http断点续传简单实现（java)

/* |8_JY2 R  
**SiteFileFetch.java %bXx!x8(  
*/ < O*6T%;  
package NetFox; ;d.K_P  
import java.io.*; Q }
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import java.net.*; C=Fzu&N}  
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public class SiteFileFetch extends Thread { $ 0|a;  
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SiteInfoBean siteInfoBean = null; //文件信息Bean +H/jK@  
long[] nStartPos; //开始位置 7
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long[] nEndPos; //结束位置 n]W_e  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 K?x,T8<aW  
long nFileLength; //文件长度 SM0M%  
boolean bFirst = true; //是否第一次取文件 >r/rc`Q  
boolean bStop = false; //停止标志 XhzGLYb~I`  
File tmpFile; //文件下载的临时信息 Rn%N&1 Ef  
DataOutputStream output; //输出到文件的输出流 Ko>&)%))$X  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） }0hL~i  
public SiteFileFetch(SiteInfoBean bean) throws IOException R$k
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{ =tTqN+4  
siteInfoBean = bean; 2],_^XBvB  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); p4>$z& _  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); #h!*dj"  
if(tmpFile.exists ()) \/7i-B]G7  
{ Z[!d*O%R_  
bFirst = false; Ey{%XR+*;  
read_nPos(); 1iT\df  
} 23(=Xp3;>  
else 73A)lU.  
{ iJFs0?*  
nStartPos = new long[bean.getNSplitter()]; .ujT!{>v/  
nEndPos = new long[bean.getNSplitter()]; yj6@7@l>A  
} X#a`K]!B  
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} G}@#u9  
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public void run() x Ha=3n  
{ !%<
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//获得文件长度 kU5.iK'  
//分割文件 4Q=ftY<  
//实例FileSplitterFetch 3Rg}+[b  
//启动FileSplitterFetch线程 fyz nuUl  
//等待子线程返回 egR9AEJvz  
try{
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if(bFirst) s}&bJ"!Z  
{ RIM`omM  
nFileLength = getFileSize(); "yziXT@V  
if(nFileLength == -1) F-(dRSDNM  
{ T`/IO.2  
System.err.println("File Length is not known!"); O/%< }3Sq  
} j;yf8Nf  
else if(nFileLength == -2) fa*Cpt:  
{ "o!{51!'  
System.err.println("File is not access!"); +,+vkpL-%  
} WE}kTq
  
else Hs"(@eDV&J  
{ ;T]d MfO  
for(int i=0;i<nStartPos.length;i++) 5 v^yQ<70  
{ $!vxVs9n  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); h)lPi   
} b/$km?R  
for(int i=0;i<nEndPos.length-1;i++) :vx$vZb  
{ A|#`k{+1-  
nEndPos = nStartPos[i+1]; L(;WxHL  
} ,iNv'  
nEndPos[nEndPos.length-1] = nFileLength; U;_[b"SW%  
} 4Ph0:^i_  
} vP%tk s+.  
~jU/<~s  
\u-0v.+|  
//启动子线程 Mj>}zbpk/  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; "}WJd$
 
for(int i=0;i<nStartPos.length;i++) o 6{\Zzp  
{ Bsf7mcXz7z  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), F+UG'4%  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), W^,S6!  
nStartPos,nEndPos,i); }*]B-\>  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); v1U?&C  
fileSplitterFetch.start(); )/ Ud^wi  
} rr`;W}3  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), d|9b~_::V  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); { kSf{>Ia  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 0oA{Jix  
nEndPos = " + nFileLength); ;?fS(Vz~  
// fileSplitterFetch[nPos.length-1].start(); .@)mxC:\K9  
lA!"z~03*  
5cr(S~Q;  
//等待子线程结束 &hHW3Q(1  
//int count = 0; t2
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//是否结束while循环 I:&/`K4,x,  
boolean breakWhile = false; snM Z0W  
R9We/FhOY  
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while(!bStop) @K223?c8l  
{ [$(%dV6O  
write_nPos(); h-a!q7]l  
Utility.sleep(500); rj]F87"  
breakWhile = true; PupM/?57  
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for(int i=0;i<nStartPos.length;i++) iO/XhSD  
{ |LG4=j.l  
if(!fileSplitterFetch.bDownOver) k;PA
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{ 2A`A\19t  
breakWhile = false; ^Jp&H\gI.  
break; (;x3} ]  
} @tohNO>  
} TQX)?^Ft  
if(breakWhile) B3m_D"?  
break; b2(RpY
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:,;K>l^U  
//count++; w1x" c>1C  
//if(count>4) 'k;4j|<  
// siteStop(); ~fl@ 2  
} _CBWb  
`=+^|Y}  
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System.err.println("文件下载结束！");
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} d4:
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catch(Exception e){e.printStackTrace ();} CQ7{1,?2  
} G
2 ]H6G$M  
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_
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//获得文件长度 'oNO-)p\#!  
public long getFileSize() DBLk!~IF  
{ *,C(\!b !?  
int nFileLength = -1; 7 J^rv9i4  
try{ mvW%  
URL url = new URL(siteInfoBean.getSSiteURL()); w&$d* E  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); #&<)! YY5  
httpConnection.setRequestProperty("User-Agent","NetFox"); \]Kh[z0"  
3uU]kD^  
mC&=X6Q]  
int responseCode=httpConnection.getResponseCode(); uJx"W  
if(responseCode>=400) yNW\?Z$@q  
{ uY_SU-v  
processErrorCode(responseCode); m p<1yY]  
return -2; //-2 represent access is error @WH@^u  
} (Q[fS:U  
76tdJ!4Z  
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String sHeader; /[:dp<  
#Lsnr.80  
O1%pxX'`S  
for(int i=1;;i++) !Bz0^1,L  
{ Y3kA?p0  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); dca;'$  
//Utility.log(in.readLine()); ]A FI\$qB\  
sHeader=httpConnection.getHeaderFieldKey(i); ELrsx{p:  
if(sHeader!=null) rn DCqv!'P  
{ HCK|~k  
if(sHeader.equals("Content-Length")) n%h^o  
{ i 8!zu!-0  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); Z UKf`m[  
break; g71[6<D  
} rG?>
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} mOo`ZcTU  
else pY4}>ju(g  
break; ]&Z))H  
} A,i75kd  
} iu**`WjI\  
catch(IOException e){e.printStackTrace ();} qQ\Y/}F  
catch(Exception e){e.printStackTrace ();} %6Q4yk  
3X9b2RY*L/  
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Utility.log(nFileLength); PFUO8>!pA\  
}:: S0l  
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return nFileLength; 5<
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} _X~87  
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//保存下载信息（文件指针位置） )
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private void write_nPos() ys_`e  
{ B1]bRxwn?  
try{  zYXV;  
output = new DataOutputStream(new FileOutputStream(tmpFile)); f}guv~K  
output.writeInt(nStartPos.length); =U|N=/y#hJ  
for(int i=0;i<nStartPos.length;i++) 1+b{}d  
{ ' |-JWH  
// output.writeLong(nPos); e\O/H<  
output.writeLong(fileSplitterFetch.nStartPos); '=][J_
 
output.writeLong(fileSplitterFetch.nEndPos); ~['Kgh_;  
} /iG*)6*^k  
output.close(); Pxn,Qw*  
} P"sA  
catch(IOException e){e.printStackTrace ();} p=/m  
catch(Exception e){e.printStackTrace ();} XdH\OJ  
} Q{e\}wN  
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//读取保存的下载信息（文件指针位置） zy*/T>{#  
private void read_nPos() -}K<ni6  
{ 9&<x17'  
try{ B|o2K}%f  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); BL@:!t  
int nCount = input.readInt(); T843":  
nStartPos = new long[nCount]; F~ Lx|)0M  
nEndPos = new long[nCount]; Em[DHfu1Q  
for(int i=0;i<nStartPos.length;i++) JNcYJ[wqv  
{ j}b\Z9)!  
nStartPos = input.readLong(); QMv@:Eo  
nEndPos = input.readLong();
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} Uye|9/w8 !  
input.close(); W0I#\b18  
} z;@*r}H  
catch(IOException e){e.printStackTrace ();} 9Fn\FYUq  
catch(Exception e){e.printStackTrace ();} !8`3GX:B_  
} SkU9ON  
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private void processErrorCode(int nErrorCode) RK w$-7O  
{ 8Lw B B  
System.err.println("Error Code : " + nErrorCode); %`Z!4L  
} NnVnUgx  
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phO;c;
y}  
//停止文件下载 E*i#?u  
public void siteStop() _X?^Cy  
{ ctcS:<r/3@  
bStop = true; V|\7')Qq  
for(int i=0;i<nStartPos.length;i++) qZ@s#UiB  
fileSplitterFetch.splitterStop(); w3jO6*_ M  
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=B.F;40  
} j65<8svl  
} I%urz!CNE*  
//负责部分文件的抓取 \d::l{VB  
**FileSplitterFetch.java J90v!p-  
*/ YJ$1N!rG  
package NetFox; m,fAeln  
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import java.io.*; 6;b~Ht  
import java.net.*; ]l8^KX'  

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public class FileSplitterFetch extends Thread { (XoH,K?{z  
+>JjvYx}\  
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String sURL; //File URL bV/jfV"%E  
long nStartPos; //File Snippet Start Position Jaz?Ys|S  
long nEndPos; //File Snippet End Position p,"g+ MwP  
int nThreadID; //Thread's ID 6AocmR0D'  
boolean bDownOver = false; //Downing is over EYA,hc  
boolean bStop = false; //Stop identical .bio7c6  
FileAccessI fileAccessI = null; //File Access interface 1^gl}^|B  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException $MJm*6h  
{ 5h;+Ky!I  
this.sURL = sURL; ~Jf{4*>y  
this.nStartPos = nStart; k1Q?'<`  
this.nEndPos = nEnd; j&k6O1_  
nThreadID = id; 0Fu~
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fileAccessI = new FileAccessI(sName,nStartPos);//定位 4>J   
} y+7PwBo%e  
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public void run() {s;U~!3aY  
{ ElUEteZ  
while(nStartPos < nEndPos && !bStop) 6uR^%W8]  
{ %j7XEh<'  
@V!r"Bkg.  
bV"G~3COy  
try{ p)+k=b  
URL url = new URL(sURL); n0is\ZK 0  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); m)oJFF  
httpConnection.setRequestProperty("User-Agent","NetFox"); [n}T|<  
String sProperty = "bytes="+nStartPos+"-"; 4WK3.6GN  
httpConnection.setRequestProperty("RANGE",sProperty); {5  sO  
Utility.log(sProperty); $
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c [5KG}  
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InputStream input = httpConnection.getInputStream(); A`R{m0A  
//logResponseHead(httpConnection); jmeRrnC}  
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c%qv9  
byte[] b = new byte[1024]; --DoB=5%8  
int nRead; ,cqF3  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) Q$fmD  
{ A@Dw<.&_I  
nStartPos += fileAccessI.write(b,0,nRead); sq'Pyz[[  
//if(nThreadID == 1) YID4w7|  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); c_>f0i  
} ?R$&Xe!5  
#^]n0!  
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Utility.log("Thread " + nThreadID + " is over!"); x,'!eCKN  
bDownOver = true; z<5m fAm  
//nPos = fileAccessI.write (b,0,nRead); =Qn ;_+Ct  
} $.bBFWk  
catch(Exception e){e.printStackTrace ();} 9H%X2#:fH  
} &y#r;L<9  
} VJS8)oI~  
+$Rt+S BD  
)(@Hd  
//打印回应的头信息 7hcNf,  
public void logResponseHead(HttpURLConnection con) e#k<d-sf6  
{ dh $bfAb  
for(int i=1;;i++) h?pkE  
{ GQ-Rtn4v  
String header=con.getHeaderFieldKey(i); \7*`}&  
if(header!=null) e zOj+vz  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); }[xs~!2F  
Utility.log(header+" : "+con.getHeaderField(header)); <'g:T
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else ?C/Te)  
break; LlSZr)X  
} Hik3wPnp  
} m?&1yU9  
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public void splitterStop() plZ>03(6Q  
{ CJ++?hB]X  
bStop = true;
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} =J~ x  
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} 0c#/hFn  
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/* OiP!vn}k  
**FileAccess.java n-@j5w+k4  
*//文件访问(定位，写) -xP!"  
package NetFox; 4f;HQ-Iv  
import java.io.*; {.?/)  
71{p+3Z&  
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public class FileAccessI implements Serializable{ J^g!++|2P  
|.3DD"*  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 S)/_muP  
RandomAccessFile oSavedFile; |u;v27  
long nPos; qQH]`#P  
@qHNE,K  
6!(@@^7{*  
public FileAccessI() throws IOException Q0ON9gqqv  
{ \0gM o&  
this("",0); #KiRfx4G  
} }3L@J8:D"  
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public FileAccessI(String sName,long nPos) throws IOException @W9x$  
{ IOV(seEY  
oSavedFile = new RandomAccessFile(sName,"rw"); ]S5JUAGkE*  
this.nPos = nPos; y?q*WUh  
oSavedFile.seek(nPos); $81*^  
} pLzk   
}_68j8`  
~Onoe $A[<  
public synchronized int write(byte[] b,int nStart,int nLen) z'EajBB\f  
{ c
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int n = -1; 0a"c2J  
try{ TG5XSy  
oSavedFile.write(b,nStart,nLen); P
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n = nLen; ]:~OG
@(  
} wg]j+r@  
catch(IOException e) ~7Tc$ "I  
{ =pC3~-;3  
e.printStackTrace (); X7g1:L1Ys  
} G"XVn~]  
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return n; [bk?!0]aV  
} KFwzy U"  
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|1>*;\o-  
} B[4KX  
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8zR~d%pK  
/* k'5?M  
**SiteInfoBean.java ksN+?E4w  
*/ }I2@%tt?  
package NetFox; fOMW"myQ  
9b*nLyYVz  
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public class SiteInfoBean { %&Q$dzgb_  
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private String sSiteURL; //Site's URL BFOq8}fX2  
private String sFilePath; //Saved File's Path jE/AA!DC#  
private String sFileName; //Saved File's Name vt9)pMs  
private int nSplitter; //Count of Splited Downloading File e;[F\ov%  
Pw61_ZZ4B\  
@>U-t{W  
public SiteInfoBean() KSNPkd6  
{//nSplitter的缺省值为5 N D2L_!g:(  
//default value of nSplitter is 5 H?X|(r|+  
this("","","",5); TBT:/Vfun  
} ={xE!"  
7!JQB
 
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) *N<&GH(j  
{ O|M{-)  
sSiteURL= sURL; BjzPz  
sFilePath = sPath; .ODR]7{  
sFileName = sName; q*7VqB  
this.nSplitter = nSpiltter; 5w@4:$=I  
:HwA 5Z#  
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} <U\B!fO'  
gY8>6'~mS  
!_cg\KU#  
public String getSSiteURL() {R?U.eJW  
{ tyqT  
return sSiteURL; hK,Sf ;5V  
} pxh"B\"4*  
VQS~\:1  
~15N7=wCM  
public void setSSiteURL(String value) 0p!>JQ]m  
{ n4#;k=mA  
sSiteURL = value; n$ou- Q  
} 4s*ZS}] o  
S-|)QGxV6  
,^. 88<  
public String getSFilePath() k+ty>bP=  
{ D,k"PaLP  
return sFilePath; Y/ .Z.FD`  
} Us0EG\Y  
Z Z:}AQ  
PU^l.  
public void setSFilePath(String value) n74V|b6W  
{ ='
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sFilePath = value; zp%Cr.)$  
} TO?R({yx*  
7OJ'){R$  
n+A?"`6*#  
public String getSFileName() 
&RnTzqv  
{ n' q4  
return sFileName; S9~+c  
} &b%zQ4%d-`  
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+2&@x=xy  
public void setSFileName(String value) 3GhRWB-U  
{ !~rY1T~  
sFileName = value; NP/Gn6fr  
} f m)pulz  
E{Ov>osq  
"q.\>MCv  
public int getNSplitter() J2xw) +  
{ ~ijVmWNk  
return nSplitter;
B=^)Ub5'  
} hUp.tK:X7o  
P>NF.BCq  
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public void setNSplitter(int nCount) K+3IWZ&+dG  
{ 9{5&^RbCp  
nSplitter = nCount; }n3/vlW9  
} |m^k_d!d  
} G2Qlt@.T  
|n,<1QY  
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/* y+c|vdW%  
**Utility.java {_ i\f ]L  
*/ Kk-S}.E  
package NetFox; 4;0lvDD  
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P'Ux%Q+B>  
public class Utility { UJCYs`y  
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lE&&_INHQ  
public Utility() AK*LyR?  
{ t>`asL  
~nh:s|l6%M  
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} S/e2P|}  
C(#u[8  
//线程睡眠 %}Ss
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public static void sleep(int nSecond) x:7b/j-  
{ !`,Sfqij  
try{ Af'" 6BS  
Thread.sleep(nSecond); ]v]qChZHd  
} jU9$Ehg I  
catch(Exception e) 34%RZG_o'  
{ odjT:Vr  
e.printStackTrace (); ;7E7!t^  
} CsoiyY -2  
} i*Sqda $  
7 /VK##z  
//日志 b`~p.c%(  
public static void log(String sMsg) w&o&jAb-M  
{ $Bs {u=+w  
System.err.println(sMsg); )ttUWy$w  
} $m].8?  
HUv/ ~^<  
C9n?@D;S  
public static void log(int sMsg) }%'?p<^M  
{ hRrn$BdLX  
System.err.println(sMsg); XINu=N(g  
} g1W.mAA3B  
} #><.oreXq  
'E/^8md>  
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/* C/vIEYG4  
**TestMethod.java $o0iLFIX/  
*/ bzuEfFaL  
package NetFox; Sjyoc<Uo  
V'8s8H  
<SgM@0m  
public class TestMethod { `_`QxM  
`.FF!P:{C*  
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public TestMethod() [<g?WPCcC  
{ ///xx/weblogic60b2_win.exe c#Sa]n  
try{ Lvq>v0|  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); QS` PpyBkd  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); F`Q[6"<a  
SiteFileFetch fileFetch = new SiteFileFetch(bean); uW@oyZ

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fileFetch.start(); zQ@I}K t  
} =|3
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catch(Exception e){e.printStackTrace ();} T92UeG  
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} |)b6>.^  
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public static void main(String[] args) vq^f}id  
{ +eyc`J  
new TestMethod(); s:/8[(A  
} 0=* 8
  
} Ma.`A  
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