http断点续传简单实现（java)

/* YM(`E9{h  
**SiteFileFetch.java { yvKUTq`  
*/ #dKHU@+U"  
package NetFox; KkF3E*q\H  
import java.io.*; /;K?Y#mf~j  
import java.net.*; `n{yls7.  
[tP6FdS/M=  
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public class SiteFileFetch extends Thread { 1I1Z),  
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SiteInfoBean siteInfoBean = null; //文件信息Bean sA}Xha  
long[] nStartPos; //开始位置 [:MpOl-KIz  
long[] nEndPos; //结束位置 |9D;2N(&!  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 <j
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long nFileLength; //文件长度 rK@UCRf  
boolean bFirst = true; //是否第一次取文件
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boolean bStop = false; //停止标志 eT4+O5t  
File tmpFile; //文件下载的临时信息 j. m(Z}  
DataOutputStream output; //输出到文件的输出流 NyTGvBf  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） MUs~ZF  
public SiteFileFetch(SiteInfoBean bean) throws IOException jcuC2t  
{ ~:|qdv%\  
siteInfoBean = bean; u>cU*E4/  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ^9ZW}AAO  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 3o>.Z;  
if(tmpFile.exists ()) |iJ+e -_R  
{ u40k9vh  
bFirst = false; G|"`kAa  
read_nPos(); [p%OIqC`pB  
} oV7A"8L^a  
else [)ybPIv]  
{ 02EbmP  
nStartPos = new long[bean.getNSplitter()]; -A\J:2a|  
nEndPos = new long[bean.getNSplitter()]; +EnJyli  
} ,XZ[L? >  
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} f7Dx.-  
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public void run() IIW6;jS  
{ 1 ^k#g,  
//获得文件长度 ;h }^f-  
//分割文件 -XSu;'4q  
//实例FileSplitterFetch 09RJc3XE9  
//启动FileSplitterFetch线程 z+J4XpX0,  
//等待子线程返回 7r_Y.  
try{ =}G `i**  
if(bFirst) 
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{ g[W`
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nFileLength = getFileSize(); 0k];%HV|  
if(nFileLength == -1) W9$mgs=S`E  
{ wkp|V{k  
System.err.println("File Length is not known!"); fR4O^6c:  
} <^Hh5kfS'  
else if(nFileLength == -2) >#MGGCGL  
{ -/s2'  
System.err.println("File is not access!"); L'>t:^QTh  
} p4|Zz:f  
else |c]Y1WwDx  
{ /y\KLa  
for(int i=0;i<nStartPos.length;i++) F
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{ 3j2% '$>E^  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); mxpncM=q  
} ZA
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for(int i=0;i<nEndPos.length-1;i++) )I`6XG  
{ o~I
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nEndPos = nStartPos[i+1];
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} #hBDOXHPf  
nEndPos[nEndPos.length-1] = nFileLength; W .c:Pulg  
} /FZ@Z]Q0G  
} z]NN ^pIa  
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ti  
//启动子线程 LZ@4,Uj  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; \mt0mv;c
 
for(int i=0;i<nStartPos.length;i++) d45JT?qg&  
{ ?1I0VA']  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Mb I';Mq  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), Tv;|K's'  
nStartPos,nEndPos,i); IEB|Y  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); O?ZCX_R:L  
fileSplitterFetch.start(); !50Fue^JM  
} =9oN#4mWK  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), s-Mzl?o  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); ?hu$  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", %h ?c  
nEndPos = " + nFileLength); ]i=\5FH e  
// fileSplitterFetch[nPos.length-1].start(); kpkN GQ2  
az(u=}  
<%(nF+rQA"  
//等待子线程结束 F:8cd^d~u  
//int count = 0; &}1PH%6  
//是否结束while循环 r+BPz%wM=O  
boolean breakWhile = false; 
& >AXB6  
;b[% L&  
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while(!bStop) &b 2Vt  
{ (~r"N?`  
write_nPos(); %} _{_Z  
Utility.sleep(500); o0>z6Ya<  
breakWhile = true; uC>X;<^  
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for(int i=0;i<nStartPos.length;i++) _RFTm.9&  
{ i0($@6Lh  
if(!fileSplitterFetch.bDownOver) T(<C8  
{ (R*K)(Nw[  
breakWhile = false; 3wEVjT-  
break; #:v e3gWl  
} *8zn\No<,  
} 7W[}7Y  
if(breakWhile) oEE*H2l\  
break; ^/wvHu[#  
1{oq8LB  
p;dH[NW  
//count++; r^?Qo  
//if(count>4) i
/nA(%_  
// siteStop(); g/b_\__A  
} @)>9l&  
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System.err.println("文件下载结束！"); ]7C=.'Y  
} D>u1ngu  
catch(Exception e){e.printStackTrace ();} *dn~-W.  
} \N\Jny  
]q0mo1-EZ!  
'H<0:bQ=I  
//获得文件长度 D7b<&D@  
public long getFileSize() :7t~p&J
 
{ ?|8H|LBIr  
int nFileLength = -1; M`$s dZ"  
try{  _2VL%  
URL url = new URL(siteInfoBean.getSSiteURL()); 3_W1)vd{
 
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); %aU4d e^  
httpConnection.setRequestProperty("User-Agent","NetFox"); |?CR|xqT  
zg!;g`Z@S  
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int responseCode=httpConnection.getResponseCode(); \4q% n  
if(responseCode>=400) (yv&&Jc  
{ (^'TT>2B  
processErrorCode(responseCode); RLN>*X  
return -2; //-2 represent access is error m$xL#omD  
} -MV</  
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String sHeader;
7z'l}*FRD  
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for(int i=1;;i++) LlP_`fA  
{ oHkF>B [  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); agqB#,i  
//Utility.log(in.readLine()); XSkN
9LqZ  
sHeader=httpConnection.getHeaderFieldKey(i); (MiEXU~v  
if(sHeader!=null) j?ihUNY!+  
{ k:nR'TI  
if(sHeader.equals("Content-Length")) ;7"}I  
{ 8BC F.y  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); JPQ[JD^]  
break; ID"'`DKxe  
} wSHE~Xx  
} ~9JU_R^%m  
else 6D,xs}j1  
break; UH1AT#?!W  
} Qi',[Xmf  
} 3A%/H`  
catch(IOException e){e.printStackTrace ();} `#&pB0.y  
catch(Exception e){e.printStackTrace ();} cg$@x\fJ  
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Utility.log(nFileLength); L-\-wXg%  
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return nFileLength; MhN)ZhsC  
} "$KU+?  
8;YeEW5  
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//保存下载信息（文件指针位置） $}0q=Lg%wv  
private void write_nPos() w?6"`Mo  
{ \xi wp.  
try{ `JyTS~v$  
output = new DataOutputStream(new FileOutputStream(tmpFile)); uM,bO*/f  
output.writeInt(nStartPos.length); S?Q4u!FC  
for(int i=0;i<nStartPos.length;i++) ZcgSVMqEX  
{ @e#eAJhU  
// output.writeLong(nPos); 6k"'3AKaR  
output.writeLong(fileSplitterFetch.nStartPos); keNPlK%>  
output.writeLong(fileSplitterFetch.nEndPos); mHjds77e  
} a<l(zJptG  
output.close(); qt5CoxeJ  
} O7|0t\)  
catch(IOException e){e.printStackTrace ();} j?D=Ij"o  
catch(Exception e){e.printStackTrace ();}
[$)C(1zY  
} [@Y<:6  
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//读取保存的下载信息（文件指针位置） elCDPZTf  
private void read_nPos() :Xc%_&)  
{ Mi&,64<  
try{ h(!x&kZq.  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); /%Lj$]S7[4  
int nCount = input.readInt(); L@Fw;G|%'  
nStartPos = new long[nCount]; Cdl#LVqs  
nEndPos = new long[nCount]; ; mF-y,E  
for(int i=0;i<nStartPos.length;i++) Mw2?U>h1  
{ u"r~5  
nStartPos = input.readLong(); tL(B gku9  
nEndPos = input.readLong(); ,:UoE  
} RWtD81(oC'  
input.close(); Yz;Hu$/  
} l`8S1~j
 
catch(IOException e){e.printStackTrace ();} 1a4HThDXP  
catch(Exception e){e.printStackTrace ();} ?ihkV?;)  
} '"LrGvkZ  
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+h^>?U,  
private void processErrorCode(int nErrorCode) | Zx  
{ X=)Ue  
System.err.println("Error Code : " + nErrorCode); S(Md  
} <U`lh
 
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//停止文件下载 :U!knb"/>  
public void siteStop() ez_qG=J .  
{ UR6.zE4=_  
bStop = true; ,<n >g;  
for(int i=0;i<nStartPos.length;i++) xlG/$`Ab  
fileSplitterFetch.splitterStop(); W(ITs}O  
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} T8E=}!68w}  
} uTGd{w@]0|  
//负责部分文件的抓取 1P(rgn:8e  
**FileSplitterFetch.java rLO1Sv  
*/ &1Dq3%$c  
package NetFox; @ qWgokf  
r# MJ  
T X.YTU  
import java.io.*; _cdrz)T  
import java.net.*; @ SaU2  
s7=CH  
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public class FileSplitterFetch extends Thread { B9pro%R1Bo  
j+AAhn  
n;8[WR)  
String sURL; //File URL q15t7-Z6  
long nStartPos; //File Snippet Start Position PP
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long nEndPos; //File Snippet End Position ogQY"c8  
int nThreadID; //Thread's ID ei)ljvvmHP  
boolean bDownOver = false; //Downing is over D+?/MrP  
boolean bStop = false; //Stop identical 4eTfb  
FileAccessI fileAccessI = null; //File Access interface
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}eh<F^  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException '"&M4.J{  
{ qeLfO  
this.sURL = sURL; x!GHUz*:uz  
this.nStartPos = nStart; (hej
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this.nEndPos = nEnd; r'xZF~}k"~  
nThreadID = id; QPf*!E  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 xo2PxU
O  
} WrH7tz  
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public void run() p2 u*{k{  
{ 9}4P%>_  
while(nStartPos < nEndPos && !bStop) ! iuDmL  
{ Qa@b-v'by  
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try{ 3Ob"R%Yo  
URL url = new URL(sURL); vI3L <[W  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); i"mN0%  
httpConnection.setRequestProperty("User-Agent","NetFox"); "L^]a$&  
String sProperty = "bytes="+nStartPos+"-"; a^_\#,}  
httpConnection.setRequestProperty("RANGE",sProperty); 0nUcUdIf+  
Utility.log(sProperty); @\0U`*]^)  
0`%eP5  
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InputStream input = httpConnection.getInputStream(); ?145^ w  
//logResponseHead(httpConnection); ;sd[Q01  
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byte[] b = new byte[1024]; BM5+;h !  
int nRead; <$bM*5sHF>  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) S}6Ty2.\  
{ "8}p>gS  
nStartPos += fileAccessI.write(b,0,nRead); As0E'n85  
//if(nThreadID == 1) D^ZG-WR  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); G"P@AOw  
} ggQ/_F8u  
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Utility.log("Thread " + nThreadID + " is over!"); C(-wA  
bDownOver = true; "D#+:ix8G|  
//nPos = fileAccessI.write (b,0,nRead); 91%QO?hz  
} BSt^QH-'  
catch(Exception e){e.printStackTrace ();} }jHS  
} MH@=Qqx#=t  
} KMC]<  
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//打印回应的头信息 6.%M:j00E  
public void logResponseHead(HttpURLConnection con) Xg+Eeg#  
{ kI7c22OJ  
for(int i=1;;i++) kT6h}d^/^  
{ jb;!"HC  
String header=con.getHeaderFieldKey(i); ]@E_Hx{
S  
if(header!=null) mQEE?/xX;  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); {*utke]}*  
Utility.log(header+" : "+con.getHeaderField(header)); n N.6?a  
else BUcPMF%\y:  
break; .*\TG/x  
} .Z%y16)T  
} 'fpm] *ig  
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public void splitterStop() l;{
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{ %N5gQXg  
bStop = true; )CgKZ"  
} @BQJKPF*  
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} >YG1sMV-J  
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/* <Y%km[Mh  
**FileAccess.java 38ac~1HjE  
*//文件访问(定位，写) Gy}WZ9{  
package NetFox; }!_x\eq^  
import java.io.*; Jr|"QRC  
~,#zdm1r@  
0 D^d-R,  
public class FileAccessI implements Serializable{ fny|^F]w  
RcJ.=?I!  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 bO8>w9MF  
RandomAccessFile oSavedFile; yM* CA,(c  
long nPos; G<1)NT\u  
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public FileAccessI() throws IOException z~Zu>Q1u[  
{ NTq#'O) f  
this("",0); 2@7f^be  
} O7<--  

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r 0mA  
public FileAccessI(String sName,long nPos) throws IOException m~7[fgN2  
{ yFt$L'#  
oSavedFile = new RandomAccessFile(sName,"rw"); )?_x$GKY  
this.nPos = nPos; `D *U@iJ  
oSavedFile.seek(nPos); _8zZ.~)  
} T}fH  
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;MSdTHN"  
public synchronized int write(byte[] b,int nStart,int nLen) 72Zp%a=  
{ ~>2DA$Ec  
int n = -1; ? 2#tIND  
try{ GFA D  
oSavedFile.write(b,nStart,nLen); W^U6O&-K  
n = nLen; kdmmfw  
} :Q\Es:y  
catch(IOException e) YoC{ t&rY  
{ Cn\5Vyrl  
e.printStackTrace (); @:2<cn`  
} r0MUv}p#|L  
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J  
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return n; Tt^PiaS!  
} /NE<?t N  
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} o`tOnwt
  
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/* BH`%3Mw  
**SiteInfoBean.java ;i;2c
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*/ ucP"<,a  
package NetFox; <H; z4  
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public class SiteInfoBean { aL)}S%5o?  
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private String sSiteURL; //Site's URL ^4G%*-   
private String sFilePath; //Saved File's Path G`;YB  
private String sFileName; //Saved File's Name GbFtX\s+5j  
private int nSplitter; //Count of Splited Downloading File ]t2zwHo#  
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3y#U|&]{  
public SiteInfoBean() <R;t>~8x  
{//nSplitter的缺省值为5 zcqv0lM '  
//default value of nSplitter is 5 [ GcH4E9r  
this("","","",5); aLo^f=S  
}
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#1,"^k^  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 0c-.h  
{ h)NZG6R  
sSiteURL= sURL; BB$(0mM^  
sFilePath = sPath; 
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sFileName = sName; HpXQD;  
this.nSplitter = nSpiltter; 9~rrN60Q  
;nSOeAF)Q  
. X:
 
} ]J '#KT{  
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public String getSSiteURL() AhyV  
{ UnE[FYx  
return sSiteURL; |>'.(
 
} $ [t7&e  
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public void setSSiteURL(String value) ~[N"Q|D3Y  
{
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sSiteURL = value; $>M-oNeC  
} w7#9t  
,P>xpfdK  
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public String getSFilePath() dvc=<!"'S  
{ #9/^)^k  
return sFilePath; ?'8('
]/  
} JmP[9"  
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 fOUW{s  
public void setSFilePath(String value) -qJ%31Mr#  
{ TXWYQ~]3w  
sFilePath = value; mVs<XnA47  
} &i5MRw_]]  
uHQf<R$:  
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public String getSFileName() W"meH~[Cp  
{ Gi+ZI{)  
return sFileName; W2`/z)[*>  
} yKhN1kY  
2=%R>&]*  
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public void setSFileName(String value) au;ZAXM|  
{ (DnrJ.QU}t  
sFileName = value; VpO+52&  
} \RF{ITV$kD  
xb (Cd  
;1MRBk,  
public int getNSplitter() |19zjhl  
{ 3UNmUDl[~  
return nSplitter; c$fYK  
} lP;X=
X>  
f\vy5''  
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public void setNSplitter(int nCount) #,5v#|u|7  
{ >D5WAQ>b  
nSplitter = nCount; |=rb#z&  
} 3;'RF#VL  
} DGJt$o=&@  
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<tn6=IV  
/* n7p,{KSQ  
**Utility.java xgQ&'&7l  
*/ ?l/+*/AR;  
package NetFox; /lb"g_  
h?-*SLT  
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public class Utility { ;!9-I%e  
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public Utility() "Nh}_jO  
{ j&|>Aa${  
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} "/g\?Nce  
8`Iz%rw&(J  
//线程睡眠 &<Iz?AVr  
public static void sleep(int nSecond) *Z}9S9YtN  
{ gNaB^IY  
try{ 8r\;8all  
Thread.sleep(nSecond); Y7GHIzX  
} @\?QZX(H  
catch(Exception e) "~,3gNTzV  
{ %SC%#_7  
e.printStackTrace (); 1$RUhxT  
} :YUQKy  
} GS qt:<Qs  
V+>.Gf  
//日志 pRc<U^Z.h  
public static void log(String sMsg) =%ry-n G  
{ P+gYLX8  
System.err.println(sMsg); N6<
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} \sc's7  
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public static void log(int sMsg) i7jI(VvB^  
{ "bmWr)  
System.err.println(sMsg); 
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} 3cB=9Y{<  
} 1<E:`,
Mn?  
UC*\3:>'n  
l}&&f8n  
/* zcCGREe=  
**TestMethod.java \eoJ6IRE\T  
*/ +sm9H"_0  
package NetFox; @q++eGm\Q  
c W^  
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public class TestMethod { c0.? d]  
!McRtxq?~  
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public TestMethod() Z_WJgH2c  
{ ///xx/weblogic60b2_win.exe XM:Y(#?l  
try{ qGhwbg  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ]s>y
se  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); +et)!2N  
SiteFileFetch fileFetch = new SiteFileFetch(bean); f~
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fileFetch.start(); ?3;0 SAh  
} x~n]r[!L  
catch(Exception e){e.printStackTrace ();} 3x3 =ke!  
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} X{-901J1  
R7NE=X4  
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public static void main(String[] args) p`T,VU&.  
{ P+(q38f[  
new TestMethod(); o`%;*tx  
} up )JU [  
} @3W
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