http断点续传简单实现（java)

/* !ldb_*)h  
**SiteFileFetch.java <;.Zms${@  
*/ wNW9xmS  
package NetFox; \dbjh{  
import java.io.*; 8_K22]c5  
import java.net.*; Q+[e)YO)  
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public class SiteFileFetch extends Thread { XnQo0 R.PW  
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SiteInfoBean siteInfoBean = null; //文件信息Bean M ,8r{[2  
long[] nStartPos; //开始位置 D!~-53f@  
long[] nEndPos; //结束位置 x(z[S$6Y\  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 hp}J_/+4n  
long nFileLength; //文件长度 @U%I 6 t  
boolean bFirst = true; //是否第一次取文件 5[M?O4
mi  
boolean bStop = false; //停止标志 Ak$ghb  
File tmpFile; //文件下载的临时信息 1@kPl[`p'  
DataOutputStream output; //输出到文件的输出流 jl=<Q.Mm7  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） o)7gKWjujP  
public SiteFileFetch(SiteInfoBean bean) throws IOException -tSWYp{  
{ H>[1DH#b  
siteInfoBean = bean; QtQku1{  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); +n]U3b  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ]S
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if(tmpFile.exists ()) m El*{]  
{ IEdC _6G  
bFirst = false; !=#E/il,  
read_nPos(); 3C8'0DB  
} rO/mK$  
else >'/G:\M>A  
{
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nStartPos = new long[bean.getNSplitter()]; )kl| 5i  
nEndPos = new long[bean.getNSplitter()]; >UpTMEQ  
} hFP$MFab  
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} sf]y\_zU  
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public void run() s@f4f__(]  
{ l0g#&V--  
//获得文件长度 Zbxd,|<|  
//分割文件 -Xkdu?6Eh  
//实例FileSplitterFetch 28-6(oG  
//启动FileSplitterFetch线程 *~fZ9EkD  
//等待子线程返回 Y2j>lf?8  
try{ <oPo?r|oM|  
if(bFirst) VY@uQ#&A  
{ /g712\?M4  
nFileLength = getFileSize(); N<:
5 r  
if(nFileLength == -1) *J?QXsg  
{ mUzNrkG(G  
System.err.println("File Length is not known!"); Y*O7lZuF%  
} S)z jfJR  
else if(nFileLength == -2) ,:QG%Et  
{ [bJ/$A  
System.err.println("File is not access!"); X4&{/;$  
} yyrCO"eh  
else 7CABM  
{ )__vPPko i  
for(int i=0;i<nStartPos.length;i++) F$ x@]  
{ ^DVr>u  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); bc5+}&W  
} ";9cYoKRY  
for(int i=0;i<nEndPos.length-1;i++) +}>whyX1  
{ ?{$Q'c_I  
nEndPos = nStartPos[i+1]; yEtSyb~GK  
} U}6'_ PRQ  
nEndPos[nEndPos.length-1] = nFileLength; /9|1eSUa  
} )dG7$,g  
} ,m!j2H}8  
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//启动子线程 c}Y(Myd  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 1okL]VrI  
for(int i=0;i<nStartPos.length;i++) N6$pOQ  
{ Uq~{=hMX  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), |h*H;@$  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), (}"r 5  
nStartPos,nEndPos,i); vAq`*]W+  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); $uawQf+S  
fileSplitterFetch.start(); 8N!E`{W  
} `.Y["f 1B  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Mvrc[s+o  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 7<AHQ<#@  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", c&3 ]%urL  
nEndPos = " + nFileLength); P`5@$1CJ  
// fileSplitterFetch[nPos.length-1].start(); \)DP(wC  
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 e1S |&W8  
//等待子线程结束 v
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//int count = 0; 4/S4bk*8  
//是否结束while循环 q>%KIBh(  
boolean breakWhile = false; wtetB')yD  
B=7bQli}  
2JYyvJ>  
while(!bStop) /Bid:@R  
{ NUEy0pLw  
write_nPos(); OTL=(k  
Utility.sleep(500); q0.+F4  
breakWhile = true;
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@
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for(int i=0;i<nStartPos.length;i++) G
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{ 8}\VlH]
 
if(!fileSplitterFetch.bDownOver) O!lZ%j@%  
{ R?Ki~'k=  
breakWhile = false; B+iVK(j'[v  
break;  1SP)`Q  
} '73dsOTIT  
} J8J~$DU\Gv  
if(breakWhile) iRS )Z)  
break; ?a7PxD.  
n wToZxHZ~  
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//count++; 5iz]3]}%  
//if(count>4) IBcCbNs!  
// siteStop(); |zKe*H/  
} 4Ucg<Z&%  

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System.err.println("文件下载结束！"); =2\k Jv3  
} nY'0*:'u  
catch(Exception e){e.printStackTrace ();} tjBs>w  
} rC14X}X6  
\
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5CueD]  
//获得文件长度 yN5g]U.Q  
public long getFileSize() 4cRF3$amd  
{ wP/&k`HQ#i  
int nFileLength = -1; 'LpJ:Th  
try{ tlV>  
URL url = new URL(siteInfoBean.getSSiteURL()); 7u6o~(  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Ha1E /b]K  
httpConnection.setRequestProperty("User-Agent","NetFox"); 84DneSpHsp  
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int responseCode=httpConnection.getResponseCode(); ,u#uk7V  
if(responseCode>=400) =GL}\I  
{ }\:3}'S.$  
processErrorCode(responseCode); xKWqDt  
return -2; //-2 represent access is error 2xhwi.u  
} HlqCL1\<  
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String sHeader; sD7Qt  
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for(int i=1;;i++) Jor>YB`X  
{ -ZlBg~E  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); zIi|z}WJ  
//Utility.log(in.readLine()); NEa:  
sHeader=httpConnection.getHeaderFieldKey(i); &W-L`aFd0  
if(sHeader!=null) wOOBW0tj  
{ 7cr@;%#  
if(sHeader.equals("Content-Length")) V8ZE(0&II}  
{ $HF. 0
2{|  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); +wXrQV  
break; ,=O`'l>K  
} AV Gu*  
} +(x^5~QX  
else O%H_._#N`  
break; l
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} n1 =B  
} f_}/JF  
catch(IOException e){e.printStackTrace ();}
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catch(Exception e){e.printStackTrace ();} P9p:x6  
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Utility.log(nFileLength); ym9Z:2g  
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return nFileLength; I 8vv  
} 9un]}7^  
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//保存下载信息（文件指针位置） 
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private void write_nPos() veAg?N<c p  
{ C8rD54A'M  
try{ I|9(*tq)  
output = new DataOutputStream(new FileOutputStream(tmpFile)); HS XS%v/Y  
output.writeInt(nStartPos.length); lYmqFd~p  
for(int i=0;i<nStartPos.length;i++) (4cWq!ax<$  
{ ^q5~;_z|  
// output.writeLong(nPos); a yn6k=F  
output.writeLong(fileSplitterFetch.nStartPos); \ T/i]z  
output.writeLong(fileSplitterFetch.nEndPos); nDuf<mw  
} ^E\{&kaUp  
output.close(); :K>v F`SM  
} fuSfBtLPR#  
catch(IOException e){e.printStackTrace ();} 7zXFQ|TP  
catch(Exception e){e.printStackTrace ();} C,~wmS )@  
} 1j0OV9-|  
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//读取保存的下载信息（文件指针位置） i]J*lM7'  
private void read_nPos() R*a5bKr  
{ d9>*a$x;/  
try{ k"D6Vyy`  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); h6<abT@I  
int nCount = input.readInt(); .) uUpY%K^  
nStartPos = new long[nCount]; B4yU}v  
nEndPos = new long[nCount]; *GleeJWz  
for(int i=0;i<nStartPos.length;i++) |x@)%QeC  
{ PtCO';9[  
nStartPos = input.readLong(); NAjY,)>'K  
nEndPos = input.readLong(); IROX]f}r(  
} 4)0 %^\p  
input.close(); QEKSbxL\W  
} i!+D ,O  
catch(IOException e){e.printStackTrace ();} BLZ#vJR  
catch(Exception e){e.printStackTrace ();} 6r! Y ~\@  
} yI/2 e[  
}P(RGKQZ"  
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private void processErrorCode(int nErrorCode) B!-hcn]y  
{ }/&Q\Sc
  
System.err.println("Error Code : " + nErrorCode); =y-L'z&r  
} M4 SJnE  
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//停止文件下载 uMVM-(g%  
public void siteStop() %|E'cdvkX  
{ _Z?{&k  
bStop = true; `q|&;wP.  
for(int i=0;i<nStartPos.length;i++) mAMi-9  
fileSplitterFetch.splitterStop(); **_`AM~  
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} t\~lGG-p  
} ddvSi6  
//负责部分文件的抓取 pYZ6-s  
**FileSplitterFetch.java Q
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*/ Atl`J.;G  
package NetFox; :W]?6=  
aEU[k>&  
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import java.io.*; KiW4>@tY  
import java.net.*; #:C;VAAp  
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public class FileSplitterFetch extends Thread { !<r+h,C  
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String sURL; //File URL  o&uO]  
long nStartPos; //File Snippet Start Position I@Zd<Rn  
long nEndPos; //File Snippet End Position 7pMl:\  
int nThreadID; //Thread's ID 3 i<,#FaL  
boolean bDownOver = false; //Downing is over ?xEQ'(UBQ  
boolean bStop = false; //Stop identical /~3~Xc~=p  
FileAccessI fileAccessI = null; //File Access interface (Mi]vK.4  
S<}2y9F  
.N2yn`
  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException HR)Dz~Obw  
{ 5\93-e  
this.sURL = sURL; VD}8ei  
this.nStartPos = nStart; jv$Y]nf  
this.nEndPos = nEnd; RtVy^~=G  
nThreadID = id; '=MaO@ @  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 fxfzi{}uj  
} 5`qt82Qm  
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public void run() A4LGF  
{ Z$qFjWp  
while(nStartPos < nEndPos && !bStop) 1d/-SxhZ  
{ K&FGTS,  
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~\= VSwJ  
try{ [A$5~/Q{U1  
URL url = new URL(sURL); &v!=\Fig4  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); LhM{LUi  
httpConnection.setRequestProperty("User-Agent","NetFox"); l`lo5:w  
String sProperty = "bytes="+nStartPos+"-"; KrOoxrDcp  
httpConnection.setRequestProperty("RANGE",sProperty); s( @w1tS.  
Utility.log(sProperty); &8'.Gwm}  
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*  
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InputStream input = httpConnection.getInputStream(); XL[/)lX{  
//logResponseHead(httpConnection); <viIpz2jh%  
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byte[] b = new byte[1024]; ;>^oe:@  
int nRead; iku8T*&uc  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 0kN;SSX!  
{ JA W}]:jC  
nStartPos += fileAccessI.write(b,0,nRead); tX;00g;U.  
//if(nThreadID == 1) .G[y^w)w}  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); o(xRq;i  
} #_yQv?J  
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Utility.log("Thread " + nThreadID + " is over!"); @$FE}j_  
bDownOver = true; |1^>n,C  
//nPos = fileAccessI.write (b,0,nRead); 3wXmX  
} >Gbj1>C}  
catch(Exception e){e.printStackTrace ();} n^|;J*rD  
} bc}X.IC  
} vW4~\]  
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//打印回应的头信息 5 e:Urv77  
public void logResponseHead(HttpURLConnection con) )6|7L)Dk  
{ `(A6uakd  
for(int i=1;;i++) =PHl|^  
{ 3/IQ]8g"  
String header=con.getHeaderFieldKey(i); $ tf;\R  
if(header!=null) W-wy<<~
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//responseHeaders.put(header,httpConnection.getHeaderField(header)); g*b 4N_  
Utility.log(header+" : "+con.getHeaderField(header)); 9tZ)#@\  
else 9xWC<i  
break; xsK{nM6g  
} %bf+Y7m  
} \RN,i]c-g/  
-_=0PW5{  
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public void splitterStop() e;b,7Qw  
{ x4v@Kk/  
bStop = true; 6cof Zc$  
} `B+%W  
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0P`wh=")  
} `mPmEV<  
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/* C("PCD   
**FileAccess.java uY0V!W  
*//文件访问(定位，写) "^-U#f>k  
package NetFox; M9Gs^  
import java.io.*; 3nuf3)  
5zJkPki  
f uojf+i  
public class FileAccessI implements Serializable{ U -~%-gFC  
xO'I*)  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 ~45u a  
RandomAccessFile oSavedFile; PpMZ-f@  
long nPos; ,CW]d#P|  
$w%oLI@kl  
/^96|  
public FileAccessI() throws IOException hT6:7_UD  
{ *ggTTHy
 
this("",0); >(z{1'f{  
} .
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|Y3!Lix  
AIsM:sV]  
public FileAccessI(String sName,long nPos) throws IOException 2'g< H-[  
{ =fMSmn1S  
oSavedFile = new RandomAccessFile(sName,"rw"); O{8"f\*  
this.nPos = nPos; b3b 4'l   
oSavedFile.seek(nPos); hTI8hh  
} .;WJ(kB\U  
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public synchronized int write(byte[] b,int nStart,int nLen) tW5\Ktjno  
{ a:@9GmtV&  
int n = -1; vy/U""w`  
try{
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oSavedFile.write(b,nStart,nLen); #1Mk9sxo  
n = nLen; EZ #UdK_  
} *
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catch(IOException e) @RotJl/>  
{ O;[PEV~  
e.printStackTrace (); BEvSX|M>x  
} n? "ti  
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return n; aM 0kV.O  
} x6HebIR+  
nzy =0Ox[  
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} uuj"Er31  
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/* d;S:<]l'  
**SiteInfoBean.java ->wY|7  
*/ ;]fpdu{  
package NetFox; hgj#VY$B  
F$r8hj`  
567ot|cc  
public class SiteInfoBean { 5!#"
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EC1q#;:  
private String sSiteURL; //Site's URL hM\QqZFyp  
private String sFilePath; //Saved File's Path Te'^O,C)y$  
private String sFileName; //Saved File's Name hx4!P(o1  
private int nSplitter; //Count of Splited Downloading File ;KQ'/nII  
B2d$!Any  
sxL;o>{  
public SiteInfoBean() 4\pA^%73  
{//nSplitter的缺省值为5 d1e'!y}R5  
//default value of nSplitter is 5 &o"Hb=k<  
this("","","",5); }=A6Jv(j  
} T.ub!,Y  
:&yRvu  
qIjC-#a=m  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) |L;'In  
{ W3UK[_qK  
sSiteURL= sURL; CW\o>yh  
sFilePath = sPath; /p\Ymq  
sFileName = sName; =@pm-rI|-  
this.nSplitter = nSpiltter; xHsH .f_{  
`^AbFV 3  
6(9Ta'ywZ  
} lk.Q6saI1  
F/j=rs,*|D  
@PwEom
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public String getSSiteURL() ?]fBds=  
{ 7P/j\frW  
return sSiteURL; IX7d[nm39  
} Ccz:NpK+  
';aPoaO %  
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public void setSSiteURL(String value) I.x0$ac7  
{ ~$r^Ur!E\  
sSiteURL = value; W<!q>8Xn?  
} BCUw"R#
 
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public String getSFilePath() K'?ab 0  
{ bG^eP:r  
return sFilePath; Jr17pu(t  
} 4n3QW%#  
2IjqTL  
hN\E8"To  
public void setSFilePath(String value) @1n0<V/  
{ m.K"IXD  
sFilePath = value; [-
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} ls*^3^O  
@TgCI`E  
@Jm$<E  
public String getSFileName() fvit+  
{ dUO~dV1  
return sFileName; EzNmsbtZ(  
} hNx`=D9[7  
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}$qy_Esl  
public void setSFileName(String value) "Wi`S;  
{ &}T`[ d_Z  
sFileName = value; )>\Ne~%  
} ,?&hqM\  
(3]7[h7  
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public int getNSplitter() 7%7_i%6wP  
{ tm]75*?  
return nSplitter; ;uoH+`pf  
} K?I@'B'  
"#4PU5.  
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public void setNSplitter(int nCount) I*lq0&  
{ boN)C?"^h  
nSplitter = nCount; *[.\S3K`  
} 7ZZSAI  
} 2A`EFk7_X  
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/* *EV
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**Utility.java _^a.kF  
*/ m@zxjIwT  
package NetFox; ^S<
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8kMMQES  
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public class Utility { tAc;O[L  
(5yg\3Jvp  
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public Utility() Opjt? ]  
{ kdmVHiGF  
sgCIY:8  
PI{sO |  
} }1_gemlf  
Wb4sfP_  
//线程睡眠 <CA lJ  
public static void sleep(int nSecond) 5lU`o  
{ !/jx4w~R  
try{ ~!:F'}bj  
Thread.sleep(nSecond); m2_&rjGz  
} ^1Yx'ua'  
catch(Exception e) JWn9&WK  
{ ;Rnb^t6Z  
e.printStackTrace (); '|]zBpz  
} -Q$$2QW!  
} 5n9F\T5  
sWX  
//日志 %< W1y  
public static void log(String sMsg) ;^rZ"2U l  
{ CiMy_`H  
System.err.println(sMsg); 3i s.c)  
} cA/2,i  
dUe"qH29s  
_puQX@i  
public static void log(int sMsg) gsU&}R1*h  
{ *g=*}
2  
System.err.println(sMsg); D6ck1pxkx  
} x65e,'  
} QPFpGS{d  
!4 hs9b  
@x
=CMF15  
/* "n8_Ag@r  
**TestMethod.java ;l`8w3fDt  
*/ =vK(-h  
package NetFox; 3)3'-wu  
KX9ZwsC0  
vW4f3(/  
public class TestMethod { -_4! id  
aoJ&< vl3  
{;-$;\D  
public TestMethod() 2XXEg>CU  
{ ///xx/weblogic60b2_win.exe *uv\V@0  
try{ CI  @I  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); {K|{a  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); }F3Z~  
SiteFileFetch fileFetch = new SiteFileFetch(bean); zc2,Mn2  
fileFetch.start(); yqBu7E$X  
} Iy,)>V%iZV  
catch(Exception e){e.printStackTrace ();} D^TKv;%d  
_n_i*p '2  
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} k[zf`x^  
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public static void main(String[] args) snK9']WXo  
{ H~$|y9>qI  
new TestMethod(); #`W8-w  
} XG[%oL  
} -#i%4[v  
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