http断点续传简单实现（java)

/* ?2_u/x  
**SiteFileFetch.java =EsKFt"  
*/ m{(D*Vuqd  
package NetFox; l yO_rZT  
import java.io.*; tN";o\!}  
import java.net.*; uSM4:!8  
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public class SiteFileFetch extends Thread { f(?>z!n0  
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SiteInfoBean siteInfoBean = null; //文件信息Bean JR'Q Th:z  
long[] nStartPos; //开始位置 _6^vxlF  
long[] nEndPos; //结束位置 g4RkkoZ>)  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 X
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long nFileLength; //文件长度 =n9adq  
boolean bFirst = true; //是否第一次取文件 5j{o0&=_$  
boolean bStop = false; //停止标志 {B?%r[nW  
File tmpFile; //文件下载的临时信息 06 K8|K  
DataOutputStream output; //输出到文件的输出流 4#;rv$ {  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） mL18FR N  
public SiteFileFetch(SiteInfoBean bean) throws IOException 7<|1 xOT  
{
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siteInfoBean = bean; 3=T<c?[  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); )8st  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); w v9s{I{P  
if(tmpFile.exists ()) =h5&\4r
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{ $-M1<?5  
bFirst = false; J U}XSb  
read_nPos(); W4|1wd}.t  
} [)Xu60?Q  
else pWbzBgM?nU  
{ s2b!Nib  
nStartPos = new long[bean.getNSplitter()]; ?n\~&n'C  
nEndPos = new long[bean.getNSplitter()]; @<W"$_r-  
}
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} iWGgt]RJ  
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public void run() 08yTTt76t  
{ j)'V_@  
//获得文件长度 .<rL2`
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//分割文件 _Dwn@{[(8  
//实例FileSplitterFetch J);1Tpm  
//启动FileSplitterFetch线程 3`SLMPI  
//等待子线程返回 j=PQoEtU'<  
try{ q,QMvUK:  
if(bFirst) K ,f1c}  
{ #
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nFileLength = getFileSize(); <W|{zAyv  
if(nFileLength == -1) ]rZ"5y  
{ wb"Jj  
System.err.println("File Length is not known!"); 8kH'ai  
} -58r*[=8  
else if(nFileLength == -2) f^:9gRt  
{ #9#N+  
System.err.println("File is not access!"); PrDvRW
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} ZKAIG=l&!  
else , $78\B^  
{ ^^3 >R`  
for(int i=0;i<nStartPos.length;i++) i.0}qS?  
{ tG^Oj:  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); Ds&)0Iwf  
} `(W V pP?  
for(int i=0;i<nEndPos.length-1;i++) Fm*n>^P@Y  
{ 7:mM`0g!  
nEndPos = nStartPos[i+1]; B%^B_s  
} ,Y &Q,  
nEndPos[nEndPos.length-1] = nFileLength; e9k}n\t3  
} 2ZNTg@o  
} 0(@8  
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/<zBcpVNV  
//启动子线程 n KDX=73  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; +3]@0VM26;  
for(int i=0;i<nStartPos.length;i++) 9)aXLM4Y  
{ <ynmA  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), TcO@q ]+S  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), &q``CCOF&  
nStartPos,nEndPos,i); D GOc!  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 7KuTC%7  
fileSplitterFetch.start(); Yt0 l'B%[u  
} 9p>3k&S  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), N$:[`,  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); Z^>3}\_v  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", wH{lp/  
nEndPos = " + nFileLength); 9t7_7{Q+;  
// fileSplitterFetch[nPos.length-1].start(); aR*z5p2-w  
{B\ar+9>  
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//等待子线程结束 QmbD%kW`3  
//int count = 0; b==<7[8  
//是否结束while循环 7!Ym~M=  
boolean breakWhile = false; o LuGW5wzj  
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while(!bStop) )Qp?N<&'  
{ @e$zEj5  
write_nPos(); 
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Utility.sleep(500); 224I%x.,  
breakWhile = true; &0Wv+2l@  
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for(int i=0;i<nStartPos.length;i++) 6yv*AmFh  
{ ,%v  
if(!fileSplitterFetch.bDownOver) iNd8M V  
{ i7mT<w>?  
breakWhile = false; |v[{k>7f  
break; %89f<F\V  
} ;}=v|Dr&I.  
} A4Q8^^byY  
if(breakWhile) **fJAANc  
break; cl^wLC'o  
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//count++; P`T&zK  
//if(count>4) GT|=Apnwr%  
// siteStop(); 6@ToPbj4  
} R l^ENrv!]  
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System.err.println("文件下载结束！"); a}hpcr({?  
} J+Q ;'J  
catch(Exception e){e.printStackTrace ();} 2/E3~X7  
} 5?kF'yksR  
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//获得文件长度 8e[kE>tS._  
public long getFileSize() aVM@^n  
{ aqoT  
int nFileLength = -1; `5=0f}E  
try{ e~i ?E  
URL url = new URL(siteInfoBean.getSSiteURL()); g5; W6QX  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Ex&f}/F  
httpConnection.setRequestProperty("User-Agent","NetFox"); #'v7mEwt  
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int responseCode=httpConnection.getResponseCode(); PfF7*}P  
if(responseCode>=400) UyEyk$6SU  
{ N6Vn/7I5%  
processErrorCode(responseCode); 6AUXYbK,  
return -2; //-2 represent access is error XB50>??NE  
} iVFHr<zk  
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String sHeader; )o SFHf  
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for(int i=1;;i++) m!$"-nh9  
{ ]9l=geZd%;  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); c03A_2%  
//Utility.log(in.readLine()); 4 "@BbVYR  
sHeader=httpConnection.getHeaderFieldKey(i); .%M=dL>  
if(sHeader!=null) %)i?\(/  
{ p*-o33Ve  
if(sHeader.equals("Content-Length")) u;F++$=  
{ Q*^zphT  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); /H:'(W_b;  
break; ,}=x8Xxr  
} @Vr?)_0  
} Hh(_sewo  
else /=FQ{tLr  
break; zX"@QB3E  
} DHaSBk  
} HZ>Xm6DnC5  
catch(IOException e){e.printStackTrace ();} +s V$s]U  
catch(Exception e){e.printStackTrace ();} I8Y[d$z  
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Utility.log(nFileLength); 7
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return nFileLength; 8;5 UO,`T  
} F7E#x  
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//保存下载信息（文件指针位置） ([qw#!;w;  
private void write_nPos() #6 e  
{  G;Q)A$-  
try{ %A,4vLe~6  
output = new DataOutputStream(new FileOutputStream(tmpFile)); JcvWE $  
output.writeInt(nStartPos.length); %t([  
for(int i=0;i<nStartPos.length;i++) 0vqXLFf   
{ ]>b.oI/  
// output.writeLong(nPos); :K#'?tH  
output.writeLong(fileSplitterFetch.nStartPos); ?>*i8*  
output.writeLong(fileSplitterFetch.nEndPos); |>gya&  
} J-:\^uP  
output.close(); Ep|W>  
} aW$sd)  
catch(IOException e){e.printStackTrace ();} a<kx95  
catch(Exception e){e.printStackTrace ();} .8<bz4  
} V44IA[  
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//读取保存的下载信息（文件指针位置） 1 xm8w$%  
private void read_nPos() *T$`5|  
{ )V*Z|,#no  
try{ m*6C *M  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); lM3UjR|@  
int nCount = input.readInt(); n-be8p)-  
nStartPos = new long[nCount]; *r6+Vz  
nEndPos = new long[nCount]; GPy+\P`  
for(int i=0;i<nStartPos.length;i++) nbj&3z,  
{ \S{ise/U  
nStartPos = input.readLong(); VC:.ya|Z  
nEndPos = input.readLong(); u7=`u/  
} QeuIAs*_  
input.close(); -fI-d1@  
} L~%@pf>  
catch(IOException e){e.printStackTrace ();} @MW
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catch(Exception e){e.printStackTrace ();} ^G.PdX$M  
} 3fgVvt-2  
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private void processErrorCode(int nErrorCode) #eD@sEn  
{  )`!i"  
System.err.println("Error Code : " + nErrorCode); y m<3  
} ftw\oGrS  
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//停止文件下载 .E-)R  
public void siteStop() /~yk  
{ v@_b"w_TY  
bStop = true; p&/}0eL y  
for(int i=0;i<nStartPos.length;i++) R#eY@N}\  
fileSplitterFetch.splitterStop(); 7%) F]  
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} _5 Zhv-7  
} p}$VBl$'  
//负责部分文件的抓取 sPuNwVX>}I  
**FileSplitterFetch.java 8<#X]I_eP+  
*/ k\8]fh)J\7  
package NetFox;
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import java.io.*; I?}YS-2  
import java.net.*; 0"]N9N;/  
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public class FileSplitterFetch extends Thread { >0z(+}]3z  
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String sURL; //File URL &sleV5V  
long nStartPos; //File Snippet Start Position I]t ",s/j
 
long nEndPos; //File Snippet End Position uH7$/  
int nThreadID; //Thread's ID T2|dFKeWG  
boolean bDownOver = false; //Downing is over 6K501!70g6  
boolean bStop = false; //Stop identical .Az'THD}  
FileAccessI fileAccessI = null; //File Access interface wiKUs0|  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException `./$hh  
{ ltRvNXx+]  
this.sURL = sURL; 2MaHD}1Jw  
this.nStartPos = nStart; ?.Z4GWyXa
 
this.nEndPos = nEnd; mxUM&`[  
nThreadID = id; ;/T=ctIs  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 k`ulDQu
 
} u hW@ Y+  
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public void run() `IL''eJug_  
{ ]w ^9qS  
while(nStartPos < nEndPos && !bStop) Y|$3%t  
{ X&R
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try{ qk!")t  
URL url = new URL(sURL); #Duz|F+%  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); hZ6CiEJB  
httpConnection.setRequestProperty("User-Agent","NetFox"); #;,dk(URo  
String sProperty = "bytes="+nStartPos+"-"; :=9?XzCC  
httpConnection.setRequestProperty("RANGE",sProperty); ^UTQcm  
Utility.log(sProperty); JtA tG%  
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+ q@kRQY;n  
InputStream input = httpConnection.getInputStream(); 67<Ym0+ =  
//logResponseHead(httpConnection); Ovu!G q  
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byte[] b = new byte[1024]; GddP)l{uCF  
int nRead; gYb}<[O!  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) kex4U6&OQB  
{ ?VVtEmIN  
nStartPos += fileAccessI.write(b,0,nRead); )"SP >2}  
//if(nThreadID == 1) _4H 9rPhf  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Y v22,|:  
} .[YM0dt  
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Utility.log("Thread " + nThreadID + " is over!"); 6XU1w  
bDownOver = true; (<y~]igy  
//nPos = fileAccessI.write (b,0,nRead); \Eqxmo  
} %C}TdG(C  
catch(Exception e){e.printStackTrace ();} b|_Pt  
} N0`v;4gF$]  
} Tp7*
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//打印回应的头信息
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public void logResponseHead(HttpURLConnection con) )q#1C]7m*  
{ cO}`PD$i  
for(int i=1;;i++) gzdR|IBa  
{ gr]:u4}  
String header=con.getHeaderFieldKey(i); HHd;<%q  
if(header!=null) !I3_KuJ5  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); t\&u  
Utility.log(header+" : "+con.getHeaderField(header)); T
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else '#JC 6#X   
break; MA9Oi(L)K  
} 9k5$rK`  
} "zpc)'$L=  
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public void splitterStop() DK-V3}`q}  
{ |#uA(V  
bStop = true; @JFfyQ {-  
} -44{b<:D  
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} l]:nncpns  
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/* V)HX+D>  
**FileAccess.java T&@xgj|!)  
*//文件访问(定位，写) qHM,#W<  
package NetFox; =}SH*xi6  
import java.io.*; 8HL$y-F  
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public class FileAccessI implements Serializable{ W ='c+3O6  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 {& Pk$Q!  
RandomAccessFile oSavedFile; #ZFedK0vv  
long nPos; /HlLfW  
,\t:R1.  
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public FileAccessI() throws IOException *RPdU.  
{ -)='htiU  
this("",0); Io8h 8N-  
} d#Hl3]wT  
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public FileAccessI(String sName,long nPos) throws IOException vUlGE  
{ PAYbsn  
oSavedFile = new RandomAccessFile(sName,"rw"); 4<P=wK=a8X  
this.nPos = nPos; jY: )W*TXt  
oSavedFile.seek(nPos); n+ot. -  
} M|HW$8V3_2  
:K-05$K  
!|\$|m<n  
public synchronized int write(byte[] b,int nStart,int nLen) ]VuB2L[D  
{ kPuY[~i%  
int n = -1; I-L52%E]  
try{ 7FQ&LF46  
oSavedFile.write(b,nStart,nLen); i.O670D  
n = nLen; A>C&`A=-  
} U04TVQ
n`  
catch(IOException e) j<BW/  
{ U-b(  
e.printStackTrace (); )sONfn  
} mgODJ  
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[:vH_(|  
return n; 4Lg!54P8  
} 5uo?KSX%  
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} #pe#(xoI  
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/* \B72 #NR  
**SiteInfoBean.java iZ^tLnc  
*/ T+a\dgd  
package NetFox; O)2==_f\  
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public class SiteInfoBean { 6}(;~/L  
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private String sSiteURL; //Site's URL a/@F?\A  
private String sFilePath; //Saved File's Path FrKI=8
 
private String sFileName; //Saved File's Name ?h$ =]  
private int nSplitter; //Count of Splited Downloading File @Rc/^B:  
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public SiteInfoBean() <6!;mb ;cX  
{//nSplitter的缺省值为5 -2D/RE7|  
//default value of nSplitter is 5 CXAW>VdK_  
this("","","",5); nfj8z@!  
} ls;!Og9  
5]c\{G  
80'!XKSP  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) =yR$^VSY  
{ .=kXO{>  
sSiteURL= sURL; 5 R*  
sFilePath = sPath; ?Q?=I,2bP  
sFileName = sName; oJ:\8>)9  
this.nSplitter = nSpiltter; Ad:}i9-x  
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} .kl.awT  
e
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public String getSSiteURL() dE_d.[!  
{ t.s;dlx[@  
return sSiteURL; *v}3So
 
} oe4r_EkYwW  
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public void setSSiteURL(String value) ?D\6@G:,#@  
{ q{c/TRp7  
sSiteURL = value; }hm"49,O  
} X2PyFe  
+";<Kd-  
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public String getSFilePath() !GAU?J;<#2  
{ aAi"  
return sFilePath; .='hYe.  
} K(: _52rt  
~d9@m#_T#~  
j,Vir"-)  
public void setSFilePath(String value) Fr|Ts>Kx  
{ # o;\5MOE%  
sFilePath = value; (fTi1 I!  
} )q8!:Z  
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public String getSFileName() y@'~fI!E4  
{ K^yZfpa8  
return sFileName; \'>8 (i~  
} Rf4}4ixkj  
j@guB:0  
!RPPwvNk4  
public void setSFileName(String value) h!!7LPxt  
{ ^5{0mn_4i  
sFileName = value; .1q4Q\B<  
} .Bs~FIe^  
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public int getNSplitter() Cvgk67C=$  
{ y88lkV4a  
return nSplitter; 9x]yu6  
} a*N<gId  
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public void setNSplitter(int nCount) :9.QhY)D  
{ uJ:SN;  
nSplitter = nCount; },& =r= B  
} B s{n  
} g-NfZj?  
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/* ln*_mM/Q%  
**Utility.java '7ps_pz  
*/ M!#[(:  
package NetFox; OGGuVY  
7.!`c-8 u  
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public class Utility { |K11Woii  
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public Utility() =JM !`[  
{ {[tx^b  
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} UPr8Q^wm  
g>&b&X&Y_  
//线程睡眠 QP={b
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public static void sleep(int nSecond) yrCY-'%  
{ wS%j!|xhlV  
try{ eNY?  
Thread.sleep(nSecond); t$k$Hd';  
} ?]Wg{\NC6  
catch(Exception e) =.9
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{ /)LI1\o  
e.printStackTrace (); r)/nx@x  
} :dM eNM-  
} O~L/>Ya  
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//日志 ZL^ svGy  
public static void log(String sMsg) "<^]d~a_  
{ JQdeI+  
System.err.println(sMsg); >SSRwYIN  
} 9?i~4&EY  
\66j4?H#  
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public static void log(int sMsg) fo$Ac  
{ #CcWsI>+w>  
System.err.println(sMsg); U|YIu!^  
} Wti?J.Csc  
} QmRE<i  
+u[?8D7Y  
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/* RLL2'8"A  
**TestMethod.java =c1t]%P,  
*/ 0f]LOg  
package NetFox; /'WIgP  
^a?H"  
\}9GK`oR  
public class TestMethod { \UR/tlw+/  
DAHQ7#qfQC  
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public TestMethod() tw?\bB  
{ ///xx/weblogic60b2_win.exe C?h`i ^ >2  
try{ f6O5k8n  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); C?47v4n-'  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 0{'%j~"  
SiteFileFetch fileFetch = new SiteFileFetch(bean); X GhV? tA  
fileFetch.start(); I6B4S"Q5<  
} Rb=8(#  
catch(Exception e){e.printStackTrace ();} hq[RU&\  
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} v<SCh)[-p  
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public static void main(String[] args) {;[W'Lc  
{ yccF#zU  
new TestMethod(); \Tii S  
} 4Bc<  
} B6hd*f  
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