http断点续传简单实现（java)

/* z:W1(/W~  
**SiteFileFetch.java .rbKvd?-}  
*/ hB*3Py27L  
package NetFox; 3nkO+qQ  
import java.io.*; 'P)[=+O?t  
import java.net.*; CQ%yki  
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public class SiteFileFetch extends Thread { P~*v}A  
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SiteInfoBean siteInfoBean = null; //文件信息Bean DWJkN4}o  
long[] nStartPos; //开始位置 /K#J63 ,  
long[] nEndPos; //结束位置 ]G2%VKkr  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 C}mWX7<Z.  
long nFileLength; //文件长度 e%DF9}M  
boolean bFirst = true; //是否第一次取文件 _:;j)J0  
boolean bStop = false; //停止标志 d`Em)3v  
File tmpFile; //文件下载的临时信息 1HNX6  
DataOutputStream output; //输出到文件的输出流 z0&I>P
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） W.U|mNJ$
 
public SiteFileFetch(SiteInfoBean bean) throws IOException r;aP`MVO<  
{ &@xeWB  
siteInfoBean = bean; &28n1  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); Sst`*PX:  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); l{x?i00tAS  
if(tmpFile.exists ()) Tn3f5ka'  
{ d
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bFirst = false; (wsvj61  
read_nPos(); bYH! P/  
} [Z?vC  
else -`ykVHgg  
{ U^X8{,8O  
nStartPos = new long[bean.getNSplitter()]; V.274e  
nEndPos = new long[bean.getNSplitter()]; Pi|oO-M  
}  =!Y{Mz  
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} :WnXoL  
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public void run() cB[.ET$  
{ 4)nQBFX  
//获得文件长度 dQL! >6a  
//分割文件 ;42D+q=s  
//实例FileSplitterFetch ;w}5:3+  
//启动FileSplitterFetch线程 eL!G, W  
//等待子线程返回 /C}fE]n{X  
try{ $pGk%8l%  
if(bFirst) )p;gm`42oY  
{ QcQ|,lA.HI  
nFileLength = getFileSize(); ;EfMTI}6K  
if(nFileLength == -1) ,/>~J]:\;  
{ b511qc"i>M  
System.err.println("File Length is not known!"); DP_bB(  
} N6<23kYM  
else if(nFileLength == -2) xX.Ox  
{ >KXT2+w  
System.err.println("File is not access!"); v)2@;Q  
} K\ \UF  
else [0e]zyB+  
{ Kn9,N@bU_  
for(int i=0;i<nStartPos.length;i++) CQ3{'"b  
{ )FqE8oN-  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); -Q8pWtt  
} 4[&6yHJ^  
for(int i=0;i<nEndPos.length-1;i++) ",rA  
{ l9.wMs*`X  
nEndPos = nStartPos[i+1]; ),6Z1 K1  
} $mOK|=tI_  
nEndPos[nEndPos.length-1] = nFileLength; g%<7Px[W  
} Va/p   
} ~+$l9~`{  
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.9g\WH#qD|  
//启动子线程
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 7_/.a9$G  
for(int i=0;i<nStartPos.length;i++) Z{n7z$s*  
{ /bylA`IMW  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), vP'R7r2Yx  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 3-8Vw$u  
nStartPos,nEndPos,i); {UYqRfgbZ  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Dx[t?-  
fileSplitterFetch.start(); {ersXQ
:  
} e"|9%AW@<  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), UrxgKTry  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); &/, BFx"  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 3)g1e=\i$  
nEndPos = " + nFileLength); Ec6{?\  
// fileSplitterFetch[nPos.length-1].start(); %3VwCuE  
[*>@hx  
xt"/e-h}  
//等待子线程结束 ^j=_=Km]  
//int count = 0; }wkBa]  
//是否结束while循环 
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boolean breakWhile = false; 1^
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while(!bStop) 6v1#i  
{ 4!gyFi6$  
write_nPos(); W#y)ukRv  
Utility.sleep(500); nhCB])u8l  
breakWhile = true; }u+R,@l/  
*G~c6BZ  

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for(int i=0;i<nStartPos.length;i++) z4J-qK~2  
{ a3lo;Cfp  
if(!fileSplitterFetch.bDownOver) :({lXGc}4?  
{ i]$7w! r&  
breakWhile = false; 65J'uN  
break; 6U+#ADo  
} G%k
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} c*1x*'j.  
if(breakWhile) ?I/,r2ODLh  
break; SKfv.9  
iKS9Xss8  
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//count++; #lLL5ji  
//if(count>4) Da@tpKU)p  
// siteStop(); LL6f40hC  
} "msg./iC  
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System.err.println("文件下载结束！"); >PGm}s_  
} kh,M'XbTo  
catch(Exception e){e.printStackTrace ();} w6"LHy[  
} MB |(,{S  
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//获得文件长度 b]g.
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public long getFileSize() O:BP35z_F  
{ $0W0+A$  
int nFileLength = -1; 'b^:"\t'Rh  
try{ Io"=X!k  
URL url = new URL(siteInfoBean.getSSiteURL()); CWN=6(y  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Y+=@5+G  
httpConnection.setRequestProperty("User-Agent","NetFox"); _RmE+Xg2  
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int responseCode=httpConnection.getResponseCode(); x
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if(responseCode>=400) 2.lnT{  
{ ~V|!\CB  
processErrorCode(responseCode); "4?hK  
return -2; //-2 represent access is error }.gg!V'9w  
} ytC{E_
 
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String sHeader; Jb$z(?S  
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for(int i=1;;i++) =91'.c<  
{ vaxg^n|v9  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); S2s-TpjB<  
//Utility.log(in.readLine()); &S-& 'ZAY  
sHeader=httpConnection.getHeaderFieldKey(i); 0,A?*CO  
if(sHeader!=null) 
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{ !KlSw,&=.6  
if(sHeader.equals("Content-Length")) x> q3w# B  
{ 0$_imjZ  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); `i:0dVs  
break; <V8i>LBlz  
} }mGD`5[`  
} aw4+1.xy  
else T8(wzs  
break; 4>Y\2O?**  
} k:qou})#4  
} A X#!9-m3  
catch(IOException e){e.printStackTrace ();} 2r0!h98  
catch(Exception e){e.printStackTrace ();} "$'~=' [  
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Utility.log(nFileLength); o'4@]ae   
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return nFileLength; (KMobIP^  
} &}$D[ 4N  
/ IS WC  
j)DZmGg&t  
//保存下载信息（文件指针位置） wE \c?*k  
private void write_nPos() eC{Z  
{ DQICD.X6R  
try{ KEN-G  
output = new DataOutputStream(new FileOutputStream(tmpFile)); -]A#G`'  
output.writeInt(nStartPos.length); .%<&W1  
for(int i=0;i<nStartPos.length;i++) t5APD?5 c  
{ Ft rw3OxN  
// output.writeLong(nPos); C
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output.writeLong(fileSplitterFetch.nStartPos); 5gEfhZQ  
output.writeLong(fileSplitterFetch.nEndPos); I}v#r8'!  
} h3IkOh4|h  
output.close(); `4q}D-'TF8  
} kZ}u  
catch(IOException e){e.printStackTrace ();} PPO<{  
catch(Exception e){e.printStackTrace ();} g
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} NGs9Jke2  
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//读取保存的下载信息（文件指针位置） jq)|
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private void read_nPos() P0(~~z&%[  
{ PZR%8 m}]u  
try{ @R&D["!  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); |Z^g\l.j{  
int nCount = input.readInt(); ` W>B8  
nStartPos = new long[nCount]; E|;5Z*  
nEndPos = new long[nCount]; vUs7#*  
for(int i=0;i<nStartPos.length;i++) O*{H;7Pv  
{ !q\w"p0X  
nStartPos = input.readLong(); 1n(}Q1fa  
nEndPos = input.readLong(); hUxhYOp  
} 6<$|;w-OV  
input.close(); JJ0 CM:xe  
} ejY5n2V#=  
catch(IOException e){e.printStackTrace ();}
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catch(Exception e){e.printStackTrace ();}  ?|J+dW  
} 
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private void processErrorCode(int nErrorCode) :*'?Ac ?  
{ C+?s~JL  
System.err.println("Error Code : " + nErrorCode); 7 aD&\?  
} \X.=3lc&  
)o</gt)  
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//停止文件下载 7B!Qq/E?g  
public void siteStop() <&%1pZ/6.  
{ %,cFX[D/)  
bStop = true; A<5`[<x$  
for(int i=0;i<nStartPos.length;i++) WbWW=(N'd  
fileSplitterFetch.splitterStop(); MxEAs}MDv  
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J8BT%  
} :_a]T-GL  
} 1 "7#|=1/  
//负责部分文件的抓取 cu?(P;mQi  
**FileSplitterFetch.java ]U1,Nh
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*/ 4`P2FnJ?  
package NetFox; O)JUY*&I5  
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import java.io.*; )$h9Y   
import java.net.*; U"Hquo  
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public class FileSplitterFetch extends Thread {
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String sURL; //File URL nCMa$+  
long nStartPos; //File Snippet Start Position z12But\<  
long nEndPos; //File Snippet End Position X5
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int nThreadID; //Thread's ID  5vF}F^  
boolean bDownOver = false; //Downing is over 9r+O!kF(  
boolean bStop = false; //Stop identical q+n1~AT  
FileAccessI fileAccessI = null; //File Access interface 0s9z @>2  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException q[OTaSQ~u^  
{ .7gE^  
this.sURL = sURL; Qb't*2c%  
this.nStartPos = nStart; r82o[+$u0K  
this.nEndPos = nEnd; o$`kpr  
nThreadID = id; }t%>_  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 _d| 62VS  
} 1 j^c  
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public void run() k\#-6evT  
{ .83v~{n  
while(nStartPos < nEndPos && !bStop) -y*_.Ws9  
{ `$sY^EX  
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try{ >`<2}Me6  
URL url = new URL(sURL); Fv)
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ^_KD&%M6  
httpConnection.setRequestProperty("User-Agent","NetFox"); bxdXZBn  
String sProperty = "bytes="+nStartPos+"-"; iE^a%|?}  
httpConnection.setRequestProperty("RANGE",sProperty); V}|v!h[O8  
Utility.log(sProperty); ? TT8|Os  
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InputStream input = httpConnection.getInputStream(); #>:(#^Uu  
//logResponseHead(httpConnection); CSL{Q  
y /:T(tk$  
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byte[] b = new byte[1024]; d$_q=ywc  
int nRead; ?5yH'9zE  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) sjzXJ`s  
{ Sn
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nStartPos += fileAccessI.write(b,0,nRead); 0)oN[
  
//if(nThreadID == 1) k<Tez{<  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 3Q$'qZw p  
} hygnC`|  
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Utility.log("Thread " + nThreadID + " is over!"); {y^|ET7  
bDownOver = true; )jk1S  
//nPos = fileAccessI.write (b,0,nRead); Sq-3-w,R~  
} D=~B7b:  
catch(Exception e){e.printStackTrace ();} ;sChxQ=.^  
} (eRKR2% q  
} !/n
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//打印回应的头信息 /iUUM t'  
public void logResponseHead(HttpURLConnection con) P YF.#@":&  
{ 9y^kb+  
for(int i=1;;i++) ?cO8'4 bq  
{ NYjS  
String header=con.getHeaderFieldKey(i); Sn(l$wk=  
if(header!=null) 3@yTzaq6  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); W ~Jzqp9g  
Utility.log(header+" : "+con.getHeaderField(header)); i$bzdc#s  
else XD^dlL  
break; _;e!ZZLG  
} fQQsb 5=i  
} "X5_-l  
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public void splitterStop() |}M0,AS  
{ If-,c^i  
bStop = true; f]ue#O   
} 7!r#(>I6?1  
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`c'  
} $U>/i@D  
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/* l`b1%0y  
**FileAccess.java Uvh~B^6  
*//文件访问(定位，写)
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package NetFox;
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import java.io.*; Y$`eg|$  
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public class FileAccessI implements Serializable{ ^q
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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 i*S|qX7``  
RandomAccessFile oSavedFile; C
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long nPos; H|;*_  
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public FileAccessI() throws IOException =`Po<7D  
{ X
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this("",0); KdT[*-  
} Q(510)  
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public FileAccessI(String sName,long nPos) throws IOException jg [H}  
{ sdJ%S*)5G$  
oSavedFile = new RandomAccessFile(sName,"rw"); (#!]fF"!x  
this.nPos = nPos; |5
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oSavedFile.seek(nPos); SyK9Is{8  
} %9C`  
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public synchronized int write(byte[] b,int nStart,int nLen) #bT8QbJ(  
{ -AjH}A[!  
int n = -1; oW1"%i%  
try{ ~x|aoozL  
oSavedFile.write(b,nStart,nLen); ~:>AR` 9G  
n = nLen; L[?nST18%  
} Kt W6AZJ  
catch(IOException e) {p`mfEE(  
{ Y?yo\(Cdx  
e.printStackTrace (); D~#Ei?aH  
} %K[daXw6E8  
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J I<3\=:+  
return n; AGOx@;w  
} I-b_h5ZD6  
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} -2F@~m|  
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/* QsiJ%O Q  
**SiteInfoBean.java Q}kfM^i  
*/ ~U6"?  
package NetFox; VeZey)Q  
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iF!mV5#  
public class SiteInfoBean { Sd},_Kh  
/X4yB"J>  
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private String sSiteURL; //Site's URL v`JF\"}S  
private String sFilePath; //Saved File's Path N.Dhu~V  
private String sFileName; //Saved File's Name *E:x E/M!2  
private int nSplitter; //Count of Splited Downloading File qmZ2d!)o  
o+nG3kRD  
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public SiteInfoBean() ><;Q@u5~  
{//nSplitter的缺省值为5 kt^yj"C>  
//default value of nSplitter is 5 NYBe"/}GS  
this("","","",5); KOjluP  
} gQ37>  
0rD#s{?  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) nV}8M  
{ #G_F`&  
sSiteURL= sURL; Sw)i1S9  
sFilePath = sPath; ncv7t|ZN  
sFileName = sName; !z"N
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this.nSplitter = nSpiltter; ?"6Ov ]  
) Qq'Wp3i  
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} V!4a*,Pz  

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public String getSSiteURL() @F>F#-2  
{ 845 W>B  
return sSiteURL; ?i~g,P]NK  
} Cq>6rn  
< f(
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public void setSSiteURL(String value) 1dFa@<5  
{ V<8K@/n@  
sSiteURL = value; d?A}qA[(  
} B5ea(j  
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j!\dn!Xwt  
public String getSFilePath() 5 L/x-i  
{ $5AC1g'  
return sFilePath; X\Y}oa."A  
} F8<"AI  
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public void setSFilePath(String value) { p;shs5  
{ 2*[QZ9U[@  
sFilePath = value; ~i ,"87$[  
} 0,_b)  
;o0#(xVz  
}7ehF6  
public String getSFileName() VO=!8Yx[  
{ qP3q  
return sFileName; 3`*Kav>"  
} k$N0lR4:p  
`'i( U7?  
h7]EB!D\A  
public void setSFileName(String value) }#1/fok  
{ ~S*b  
sFileName = value; %{!R l@  
} +m)q%I>  
&]F3#^!^  
jV
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public int getNSplitter() dRW$T5dac  
{ nv0#~UgE#a  
return nSplitter; ve Tx, \6@  
} !R'g59g  
${I*nh>=  
u.,Q4u|!  
public void setNSplitter(int nCount) .@#A|fgv  
{ 6cz/n8Mg  
nSplitter = nCount; z.36;yT/  
} X^s2BW  
} %Jp|z? [/  
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/* e(?]SU|  
**Utility.java =2Cj,[$  
*/ wM~H(=s`D  
package NetFox; wi_

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public class Utility { ),(V6@Z?  
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o*5U:'=5}  
public Utility() IgIYguQ  
{ /
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=-"c*^$]  
} NX[4PKJ0C  
M f~}/h  
//线程睡眠 7f3O  
public static void sleep(int nSecond) 6gH{R$7L=  
{ cl@
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try{ k^\pU\J  
Thread.sleep(nSecond); 5]5 KB;  
} =Yz'D|=t  
catch(Exception e) K/L;8a  
{ ?QZ"JX])  
e.printStackTrace (); E&`Nh5JfC  
} >R\lqLILb,  
} l+*&:Q/  
rx0~`cVV:  
//日志 xtfBfA  
public static void log(String sMsg) i,IB!x  
{ H/+B%2Zj  
System.err.println(sMsg); z^<L(/rg9"  
} bN$r k|  
\$sjrqKnu  
+Q$h ]^>~  
public static void log(int sMsg) Wp)*Mbq@  
{ Lfog {Vzs  
System.err.println(sMsg); #]P9b@@e  
} nUS| sh  
} !3X0FNGq  
D^Jk@<*  
/FD5G7ES  
/* -I.d}[  
**TestMethod.java 1)m@?CaI`  
*/ TaE~s  
package NetFox; lVOu)q@l7g  
x'<K\qp{{  
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public class TestMethod { |`Or'%|PR  
J(DN!  
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public TestMethod() LbEM^D  
{ ///xx/weblogic60b2_win.exe UT0){%2@  
try{ [NMVoBvG  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); u .f= te  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 21hv%CF\9  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ^XbU~3(  
fileFetch.start(); }}v9 `F  
} 6AG`&'"  
catch(Exception e){e.printStackTrace ();} 1#IlWEg  
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[S5\#=_4S  
} gzoEUp=s  
'R-3fO???  
@,Gxk   
public static void main(String[] args) g0R~&AN!g  
{ ktIi$v  
new TestMethod(); 2 3OC2|  
} 7X@mSXis  
} ~t9tnLc$  
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