http断点续传简单实现（java)

/* :w?:WH?2L  
**SiteFileFetch.java U-wq- GT  
*/ i}v}K'`  
package NetFox; $.suu^>^w  
import java.io.*; (=S"Kvb~#  
import java.net.*; ^KaqvG$ed  
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public class SiteFileFetch extends Thread { h(+m<J  
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SiteInfoBean siteInfoBean = null; //文件信息Bean l(3'Re  
long[] nStartPos; //开始位置 se^NQ=  
long[] nEndPos; //结束位置 s$SU vo1J  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 XvfcPI6  
long nFileLength; //文件长度 7eaA]y~H  
boolean bFirst = true; //是否第一次取文件 tEpIyC  
boolean bStop = false; //停止标志 1kz
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File tmpFile; //文件下载的临时信息 #;qFPj- v  
DataOutputStream output; //输出到文件的输出流 doxdRYKL  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） P3,Z5|)  
public SiteFileFetch(SiteInfoBean bean) throws IOException X~IRpzC  
{ [[/ }1%  
siteInfoBean = bean; wHBHkz  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); CrRQPgl+u  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 60U{ e}Mkb  
if(tmpFile.exists ()) $ uz1  
{ +l[Z2
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bFirst = false; i5L+8kx4  
read_nPos(); ,T,B0  
} >q} !>k$B  
else ?34EJ !  
{ vy2*BTU?  
nStartPos = new long[bean.getNSplitter()]; =,/A\F  
nEndPos = new long[bean.getNSplitter()]; !%Z)eO~Z  
} P ],)  
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} ~I/>i&|M1  
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public void run() 6,V.j>z  
{ A9fjMnw  
//获得文件长度 m-Z'K_oQ  
//分割文件 c1)BGy
li  
//实例FileSplitterFetch OTNZ!U/)j  
//启动FileSplitterFetch线程 Hz!
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//等待子线程返回 qJbhPY8Ak  
try{ <manv8*6  
if(bFirst) 8a":[Q[  
{ e@2E0u4   
nFileLength = getFileSize(); ;QvvU[eb  
if(nFileLength == -1) laD.or  
{ &8:iB {n  
System.err.println("File Length is not known!"); [`Qp;_K?t  
} Gct&}]3pm  
else if(nFileLength == -2) 0%qctZy  
{ YP .%CD(K  
System.err.println("File is not access!"); VAF:Z  
} R.T?
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else NXWIE4T>*^  
{ QvK]<HEr  
for(int i=0;i<nStartPos.length;i++) DS[l
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{ )=,9`+Zta  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); u #=kb5}{  
} b
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for(int i=0;i<nEndPos.length-1;i++) xRTg [  
{ l b1sV  
nEndPos = nStartPos[i+1]; [6RV'7`Abj  
} +*:x#$phx  
nEndPos[nEndPos.length-1] = nFileLength; !Wdt:MUI8  
} ]X"i~$T1S  
} L[QI 5N  
"PDSqYA  
+n8I(l=  
//启动子线程 9rf|r 3  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; )@lo ';\  
for(int i=0;i<nStartPos.length;i++) $S)e"Po~5  
{ 8^~ZNU-~v  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), <5!RAdaj+  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 0
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nStartPos,nEndPos,i); YiI:uG!|D  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); tUAY]BJ*s  
fileSplitterFetch.start(); #(7RX}  
} 0t:|l@zB  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), *C:q _/  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 5f^`4pT  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", m|?" k38  
nEndPos = " + nFileLength); 45O6TqepN  
// fileSplitterFetch[nPos.length-1].start(); w4<u@L  
L[[H&#\  
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//等待子线程结束 P".qL5  
//int count = 0; sVm'9k  
//是否结束while循环 |\r\i&|g1  
boolean breakWhile = false; Q&U= jX  
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while(!bStop) -"JE-n  
{ E/ed0'|m  
write_nPos(); WG[0$j  
Utility.sleep(500); "d^lS@~  
breakWhile = true; 2QuypVC ]  
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for(int i=0;i<nStartPos.length;i++) B& f~.UH  
{ =ILo`Q~  
if(!fileSplitterFetch.bDownOver) &MGgO
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{ A`8}J4  
breakWhile = false; :-'ri Ry  
break; 9787uj]Y}H  
} NNpa69U  
} m5Laq'~0_  
if(breakWhile) u #QSa$P  
break; &WWO13\qd  
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//count++; Ei(`gp  
//if(count>4) GMp'KEQQ  
// siteStop(); gdn,nL`dP  
} vH\nL>r
 
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System.err.println("文件下载结束！"); o>k-~v7  
} "lj:bxM2C  
catch(Exception e){e.printStackTrace ();} K0!#l Br  
} n#AH@`&i  
7^}Z%c  
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//获得文件长度 -8J@r2\
 
public long getFileSize() Gqu0M`+7  
{ u6&Ixi/s'  
int nFileLength = -1; y&|{x "  
try{ vP;tgW9Qk  
URL url = new URL(siteInfoBean.getSSiteURL()); .\\#~r`t3  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); :r+ 1>F$o  
httpConnection.setRequestProperty("User-Agent","NetFox"); H;}ue  
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int responseCode=httpConnection.getResponseCode(); R_&V.\e_  
if(responseCode>=400) TgG)btQ  
{ ~9 nrS9)  
processErrorCode(responseCode); R1%T>2"~&  
return -2; //-2 represent access is error fH{$LjH(  
} VH*(>^OfF  
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String sHeader; dKG<"
 
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for(int i=1;;i++) 4y)1*VU:  
{ Hd}t=6  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ,$*klod  
//Utility.log(in.readLine()); )CU(~s|s  
sHeader=httpConnection.getHeaderFieldKey(i); {_D'\i(Y_  
if(sHeader!=null) Cf 8-%  
{ gU$3Y#R  
if(sHeader.equals("Content-Length")) 0a;zT O/"v  
{ rV{e[fGd  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); dz DssAHy  
break; je0 ?iovY  
} 2z l  
} 1%{(?uz9  
else @uWD>(D  
break; QpZhxp  
} sVf7g?  
} cE#Y,-f  
catch(IOException e){e.printStackTrace ();} V)@scB|>,  
catch(Exception e){e.printStackTrace ();} ]5L3[A4Vu  
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Utility.log(nFileLength); -4a&R=%p  
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return nFileLength; *GMRu,u2  
} w5Z3e^g  
V _,*  
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//保存下载信息（文件指针位置） b8O:@j2  
private void write_nPos() {oO!v}]  
{ 7:]I@Gc'  
try{ ]itvu:pl%  
output = new DataOutputStream(new FileOutputStream(tmpFile)); lgU7jn  
output.writeInt(nStartPos.length); ]F,5Oh :OY  
for(int i=0;i<nStartPos.length;i++) oo`mVRVf  
{ \;4RD$J  
// output.writeLong(nPos); dP )YPy_`  
output.writeLong(fileSplitterFetch.nStartPos); WFTTBUoH  
output.writeLong(fileSplitterFetch.nEndPos); P'zA=Rd&~>  
} `CW=*uBH  
output.close(); LqW~QEU(  
} jQc$>M<"o  
catch(IOException e){e.printStackTrace ();} th !Gc  
catch(Exception e){e.printStackTrace ();} ! @|"84  
} [<6ez;2q'  
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//读取保存的下载信息（文件指针位置） Nq-qks.&  
private void read_nPos() eR?`o!@y  
{ IpHGit28  
try{ L ej3? k  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile));
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int nCount = input.readInt(); 2wikk]Z  
nStartPos = new long[nCount]; kz]qk15w  
nEndPos = new long[nCount]; (;\JCeGA  
for(int i=0;i<nStartPos.length;i++) TtlZum\  
{ 5@+4>[t
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nStartPos = input.readLong(); z" 4$mh  
nEndPos = input.readLong(); V4iN2  
} [/\}:#MLe  
input.close(); 5Q =o.wf  
} *}Vg]3$4  
catch(IOException e){e.printStackTrace ();} 5!-'~W  
catch(Exception e){e.printStackTrace ();} rdSkGb  
} ~Cm_=[  
l'm!e'7_  
7;5SK:X%dm  
private void processErrorCode(int nErrorCode) ;5MI8  
{ qJj"WU5  
System.err.println("Error Code : " + nErrorCode); l*^c?lp)  
} "K;f[&xO,o  
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//停止文件下载 ) 7w%\i{M  
public void siteStop() "MOM@4\  
{ 2Jm#3zFYz3  
bStop = true; I82GZL  
for(int i=0;i<nStartPos.length;i++) v4OroG=^  
fileSplitterFetch.splitterStop(); }fU"s"  
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} K!g!tA$  
} C;>!SRCp  
//负责部分文件的抓取 wkc)2z   
**FileSplitterFetch.java )&Af[mS  
*/ ~+ [T{{  
package NetFox; 2D;2QdO  
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@` 5P^H7  
import java.io.*; S+2we  
import java.net.*; ;iq H:wO  
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public class FileSplitterFetch extends Thread { D6N32q@  
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String sURL; //File URL pm` f?
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long nStartPos; //File Snippet Start Position ;2N: =Rv  
long nEndPos; //File Snippet End Position vX30Ijm  
int nThreadID; //Thread's ID B5v5D[ o5  
boolean bDownOver = false; //Downing is over pmfL}Dn  
boolean bStop = false; //Stop identical A9Kt^HR  
FileAccessI fileAccessI = null; //File Access interface Iw;i ".
 
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException #V9do>Cu%  
{ MMU>55+-  
this.sURL = sURL; OjWg>v\v  
this.nStartPos = nStart; FeL!%z  
this.nEndPos = nEnd; #n_t5 O[  
nThreadID = id; bt'lT  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 ;.+C  
} PjE%_M<  
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public void run() z?<Xx?Kk  
{ j4%\'xj:  
while(nStartPos < nEndPos && !bStop) 4OOI$J$Jh  
{ y/Ui6
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try{ U_sM==~  
URL url = new URL(sURL); W4#E&8g%  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); TUN6`/"  
httpConnection.setRequestProperty("User-Agent","NetFox"); w!r.MWE  
String sProperty = "bytes="+nStartPos+"-"; xey?.2K1A  
httpConnection.setRequestProperty("RANGE",sProperty); nTv^][
 
Utility.log(sProperty); "Wg5eML0  
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InputStream input = httpConnection.getInputStream(); f?lnBvT|b  
//logResponseHead(httpConnection); uWLf9D"  
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byte[] b = new byte[1024]; NQx>u  
int nRead; )1/J5DI @8  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) [{PmU~RMYf  
{ x-T7 tr&(  
nStartPos += fileAccessI.write(b,0,nRead); vhrURY.
  
//if(nThreadID == 1) {!*dk V  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); PTpGZ2FZ  
} .2 }5Dc,eR  
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Utility.log("Thread " + nThreadID + " is over!"); f
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bDownOver = true; YK V"bI  
//nPos = fileAccessI.write (b,0,nRead); _SrkR7  
} $-uMWJ)l  
catch(Exception e){e.printStackTrace ();} u>.>hQ  
} ~}Z'/zCZf  
}
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//打印回应的头信息 5N[H@%>QO  
public void logResponseHead(HttpURLConnection con) l8 XY  
{ "b0!h6$!H  
for(int i=1;;i++) x8Nij:K#  
{ w1)SuMFK_  
String header=con.getHeaderFieldKey(i);  WYW@%t  
if(header!=null) W;T(q~XK  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); pW5PF)([  
Utility.log(header+" : "+con.getHeaderField(header)); }4_c~)9Q  
else ^20x\K  
break; J1d|L|M  
} aFDCVm%U|  
} h5ZxxtGU  
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public void splitterStop() ,QHn} 3fW  
{ ~p$ncIr2Q  
bStop = true; W4S]2P>T  
} ^"4u1  
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} }J] P`v  
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/* .GuZV'  
**FileAccess.java g&L $5  
*//文件访问(定位，写) {ud^+I&  
package NetFox; 2"B3Q:0he|  
import java.io.*; 0zqTX< A  
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7.(vog"I)  
public class FileAccessI implements Serializable{ Yd$64d7,h  
N0
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 K9Bi2/N  
RandomAccessFile oSavedFile; ?`Som_vKO  
long nPos; J.pe&1  
* TR~>|  
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public FileAccessI() throws IOException Clzz!v  
{ UE/N-K)`  
this("",0); %M;{+90p>t  
} E3E$_<^  
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public FileAccessI(String sName,long nPos) throws IOException P8;f^3V(+/  
{ ot.R Gpg%  
oSavedFile = new RandomAccessFile(sName,"rw"); :]-? l4(%  
this.nPos = nPos; 2s8(r8AI  
oSavedFile.seek(nPos); 0%5x&vx'S  
} jY5BVTWnV  
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public synchronized int write(byte[] b,int nStart,int nLen) me/ae{  
{ P7p'j  
int n = -1; -g)*v<Fb5  
try{ IP+1 :M  
oSavedFile.write(b,nStart,nLen); ~*uxKEH  
n = nLen; 9{5 c}bX  
} /pDI \]  
catch(IOException e) m7~[f7U  
{ 1w|V'e?kb  
e.printStackTrace (); &)|3OJ'o  
} G/C5o=cY  
$;t#pN/`  
Ss{  
return n; {T[/B"QZG  
} 3a#
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} &tw   
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/* iiZK^/P$  
**SiteInfoBean.java xj!_]XJ^w  
*/ a4M`Bk;mb  
package NetFox; 'zhw]L;'g  
id.W"5+  
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public class SiteInfoBean { c/57_fOK  
~ ]q^Akq  
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private String sSiteURL; //Site's URL 6'6@VB  
private String sFilePath; //Saved File's Path WwDxZ>9jw  
private String sFileName; //Saved File's Name mckrR$>  
private int nSplitter; //Count of Splited Downloading File M('cG  
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public SiteInfoBean() ;pNHT*>u,  
{//nSplitter的缺省值为5 HH|&$C|64  
//default value of nSplitter is 5 b
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this("","","",5); 1W5\
  
} +B@NSEy/+  
,&HZvU&  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) tH"SOGfSt  
{ `8TM<az-L  
sSiteURL= sURL; %6"b< MAO  
sFilePath = sPath; >1tGQ c
g  
sFileName = sName;
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this.nSplitter = nSpiltter; y=\jQ6Fc  
*[7,@S/<F  
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}
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public String getSSiteURL() ZjEO$ts=@  
{ )B*?se]LJ  
return sSiteURL; \sC
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} KW&&AuPb}  
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public void setSSiteURL(String value) [NvEXTd  
{ _'H<zZo  
sSiteURL = value; nHKEtKDd  
} 0 \LkJ*i  
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public String getSFilePath() 2c%}p0<;|?  
{ !icpfxOpjQ  
return sFilePath; Hs=!.tZ,  
} u."fJ2}l0X  
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public void setSFilePath(String value) 4!k={Pd  
{ a LmVOL{  
sFilePath = value; D?\K~U* >  
} -'PpY302  
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-;P<Q`{I  
public String getSFileName() Rc6 )v  
{ HnP;1Gi  
return sFileName; 0"2 
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} m]-8?B1`Y  

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public void setSFileName(String value) (v4  
{ 5&X  
sFileName = value; _kY5
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} btOTDqG`a  
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public int getNSplitter() "}OFwes
  
{ ,\IqKRcYU  
return nSplitter; 'hekCZZ_I  
} #h3+T*5} 6  
'o7PIhD"  
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public void setNSplitter(int nCount) /5x`TT  
{ %C3cdy_c  
nSplitter = nCount; 4o*V12_r'4  
} =O;SXzgE  
} k( g$_ ]X  
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/* 6gKOpa  
**Utility.java 6#KI? 6  
*/ vR)7qX}  
package NetFox; '.K,EM!-~h  
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wa  
*.*:(7`  
public class Utility { Q jBCkx]g  
9#(QS+q~  
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public Utility() @}?D<O8#"#  
{ =a!6EkX *  
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} - X_w&  
1ZL_;k  
//线程睡眠 O0{  
public static void sleep(int nSecond) V`M,d~:Pr"  
{ pHvE`s"Ea  
try{ vQ/\BN  
Thread.sleep(nSecond); *_QHtZG  
} U959=e  
catch(Exception e) c
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{ +lT]s#Fif  
e.printStackTrace (); wY.g-3  
} i/J NG  
} %^l&fM*  
u}1vn}F{  
//日志 )/Xrhhx  
public static void log(String sMsg) YgiGI <U  
{ I7PWOd  
System.err.println(sMsg); "J5Pwvs-  
} M=WE^v!b  
\z`d}\3(R  
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public static void log(int sMsg) YhT1P fl  
{ &iOtw0E  
System.err.println(sMsg); 3K!0 4\  
} E E|zY%  
} H27Oq8  
#=H}6!18  
*Z`eNz}  
/* S.)7u6/_!  
**TestMethod.java ]0i2]=J&,  
*/ %B&?D@  
package NetFox; ~fp+@j-A  
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,*Z[P%<9  
public class TestMethod { 6J-
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'(pdk  
m=.7f
9  
public TestMethod() ~}0hN]*G  
{ ///xx/weblogic60b2_win.exe ZU.)K
>'  
try{ :ZfUjqRE  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ).!14Gjo  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); O4PdN?  
SiteFileFetch fileFetch = new SiteFileFetch(bean); :_\!t45  
fileFetch.start(); ?SOF n  
} m=iov2K>  
catch(Exception e){e.printStackTrace ();} P>T*:!s;  
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R,w54},  
} T:S
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e3={$Ah  
public static void main(String[] args) .(dmuV9  
{ /9+A97{  
new TestMethod(); A Wh*<H  
} Vc52s+7=8  
} b)hOz
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