http断点续传简单实现（java)

/* dOFxzk,g&R  
**SiteFileFetch.java EV@xUq!x.  
*/ JeJ
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package NetFox; 7K`A2  
import java.io.*; L44-: 3  
import java.net.*; a<[@p  
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public class SiteFileFetch extends Thread { 0j1I  
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SiteInfoBean siteInfoBean = null; //文件信息Bean LmLV2f  
long[] nStartPos; //开始位置 @>J4K#"  
long[] nEndPos; //结束位置 ?<Dinq  
FileSplitterFetch[] fileSplitterFetch; //子线程对象
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long nFileLength; //文件长度 m&OzT~?_>N  
boolean bFirst = true; //是否第一次取文件 IN!m  
boolean bStop = false; //停止标志 M[0@3"}}  
File tmpFile; //文件下载的临时信息 w*ig[{ I  
DataOutputStream output; //输出到文件的输出流 Got5(^'c  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 'hL\xf{  
public SiteFileFetch(SiteInfoBean bean) throws IOException p3*}!ez4  
{ S2"p(  
siteInfoBean = bean; laqW {sX^5  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); DY6wp@A  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); KX9+*YY,  
if(tmpFile.exists ()) ">kfX1LT  
{ X;T(?,,  
bFirst = false; :JqH.Sqk  
read_nPos(); Cl]E rg  
} ~?dPF;.6_  
else aU2O5z&  
{ {vAq08  
nStartPos = new long[bean.getNSplitter()]; a Kb2:1EQ  
nEndPos = new long[bean.getNSplitter()]; A1p;Ye
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} JLRw`V,o7  
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} e.i5j^5u  
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public void run() 8@qYzSx[  
{ 8J%^gy>m]  
//获得文件长度 ;t@zH+*}  
//分割文件 . #;ZM[v  
//实例FileSplitterFetch `jJ5us  
//启动FileSplitterFetch线程 ~;|
  
//等待子线程返回 GLL,  
try{ iy8UrgG;l  
if(bFirst) U\y];\~H  
{ [[?:,6I  
nFileLength = getFileSize();
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if(nFileLength == -1) b IcLMG s  
{
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System.err.println("File Length is not known!"); lx~!FLn  
} Ud:v3"1  
else if(nFileLength == -2) rU5gQq
;  
{ (M6B$:  
System.err.println("File is not access!"); OUe@U;l{Z  
} Rw*l#cr=.  
else ^l ~i>:V  
{ S(Xab_DT)H  
for(int i=0;i<nStartPos.length;i++) K3TMTY<p  
{ M=e]v9  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); w:&m_z#M  
} C2,,+* v  
for(int i=0;i<nEndPos.length-1;i++) cxrUk$f  
{ 3t(nV4uDF  
nEndPos = nStartPos[i+1]; ./)A6O*#  
} Xf9<kbRw/  
nEndPos[nEndPos.length-1] = nFileLength; KQ xKU?b1  
} 1,Uv;s;{  
} x\!Qe\lE  
)`^t,x<S  
d$kGYMT"  
//启动子线程 VLN=9  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; :sFP{rFx~  
for(int i=0;i<nStartPos.length;i++) CfoSow-  
{ Ip( IGR"  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), S?*v p=  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), N|T%cdh:/  
nStartPos,nEndPos,i); qp^O\>c  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); xRJv_=dT  
fileSplitterFetch.start(); "Q#/J)N  
} 'i{kuTv  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), _UYt  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); |SZRO,7x  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 3.?PdK&C  
nEndPos = " + nFileLength); Ej ip%m  
// fileSplitterFetch[nPos.length-1].start(); 4\Y2{Z>P?  
b|wCR%  
"Nn/vid;  
//等待子线程结束 NHUx-IqOX  
//int count = 0; G{i}z^n  
//是否结束while循环 \q(RqD  
boolean breakWhile = false;  s6rdQI]  
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while(!bStop) EMmNlj6  
{ y1(smZU  
write_nPos(); 9PVM06   
Utility.sleep(500); ,Zb]3  
breakWhile = true; *;(
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for(int i=0;i<nStartPos.length;i++) UW<V(6P  
{ qXkc~{W_  
if(!fileSplitterFetch.bDownOver) HjbC>*  
{ 0~H(GG$VH  
breakWhile = false; vL`w
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break; Ti!j  
} QSW62]=vV  
} pV(b>
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if(breakWhile) C+cSy'VIK!  
break; @U_w:Q<9u  
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9l@VxX68M  
//count++; `)&-;CMY  
//if(count>4) ddmTMfH  
// siteStop(); z"u4t.KpL  
} mZDrvTI'  
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System.err.println("文件下载结束！"); GNA:|x  
} Rgw\qOb  
catch(Exception e){e.printStackTrace ();} H*!j\|v0  
} =4"D8UaHr  
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5. 5
 
//获得文件长度 @>_`g=  
public long getFileSize() h)"PPI  
{ @H"~/m_o  
int nFileLength = -1; j08}5Eo  
try{ 0"(5\T  
URL url = new URL(siteInfoBean.getSSiteURL()); G)';ucs:,  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); <YP>c  
httpConnection.setRequestProperty("User-Agent","NetFox"); scCOiK)  
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int responseCode=httpConnection.getResponseCode(); G,e>dp_cPu  
if(responseCode>=400) EkgS*q_  
{ lplEQ]J|  
processErrorCode(responseCode); WLQm|C,  
return -2; //-2 represent access is error P&V,x`<Z  
} mEmz
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String sHeader; 1D&Q{?RM  
]vMr@JM-G  
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for(int i=1;;i++) x1W<r)A )r  
{ y5 $h  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ZMy0iQ@  
//Utility.log(in.readLine()); d_BECx<\  
sHeader=httpConnection.getHeaderFieldKey(i); YgNt>4K  
if(sHeader!=null) ^]3Y11sI  
{ sWP5=t(i+9  
if(sHeader.equals("Content-Length")) Yj|Oy  
{ ,`v)nwP  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); fHCLsI  
break; 5e~\o}
]  
}  #:_qo  
} XMd-r8yYr  
else N W :_)1  
break; oJ\UF S  
} TYGUB%A  
} V.vA~a  
catch(IOException e){e.printStackTrace ();} t&T0E.kh*X  
catch(Exception e){e.printStackTrace ();} &[f.;1+C  
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Utility.log(nFileLength); Q0i.gEwe  
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return nFileLength; Ol1[o  
} U8KB@E  
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//保存下载信息（文件指针位置） dR<sBYo  
private void write_nPos() ,4zwd@&O  
{ w$WN` =  
try{ 9"Oz-!Y4  
output = new DataOutputStream(new FileOutputStream(tmpFile)); >j5) MF{"  
output.writeInt(nStartPos.length); i\lur ET  
for(int i=0;i<nStartPos.length;i++) eVyXh>b*  
{ 4n @}X-)  
// output.writeLong(nPos); zV_U/]y  
output.writeLong(fileSplitterFetch.nStartPos); 'VcZ_m:  
output.writeLong(fileSplitterFetch.nEndPos); [,Q(~Qb  
} !qsk;Vk7Z  
output.close(); s!esk%h{K  
} !'o5X]s  
catch(IOException e){e.printStackTrace ();} XW w=3$  
catch(Exception e){e.printStackTrace ();} '^)Ve:K-.  
} w?)v#]<-  
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//读取保存的下载信息（文件指针位置） sgp5b$2T.  
private void read_nPos() $_CE!_G&)  
{ =p,+a/*  
try{ WL$nchS9  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); v!n\A}^:  
int nCount = input.readInt(); d0$dQg  
nStartPos = new long[nCount]; 23 j{bK  
nEndPos = new long[nCount]; ~N2){0j4  
for(int i=0;i<nStartPos.length;i++) j&6'sg;n)  
{ 2`hc0 IE  
nStartPos = input.readLong();
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nEndPos = input.readLong(); WPi^;c8  
} YUU|!A8x  
input.close(); NWWa
g}  
} c Q:.V  
catch(IOException e){e.printStackTrace ();} -\6nT'P  
catch(Exception e){e.printStackTrace ();} ]#=43  
} H=Rqr  
xP%`QTl\  
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private void processErrorCode(int nErrorCode) g^ZsV:D  
{ eYZ{mo7  
System.err.println("Error Code : " + nErrorCode); hbRDM'  
} hfT HP  
~L$B]\/A5  
_i{$5JJ+K2  
//停止文件下载 S`HshYlE q  
public void siteStop() m99j]wr~c  
{ P=PcO>  
bStop = true; wQbN5*82  
for(int i=0;i<nStartPos.length;i++) 2g5Ft  
fileSplitterFetch.splitterStop(); ^HYmi\`  
UQ6UZd37   
[ fvip_Pt  
} u3)Oj7cX  
} ],CJSA!5F  
//负责部分文件的抓取 #U45;idp  
**FileSplitterFetch.java 'zCJ
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*/ r2A%.bL#  
package NetFox; ,CqJ((  
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^*.S7.;2o  
import java.io.*; 9s\(yC8h  
import java.net.*; g&9E>wT  
;/+VHZP;  
+]Ca_`  
public class FileSplitterFetch extends Thread { Y2709LWmP  
7|4hs:4mD  
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String sURL; //File URL ;d$PQi  
long nStartPos; //File Snippet Start Position *fyC@fI>  
long nEndPos; //File Snippet End Position ^DVj_&~  
int nThreadID; //Thread's ID +p6cG\Gp  
boolean bDownOver = false; //Downing is over (qd$wv^h  
boolean bStop = false; //Stop identical [=M0%"  
FileAccessI fileAccessI = null; //File Access interface F[PIo7?K  
[<SM*fQ>t  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException .3WDtVE  
{ F7$x5h@  
this.sURL = sURL; 0sq?;~U  
this.nStartPos = nStart; 3Mw
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this.nEndPos = nEnd; :N03$Tvl  
nThreadID = id; [0|g3K!A  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 UB[tYZ  
} JTbg8b  
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public void run() Kq!E<|yM  
{ vlYDhjZk#  
while(nStartPos < nEndPos && !bStop) sVP[7&vr~  
{ lF-;h{   
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try{ Ar&]/X,WG  
URL url = new URL(sURL); 8BZTHlUB  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 9F+i+(\,b  
httpConnection.setRequestProperty("User-Agent","NetFox"); P|}~=2J  
String sProperty = "bytes="+nStartPos+"-"; V_Z~$  
httpConnection.setRequestProperty("RANGE",sProperty); MgJiJ0y  
Utility.log(sProperty); mXZOkx{  
@Dc?fyY*o<  

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InputStream input = httpConnection.getInputStream(); tI50z khaB  
//logResponseHead(httpConnection); r,}U-S.w  
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byte[] b = new byte[1024]; T&Dt;CSF  
int nRead; W\09hZ
6  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) j" wX7  
{ YrAaL"20  
nStartPos += fileAccessI.write(b,0,nRead); Mazjn?f  
//if(nThreadID == 1) }`k >6B  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); J }izTI  
} 8joJe>9VJ  
+$i-"^  
,arFR'u>  
Utility.log("Thread " + nThreadID + " is over!"); |k5uVhN  
bDownOver = true; d{_tOj$  
//nPos = fileAccessI.write (b,0,nRead); Oi{X \Y  
} yQ\K;  
catch(Exception e){e.printStackTrace ();} U9:?d>7  
} ,EPs>#
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} sO7$
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//打印回应的头信息 [s?H3yQ.  
public void logResponseHead(HttpURLConnection con) A#9@OWV5f  
{ I"awvUP]a[  
for(int i=1;;i++) Y9F78=Q  
{ SI
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String header=con.getHeaderFieldKey(i); M$O}roOa  
if(header!=null) c
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//responseHeaders.put(header,httpConnection.getHeaderField(header)); y- S]\tu  
Utility.log(header+" : "+con.getHeaderField(header)); I}oxwc  
else K{[ySB  
break; dRg1I=|{_  
} 51.! S  
} rAqg<fR*  
(1e;7sNG@  
+ >o/Ob  
public void splitterStop() e-<fkU9^W  
{ i9}n\r0=c  
bStop = true; b~\gV_Z  
} zo66=vE!  
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} 3\eb:-B:@  
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/* ]9z{ 95  
**FileAccess.java ;c73:'e  
*//文件访问(定位，写) f:L%th  
package NetFox; uiq)?XUKv  
import java.io.*; i|u3Qt5  
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[sG=(~B
U  
public class FileAccessI implements Serializable{ U(5(0r  
>O[# 661  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 *LJN2;  
RandomAccessFile oSavedFile; BBw]>*  
long nPos; 'qBg^c  
:HhLc'1Jw  
oD_'8G}  
public FileAccessI() throws IOException eN]0]9JO  
{ Qg  
this("",0); btb-MSkO  
} k!E`Xeob  
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public FileAccessI(String sName,long nPos) throws IOException q[]EVs0$ew  
{ (1\!6  
oSavedFile = new RandomAccessFile(sName,"rw"); jM1|+o*Wr  
this.nPos = nPos; $5nOiaQL  
oSavedFile.seek(nPos); rly3f  
} s$xctIbm?,  
w#_xV =  
3$+|nP:U  
public synchronized int write(byte[] b,int nStart,int nLen) ~V3pj('/)'  
{ Y}(#kqh>  
int n = -1; ]5D?Sc#-  
try{ DV +DJcF  
oSavedFile.write(b,nStart,nLen); #9z\Wblr  
n = nLen; (_-<3)q4  
} 'LIJpk3J  
catch(IOException e) Q%~b(4E^7P  
{ {>>ozB.  
e.printStackTrace (); p"ht|x  
} FCQIfJ#  
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return n; PIP2(-{ai  
} SiHZco I  
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} [0N==Ym1  
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/* q.i@Lvu#  
**SiteInfoBean.java Q)yhpwrX  
*/ mJ0nyj
X^  
package NetFox; ?1}1uJMj-  
j['Z|Am"l  
LKY4rY!|@d  
public class SiteInfoBean { MdT'xYomzQ  
tDFN *#(  
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private String sSiteURL; //Site's URL F>&Q5Kl R  
private String sFilePath; //Saved File's Path Oa\!5Pw1  
private String sFileName; //Saved File's Name '#[U7(lIQ  
private int nSplitter; //Count of Splited Downloading File A:[La#h|p  
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2H fP$.  
public SiteInfoBean() wG2lCv`
d  
{//nSplitter的缺省值为5 ON _uu]=  
//default value of nSplitter is 5 G\tTwX4  
this("","","",5); 
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} 0wXfu"E{  
^Qz8`1`;Z  
vjaIFyj  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) GEfX,9LF&  
{ ?rXh x{vD  
sSiteURL= sURL; 3(%hHM7DM  
sFilePath = sPath; !cT#G  
sFileName = sName; =K{$?%"  
this.nSplitter = nSpiltter; YFOK%7K  
-QCo]:cp  
Z'<=06  
}
(:].?o  
bG67TWY)  
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public String getSSiteURL() ~|@aV:k  
{ ~;#J&V@D  
return sSiteURL; \ntmD?kA  
} )ruC_)  
r|cl6s!P  
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public void setSSiteURL(String value) pmB}a7  
{ ja70w:ja  
sSiteURL = value; MX6*waQ-<  
} b_cnVlN[  
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public String getSFilePath() +[`
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{ )mxY]W+  
return sFilePath; Ki}PO`s  
} }qT @.  
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6G7B&"&  
public void setSFilePath(String value) z,}1K!  
{ `23&vGk}  
sFilePath = value; )y'`C@ijI  
} r vVU5zA4H  
e{U`^ao`F8  

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public String getSFileName() j{>E.F2.  
{ k!t5>kPSQ
 
return sFileName; nVw
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} REB8_H"  
?(>7v[=iT  
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public void setSFileName(String value) D}vgXzD  
{ 6Z ~>d;&9  
sFileName = value; >FFZ8=  
} ?tE}89c  
^
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^2|gQ'7<  
public int getNSplitter() uCF+Mp  
{ 7<x0LW  
return nSplitter; AUcq\Ys  
} |OF<=GGO+  
;#78`x2  
t= "EbPE  
public void setNSplitter(int nCount) ^v*ajy.>  
{ 6Bmv1n[X^h  
nSplitter = nCount; }lML..(
(1  
} 7'7bIaJk  
} %>Z=#1h/a  
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/* qi`*4cas*A  
**Utility.java B@e,3:  
*/ *58
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package NetFox; @jN!j*Y H  
|;6FhDW+'  
?0hk~8c  
public class Utility { zN#$eyt  
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public Utility() LTS3[=AB  
{ ] $$ciFM  
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} fC.-* r  
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//线程睡眠 Y<:%_]]  
public static void sleep(int nSecond) ktU98Bk]  
{ Sq/M %z5'  
try{ m
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Thread.sleep(nSecond); f?#:@ zcL  
} s#&jE GBug  
catch(Exception e) kR7IZo"q  
{ x%k4Lm  
e.printStackTrace (); Ig"K
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} RR{]^g51  
} 63UAN0K%  
@]6)j&  
//日志 ^TVy:5Ag  
public static void log(String sMsg) <5@+:7Dv  
{ 50rCW)[#  
System.err.println(sMsg); =bded(3Z  
} W>K2d  
!-2nIY!  
r-^
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public static void log(int sMsg) i cQsA  
{ ?qAX *j  
System.err.println(sMsg); S"CsY2;  
} 1m|Oi%i4  
} }<uD[[FLB  
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9Vxsv*OR,  
/* $.R$I&U  
**TestMethod.java r&A#h;EQX2  
*/ 3lMmSKN  
package NetFox; g v&xC 6>  
3*CF!Y%  
<\8dh(>  
public class TestMethod { Yt++?  
;EW]R9HCH  
93kSBF#  
public TestMethod()  h#^I
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{ ///xx/weblogic60b2_win.exe @NlnZfMu  
try{ @bmu4!"d  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 7F4$k4r<  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); dZ9[wkn  
SiteFileFetch fileFetch = new SiteFileFetch(bean); Os*,@N3t  
fileFetch.start(); yi"V'Us  
} %&c[g O!Za  
catch(Exception e){e.printStackTrace ();} *oY59Yf  
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} L,[0*h  
p W:[Q\rSj  
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public static void main(String[] args) 8~ .r/!wfy  
{ >sm< < gVb  
new TestMethod(); A{: a kK  
} Z=z'j8z3  
} |08tQ  
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