http断点续传简单实现（java)

/* s1e:v+B]  
**SiteFileFetch.java 4H|(c[K;  
*/ xj[(P$,P  
package NetFox; xia|+  
import java.io.*; ap{
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import java.net.*; O9g{+e`  
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public class SiteFileFetch extends Thread { TpHfS]W-P  
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SiteInfoBean siteInfoBean = null; //文件信息Bean *&d<yJM`b  
long[] nStartPos; //开始位置 (ZY@$''  
long[] nEndPos; //结束位置 V^\8BVw  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 [-)r5Dsdq  
long nFileLength; //文件长度 i} N8(B(  
boolean bFirst = true; //是否第一次取文件 HO[wTB|D]  
boolean bStop = false; //停止标志 ' 4ER00  
File tmpFile; //文件下载的临时信息 ET[kpL  
DataOutputStream output; //输出到文件的输出流 TOoQZTI  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） k%E2n:|*  
public SiteFileFetch(SiteInfoBean bean) throws IOException 04*6(L)h*  
{ KID,|K  
siteInfoBean = bean; A0Zt8>
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//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); bzvh%RsW  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); E@P %v{)  
if(tmpFile.exists ()) Qu7T[<  
{ >P/][MT  
bFirst = false; xY$iz)^0&  
read_nPos(); @"o@}9=d  
} kWNV%RlSx  
else &[At`Nw71  
{ 1?| flK  
nStartPos = new long[bean.getNSplitter()]; 0 s70r  
nEndPos = new long[bean.getNSplitter()]; 2hee./F`  
} wN2QK6Oc  
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} Y& F=t/U2  
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public void run() (I@rLvZr{  
{ eQVZO>)P1+  
//获得文件长度 J@OB`2?Zv  
//分割文件 [xT:]Pw}  
//实例FileSplitterFetch RGK8'i/X  
//启动FileSplitterFetch线程 a&k_=/X&  
//等待子线程返回 (%U@3._  
try{ 5bA)j!#)|X  
if(bFirst) CEC nq3  
{ fPR$kch  
nFileLength = getFileSize(); %eJGte-  
if(nFileLength == -1) CT\;xt,S  
{ ]IL;`>Gp  
System.err.println("File Length is not known!"); 7^M9qTEHp  
} /l{&iLz[  
else if(nFileLength == -2) m~>Y{F2  
{ 3 E3qd'  
System.err.println("File is not access!"); _$p$")  
} 3( ]M{4j  
else 7c;9$j  
{ jr)7kP@  
for(int i=0;i<nStartPos.length;i++) Ed:eGm }  
{ 0x9x@gF  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); iA,kX\nK  
} >OP+^^oZ<  
for(int i=0;i<nEndPos.length-1;i++) f"(X(1F  
{ c5Q<$86  
nEndPos = nStartPos[i+1]; &|aqP \Q5  
} i[ $0
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nEndPos[nEndPos.length-1] = nFileLength; c)Ic#<e(  
} DaH?@Q
 
} gZEi]/8_  
5"/J^"!h  
.7 asW(  
//启动子线程 *c)uGz'cD  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; /1 RAAa  
for(int i=0;i<nStartPos.length;i++) \V>?Do7  
{ gt\MS;jMa  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), c,Euv>*`  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), vm'5s]kdh
 
nStartPos,nEndPos,i); @w>zF/  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); WsFk:h'r  
fileSplitterFetch.start(); tV9LD>3  
} ](B@5-^  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), $O{duJU  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); s!9dQ.  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", |8bq>01~  
nEndPos = " + nFileLength); fgj^bcp-  
// fileSplitterFetch[nPos.length-1].start(); '<R>E:5  
{} Bf  
uHIiH@S  
//等待子线程结束 KIeT!kmDl  
//int count = 0; 5*\\J&H  
//是否结束while循环 kSc{^-<R  
boolean breakWhile = false; ^ZM0c>ev=l  
2S8P}$mM  
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while(!bStop) O'GG Ti]e  
{ vfB2XVc  
write_nPos(); +f0~D(d!_  
Utility.sleep(500); +x]9+D&  
breakWhile = true; azP+GM=i7  
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for(int i=0;i<nStartPos.length;i++) "C?5f]T  
{ F/1#l@qN  
if(!fileSplitterFetch.bDownOver) + <c^=&7Lq  
{ s!+"yK  
breakWhile = false; 4Iq'/r  
break; z5*=MlZ)R.  
} jEz+1Nl)  
} @=5qT]%U3J  
if(breakWhile) :y2p@#l#  
break; +uWYK9  
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//count++; hSGb-$~F  
//if(count>4) 7B3w\
 
// siteStop(); *[eL~oN.c  
} ySbqnw'  
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System.err.println("文件下载结束！"); "&Qctk`<P  
} ?8,%
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catch(Exception e){e.printStackTrace ();} rC_*sx r^  
} g`k?AM\  
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]  
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//获得文件长度 to"'By{9  
public long getFileSize() P%Ay3cR+E  
{ i77GE  
int nFileLength = -1; Q>qFM9Z  
try{ k#}g,0@  
URL url = new URL(siteInfoBean.getSSiteURL()); ?hYqcT[%  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); !}M,  
httpConnection.setRequestProperty("User-Agent","NetFox"); 2}vg U$a  
-V %gVI[  
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int responseCode=httpConnection.getResponseCode(); w>xV  
if(responseCode>=400) ]+DI.%   
{ ~Z$bf>[(R7  
processErrorCode(responseCode); X
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return -2; //-2 represent access is error BsZ{|,oQnZ  
} ;oH,~|K  
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3}1ss
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String sHeader; 1on'^8]0  
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for(int i=1;;i++) ,}D}oo*  
{ Uf*EJ1Ei  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); n,M)oo1G  
//Utility.log(in.readLine()); ^4v*W;Q  
sHeader=httpConnection.getHeaderFieldKey(i); L3(^{W]|  
if(sHeader!=null) 1+y"i<3)  
{ Z
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if(sHeader.equals("Content-Length")) ?lCd{14Mkh  
{ N?4q  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); RAs0]K  
break; io4A>>W==/  
} tZWrz e^  
} M] V.!z9B  
else {Z{o"56f  
break; zGcqzYbuA  
} (3,.3)%`  
} |-2}j2'  
catch(IOException e){e.printStackTrace ();} O,V9R rG  
catch(Exception e){e.printStackTrace ();} #6S75{rnW"  
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Utility.log(nFileLength); \[wCp*;1}  
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return nFileLength; H ;@!?I  
} y@ek=fT%4  
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"u')g&   
//保存下载信息（文件指针位置） \Mx JH[  
private void write_nPos() @fn6<3  
{ &$fbP5uAZ  
try{ j,%EW+j$  
output = new DataOutputStream(new FileOutputStream(tmpFile)); T*q"N?/4  
output.writeInt(nStartPos.length); !#D=w$@r:  
for(int i=0;i<nStartPos.length;i++) bNzqls$  
{ }3/~x  
// output.writeLong(nPos); *8g<R  
output.writeLong(fileSplitterFetch.nStartPos); ]Nk!4"  
output.writeLong(fileSplitterFetch.nEndPos); @O3/3vi1  
} (hZ:X)E>  
output.close(); +`| *s3M  
} :9d\Uj,  
catch(IOException e){e.printStackTrace ();} ZKbDp~  
catch(Exception e){e.printStackTrace ();} V/#v\*JHFc  
} CSn<]%GL  
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X1J;1hRUP  
//读取保存的下载信息（文件指针位置） 7$T8&Mh  
private void read_nPos() &&RA4  
{
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try{ /r$&]C:Fi  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile));  ~Nh&.a  
int nCount = input.readInt(); 2g`[u|  
nStartPos = new long[nCount]; ~5#)N{GbY  
nEndPos = new long[nCount]; }B!cv{{  
for(int i=0;i<nStartPos.length;i++) M?:\9DDd  
{ r:l96^xs  
nStartPos = input.readLong(); ,r+"7$  
nEndPos = input.readLong(); Etnb3<^[t  
} ?g
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input.close(); >2-F2E,  
} Z^6#4Q]YC  
catch(IOException e){e.printStackTrace ();} CUhV$A#oo  
catch(Exception e){e.printStackTrace ();} *=nO  
} 2*[Un(  
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private void processErrorCode(int nErrorCode) fNhT;Bux  
{ c;V D}UD'  
System.err.println("Error Code : " + nErrorCode); P1d,8~;  
} %O) Z  
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//停止文件下载 ?eWJa  
public void siteStop() ^e9aD9  
{ yz)ESQ~va  
bStop = true; &6"P7X  
for(int i=0;i<nStartPos.length;i++) lCFU1 GHH  
fileSplitterFetch.splitterStop(); _nX%#/{  
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} p{H0dj^|  
} G,DOBA  
//负责部分文件的抓取 "a(1s},  
**FileSplitterFetch.java S%+R#A1  
*/ t"YIq/08  
package NetFox; d^aNR Lv  
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import java.io.*; Mvof%I  
import java.net.*; NWISS  
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public class FileSplitterFetch extends Thread { *)%dXVf  
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String sURL; //File URL IQ{?_'  
long nStartPos; //File Snippet Start Position UX}*X`{  
long nEndPos; //File Snippet End Position 3}4#I_<$F@  
int nThreadID; //Thread's ID @&:VKpu\  
boolean bDownOver = false; //Downing is over uX0 Bp8P  
boolean bStop = false; //Stop identical d^SE)/j  
FileAccessI fileAccessI = null; //File Access interface Qp69Sk@H{  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 3/tJDb5  
{ q!2<=:f  
this.sURL = sURL; sX~45u \  
this.nStartPos = nStart; 9Z9l:}bO  
this.nEndPos = nEnd; .\4l'THn,0  
nThreadID = id; K{FhT9R'  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 Z!)f*  
}
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public void run() '_E c_F  
{ ^6&_|f  
while(nStartPos < nEndPos && !bStop) UC#"=Xd4  
{ <[5#c*A  
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try{ ]W|RtdF3.N  
URL url = new URL(sURL); K Dz]wNf  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); %%x0w^  
httpConnection.setRequestProperty("User-Agent","NetFox"); r4S=I  
String sProperty = "bytes="+nStartPos+"-"; k) 3s
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httpConnection.setRequestProperty("RANGE",sProperty); \d$Rd")w  
Utility.log(sProperty); /sH0x,V  
yjR)Z9t  
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InputStream input = httpConnection.getInputStream(); %OFj  
//logResponseHead(httpConnection); Nc
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byte[] b = new byte[1024]; ywe5tU  
int nRead; 7A[Ogro  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) $%;jk  
{ Wa{%0inZ  
nStartPos += fileAccessI.write(b,0,nRead); hJ4S3b  
//if(nThreadID == 1) Ir>2sTrm  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); z^9E;  
} VX&WlG`wa  
l"?]BC~  
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Utility.log("Thread " + nThreadID + " is over!"); [nC4/V+-  
bDownOver = true; $&Ac5Zo%}  
//nPos = fileAccessI.write (b,0,nRead); +qZc} 7rJF  
} k)Zn>  
catch(Exception e){e.printStackTrace ();} x36NL^  
} fYs?D+U;PF  
} p&m ^
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//打印回应的头信息 YVJ+' A=|  
public void logResponseHead(HttpURLConnection con) uYY=~o[ Tw  
{ M(NH9EE  
for(int i=1;;i++) +yiU@K).0  
{ [}@n*D$  
String header=con.getHeaderFieldKey(i); }*Dd/'2+1  
if(header!=null) c0SX]4} G  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); n'Bmz  
Utility.log(header+" : "+con.getHeaderField(header)); tz3]le|ml  
else QWQ!Ak  
break; WySNL#>a  
} 4xpj<  
} =}"R5  
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public void splitterStop() q<
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{ a
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bStop = true; {dDq*sLf  
} 22PGWSQ  
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} QT7_x`#J~o  
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/* =P)"NP7f'  
**FileAccess.java ]|t9B/()i  
*//文件访问(定位，写) |iAEDZn  
package NetFox; iq,ah"L  
import java.io.*; rAL1TU(vm  

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public class FileAccessI implements Serializable{ >Sh0d
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xP
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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 2NyUmJ42  
RandomAccessFile oSavedFile; W3"vTZJF  
long nPos; k"0%' Y  
]}_p3W "Y9  
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public FileAccessI() throws IOException ysL0hwir  
{ j-j'phK  
this("",0); RFhU#  
} [2=^C=52  
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*h>OW  
public FileAccessI(String sName,long nPos) throws IOException CgN]dx*`  
{ 3e#x)H/dr  
oSavedFile = new RandomAccessFile(sName,"rw"); >
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this.nPos = nPos; $#TID=  
oSavedFile.seek(nPos); o.p+j  
} O.]_Ry\OXA  
3&O% &  
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public synchronized int write(byte[] b,int nStart,int nLen) _F! :(@}  
{ #W_i{
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int n = -1; SnH:(tO[X  
try{ [5x+aW%ql  
oSavedFile.write(b,nStart,nLen); ="/R5fp  
n = nLen; P0a>+^:%  
} "r:H5) !  
catch(IOException e) (MZ A  
{ -Mr{+pf  
e.printStackTrace (); -$xKv4  
} D WsCYo  
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return n; |G[
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} ]}
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} >ly&+3S  
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/* FRb&@(;  
**SiteInfoBean.java y.L|rRe@P  
*/ Wh#os,U$  
package NetFox; ,| $|kO/  
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L&+% Wd~  
public class SiteInfoBean { mABwM$_  
?FkQe~FN{  
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private String sSiteURL; //Site's URL <|mE9u  
private String sFilePath; //Saved File's Path ,ivWVsN*]  
private String sFileName; //Saved File's Name t't^E,E .@  
private int nSplitter; //Count of Splited Downloading File v'mJ~tz  
%#[r_QQ^  
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public SiteInfoBean() +OV%B .  
{//nSplitter的缺省值为5 l:>qR/|m  
//default value of nSplitter is 5 ctnAVm  
this("","","",5); \9&YV;Ct  
} :< KSf#O  
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]w1BJZa36  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) PM#
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{ V\e13cL]  
sSiteURL= sURL; `?Y_0Nh>  
sFilePath = sPath; d;@E~~o?B]  
sFileName = sName; ^sr:N5~z`  
this.nSplitter = nSpiltter; hlABu)B'1  
j TB<E=WC  
%fexuy4  
} wN/*|?`Z  
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public String getSSiteURL() 2zmQp  
{ mR!&.R?  
return sSiteURL; Q6s5#7h'"  
} Kt/+PS  
iA1;k*)q  
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public void setSSiteURL(String value) LOyCx/n  
{ r1^m#!=B  
sSiteURL = value; 5bGjO&$l  
} J?|K
#<%  
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*Bb|N--jI  
public String getSFilePath() \E ? iw.}  
{ .O@q5G  
return sFilePath; {7
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} K%aPl~e  
[F BCz>  
5kRwSOG%'  
public void setSFilePath(String value) ~%8Q75tn.  
{ _k"&EW{ Ii  
sFilePath = value; qCxD{-9x{  
} % RBI\tj  
O=!)})YG  
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public String getSFileName() h1G*y  
{ Cnc\sMDJ\B  
return sFileName; ,&zjOc_v  
}  01UR  
^J*G%*  
{{4p{  
public void setSFileName(String value) 1b %T_a  
{ {YO%JTQ  
sFileName = value; p'uqh e X  
} t^bdi}[  
S,)|~#5x  
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public int getNSplitter() 6|"!sW`%N  
{ J4*:.8Ki  
return nSplitter; w50Bq&/jX  
} fW4cHB9|  
[iO$ c]!H  
+|}K5q\  
public void setNSplitter(int nCount) #<PA- y  
{ 35N/v G0  
nSplitter = nCount;
7KSGG1ts  
} n'&`9M['%d  
} W2W2WyPk  
U_ ?elz\  
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/* h3;o!FF  
**Utility.java H-\{w   
*/ >`rNT|rg  
package NetFox; 5E oWyy  
HHu7{,  
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public class Utility { !7"K>m<  
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public Utility()
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{ 'Kso@St`o  
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} XnI ;7J  
"jQe\  
//线程睡眠 "<jEI /  
public static void sleep(int nSecond) L/iVs`qF  
{ _{Q?VQvZ  
try{ mJDKxgGK  
Thread.sleep(nSecond); ~=AKX(Q  
} S'-`\%@7  
catch(Exception e) QSs$   
{ 
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e.printStackTrace (); 1f pS"_}  
} J PzQBc5e  
} Ignv|TYG  
U3j~}H.D1  
//日志 gHh.|PysW  
public static void log(String sMsg) @;n$caw  
{ VgZaDd;  
System.err.println(sMsg); ID)gq_k[8,  
} /@nRL  
3!oQmG_T  
^tKOxW# a  
public static void log(int sMsg) ?#EXG  
{ @gqs4cg{f  
System.err.println(sMsg); )D@n?qbG  
} `F+x]<m!  
} ssJDaf79  
sc $QbOc  
cVHE}0Xd(  
/* %}ApO{  
**TestMethod.java EAd:`X,Y  
*/ =Z>V}`n  
package NetFox; -ynLuq#1A  
]-5jgz"  
2eR+dT  
public class TestMethod { 5 *pN<S  
ks#Z~6+3  
/jn3'q_,  
public TestMethod() 4@mXtA  
{ ///xx/weblogic60b2_win.exe ;`PkmA
g  
try{ k-ex<el)#  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 7" STS7_  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); $H:h(ia:  
SiteFileFetch fileFetch = new SiteFileFetch(bean); `w=H'"Zv  
fileFetch.start(); dK;\`>8  
} jme5'FR
 
catch(Exception e){e.printStackTrace ();} eeJt4DV8v  
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} ;7n*PBUJJ  
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public static void main(String[] args) -J7,Nw  
{ \;:@=9`  
new TestMethod(); "`3^MvC  
} pOI`,i}.  
} 6p=xgk-q  
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