http断点续传简单实现（java)

/* >0T Za  
**SiteFileFetch.java Onw24&  
*/ 'F7VM?HBfg  
package NetFox; %t[K36,p  
import java.io.*; [q3+$W \r  
import java.net.*; >)3VbO  
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public class SiteFileFetch extends Thread { !M^\f N1  
*Ru2:}?MpS  
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SiteInfoBean siteInfoBean = null; //文件信息Bean
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long[] nStartPos; //开始位置 `)tA YH  
long[] nEndPos; //结束位置 HTR1)b  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 ~K`1  
long nFileLength; //文件长度 bjzx!OCpV  
boolean bFirst = true; //是否第一次取文件 Ow)R|/e/  
boolean bStop = false; //停止标志 R&Ci/  
File tmpFile; //文件下载的临时信息 no|Gq>Xp  
DataOutputStream output; //输出到文件的输出流 TY6 rwU  
|[LE9Lq/  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） jyQVSQs  
public SiteFileFetch(SiteInfoBean bean) throws IOException ,C:o`fQ\  
{ $3#%aA!(#  
siteInfoBean = bean; C{&)(#*L  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); K'Spbn!nC  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 0H+c4IW  
if(tmpFile.exists ()) #8U
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{ "i%jQL'.  
bFirst = false; LS6ry,D"7  
read_nPos(); -l[jEJS}  
} (}jL_E  
else 9I kUZW  
{ jCQho-1QN  
nStartPos = new long[bean.getNSplitter()]; Z Xb}R^O-  
nEndPos = new long[bean.getNSplitter()]; Y|RdzCM  
} hVf^  
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} |_nC6;  
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public void run() PpFsp( )x  
{ ! Rvn'|!  
//获得文件长度 e1uMR-Q  
//分割文件 2LK]Q/WG,+  
//实例FileSplitterFetch ]3+``vL  
//启动FileSplitterFetch线程 
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//等待子线程返回 [g
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try{ k%Eh{dA  
if(bFirst) i|4_m  
{ xYwkFB$$*  
nFileLength = getFileSize(); 2-s7cXs  
if(nFileLength == -1) OZT^\Ky_l  
{ sg$4G:l  
System.err.println("File Length is not known!"); [#Fg\2bq_y  
} ,LZ(^u  
else if(nFileLength == -2) 5~U:@Tp  
{
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System.err.println("File is not access!"); 74]a/'
4  
} @d)LRw.I  
else ohsH2]C  
{ ,R~eY?{a  
for(int i=0;i<nStartPos.length;i++) .YC;zn^  
{ -|[~sj-p  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ?Pnx~m{%*  
} fYn{QS?  
for(int i=0;i<nEndPos.length-1;i++) QS;F+cmTh  
{ :H\&2/j  
nEndPos = nStartPos[i+1]; :~33U)?{T  
} $T/#1w P  
nEndPos[nEndPos.length-1] = nFileLength; = t-fYV  
} [-58Ezyr  
} $?$9y^\  
)E~_rDTl  
QkE,T0,/?h  
//启动子线程 Ut_mrb+W  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; !.X_/$c  
for(int i=0;i<nStartPos.length;i++) @'gl~J7  
{ UE;Bb
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fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), w+Vk3c5uI)  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), v F[CWV.  
nStartPos,nEndPos,i); x~Agm_Tu+'  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 6RP+4c  
fileSplitterFetch.start(); Mr.JLW  
} L$}g3{  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), PGY9*0n  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); }$:#+ (17  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", u<kD}  
nEndPos = " + nFileLength); XN(tcdCG  
// fileSplitterFetch[nPos.length-1].start(); >2Ca5C  
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|z+9km7,  
//等待子线程结束 +f|6AeE  
//int count = 0; IfB/O.;Kz  
//是否结束while循环 XNlhu^jh  
boolean breakWhile = false; C fSl 54  
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9gR.RwR X  
while(!bStop) !o<ICHHH  
{ "&
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write_nPos(); A
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Utility.sleep(500); K7Gm-=%  
breakWhile = true; }9=2g`2Q  
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for(int i=0;i<nStartPos.length;i++) 8nsZ+,@+[  
{ ]738Z/)^  
if(!fileSplitterFetch.bDownOver) 3cHtf  
{ M5 `m.n<  
breakWhile = false; ^]7,1dH}M  
break; Qg>0G%cXU  
} 4Cd#sQ  
} 4oN${7k0  
if(breakWhile) v~`*(Hh  
break; s ^3[W0hL  
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//count++; Of#K:`1@  
//if(count>4) esteFLm`6  
// siteStop(); z^3Q.4Qc6^  
} CpSK(2j  
)7w@E$l"  
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System.err.println("文件下载结束！"); ctK65h{Eo  
} )2]a8JVf  
catch(Exception e){e.printStackTrace ();} RF!'K ko  
} ZYDWv/u  
]<+3Vw  
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//获得文件长度 FW5}oD(H  
public long getFileSize() yp?w3|`4;  
{ hv{87`L'K(  
int nFileLength = -1; pX^=be_  
try{ [,GU5,o  
URL url = new URL(siteInfoBean.getSSiteURL()); b"&E,=L  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); y<v|X2  
httpConnection.setRequestProperty("User-Agent","NetFox"); T g{UK  
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int responseCode=httpConnection.getResponseCode(); {=6)SBjf  
if(responseCode>=400) B5 &YL  
{ Br&^09S  
processErrorCode(responseCode); *:[b'D!A  
return -2; //-2 represent access is error (:l(_-O  
} 5pmQp}}R  
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!pl_Ao~(  
String sHeader; Rhv%6ekI  
}>,CUz  
p>&S7M/9  
for(int i=1;;i++) -tMA  
{ b@!:=_Mr  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); jJc07r']  
//Utility.log(in.readLine()); F:,#?  
sHeader=httpConnection.getHeaderFieldKey(i); >"b[r  
if(sHeader!=null) 8(^ ,r#Gy  
{ kJ__:rS(T_  
if(sHeader.equals("Content-Length")) hm6pxFkX_  
{ 'mUI-1GkT  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); jNIUsM8e  
break; j6}$+!E  
} %!yxC  
} D$mf5G &  
else @C07k^j=U  
break; ",QPb3  
} >HX)MwAP  
} _<3r'Y,  
catch(IOException e){e.printStackTrace ();} M_; w%FV  
catch(Exception e){e.printStackTrace ();} $Ba`VGP>)3  
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Utility.log(nFileLength); 58PKx5`D  
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return nFileLength; 4/f[`].#W  
} l<Lz{)OR  
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//保存下载信息（文件指针位置） wM0E%6 P  
private void write_nPos() =nw0# '  
{ u X>PefR  
try{ '(
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output = new DataOutputStream(new FileOutputStream(tmpFile)); 4Lw'v:(  
output.writeInt(nStartPos.length); 5c)<'EP  
for(int i=0;i<nStartPos.length;i++) YMK>+y[+4  
{ 9GaL0OWo  
// output.writeLong(nPos); {n6\g]p3  
output.writeLong(fileSplitterFetch.nStartPos); mgxz1d  
output.writeLong(fileSplitterFetch.nEndPos); p8_2y~!  
} juXC?2c  
output.close(); 1P \up  
} /XN*)m  
catch(IOException e){e.printStackTrace ();} n-W?Z'H{r  
catch(Exception e){e.printStackTrace ();} [{?;c+[  
} *n,UOHlO  
 J(^ >?d'  
69rwX"^  
//读取保存的下载信息（文件指针位置） D*qzNT@`LR  
private void read_nPos() v23TL
  
{ y6\ [1nZ  
try{ {aT92-D3  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); FJW`$5?  
int nCount = input.readInt(); -h=c=P  
nStartPos = new long[nCount]; tfsh!)u?  
nEndPos = new long[nCount]; &
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for(int i=0;i<nStartPos.length;i++) tgc@7  
{ ea>[BB3#  
nStartPos = input.readLong(); wD}EW  
nEndPos = input.readLong(); bIq-1 Y(  
} <jg8y'm@0  
input.close(); |fx#KNPf]  
} +H[Q~P8'[  
catch(IOException e){e.printStackTrace ();} H8(C>w-'  
catch(Exception e){e.printStackTrace ();} 1ZKz3)K  
} C9GU6Ao  
tjt=N\;  
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private void processErrorCode(int nErrorCode) A7.JFf>  
{ rpx0|{m  
System.err.println("Error Code : " + nErrorCode); f x%z|K  
} EmF]W+!z%  
1 iquHn  
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//停止文件下载 cj`#Tg.  
public void siteStop() JE/l#Q!  
{ O3!Ouh&  
bStop = true; 2YaTT& J  
for(int i=0;i<nStartPos.length;i++) ~>4@;  
fileSplitterFetch.splitterStop(); t&8<k+m  
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Z"
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} tnA_!$Y a  
} -aC!0O y`  
//负责部分文件的抓取 *1R##9\jU7  
**FileSplitterFetch.java {V{0^T-  
*/ xh=FkY&d  
package NetFox; gD,A9a(3  
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3
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import java.io.*; >t2]Ssi(  
import java.net.*; M^Q&A R'F  
buc,M@>  
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public class FileSplitterFetch extends Thread { 4V!1/w  
zsHG=Ee*  
k\Yu5)  
String sURL; //File URL Qfwwh`;  
long nStartPos; //File Snippet Start Position ;L#LDk{Za  
long nEndPos; //File Snippet End Position zojuH8  
int nThreadID; //Thread's ID |2WxcW]U.%  
boolean bDownOver = false; //Downing is over &@-1"-H  
boolean bStop = false; //Stop identical ,<`|-oa  
FileAccessI fileAccessI = null; //File Access interface pg5@lC]J  
*Pa2bY3:  
&n}8Uw0440  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException QJ[(Y@ O6a  
{ C]aOgt/U  
this.sURL = sURL; h9,wiT  
this.nStartPos = nStart; l2z`<2mp  
this.nEndPos = nEnd; AM1/\R  
nThreadID = id; }G"r3*  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 Q>cL?ie  
} #nxER  
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public void run() /h{go]&N
b  
{ *>?):-9"6N  
while(nStartPos < nEndPos && !bStop) ;LwFbkOuU  
{ fRZUY<t  
\VoB=Ac&  
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try{ ?6_"nT*}  
URL url = new URL(sURL); ~gSF@tz@  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); MYur3lj%_  
httpConnection.setRequestProperty("User-Agent","NetFox"); FKDamHL<  
String sProperty = "bytes="+nStartPos+"-"; t;Fbt("]:  
httpConnection.setRequestProperty("RANGE",sProperty); COxZ
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Utility.log(sProperty); @n5;|`)\  
+!mNm?H[!  
7I@9v=xV  
InputStream input = httpConnection.getInputStream(); Qi(e`(,'  
//logResponseHead(httpConnection); /1[}G
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byte[] b = new byte[1024]; 9q@z
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int nRead; !UUmy% 9  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) awj}K  
{ xfbK eS8  
nStartPos += fileAccessI.write(b,0,nRead); bxPY'&  
//if(nThreadID == 1) > Z.TM=qj  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Eg287B  
} ?NL&x  
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4\ uZKv@,  
Utility.log("Thread " + nThreadID + " is over!"); <lg"M;&Ht  
bDownOver = true; aPcGI  
//nPos = fileAccessI.write (b,0,nRead); {9m!UlTtw  
} ~@)-qV^~  
catch(Exception e){e.printStackTrace ();} Vz=j)[  
} n $D}0wSM/  
} XL"v21X  
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s>9z+;~!  
//打印回应的头信息 %l9WZ*yZ`2  
public void logResponseHead(HttpURLConnection con) F3H:I"4  
{ _oMs `"4K  
for(int i=1;;i++) 5JXzfc9rL  
{ 7(nz<z p  
String header=con.getHeaderFieldKey(i); <:kTTye|  
if(header!=null) ]$XBd{\D{  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); cNuuz
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Utility.log(header+" : "+con.getHeaderField(header)); '6dD^0dZ  
else xv(xweV+d  
break; softfjl&l  
} '.}6]l  
} yNb

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public void splitterStop() iuH8
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{ qxg7cj2  
bStop = true; 7~%  
} F$sF
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} mZ& \3m=  
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/ut~jf`  
/* UG^?a  
**FileAccess.java *x#&[>  
*//文件访问(定位，写) /pSUn"3  
package NetFox; /v|68x6  
import java.io.*; ba:mO$  
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709Uv5  
public class FileAccessI implements Serializable{ t
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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 2y .-4?e  
RandomAccessFile oSavedFile; h
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long nPos; j 44bF/  
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public FileAccessI() throws IOException [M8qU$&?]  
{ #%=vy\r  
this("",0); e{rHO,#A>  
} 3ZJagJ\O  
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public FileAccessI(String sName,long nPos) throws IOException wr;|\<c  
{ 8n."
5,P  
oSavedFile = new RandomAccessFile(sName,"rw"); ixI5Xd<  
this.nPos = nPos; _sf0{/< )  
oSavedFile.seek(nPos); 6{Cu~G{]N  
} J:TI>*tn  
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public synchronized int write(byte[] b,int nStart,int nLen) u;'<- _
 
{ *nUpO]  
int n = -1; c|;|%"Mk  
try{ !Z0rTC3d  
oSavedFile.write(b,nStart,nLen); r{6B+3J  
n = nLen; 9'/|?I  
} OV@h$fg  
catch(IOException e) l
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{ Z+h70,|  
e.printStackTrace (); z"P,=M6De  
} Gad2EEZ%0  
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YK=#$,6  
return n; 65e Wu=T  
} ;P0Y6v3  
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} lj SR?:\  
uI:3$  
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/* SUnmp  
**SiteInfoBean.java r1az=$  
*/ >.nt'BQ  
package NetFox; "<n"A7e  
/x8C70W^  
*O}'2Ht6\  
public class SiteInfoBean { M]/wei"X  
V]S06>P  
w2C!>fJ]1  
private String sSiteURL; //Site's URL Mpl,}Q!c  
private String sFilePath; //Saved File's Path @vYN7  
private String sFileName; //Saved File's Name E.Q} \E  
private int nSplitter; //Count of Splited Downloading File
Z :i"|;  
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public SiteInfoBean() 4Uy>#IL  
{//nSplitter的缺省值为5 $j4?'-i=e  
//default value of nSplitter is 5 Kg0\Pvg8?T  
this("","","",5); [m+O0VK$  
} ]v,y(yl  
]!Aze^7;  
~JmxW;|_x)  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) \g6 #MNW  
{ O@(.ei*HJ!  
sSiteURL= sURL; }${ZI  
sFilePath = sPath; ALt";8Oa  
sFileName = sName; ~\s &]L  
this.nSplitter = nSpiltter; .2S
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} wb Tg  
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nF[eb{GR`  
public String getSSiteURL() Z a y'/b  
{ qA_DQ):  
return sSiteURL; /:L&uqA  
} cZK?kz_Y  
n,'AFb4AF  
w.F3o4YP  
public void setSSiteURL(String value) u'n%BVt
 
{ xXh]z|  
sSiteURL = value; q\pc2Lh?^  
} 4hr+GO@o(  
g8*|"{  
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public String getSFilePath() 5xV/&N  
{ 2iINQK$  
return sFilePath; I$qtfGr  
} McI4oD~"  
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public void setSFilePath(String value) ez9M]! 8Lt  
{ fq!6#Usf;i  
sFilePath = value; vlKKP

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} eDZ3SIZ  
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yaGVY*M0  
public String getSFileName() .BTT*vL-  
{ W p* v Vv  
return sFileName; ^?VT y5yp  
} \Nn%*?f  
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public void setSFileName(String value) tZ2iSc  
{ 30v1VLR_)  
sFileName = value;
b,V=B{(~  
} oDDH;Q"M(  
5GpK
X  
2Yf;b9-k  
public int getNSplitter() %+JTQy  
{ EHM 7=|#  
return nSplitter; cmLu T/oV  
} Ah
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c oz}VMp  
Z#V\[  
public void setNSplitter(int nCount) ng6p#F,3  
{ X)+sHcE~#  
nSplitter = nCount; vPq\reKe  
} PvCE}bY{}  
} v2z
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)bg,rESM  
Jg6[/7*m  
/* x%7x^]$  
**Utility.java f6C+2L+Hr  
*/ Re ur#K  
package NetFox; kqB00 ;  
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*==nOO9G  
public class Utility { 'V{
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public Utility() F!t13%yeu?  
{ laJ%fBWmbi  
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9!C?2*>A P  
} Z'kYf  
d> AmM!J  
//线程睡眠 iR=aYT~  
public static void sleep(int nSecond) ~ZC=!|Q#  
{ /T(~T  
try{ k&;L(D  
Thread.sleep(nSecond); xfSvvCy  
} *9&YkVw~  
catch(Exception e) w`_9*AF9  
{ -"L6^IH7  
e.printStackTrace (); &y?B&4|hM  
} 8TvPCZ$x  
} ~PAn _]Z  
MUl+Oy>  
//日志 b=l}|)a  
public static void log(String sMsg) pQ\ [F  
{ fX|,s2-FW  
System.err.println(sMsg); l.)!jWY  
} AVZ@?aJgF  
jO.E#Ei}~  
Q;M\P/f  
public static void log(int sMsg) m"}G-#  
{ C5 !n{  
System.err.println(sMsg); @vh>GiR){  
} (8R M|&  
} l<6/ADuS  
Y{@[)M{<  
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/* |Ay#0uQ5Y  
**TestMethod.java Br??Gdd  
*/ ?xs0J  
package NetFox; Ymvd=F   
96j2D8=w  
,#haai(  
public class TestMethod { V [>5  
:b-(@a7>  
OR{"9)I  
public TestMethod() M XQ7%G  
{ ///xx/weblogic60b2_win.exe \/Y<.#?_  
try{ ,{at?y*  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); iiscm\  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); DdgFBO  
SiteFileFetch fileFetch = new SiteFileFetch(bean); h]$zub
 
fileFetch.start(); &y+eE?j  
} p04w83 jX  
catch(Exception e){e.printStackTrace ();} V5w^Le_^  
lHXH03  
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} q[ZYlF,Ho  
 ovO^uWz`  
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public static void main(String[] args) Hua8/:![+  
{ h,g~J-x`|  
new TestMethod(); ZAwl,N){
 
} w@We,FUJN  
} z_TK (;j  
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