  
{ J~}sQ{ 0  
bStop = true; ANWfRtiU#  
} z>]P_E~`}  
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} R`KlG/Tk  
`
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/* Y#[xX2z9  
**FileAccess.java D,\hRQ  
*//文件访问(定位，写)  T_)G5a  
package NetFox; *(E]]8o  
import java.io.*; )sN}ClgJ  
0uL*-/|  
g>E.Snj}  
public class FileAccessI implements Serializable{ +R"Y~ m{F  
$:|?z_@  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 o4U0kiI@  
RandomAccessFile oSavedFile; 8B!MgNKV  
long nPos; C&HN#Q_  
56o(gCj?y  
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public FileAccessI() throws IOException *Za'^Z2  
{ AcP d(Pc  
this("",0); ?k`UQi]Q  
} 'D'H)J  
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public FileAccessI(String sName,long nPos) throws IOException b|pp}il  
{ u.ej<Lo  
oSavedFile = new RandomAccessFile(sName,"rw"); +\-cf,WkI  
this.nPos = nPos; :'2h0 5R  
oSavedFile.seek(nPos); +I3j2u8L  
} nT :n>ja  
K2
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public synchronized int write(byte[] b,int nStart,int nLen) ?U+nR/H:6  
{
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int n = -1; !?)aZ |r  
try{ I;Pd}A_}=_  
oSavedFile.write(b,nStart,nLen); yXQ 2
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n = nLen; 6t=)1T  
} .WLwAL  
catch(IOException e)
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{ #+&"m7 s  
e.printStackTrace (); tH=jaFJ   
} ZZ>F ^t  
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return n; [}I|tb>Pg  
} 9zl-C*9vj  
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} (QTQxZ
 
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/* {>UT'fa-  
**SiteInfoBean.java .On3ZN  
*/ h<G7ocu!  
package NetFox; ; GEr8_7  
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public class SiteInfoBean { G/ H>M%M  
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private String sSiteURL; //Site's URL E|3[$?=R  
private String sFilePath; //Saved File's Path </pt($  
private String sFileName; //Saved File's Name @HE<\Z{ KI  
private int nSplitter; //Count of Splited Downloading File .P#t"oW}  
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=)}Yw)
 
public SiteInfoBean() 5/R ~<z  
{//nSplitter的缺省值为5 O03F@v  
//default value of nSplitter is 5
>9y!M'V  
this("","","",5); %?3$~d\n  
} jx'hxC'3  
l{QlJ>%~{;  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) dVMLn4[,MA  
{ OaKr_m  
sSiteURL= sURL; tkQrxa|  
sFilePath = sPath; oT|:gih5  
sFileName = sName; @~&|BvK% \  
this.nSplitter = nSpiltter; 1:RK~_E  
tr58J%Mu  
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} Wo Z@  
]E.\ |I(  
{Y3:Y+2X3*  
public String getSSiteURL() kZ;Y/DH  
{ cqaq~  
return sSiteURL; OepQ Z|2  
} <sn,X0W  
PZY6 I  
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public void setSSiteURL(String value) tkmzOc H  
{ 3e>U(ES  
sSiteURL = value; e~SRGyIww  
} r)B55;*Fh  
v|dt[>G  
b'I@TLE')  
public String getSFilePath() 3lbGG42:  
{ WD5jO9Oai  
return sFilePath; :)y3&I  
} ixL[(*V  
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public void setSFilePath(String value) PzT@q\O  
{ --k!KrL  
sFilePath = value; :Dfl,=S  
} 1+[,eq  
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public String getSFileName() .$1S-+(kV  
{ 9I}Uh#]k<  
return sFileName; pq%inSY  
} Vh^ :.y  
:QF`Orb!^  
|"[;0)dw^  
public void setSFileName(String value) TEbIU8{Y  
{ i6S["\h>  
sFileName = value; Esm=sPW  
} P`S'F_I
N  
l3y}nh+ 8  
P~V ^Efz{  
public int getNSplitter() 7%&e4'SZO  
{ Od~e*gA8  
return nSplitter; *q;83\  
} WR u/7$8  
R
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nm)/BK  
public void setNSplitter(int nCount) JEK_W<BD  
{ #bCUI*N"P  
nSplitter = nCount; =@&>r5W1  
} 8w#4T:hsuN  
} 7#N ?{3i  
"Xl"H/3r  
jAovzZ6BL  
/* %zR5q  Lb  
**Utility.java [;l;kom  
*/ 3#aLCpVla  
package NetFox; ^5)=)xVF  
{E}D6`{  
~fs} J  
public class Utility { #ApmJLeCO  
cEn|
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public Utility() flz7{W  
{ 7<(kvE*x  
~jzT;9:  
p@h<u!rL8  
} @LY[kt6o  
[q/eRIS_  
//线程睡眠
f(\S+4  
public static void sleep(int nSecond) C+_UIx]A  
{ ?0-3J )kW  
try{ )TBm?VMe  
Thread.sleep(nSecond); =`2jnvx  
} A'"J'q*t  
catch(Exception e) :GFK |  
{ I]42R;Sc  
e.printStackTrace (); @i#=1)Ze  
} |+Z-'k~Q  
}
Ir(U7D  
R8YU#D (Q  
//日志 }9N-2]  
public static void log(String sMsg) W"\+jHF"  
{ of >  
System.err.println(sMsg); =L;g:hc<  
} r=xec@R]*  
ys:F  
)`2ncb   
public static void log(int sMsg) - ^Y\'y2  
{ `Gx 5=Bm;  
System.err.println(sMsg); |oQhtk8.  
} m 0Uu2Z4  
} JdUI:(  
9H53H"5q  
KM[&WT  
/* a/rQ@c>  
**TestMethod.java DcC|oU[  
*/ ]ki) (Bb  
package NetFox; <e wcWr  
xa967Ki9"  
gt=@v())  
public class TestMethod { dKevhm)R"  
5A%Uv*  
]vw%J ^7:a  
public TestMethod() FTzc,6  
{ ///xx/weblogic60b2_win.exe uTdz$Nh  
try{ 7.+vp@+  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); )% gU  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); :OqEkh"$#  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 1_8@yO  
fileFetch.start(); {$7vd  
} 8|u8J0^  
catch(Exception e){e.printStackTrace ();} jN(c`Gb  
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'b6qEU#  
} I9nm$,i]7  
\K lY8\c[  
+
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public static void main(String[] args) };'~@%U]/  
{ .
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new TestMethod(); '#yIcV$  
} 2+K-I  
} Cd_H<8__  
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