http断点续传简单实现（java)

/* tJybR"NQ  
**SiteFileFetch.java %~y>9K  
*/ Sg4{IU  
package NetFox; |-)8=QDz)r  
import java.io.*; #=VYq4B=  
import java.net.*; 9?8PMh.  
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public class SiteFileFetch extends Thread { dt^h9I2O  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 7YR|6{@  
long[] nStartPos; //开始位置 y$_@
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long[] nEndPos; //结束位置 R|v'+bv  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 H]pI$t3~  
long nFileLength; //文件长度 
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boolean bFirst = true; //是否第一次取文件 XbqMWQN*  
boolean bStop = false; //停止标志 ]8}51y8  
File tmpFile; //文件下载的临时信息 yu)^s!UY;  
DataOutputStream output; //输出到文件的输出流 AYgXqmH~+  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） DU0/if9.  
public SiteFileFetch(SiteInfoBean bean) throws IOException B6Eu."T  
{ ^lAM /   
siteInfoBean = bean; 8;V9%h`P>  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); nYFrp)DLK  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); FY ms]bv  
if(tmpFile.exists ()) YZj*F-}  
{ NC#F:M;b  
bFirst = false; <S041KF.{6  
read_nPos(); *8WB($T}  
} |1RVm?~i  
else m1U:&{:^  
{ T!8^R|!a6  
nStartPos = new long[bean.getNSplitter()];
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nEndPos = new long[bean.getNSplitter()]; @p L9a1PJv  
} xH xTL>,?  
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} ocFk#FW  
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public void run() ~/]]H;;^u  
{ #3QPcoxa  
//获得文件长度 b7Jxv7$e  
//分割文件 iN[x *A|h  
//实例FileSplitterFetch =9X1+x  
//启动FileSplitterFetch线程 68Gywk3]=u  
//等待子线程返回 _ i}W1i  
try{ l2qvYNMw  
if(bFirst) d51'[?(  
{ Aj)Q#Fd[  
nFileLength = getFileSize(); xwf-kwF8^  
if(nFileLength == -1) y=Kqv^  
{ t/\
 
System.err.println("File Length is not known!"); I70c,4_G  
} "FWx;65CR  
else if(nFileLength == -2) ,|{`(y/v  
{ /{\ /e"5  
System.err.println("File is not access!"); I I+y  
} l6ym <V(1p  
else ;^5k_\  
{ yGdX>h  
for(int i=0;i<nStartPos.length;i++) =FrB{Eu  
{ s*ZE`/SM3  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); } #rTUX  
} t$18h2yOL  
for(int i=0;i<nEndPos.length-1;i++) d )O^(y1r  
{ e@Lxduq  
nEndPos = nStartPos[i+1]; NOo?  
} (Jk&U8y  
nEndPos[nEndPos.length-1] = nFileLength; lPZ(c%P  
} n^Ca?|} ,  
} +e-F`k  
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//启动子线程 #$I@V4O;#  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; D\AVZ76F1  
for(int i=0;i<nStartPos.length;i++) Uj):}xgi'  
{ l1)~WqhE}  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), X0VSa{  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), >u?.gJm~  
nStartPos,nEndPos,i); V4n~Z+k  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); .eR1\IAm  
fileSplitterFetch.start(); r3l1I}  
} P>VoA  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), )*~A|[  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); zuV%`n  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", "bm|p/A  
nEndPos = " + nFileLength); m2c'r3UEu  
// fileSplitterFetch[nPos.length-1].start(); )l7XZ_gw'  
;=Ma+d#  
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//等待子线程结束 >fH0>W+!  
//int count = 0; "' JnFM  
//是否结束while循环 /MGapmqV9  
boolean breakWhile = false; ]JrD@ Vy  
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while(!bStop) &-3e3)  
{ eDJnzh83  
write_nPos(); X0G,tl  
Utility.sleep(500); ;6W]f([  
breakWhile = true; &h-_|N  
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for(int i=0;i<nStartPos.length;i++) C!j3@EZ$  
{ <]qNjsdb9"  
if(!fileSplitterFetch.bDownOver) 3iCe5VF  
{ wa"0`a:`;  
breakWhile = false; rwRZGd *p  
break; {821e&r  
} CS7b3p!I  
} |U%NPw5  
if(breakWhile) 'J,UKK\5  
break; LwC?t3n
 
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//count++; qGk.7wf%  
//if(count>4) Q@VA@N=w  
// siteStop(); @dWA1tM  
} l<v{8:,e#  
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System.err.println("文件下载结束！"); GV0\+A"vD  
} |+Y-i4t  
catch(Exception e){e.printStackTrace ();} _:r8UVAT.  
} ,:?ibE=  
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//获得文件长度 /Q1 b%C  
public long getFileSize() _3`GZeGV  
{ UPhO=G  
int nFileLength = -1; *k{Llq  
try{ y%TqH\RKv  
URL url = new URL(siteInfoBean.getSSiteURL()); kR<sSLEb  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); f2WVg;Z  
httpConnection.setRequestProperty("User-Agent","NetFox"); aTvyzr1  
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int responseCode=httpConnection.getResponseCode(); yKML{N1D  
if(responseCode>=400) o?baiOkH  
{ .>"xp6  
processErrorCode(responseCode); '12m4quO  
return -2; //-2 represent access is error qs]W2{-4~  
} y\FQt];z)  
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#{6VdWZ  
String sHeader; xWxHi6U(  
*
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for(int i=1;;i++) A;co1,]gR  
{ f(Xin3#'  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); $H<_P'h-B  
//Utility.log(in.readLine()); C*YQ{Mz(f  
sHeader=httpConnection.getHeaderFieldKey(i); -'&l!23a~  
if(sHeader!=null) XJ7B
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{ .\b.l@O<Z  
if(sHeader.equals("Content-Length")) b `P6Ox3  
{ jJ2rfdfj  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); gq('
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break; ?p{-Yp*h  
} OLG)D#m(4/  
} rmjuNy=(  
else i+`8$uz  
break; ,a5q62)q  
} 4
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} K_MEd1l  
catch(IOException e){e.printStackTrace ();} g2f"tu_/%  
catch(Exception e){e.printStackTrace ();} {QEvc  
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Utility.log(nFileLength); ui?@:=  
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return nFileLength; (Aw@}!  
} \;XJ$~>  
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//保存下载信息（文件指针位置） o

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private void write_nPos() YIN* '!N  
{ 
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try{ y>C !cYB  
output = new DataOutputStream(new FileOutputStream(tmpFile)); "smU5 s,P  
output.writeInt(nStartPos.length); / B!j`UK  
for(int i=0;i<nStartPos.length;i++) \4 b^*`d  
{ ?8753{wk  
// output.writeLong(nPos); %g?M?D8Ud3  
output.writeLong(fileSplitterFetch.nStartPos); v}!lx)#  
output.writeLong(fileSplitterFetch.nEndPos); 61_PSScSY  
} Ja1`S+  
output.close(); `@y~
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} CV[9i  
catch(IOException e){e.printStackTrace ();} J{4=:feIC?  
catch(Exception e){e.printStackTrace ();} $}4ao2  
} D?BegF  
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//读取保存的下载信息（文件指针位置） 24od74\  
private void read_nPos() Af\@J6viF7  
{ ",~ZO<P  
try{ $bhI2%_`M  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); z^wo
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int nCount = input.readInt(); oyiG04H&  
nStartPos = new long[nCount]; n{W(8K6d@[  
nEndPos = new long[nCount];
/
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for(int i=0;i<nStartPos.length;i++) =o~mZ/ 7=M  
{ %]F/!n  
nStartPos = input.readLong(); 6(7 56  
nEndPos = input.readLong(); Wt%Wpb8
  
} /\,3AInLb  
input.close(); I?1BGaAA  
} blomB2vQ  
catch(IOException e){e.printStackTrace ();} o5]-Kuw`  
catch(Exception e){e.printStackTrace ();} ea{zL  
} ]R~hzo  
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private void processErrorCode(int nErrorCode) iklZ[G%A0  
{ }se3y  
System.err.println("Error Code : " + nErrorCode); |

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} "uplk8iCJ  
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//停止文件下载 xsU%?"r  
public void siteStop() (e;/Smol  
{ _k}Qe;  
bStop = true; #bcZ:D@FC  
for(int i=0;i<nStartPos.length;i++) J<0sT=/2$  
fileSplitterFetch.splitterStop(); QUkP&sz  
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} }S*]#jr&  
} |A68+(3u  
//负责部分文件的抓取 0OlT^  
**FileSplitterFetch.java 1Y"9<ry  
*/ jjrE8[  
package NetFox; N~b0b;e  
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import java.io.*; bR}fj
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import java.net.*; `s69p'<;p  
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public class FileSplitterFetch extends Thread { M:.+^.h  
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String sURL; //File URL Z molL0y  
long nStartPos; //File Snippet Start Position 97HI9R  
long nEndPos; //File Snippet End Position ;wJe%Nw?  
int nThreadID; //Thread's ID Js:U1q  
boolean bDownOver = false; //Downing is over ;I@\}!%H  
boolean bStop = false; //Stop identical /)RH-_63  
FileAccessI fileAccessI = null; //File Access interface ` ,
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException u)zv`m  
{ tYgHJ~1L*  
this.sURL = sURL; DBGU:V,85  
this.nStartPos = nStart; K8&) kfyI  
this.nEndPos = nEnd; !ni 1 qM  
nThreadID = id; 'cu14m_  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 oP T)vN?  
} +tt!xfy  
:
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public void run() +2tFX  
{ # bjK]+  
while(nStartPos < nEndPos && !bStop) 3_9CREZCl  
{ FzSL[S4i  
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try{ *Ej;}KSv  
URL url = new URL(sURL); 0nBDF79  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); }%c>Hh  
httpConnection.setRequestProperty("User-Agent","NetFox"); |Y6;8e`H  
String sProperty = "bytes="+nStartPos+"-"; _B^X3EOc  
httpConnection.setRequestProperty("RANGE",sProperty); Xk'Pc0@a  
Utility.log(sProperty); pyX:$j2R+%  
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InputStream input = httpConnection.getInputStream(); \N-3JOVy  
//logResponseHead(httpConnection); F+NX [  
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byte[] b = new byte[1024]; mJ(ElDG  
int nRead; 7;Lv_Y"b  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) Xf"< >M  
{ O8>&J-+2  
nStartPos += fileAccessI.write(b,0,nRead); v>nBdpjXh  
//if(nThreadID == 1) rtbV*@Z  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 2yFT` 5+H4  
} _E8Cvaob  
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Utility.log("Thread " + nThreadID + " is over!"); 4i&Rd1#0dI  
bDownOver = true; 8mLW^R:`  
//nPos = fileAccessI.write (b,0,nRead); UqsOG<L'6  
} &PApO{#Q  
catch(Exception e){e.printStackTrace ();} ai?N!RX%H  
} O#):*II`9  
} yJ]Va $M  
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//打印回应的头信息 3b#L*-  
public void logResponseHead(HttpURLConnection con) F&+qd`8J  
{ 4Z=`;  
for(int i=1;;i++) ] >w@@A  
{ &tf(vU;,'  
String header=con.getHeaderFieldKey(i); k' Fu&r  
if(header!=null) A)j!Wgs^z  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ~H   
Utility.log(header+" : "+con.getHeaderField(header)); }kItVx  
else G;W2Z,  
break; K0B<9Wi|  
} Fv)E:PnKC  
} g)ZMU^1  
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public void splitterStop() @^ti*`  
{ f52P1V]  
bStop = true; d-m.aP)y:  
} ux!YVvTPd  
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} 34"PtWbV>  
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/* 7{w}0PMx  
**FileAccess.java %\|{_]h}y  
*//文件访问(定位，写) QY<5o;m`  
package NetFox; '+vmC*-I(  
import java.io.*; r_,;[+!  
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public class FileAccessI implements Serializable{ _/%,cYVc8!  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 rev*G:  
RandomAccessFile oSavedFile; %yjD<2J;  
long nPos; v[8+fd)}S  
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public FileAccessI() throws IOException n|rKo<Y0  
{ nSBhz  
this("",0); y:Of~ ]9@  
} ; Ad5Jk  
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public FileAccessI(String sName,long nPos) throws IOException ?YS 3)  
{ tk=S4/VWv  
oSavedFile = new RandomAccessFile(sName,"rw"); {i8zM6eC  
this.nPos = nPos; SZ$WC8AX  
oSavedFile.seek(nPos); >zL5*:G  
} m_Q&zp["  
_!, J iOI  
c>>.>^5  
public synchronized int write(byte[] b,int nStart,int nLen) 1^= QIX  
{ nu-&vX  
int n = -1; :E~rve'  
try{ #RU8yT  
oSavedFile.write(b,nStart,nLen); E!mv}  
n = nLen; 'x"(OdM:[  
} 2=0HQXXrq  
catch(IOException e) 8=joVbs  
{ w=rD8@  
e.printStackTrace (); u-4@[*^T$  
} DC-d@N+  
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return n;
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} c>^(=52Q  
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} vxI9|i  
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/* ,J!$Q0e  
**SiteInfoBean.java /"u37f?[^  
*/ Rq[d\BN0.d  
package NetFox; Ur>1eN%9'  
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public class SiteInfoBean {  fCJjFL:  
[?KGLUmTAI  
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private String sSiteURL; //Site's URL aVc{ aP  
private String sFilePath; //Saved File's Path 3+h
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private String sFileName; //Saved File's Name 'EXx'z;/#  
private int nSplitter; //Count of Splited Downloading File |b.xG_-s1  
bP#!U'b"=  
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public SiteInfoBean() hdrsa}{g  
{//nSplitter的缺省值为5 \y=oZk4  
//default value of nSplitter is 5 q^EY?;Y  
this("","","",5); DmLx"%H3  
} |ll
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9_O4yTL  
23>[-XZb[O  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) lNa+NtQu  
{ 1nskf*Z  
sSiteURL= sURL; %>i:C-l8  
sFilePath = sPath; *pS 7,Hm  
sFileName = sName; F!0iM)1o  
this.nSplitter = nSpiltter; ` K{k0_{  
}shxEsq  
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} /YF:WKr2  
c:9n8skE7  
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public String getSSiteURL() cAEvv[  
{ .\^0RyJE  
return sSiteURL; Hy[: _E  
} er)I".|  
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public void setSSiteURL(String value) BU/A\4xQ,Y  
{ V<I(M<Dj  
sSiteURL = value; IyyBW2  
} KBN% TqH|  
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ck  
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public String getSFilePath() bP9ly9FH  
{ @3O)#r}\  
return sFilePath; `!HD. E[2c  
} SXOAa<u5  
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D@*<O=_D(  
public void setSFilePath(String value) f;zNNx< ;  
{ m3lz#Pm'0  
sFilePath = value; r%ES#\L6+|  
} @>(KEjQTz  
&9#m]
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- Fbp!*. u  
public String getSFileName() YoKyiO!   
{ 0^-1d2Z~  
return sFileName; 1w^wa_qx  
} fj5g\m  
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public void setSFileName(String value) cu0IFNF}[  
{ =79R;|5  
sFileName = value; Z,38eQpM  
} 0d9z8y  
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public int getNSplitter() 2L^)k?9>g+  
{ @ivd|*?k0  
return nSplitter; Y7VO:o  
} YzI;
)  
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public void setNSplitter(int nCount) Fr8GGN~/  
{ }#O!GG{  
nSplitter = nCount; oY18a*_>M1  
} }p7iv:P=3  
} }6c>BU}DF  
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/* MePD:;mm^  
**Utility.java $>XeC}"x68  
*/ ~t`s&t'c|  
package NetFox; ?0VR2Yb${b  
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public class Utility { %T{]l;5  
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public Utility() jV3PTU  
{ =^nb+}Nz(  
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A IP~A]T  
} az(<<2=  
PLyity-L[7  
//线程睡眠 \n)',4mY  
public static void sleep(int nSecond) Zh<;r;2  
{ )|F|\6:ne  
try{ +T+@g8S  
Thread.sleep(nSecond); O<gfZ>  
} #@S%?`4,
 
catch(Exception e) jhNFaBrS  
{ 0CrsZtX  
e.printStackTrace (); p~qe/  
} Z'JS@dV  
} B[t^u\Fk  
S\e&xUA;|  
//日志 xAQtX=FoX+  
public static void log(String sMsg) C9n%!()>  
{ .V?:&_}_I6  
System.err.println(sMsg); W(s4R,j  
} QU|_ r2LM  
a:h<M^n049  
|"3<\$[  
public static void log(int sMsg) I{`70  
{ wHc my  
System.err.println(sMsg); HGDrH   
} l
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} (jgk! 6  
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/* +&Ld`d!n  
**TestMethod.java %@/^UE:  
*/ J-F".6i5  
package NetFox; G6sK3K  
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RK>Pe3<  
public class TestMethod { )O]T}eI  
@;Ttdwg#J  
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public TestMethod() AlSO  
{ ///xx/weblogic60b2_win.exe 6OES'3Cy  
try{ +L(amq;S  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ly[LF1t  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); E$e7(D  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ~4S$+*'8  
fileFetch.start(); rz?Cn X.t  
} *Gbhk8}V'  
catch(Exception e){e.printStackTrace ();} RpHlq  
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} 24mdhT|  
H"C'<(4*\  
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public static void main(String[] args) _"DS?`z6  
{ 4`IM[DIG~  
new TestMethod(); y7R#PkQ~  
} ou|emAV  
} DX>a0-Xj  
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