http断点续传简单实现（java)

/* +FTc/r  
**SiteFileFetch.java )5Khl"6!z  
*/ K&L!O3#(  
package NetFox; _ >OP  
import java.io.*; ANhtz1Fl  
import java.net.*; K|P0nJT  
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public class SiteFileFetch extends Thread { 2zBk#c+
  
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SiteInfoBean siteInfoBean = null; //文件信息Bean @k?vbq  
long[] nStartPos; //开始位置 QHk\Z  
long[] nEndPos; //结束位置 Dl;hOHvKk  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 7AqgX0)  
long nFileLength; //文件长度 Tru{8]uMH  
boolean bFirst = true; //是否第一次取文件 7Q .Su  
boolean bStop = false; //停止标志 \
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File tmpFile; //文件下载的临时信息 r<`:Q]  
DataOutputStream output; //输出到文件的输出流 d9f7 &  
+K4XMf  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） ]at$ohS  
public SiteFileFetch(SiteInfoBean bean) throws IOException (g##wa)L  
{ a1cX+{W  
siteInfoBean = bean; |`T(:ZKXZ2  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); CY1WT  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info");
+Iyyk02V  
if(tmpFile.exists ()) &`D$w?beg  
{ U zy@\  
bFirst = false; MKHnA|uQ](  
read_nPos(); ]&*POri&  
} 9p{4-]  
else #t+?eye~  
{ G]K1X"W?  
nStartPos = new long[bean.getNSplitter()]; #I/P9)4  
nEndPos = new long[bean.getNSplitter()]; Qa{5]+E  
} 1V%tev9a  
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} U4!bW  
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public void run() F\:
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{ |a(KVo  
//获得文件长度 VeA@HC`?"  
//分割文件 ^)AECn  
//实例FileSplitterFetch V*p[6{
U0  
//启动FileSplitterFetch线程 n ay\)  
//等待子线程返回 h,{m{Xh  
try{ RHF"$6EAFG  
if(bFirst) uJ% <+I  
{ 7>Scf  
nFileLength = getFileSize(); 22l'kvo4"  
if(nFileLength == -1) !dqC6a  
{ Kr
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System.err.println("File Length is not known!"); Fy=GU<&AI  
} EmNVQ1w  
else if(nFileLength == -2) Za|7gt];l  
{ m eF7[>!U  
System.err.println("File is not access!"); */aY$aWv  
} .n 9.y8C  
else V._-iw]v  
{ 9[eiN  
for(int i=0;i<nStartPos.length;i++) $@AJg  
{ GkAd"<B  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); -X.#Y6(  
} ~;"eNg{T  
for(int i=0;i<nEndPos.length-1;i++) (}A$4?  
{ ,1]UOQ>AP  
nEndPos = nStartPos[i+1]; '}OdF*L  
} TFSdb\g  
nEndPos[nEndPos.length-1] = nFileLength; #7uH>\r  
} +25}X{r$_  
} #VQZ"7nI@  
VfnL-bDGV  
>.?yz
  
//启动子线程 r_7%|T8  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; P;5)Net1X  
for(int i=0;i<nStartPos.length;i++) ,ri&zbB  
{ t^#1=nK  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), +t7HlAXB#  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), IFLphm
5  
nStartPos,nEndPos,i); N8sT?  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); > X~\(|EM  
fileSplitterFetch.start(); xQ9t1b|{e  
} q!z?Tn#!jd  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), s< tG  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); uKx:7"KD  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", }8O9WS  
nEndPos = " + nFileLength); }&v}S6T  
// fileSplitterFetch[nPos.length-1].start(); L$ T2 bul  
"aGmv9\  
rZUTBLZ`j  
//等待子线程结束 &9e  
//int count = 0; v`h>5#_[  
//是否结束while循环 d?oXz|;H(  
boolean breakWhile = false; (B#FLoK  
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while(!bStop) gwaSgV$z  
{ 4MC]s~n  
write_nPos(); KloX.
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Utility.sleep(500); xW"O|x$6  
breakWhile = true; S^s-m
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Ar%*NxX  
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for(int i=0;i<nStartPos.length;i++) '(K4@[3t  
{ dsIbr"m  
if(!fileSplitterFetch.bDownOver) eF3NyL(A  
{ B)q}]Qn  
breakWhile = false; a^_K@  
break; U&3!=|j  
} Y{dSQ|xz^  
} uQdeKp4(  
if(breakWhile) 7w73,r/D8A  
break; e1[ReZW  
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|q4=*Xq  
//count++; g$Tsht(rHD  
//if(count>4) TOiLv.Dor  
// siteStop(); qO@vXuul,  
} [n9l[dN  
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System.err.println("文件下载结束！"); a`Bp^(f}  
} AO<T6VK  
catch(Exception e){e.printStackTrace ();} nOC\ =<Nsg  
} V lZ+x)E  
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//获得文件长度 EWJB/iED  
public long getFileSize() *twGIX
 
{ CH7a4qL`  
int nFileLength = -1; AMrYT+1  
try{ $NCvF'  
URL url = new URL(siteInfoBean.getSSiteURL()); /l`zZ>  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); s}JifY`  
httpConnection.setRequestProperty("User-Agent","NetFox"); 'v'[_(pq  
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int responseCode=httpConnection.getResponseCode(); s:{[Y7\?  
if(responseCode>=400) 9DBX.|  
{ ij:xr% FJ  
processErrorCode(responseCode); 'e:4  
return -2; //-2 represent access is error ]MCH]/  
} <.`i,|?MHS  
9@1n:X  
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String sHeader; L#`X ]E  
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*  
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for(int i=1;;i++) i~x]!!  
{ 6$#,$aO  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); Km
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//Utility.log(in.readLine()); 5k
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sHeader=httpConnection.getHeaderFieldKey(i); Gd!_9S`68  
if(sHeader!=null) km>ZhsqD  
{ /Ey%aA4v  
if(sHeader.equals("Content-Length")) QXj#Brp  
{ ~{DJ,(N"n  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); {"jtR<{)  
break; l_k:OZ  
}  XY)X-K$  
} Q'U!  
else a[;
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break; 
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} AXcmN  
} 0SD'&   
catch(IOException e){e.printStackTrace ();} Xf ^_y(?  
catch(Exception e){e.printStackTrace ();} 5[2kk5,  
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Utility.log(nFileLength); )h ,v(Rxa  
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return nFileLength; @nqM
#  
} [<r.M<3  
]9_t
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//保存下载信息（文件指针位置） ]U@~vA#''  
private void write_nPos() q1HJ_y  
{ KrP?*yk  
try{ "T[BSj?E  
output = new DataOutputStream(new FileOutputStream(tmpFile)); #^9bBF/  
output.writeInt(nStartPos.length); NJJ=c
h  
for(int i=0;i<nStartPos.length;i++) %,$xmoj9O]  
{ m|JA}&A  
// output.writeLong(nPos); @GXKqi  
output.writeLong(fileSplitterFetch.nStartPos); 4SUzR\  
output.writeLong(fileSplitterFetch.nEndPos); T5`ML'Dej  
} G9&2s%lu.e  
output.close(); I>rTqOK  
} IqlCl>_j  
catch(IOException e){e.printStackTrace ();} [qY yr
  
catch(Exception e){e.printStackTrace ();} =XYc2.t  
} 1z|bQ,5  
xA^E+f:W_  
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//读取保存的下载信息（文件指针位置）  G>?kskm  
private void read_nPos() V~jp  
{ ,XscO7  
try{ dU_;2d$  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); FD!8
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int nCount = input.readInt(); 6yYjZ<  
nStartPos = new long[nCount]; %qsl<
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nEndPos = new long[nCount]; ] 0L
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for(int i=0;i<nStartPos.length;i++) nGX3_-U4  
{ {nM1$  
nStartPos = input.readLong(); |[r7
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nEndPos = input.readLong(); Xm<_!=  
} FaJK R  
input.close(); *]/iL#  
} f4,|D |  
catch(IOException e){e.printStackTrace ();} pC,Z=+:  
catch(Exception e){e.printStackTrace ();} J e|  
} 3ouy-SQ  
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private void processErrorCode(int nErrorCode) %yc-D]P/  
{ ?=)lbSu K  
System.err.println("Error Code : " + nErrorCode); Y8%l)g  
} $XcH
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//停止文件下载 iM7^  
public void siteStop() CN` ~DD{  
{ S;t`C~l
\  
bStop = true; Y>C05?>  
for(int i=0;i<nStartPos.length;i++) 9%21Q>Y?b  
fileSplitterFetch.splitterStop(); g :B4zlKG  
)^P54_2  
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} jLn#%Ia}  
} AMB{Fssz  
//负责部分文件的抓取 sWse (_2  
**FileSplitterFetch.java  mVS^HQ:  
*/ y5c\\e  
package NetFox; ,%A|:T]  
#mJRL[V5^  
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import java.io.*; uDJ;GD[yc  
import java.net.*; >Mh\jt\  
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public class FileSplitterFetch extends Thread { H_XspiB@  
*MlEfmB(  
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String sURL; //File URL g/68& M  
long nStartPos; //File Snippet Start Position gREk,4DAv  
long nEndPos; //File Snippet End Position 'Qg!ww7O  
int nThreadID; //Thread's ID g-!  
boolean bDownOver = false; //Downing is over *@^@7`W  
boolean bStop = false; //Stop identical K:XP;#OsP  
FileAccessI fileAccessI = null; //File Access interface [;yH.wn#5  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 8kcMgCO  
{ 9iJ$M!  
this.sURL = sURL; a6xo U;T  
this.nStartPos = nStart; :J@3:+sr  
this.nEndPos = nEnd; dPpJDY0  
nThreadID = id; [\eVX`it  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 mA.,.<xE@  
} 6
~jAh@-  
1_!?wMo:f  
#Vmf 6  
public void run() V'RbTFb9Z  
{ mrsmul{  
while(nStartPos < nEndPos && !bStop) ZDL1H3;R  
{ +w.$"dF!  
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31 <0Nw;l  
try{ ?+yM3As9_V  
URL url = new URL(sURL); N<
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); IUEpE9_  
httpConnection.setRequestProperty("User-Agent","NetFox"); #^]vhnbN  
String sProperty = "bytes="+nStartPos+"-"; lw~ V  
httpConnection.setRequestProperty("RANGE",sProperty); Xm|~1 k_3  
Utility.log(sProperty); ){)
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InputStream input = httpConnection.getInputStream(); ' =5B  
//logResponseHead(httpConnection); smQl^ 6a  
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byte[] b = new byte[1024]; HnjA78%i  
int nRead; djnES,^%9  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) !"yr;t>|Zb  
{ 7T6Zlp  
nStartPos += fileAccessI.write(b,0,nRead); 5y g`

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//if(nThreadID == 1) $v#`2S(7  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); &L+.5i  
} 7q;`~tbC  
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Utility.log("Thread " + nThreadID + " is over!"); (y6}xOa(  
bDownOver = true; :Cx|(+T  
//nPos = fileAccessI.write (b,0,nRead); }@t"B9D  
} VoUo!t:(+  
catch(Exception e){e.printStackTrace ();} QD3tM5(Yr  
} P%Vq#5  
} a:l-cZ/!  
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;/Z-|+!IJt  
//打印回应的头信息 0,m]W)  
public void logResponseHead(HttpURLConnection con) "@hd\w{.  
{ #\=7
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for(int i=1;;i++) _A!Fp0}`  
{ "9c=kqkX  
String header=con.getHeaderFieldKey(i); b+:J?MR;}  
if(header!=null) .QKyB>s  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); RjvW*'2G  
Utility.log(header+" : "+con.getHeaderField(header)); =9 )k:S(  
else ZQf
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break; y9d"sqyh  
} `#l3a
 
} (57!{[J  
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public void splitterStop() pw4^E|X  
{ itirh"[  
bStop = true; ,>b>I#{  
} *IWW,@0  
8 I_  
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} 7M7Ir\d0lp  
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/* &*7KQd  
**FileAccess.java 9NU0K2S  
*//文件访问(定位，写) Kw?3joy  
package NetFox; /u.ZvY3,  
import java.io.*; 3BCD0 %8  
E}S%yD[  
D@68_sn  
public class FileAccessI implements Serializable{ O8bxd6xb  
KfBT'6t  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 J=$\-  
RandomAccessFile oSavedFile; 3Y2~HuM  
long nPos; <C(o0u&/  
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public FileAccessI() throws IOException 
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{ :(X3?%  
this("",0); "EMW'>&m  
} Rb0I7~Z%'d  
0]
  
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public FileAccessI(String sName,long nPos) throws IOException :[
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{ n8F5z|/  
oSavedFile = new RandomAccessFile(sName,"rw"); @ G)yz!H  
this.nPos = nPos; ;H~<.
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oSavedFile.seek(nPos); NvJ5[W  
} ~o%igJ }.C  
xH*X5?  
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public synchronized int write(byte[] b,int nStart,int nLen) qJdlZW<  
{ )'U0n`=  
int n = -1; A/'po_'uy  
try{ ]1<GZ`  
oSavedFile.write(b,nStart,nLen); 9/(jY$Ar  
n = nLen; 3)W zX  
} h5@GeYda  
catch(IOException e) gd*Gn"  
{ b@;Wh-{d  
e.printStackTrace (); _#:/ ~Jp  
} h.PBe  
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return n; TMj;NSc3  
} I
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} 'q)g,2B%  
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/* =,(TP  
**SiteInfoBean.java MY@&^71i4  
*/ G*@!M%/  
package NetFox; _
2!8,MX  
VWE>w|'  
;[Mvk6^'R  
public class SiteInfoBean { h0rPMd(K
 
8XB[CbO  
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private String sSiteURL; //Site's URL rKrHd  
private String sFilePath; //Saved File's Path f 5v&4  
private String sFileName; //Saved File's Name k9;^|Cm k  
private int nSplitter; //Count of Splited Downloading File c;$4}U4  
h<Aq|*  
ai/|qYf  
public SiteInfoBean() _?I{>:!|  
{//nSplitter的缺省值为5 cl%+m  
//default value of nSplitter is 5 V]p{jLG  
this("","","",5); Mu?|<#s  
} hL&$` Q  
aaR& -M@  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 4a-JC"  
{ =n5'~1?X?  
sSiteURL= sURL; 4KM-$h,4O  
sFilePath = sPath; PW5]+ |#  
sFileName = sName; Cd}^&z  
this.nSplitter = nSpiltter; \_ 3>v5k|  
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} 9D3{[  
/kbU<  
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public String getSSiteURL() f82%nT  
{ [k6I#v<&  
return sSiteURL; SeD}H=,@  
} -&5YRfr!  
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public void setSSiteURL(String value) K($l>PB,y@  
{ l_^SU8i57  
sSiteURL = value; 1[!v{F%]  
} !!y]pMjJa@  
t}YcB`q)  
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public String getSFilePath() vk92j?  
{ b6N[t _,  
return sFilePath; p{g4`o  
} ??,[-Oi  
}Kp!,  
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public void setSFilePath(String value) ,CfslhO{j  
{ V*giF`gq  
sFilePath = value; Q/+`9z+c  
} Dr3_MWJ+  
,vR?iNd:q[  
8 "l PiW3  
public String getSFileName() m\6/:~qWW  
{ }/cReX,so  
return sFileName; Y[{:?i~9,  
} SYCL\b  
-&1(~7  
nkW})LyB\  
public void setSFileName(String value) ]`/>hH>+~9  
{ .XJ'2yKof  
sFileName = value; 7n7Xyb  
} )+G"57p  
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public int getNSplitter() {R}F4k  
{ DB/~Z  
return nSplitter; mmTpF]t ?`  
} 7Sx|n}a-3  
@J[@Pu O  
:@(('X(".  
public void setNSplitter(int nCount) gP2zDI   
{ tT}b_r7h(1  
nSplitter = nCount; jn<?,UABD  
} uX_H;,n  
} o(*\MTt?  
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/* 5h5izA'0'  
**Utility.java v e&d"8+]  
*/ 7>N~l  
package NetFox;  /8x';hQ  
azPH~'E'  
{^N,=m\  
public class Utility { u8Ys2KLpL  
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public Utility() G4* LO  
{ #Rw!a#CX.  
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} h `Lr5)B'  
S!(3-{nC  
//线程睡眠 n'~==2  
public static void sleep(int nSecond) 7he73  
{ 1m*)MZ)  
try{ EA"hie7  
Thread.sleep(nSecond); lLD
#|T3  
} \V? .^/  
catch(Exception e) mY"7/dw<v  
{ 8A>OQR  
e.printStackTrace (); #l=yD]tPU  
} 1djZ5`+  
} 6{h\CU}"  
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//日志 "#1\uoH  
public static void log(String sMsg) e?>  
{ vV,TT%J8D  
System.err.println(sMsg); y]db]pP5  
} FZ"n6hWA  
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public static void log(int sMsg) RkYdK$|K  
{ Y%KowgP\  
System.err.println(sMsg); `"5Ub,~  
} +A}t_u3<  
} fap`;AuwK  
r w?wi}}gn  
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/* q0.!T0i  
**TestMethod.java
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*/ ^'`b\$km-0  
package NetFox; )|~K&qn`  
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public class TestMethod { *u},(4Qf  
m<CrkKfpG  
f:>y'#P  
public TestMethod() 69c4bT:b"  
{ ///xx/weblogic60b2_win.exe hb`9Vn\-E  
try{ \|PiQy*_?  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); .9J^\%JD  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); y``\^F  
SiteFileFetch fileFetch = new SiteFileFetch(bean);
JRl=j2z  
fileFetch.start(); H$`U] =s|  
} \c_g9Iqa  
catch(Exception e){e.printStackTrace ();} ;s+/'(*  
OSBR2Z;=  
M':-f3aT%  
} V:\:[KcL^  
csP4Oq\g[  
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public static void main(String[] args) lc,k-}n  
{ K#R]of~/  
new TestMethod(); ;hT3N UCA  
} 2F4<3k!&  
} WtOjPW  
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