http断点续传简单实现（java)

/* 3%+!qm  
**SiteFileFetch.java HC=ZcK'W  
*/ cQ]c!G|a4  
package NetFox; k'_f?_PBu  
import java.io.*; h% KEg667  
import java.net.*; aAbA)'G  
@ x .`z
  
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public class SiteFileFetch extends Thread { c`/VYgcTqB  

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SiteInfoBean siteInfoBean = null; //文件信息Bean {i+ o'Lw  
long[] nStartPos; //开始位置 {sf ,(.W  
long[] nEndPos; //结束位置 HUMy\u84H  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 gV-*z}`U  
long nFileLength; //文件长度 q1q9W@H  
boolean bFirst = true; //是否第一次取文件 +;\w'dBi,  
boolean bStop = false; //停止标志 }K={HW1>  
File tmpFile; //文件下载的临时信息 'pT13RFD  
DataOutputStream output; //输出到文件的输出流 ? )h8uf4  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） c9G%;U)  
public SiteFileFetch(SiteInfoBean bean) throws IOException [-VK!9pQ  
{ $OG){'X  
siteInfoBean = bean; ,oUzaEX
 
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); Z.&/,UU:4  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ]tXIe?>9  
if(tmpFile.exists ()) h (q,T$7W  
{ +SF
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bFirst = false; $#-rOi /  
read_nPos(); (6B;  
} %g:'6%26  
else Y6&v&dA;  
{ 'YB[4Q /0  
nStartPos = new long[bean.getNSplitter()]; PJ;WNo8  
nEndPos = new long[bean.getNSplitter()]; 5+11J[~{  
} (c)=Do=  
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} `u}_O(A1pA  
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public void run() U#cGd\b  
{ #Lpw8b6  
//获得文件长度 [Q{\Ik  
//分割文件 ?)J/uU2w  
//实例FileSplitterFetch D{s87h  
//启动FileSplitterFetch线程 i%!<6K6UT  
//等待子线程返回 "5L?RkFi\  
try{ r-wCAk}m*?  
if(bFirst) %'ah,2a%  
{ 4~3 n =
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nFileLength = getFileSize(); *~g*J^R
}  
if(nFileLength == -1) 
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{ \wD/TLS}  
System.err.println("File Length is not known!"); CV\^gTPmx  
} EYn?YiVFU  
else if(nFileLength == -2) w$/lq~zU  
{ h$kz3r;b,"  
System.err.println("File is not access!"); o S=!6h  
} pHmqwB~|  
else iphC\*F  
{ iAZ8Y/  
for(int i=0;i<nStartPos.length;i++) '=vZAV`  
{ i_Hm?Bi!F  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); {PX&#,_  
} J/'Fj?
 
for(int i=0;i<nEndPos.length-1;i++) gkO^J{_@q  
{ ~1D^C |%  
nEndPos = nStartPos[i+1]; 9c[X[Qc  
} W,NqevXo:  
nEndPos[nEndPos.length-1] = nFileLength; `X5!s  
} >U,&V%y  
} ttUK~%wSx  
t*9 g
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I)V=$r{  
//启动子线程 g%l ,a3"  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 'o6}g p)  
for(int i=0;i<nStartPos.length;i++) ",3v%$>  
{ 6w7;  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Nna.NU1  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), kW)3naUf<  
nStartPos,nEndPos,i); u0Wt"d-=  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); <HoCt8>U  
fileSplitterFetch.start(); zI4rAsysL  
}  y Ne
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// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 5aizWz  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); T8a' 6otc  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", y<kUGsD  
nEndPos = " + nFileLength); &'$Bk5D@G  
// fileSplitterFetch[nPos.length-1].start(); $uHQl#!;  
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//等待子线程结束 v']_)  
//int count = 0; oh< -&3Jn  
//是否结束while循环 +#MXeUX"  
boolean breakWhile = false; O3@DU#N&s  
u
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while(!bStop) ;:D-}t;  
{ ;.uYWP|9  
write_nPos(); #+1|O;PB#  
Utility.sleep(500); -n.m "O3  
breakWhile = true; yuZLsH  
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for(int i=0;i<nStartPos.length;i++) n"htx|v  
{ OW@%H;b  
if(!fileSplitterFetch.bDownOver) Jz`jN~  
{ dhtH&:J<;  
breakWhile = false; Q4m> 3I  
break; 4j=3'Z|  
} M5h r0R{  
} IFTNr2I  
if(breakWhile) 20V~?xs~  
break; = g{I`u  
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:s_>y_=g  
//count++; K>DN6{hnV;  
//if(count>4) Cq!eAc  
// siteStop(); FE\E%_K'n7  
} kw$7G1Q  
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System.err.println("文件下载结束！"); rJ Jx8)M  
} Cjf[]aNJe`  
catch(Exception e){e.printStackTrace ();} 9VxM1-8Gs  
} p-}X=O$  

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//获得文件长度 Ei_~K';  
public long getFileSize() cF8 2wg  
{ _/LGGt4&%  
int nFileLength = -1; f\hMTebma$  
try{ ]?4;Lw  
URL url = new URL(siteInfoBean.getSSiteURL()); ~o!-[  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Vx$;wU Y  
httpConnection.setRequestProperty("User-Agent","NetFox"); %Xd*2q4*  
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int responseCode=httpConnection.getResponseCode(); n{;Q"\*Sg  
if(responseCode>=400) 0#8  
{ 0(7 IsG=t  
processErrorCode(responseCode); >}V?GK36  
return -2; //-2 represent access is error tVRN3fJH  
} `3F#k[IR  
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String sHeader; 8z1z<\  
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for(int i=1;;i++) 5*$yY-A  
{ O=2|'L'h!  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); I_<VGUk  
//Utility.log(in.readLine()); 6j(/uF4!#  
sHeader=httpConnection.getHeaderFieldKey(i); vUpAW[[  
if(sHeader!=null) ^!1!l-  
{ ">bhxXeiN  
if(sHeader.equals("Content-Length")) ZIx-mC5  
{ P4[kW}R  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); >$
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break; oN1D&*  
} Wi&v?nm  
} XR+ SjCA  
else -$Z1X_~;)<  
break; !rUP&DA  
} l53i {o  
} >_?i)%+)  
catch(IOException e){e.printStackTrace ();} TwkT|Piw S  
catch(Exception e){e.printStackTrace ();} 4`,(*igEv  
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Utility.log(nFileLength); 0#]fEi  
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return nFileLength; 072C!F  
} }emUpju<C  
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//保存下载信息（文件指针位置） 1q7&WG  
private void write_nPos() <VxA&bb7c  
{ P-\f-FS  
try{ -+WAaJ(b  
output = new DataOutputStream(new FileOutputStream(tmpFile)); {zb'Z Yz  
output.writeInt(nStartPos.length); i|^Q{3?o#  
for(int i=0;i<nStartPos.length;i++) !UT'4Fs  
{ ;@ePu  
// output.writeLong(nPos); -8n1y[  
output.writeLong(fileSplitterFetch.nStartPos); aN0[6+KP;  
output.writeLong(fileSplitterFetch.nEndPos); $f =`fPo  
} ]@$^Ju
,  
output.close(); cLZ D\1Mt  
} P=n_wE  
catch(IOException e){e.printStackTrace ();} Yqs=jTq`{  
catch(Exception e){e.printStackTrace ();} ETHcZ  
} z&%i
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//读取保存的下载信息（文件指针位置） r{R-X3s
 
private void read_nPos() P~\rP6 ;  
{ MRLiiIrq,5  
try{ B"GC|}N)v  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); :'p)xw4K|  
int nCount = input.readInt(); *J-pAN  
nStartPos = new long[nCount]; G8M~}I/)  
nEndPos = new long[nCount]; 3:WqUb\QK  
for(int i=0;i<nStartPos.length;i++) %OBW/Ti  
{ 0<m7:D Gd  
nStartPos = input.readLong(); &BPYlfB1  
nEndPos = input.readLong(); gRY#pRT6d  
} << 6GE  
input.close(); Cf[tNq  
} roS" q~GS,  
catch(IOException e){e.printStackTrace ();} v,-Tk=qP  
catch(Exception e){e.printStackTrace ();} v?`R8  
} Q#p)?:o/  
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private void processErrorCode(int nErrorCode) `yfZ{<  
{ 0nwi5  
System.err.println("Error Code : " + nErrorCode); <j'K7We/tP  
} rbd0`J9fq  
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u nv:sV#b  
//停止文件下载 JG!B3^qB  
public void siteStop() >+%#m'Y&&  
{ ~wa4kS<>  
bStop = true; 8:TX9`,  
for(int i=0;i<nStartPos.length;i++) 7:UeE~uB:  
fileSplitterFetch.splitterStop(); d7V/#34  
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} jW:7PS  
} NljpkeX'  
//负责部分文件的抓取 (ks>F=vk*  
**FileSplitterFetch.java I
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*/ 8&@=Anc&q  
package NetFox; [5P-K{Ko  
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import java.io.*; TZgtu+&  
import java.net.*; E^-c
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public class FileSplitterFetch extends Thread { +p\E%<uQ
 
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String sURL; //File URL ? $B4'wc5  
long nStartPos; //File Snippet Start Position Km5_P##  
long nEndPos; //File Snippet End Position Gld~Gy
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int nThreadID; //Thread's ID @)b'3~D  
boolean bDownOver = false; //Downing is over ko}& X=  
boolean bStop = false; //Stop identical ;<FAcR  
FileAccessI fileAccessI = null; //File Access interface %j&vV>2  
+-!3ruwSn  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException :BxO6@>Xc  
{ H1-DK+Q:  
this.sURL = sURL; BwH
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this.nStartPos = nStart; )9Q+07  
this.nEndPos = nEnd; ,kJ'_mq  
nThreadID = id; ,l&?%H9q  
fileAccessI = new FileAccessI(sName,nStartPos);//定位  P@O_MT  
} =i)%AnZ^9  
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public void run() P`Zon  
{ u$JAjA
 
while(nStartPos < nEndPos && !bStop) "(mJupI  
{ I"x'  
*8)?ZZMM  
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try{ oywPPVxj  
URL url = new URL(sURL); v/ry" W  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ranem0KQ)]  
httpConnection.setRequestProperty("User-Agent","NetFox"); phDIUhL$z  
String sProperty = "bytes="+nStartPos+"-"; 1L<TzQ  
httpConnection.setRequestProperty("RANGE",sProperty); "
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Utility.log(sProperty); "W5MZ  
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InputStream input = httpConnection.getInputStream(); j}Tv/O,f  
//logResponseHead(httpConnection); @*hv|zjs  
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byte[] b = new byte[1024]; AON |b\?  
int nRead; >)K3  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) !/}4_s`,  
{ 6Jgl"Jw8  
nStartPos += fileAccessI.write(b,0,nRead); rRevyT
s  
//if(nThreadID == 1) 8J,^O04<  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ^$oa`B^2JM  
} Apu-9|oP  
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Utility.log("Thread " + nThreadID + " is over!"); C6gSj1  
bDownOver = true; 6O/L~Z*t  
//nPos = fileAccessI.write (b,0,nRead); ~;(\a@ _  
} tM5(&cQ!d  
catch(Exception e){e.printStackTrace ();} z 4}"oQk:r  
} 7O)ATb#up  
} }6l:'nW  
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//打印回应的头信息 4s m [y8  
public void logResponseHead(HttpURLConnection con) Y5E0n(Z  
{ *l d)nH{  
for(int i=1;;i++) VY/r2o#  
{ /,:cbpHsu  
String header=con.getHeaderFieldKey(i); /%m?D o  
if(header!=null) nWelM2  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); }'<Z&NW6  
Utility.log(header+" : "+con.getHeaderField(header)); moM'RO,M  
else K14.!m  
break; +Vg(2Xt  
} bN?*p($/  
} L@MCB-@V  
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public void splitterStop() 9ZOQNN<ex  
{ _ (b4|hJ'  
bStop = true; kYS#P(1  
} /;_$:`|/  
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} @{V`g8P>  
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/* i.9}bw 9u@  
**FileAccess.java ';eAaDM  
*//文件访问(定位，写) .dzw5R&  
package NetFox; 5@.8O
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import java.io.*; KUW )F  
<> =(BAw  
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public class FileAccessI implements Serializable{ qw4wg9w5p  
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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 {(-TWh7V  
RandomAccessFile oSavedFile; *)r_Y|vg  
long nPos; (q"S0{  
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public FileAccessI() throws IOException qUe2(/TQu  
{ PJb/tKC  
this("",0); f:q2JgX  
} QdZHIgh`i  
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public FileAccessI(String sName,long nPos) throws IOException \(Dm\7Q.  
{ $xvwnbq#y  
oSavedFile = new RandomAccessFile(sName,"rw"); -XECYwTh  
this.nPos = nPos; +L?;g pVE&  
oSavedFile.seek(nPos); = r=/L  
} B%Oi1bO  
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public synchronized int write(byte[] b,int nStart,int nLen) .O5|d+S  
{ #;2mP6a[  
int n = -1; W[!bF'-10  
try{ };(2 na  
oSavedFile.write(b,nStart,nLen); 1%.CtTi  
n = nLen; ~O;?;@  
} -?T|1FA,  
catch(IOException e) ^-#:T  
{ vO{[P#L}  
e.printStackTrace (); 1iY?t  
} Z_<Wr7D  
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return n; c1%ki%J#  
} 1 xrmmK  
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} uN9.U  _  
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/* nNM)rW  
**SiteInfoBean.java "^pF2JI  
*/ 5tbi};  
package NetFox; A-hWg;  

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public class SiteInfoBean { =>C3IR/  
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private String sSiteURL; //Site's URL [0NH#88ym<  
private String sFilePath; //Saved File's Path <CP't[  
private String sFileName; //Saved File's Name >>7m'-k%D  
private int nSplitter; //Count of Splited Downloading File $_Lcw"xO  
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public SiteInfoBean() C"}]PW  
{//nSplitter的缺省值为5 /Bnh%6#ab  
//default value of nSplitter is 5 IW|1)8d  
this("","","",5); yw?UA  
} +QrbW  
9/GC8*+  
 - zEQ/6  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) }WkR-5N  
{ T8QRO%t  
sSiteURL= sURL; :'dH)yO  
sFilePath = sPath; W{'tS{  
sFileName = sName; ! +Hc(i  
this.nSplitter = nSpiltter; !Ys.KDL  
x:Tm4V{  
PsMCs|*  
} _1Iw"K49Qx  
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public String getSSiteURL() ~_L_un.R  
{ Jqi^Z*PuX  
return sSiteURL; ?<$DQ%bf  
} 0jwex  
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n47v5.Wn  
public void setSSiteURL(String value) b{d@:"  
{ t?kb
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sSiteURL = value; n|iO)L\9aB  
} ^RS`q+g  
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public String getSFilePath() q:v&wb%  
{ RnkrI~x  
return sFilePath; xBcE>^{1.  
} X6@G)68  
Ik|nL#JH]  
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public void setSFilePath(String value) PM%Gsy]q  
{ *9Nq^+  
sFilePath = value; Yf(QU`w_  
} -z4
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public String getSFileName() o;@T6-VH  
{ jz;"]k  
return sFileName; Dos`lh  
} F\;G'dm  
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public void setSFileName(String value) E|d 8vt  
{ +Te;L
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sFileName = value; sk_Q\0a  
} EWg\\90  
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public int getNSplitter() }A%Sx!7
~  
{ +H~})PeQ  
return nSplitter; l;SqjkN  
} anTS8b   
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public void setNSplitter(int nCount) .qCD(XZ+  
{ Ytnk^/Z1L  
nSplitter = nCount; AA um1xl  
} Rx 4 ;X  
} *1KrI9i  
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/* /r Hd9^Y  
**Utility.java Hb;#aXHSd  
*/ F\Gi;6a  
package NetFox; :)\<  
$>;U^-#3  
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public class Utility { _$?SKid|o  
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public Utility() ^MGgFS]G  
{ qqSf17sW  
~%QVjzMC  
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} COa"zg  
8rXu^  
//线程睡眠 H1>}E5^?  
public static void sleep(int nSecond) ~ b;%J:  
{ v'*#P7%Kf  
try{ g,!6,v@  
Thread.sleep(nSecond); 1#9Q1@'OS  
} MGd 7Ont  
catch(Exception e) k!K}<sX2  
{ shO
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e.printStackTrace (); d3# >\QCD9  
} eEIa=MB*  
} d3AOuVUf  
:Uf\r `a9  
//日志 \4`~J@5Y  
public static void log(String sMsg) u+GtH;<;  
{ ;5A  
System.err.println(sMsg); k"V| f&  
} bBBW7',[a  
#]'#\d#i  
%B$~yx3#  
public static void log(int sMsg) MS-}IHO  
{ vcnUb$%  
System.err.println(sMsg); k1HukGa  
} pzP~,cdf  
} iXt >!f*  
gf^"sfNk  
@54D<Lj  
/* hTZaI*  
**TestMethod.java y_:i'Ri.  
*/ C#`VVtei  
package NetFox; Lf|5miO  
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public class TestMethod { oO-kO!59y  
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public TestMethod() /AX1LYlr  
{ ///xx/weblogic60b2_win.exe 8S[`(] )  
try{ z^to"j  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); Iq`:h&'!L  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); A"8`5qa  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ,c#=qb8""  
fileFetch.start(); 8*;88vW"2  
} sG`:mc~0  
catch(Exception e){e.printStackTrace ();} JW;DA E<  
,lLkAd?q  
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} K'EGm #I  
)2KQZMtgm]  
|-l)$i@  
public static void main(String[] args) %Ji@\|Zkf  
{ 8|uFW7Q  
new TestMethod(); ^T83E}  
} ?r"'JO.w  
} K r9 P#Y  
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