http断点续传简单实现（java)

/*  igo9~.  
**SiteFileFetch.java ( unmf,y  
*/ /<)Vd  
package NetFox; Wxj_DTi[1"  
import java.io.*; bL xZ5C7t  
import java.net.*; %M`48TW)  
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public class SiteFileFetch extends Thread { !'H$08Ql}  
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SiteInfoBean siteInfoBean = null; //文件信息Bean i2Wvu3,D3-  
long[] nStartPos; //开始位置 b*Y Wd3  
long[] nEndPos; //结束位置 .=;IdLO,Bf  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 %>$<s<y  
long nFileLength; //文件长度 _Z(t**Zh6y  
boolean bFirst = true; //是否第一次取文件 8)>x)T  
boolean bStop = false; //停止标志 (T*$4KGV  
File tmpFile; //文件下载的临时信息 OK]
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DataOutputStream output; //输出到文件的输出流 ,gw9R9 x_  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） u{DEOhtI4  
public SiteFileFetch(SiteInfoBean bean) throws IOException estiS  
{ ~5+RK16  
siteInfoBean = bean; YH\9Je%jx  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ~yJ2@2I  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); |OJWQU![by  
if(tmpFile.exists ()) (=^KP7  
{ WnG2\(U  
bFirst = false; qm$(_]R~`  
read_nPos(); $A?9U}V#^  
} n1PptR  
else }sH[_%)  
{ N[@H107`  
nStartPos = new long[bean.getNSplitter()]; vu0Ue  
nEndPos = new long[bean.getNSplitter()]; :e7\z  
} o,WjM[e  
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} 3tZIL  
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public void run() #VrIU8Q7'  
{ I6 ?(@,  
//获得文件长度 _f0AV;S:vd  
//分割文件 t}eyfflZ  
//实例FileSplitterFetch %]Z4b;W[Y  
//启动FileSplitterFetch线程 '{AB{)1  
//等待子线程返回 ~uc7R/3ss  
try{ pA*C|g  
if(bFirst) w*6b%h%ww  
{ 74M9z  
nFileLength = getFileSize(); .
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if(nFileLength == -1) \<pr28  
{ y;ElSt;S  
System.err.println("File Length is not known!"); :C>7HEh-2_  
} 'O(=Pz  
else if(nFileLength == -2) Gt.'_hf Js  
{ wNHn.  
System.err.println("File is not access!"); Fs~(>w@  
} 83c2y;|8  
else o=YOn&@%  
{ M?lh1Yu"  
for(int i=0;i<nStartPos.length;i++) ~snj92K  
{ L"&T3i  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); 0<%$lr  
} g[G/If  
for(int i=0;i<nEndPos.length-1;i++) ^0.8-RT  
{ es*$/A  
nEndPos = nStartPos[i+1]; Dylm=ZZa  
} F_*']:p  
nEndPos[nEndPos.length-1] = nFileLength; W q<t+E[  
} ,Iyc0  
} Iuxf`sd  
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//启动子线程 ]B3](TH"  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; #r9+thyC  
for(int i=0;i<nStartPos.length;i++) <(KCiM=E$  
{ -iiX!@  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), wGti|7Tu*  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), vntJe^IaFd  
nStartPos,nEndPos,i); AU\=n,K7  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); S=k!8]/d|  
fileSplitterFetch.start(); Y$L` G  
} +fk*c[FG  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 7z$Z=cs  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); ]u5TvI,C  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", Hi09?AX  
nEndPos = " + nFileLength); QH-CZ6M  
// fileSplitterFetch[nPos.length-1].start(); fi HE`]0
 
2?~nA2+vm  
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//等待子线程结束 :C_/K(Rkl  
//int count = 0; (C. $w  
//是否结束while循环 1(Is 7  
boolean breakWhile = false; nNCR5&,q  
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while(!bStop) `Xos]L'w  
{ dq '2y  
write_nPos(); c6[m'cy  
Utility.sleep(500); >B{qPrmI  
breakWhile = true; ]pvHsiI:  
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for(int i=0;i<nStartPos.length;i++) z}Cjk6z@  
{ @4;'>yr(  
if(!fileSplitterFetch.bDownOver) $L^%*DkM  
{ 5$=[x!x  
breakWhile = false; tKt}]KHV  
break; 5b:1+5iF-  
} ?V2P]|  
} Ln#o:"
E  
if(breakWhile) L"'=[O~  
break; -4x! #|]  
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//count++; QG*hQh  
//if(count>4) aA4RC0'  
// siteStop(); lf`ULY4{  
} t5E$u(&+'B  
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System.err.println("文件下载结束！"); <Z-Pc?F&(k  
} {>hxmn   
catch(Exception e){e.printStackTrace ();} 4dbX!0u1l  
} ,?yjsJd.  
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//获得文件长度 0hoMf=bb$  
public long getFileSize() d`= ~8`  
{ 1vo3aF  
int nFileLength = -1; (n kg  
try{ Tg^8a,Lt  
URL url = new URL(siteInfoBean.getSSiteURL()); 9\Gk)0  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); eI ( S)q  
httpConnection.setRequestProperty("User-Agent","NetFox"); 2-'_Nwkl*  
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int responseCode=httpConnection.getResponseCode(); 6{5T^^x?<  
if(responseCode>=400) 'yCVB&`b  
{ 2;sTSGDG  
processErrorCode(responseCode); %/3+
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return -2; //-2 represent access is error >c0leT  
} d9JAt-6z2  
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String sHeader; Lz1KDXr`)+  
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for(int i=1;;i++) |$/#,Dv7  
{ @rT$}O1?`  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); F2zo !a8  
//Utility.log(in.readLine()); oqvu8"  
sHeader=httpConnection.getHeaderFieldKey(i); Ei:m@}g  
if(sHeader!=null) nN&dtjoF  
{ M;XU"8  
if(sHeader.equals("Content-Length")) QyA^9@iVs  
{ #Tc`W_-  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); Mcc%&j
 
break; 3DO*kM1s@  
} OD}Uc+;K  
} f=91 Z_M  
else ,$!fyi[;C  
break; jkl dr@t  
} 1CJ1-]S(3  
} s>L-0vG  
catch(IOException e){e.printStackTrace ();} d1#lC*.Sg  
catch(Exception e){e.printStackTrace ();} @8c@H#H  
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Utility.log(nFileLength); @wD#+Oz  
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return nFileLength; gIweL{Pc  
} i+S%e,U*  
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//保存下载信息（文件指针位置） vV"YgN:  
private void write_nPos() .K^gh$z!  
{ Ew]&~:$Ki  
try{ LntRLB'  
output = new DataOutputStream(new FileOutputStream(tmpFile)); '\QJ{/JV  
output.writeInt(nStartPos.length); :JBtqpo2  
for(int i=0;i<nStartPos.length;i++) j7);N  
{ [|$C2Dhw=  
// output.writeLong(nPos); DPY+{5
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output.writeLong(fileSplitterFetch.nStartPos); ug}u>vQ>  
output.writeLong(fileSplitterFetch.nEndPos); IHW s<U  
} [6K[P3UZx  
output.close(); |9i[*]  
} E @r &K  
catch(IOException e){e.printStackTrace ();} Lwtp,.)pR  
catch(Exception e){e.printStackTrace ();} I5j|\ /Ht  
} `!X8Cn  

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//读取保存的下载信息（文件指针位置） xTG5VBv  
private void read_nPos() r+Sv(KS4i^  
{ Xr o5~G  
try{ Rex86!TO  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); pbh>RS=ri  
int nCount = input.readInt(); DQObHB8L  
nStartPos = new long[nCount]; = <A0;  
nEndPos = new long[nCount]; ~Q^.7.-T  
for(int i=0;i<nStartPos.length;i++) hH$9GL{H  
{ ~d<&OL  
nStartPos = input.readLong(); tHqa%  
nEndPos = input.readLong(); Jl\U~i  
} \1?'JdN  
input.close(); ?!"pzDg  
} c;KMox/  
catch(IOException e){e.printStackTrace ();} `}ZtK574  
catch(Exception e){e.printStackTrace ();} ?1|\(W#  
} 9h+TO_T@F  
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private void processErrorCode(int nErrorCode) ',+Zqog92  
{ ~mHrgxQ-  
System.err.println("Error Code : " + nErrorCode); 0T@axQ[%  
} z2R?GQ5 A  
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>}Mw"   
//停止文件下载 ME>Sh~C\  
public void siteStop() n[;)(  
{ C!K&d,M  
bStop = true; YajAz5N  
for(int i=0;i<nStartPos.length;i++) )~xH!%4F  
fileSplitterFetch.splitterStop(); lV./K;\T  
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} ifWQwS/,a  
} "J&WH~8+N  
//负责部分文件的抓取 1uyd+*/(xP  
**FileSplitterFetch.java _b)Ie`a.H  
*/ hBz>E 4mEv  
package NetFox; !gsrPM  
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import java.io.*; J}-e9vK-#  
import java.net.*; 4F -<j!  
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public class FileSplitterFetch extends Thread { CG3
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String sURL; //File URL a
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long nStartPos; //File Snippet Start Position # dUi['  
long nEndPos; //File Snippet End Position Q"!GdKM  
int nThreadID; //Thread's ID 71IM`eL=ED  
boolean bDownOver = false; //Downing is over ^IvQdVB  
boolean bStop = false; //Stop identical 0<<ATw$aQ  
FileAccessI fileAccessI = null; //File Access interface 9%Vy,  
_9=cxwi<w  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException '19?  
{ ([SJ6ff]&  
this.sURL = sURL; vwAhNw2-  
this.nStartPos = nStart; s[7/w[&  
this.nEndPos = nEnd; '"hSX=  
nThreadID = id; ;i [;%  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 oFzmH!&ED  
} Fo0s<YlS-  
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public void run() ]R^xO;g'  
{ I4<_y5  
while(nStartPos < nEndPos && !bStop) ZBH^
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{ x*X{*?5@  
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try{ oOLj? 0t  
URL url = new URL(sURL); W8-vF++R  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); t3v_o4`&  
httpConnection.setRequestProperty("User-Agent","NetFox"); s`yg?CR`,  
String sProperty = "bytes="+nStartPos+"-"; N]ebKe  
httpConnection.setRequestProperty("RANGE",sProperty); 8"[{[<-   
Utility.log(sProperty); y\9#"=+  
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InputStream input = httpConnection.getInputStream(); {XC[Ia6jtL  
//logResponseHead(httpConnection); @bAuR  
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byte[] b = new byte[1024]; W%MS,zkAE  
int nRead; +T,0,^*  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) LOwd mj  
{ #Hl?R5  
nStartPos += fileAccessI.write(b,0,nRead); L|'B*  
//if(nThreadID == 1) 05jjLM'e  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); zG%'Cw)8  
} bx-:aC)]2  
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Utility.log("Thread " + nThreadID + " is over!"); oe=1[9T"  
bDownOver = true; o>]z~^c  
//nPos = fileAccessI.write (b,0,nRead); m*lcIa  
} yI-EF)A@;  
catch(Exception e){e.printStackTrace ();} oykb8~u}}  
} F0kAQgUv  
} W]>%*n  
iJKGzHvS  
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//打印回应的头信息 fgA-+y  
public void logResponseHead(HttpURLConnection con) ]T.+(\I  
{ Zv8GrkK  
for(int i=1;;i++) ,nV4%Aa  
{ G2sj<F=AV  
String header=con.getHeaderFieldKey(i); z${[Z=  
if(header!=null) wIWO?w2  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); Vkf{dHjW  
Utility.log(header+" : "+con.getHeaderField(header)); fMM%,
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else hdmKD0  
break; 7^d7:1M  
} \W\*'C8q\  
} 9pWSvalw9  
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public void splitterStop() {lppv(U  
{ Bob-qCBV  
bStop = true; >4+KEK  
} h$6~3^g:P  
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} hL}ZP
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/* $e uI  
**FileAccess.java
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*//文件访问(定位，写) mGJRCK_  
package NetFox; "];@N!dA  
import java.io.*; z'"Y+EWN  
[1z.JfC :S  
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public class FileAccessI implements Serializable{ Y|tK19  
#]gmM  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 eYu0")  
RandomAccessFile oSavedFile; NQvI=R-g  
long nPos; DhsvN&yNM  
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public FileAccessI() throws IOException |TR
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{ @:>gRD  
this("",0); ~zWLqnS}  
} hp2$[p6O  
h b8L[ 4  
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public FileAccessI(String sName,long nPos) throws IOException ;=6EBP%  
{ ,^DP  
oSavedFile = new RandomAccessFile(sName,"rw"); B^ddi  
this.nPos = nPos; A<(DYd1H  
oSavedFile.seek(nPos); Ea-U+7JC  
} Qam48XZ >  
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public synchronized int write(byte[] b,int nStart,int nLen) H(y Gh  
{ @S>;t)\J  
int n = -1; 64>CfU(  
try{ #5{BxX&\  
oSavedFile.write(b,nStart,nLen); "{Y6.)x  
n = nLen; <vD(,||  
}  Wu8^Z Z{  
catch(IOException e) AD@ {7  
{ 6GqC]rd*:  
e.printStackTrace (); >vO+k^'Y  
} :-$8u;!M  
#l3)3k*;  
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return n;
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} xH}bX-
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} vJV/3-yX  
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/* ["4Tn0g ;  
**SiteInfoBean.java ]]3rSXs2}J  
*/ LIQ].VxIs  
package NetFox; gU NWM^n  
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public class SiteInfoBean { ,CuWQ'H  
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private String sSiteURL; //Site's URL 5C^@w
 
private String sFilePath; //Saved File's Path U%[ye0@:  
private String sFileName; //Saved File's Name a/1;|1a.  
private int nSplitter; //Count of Splited Downloading File * 1xs/$`  
6 .)Xeb"  
3
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public SiteInfoBean() vLyazVj..  
{//nSplitter的缺省值为5 B&0W P5OF  
//default value of nSplitter is 5 %~gI+0HK  
this("","","",5); 7mM
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} cO5zg<wF  
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ed  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) zNdkwj p+  
{ ASre@pW  
sSiteURL= sURL; (Cfb8\~  
sFilePath = sPath; QCE7VV1Rw  
sFileName = sName; 0Oc?:R'$  
this.nSplitter = nSpiltter; $(]nl%<Q  
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} gZ7R^] k  
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public String getSSiteURL() w>=N~0@t  
{ c;fLM`{*  
return sSiteURL; 7v)
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} d!YP{y P  
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public void setSSiteURL(String value) lG%697P  
{ +A)> zx  
sSiteURL = value; V[KN,o{6  
} pt,L  
a !%,2|U  
}(|gC,  
public String getSFilePath() w}zmcO:x  
{ ?+^p$'5
 
return sFilePath; a.}#nSYP  
} {\P%J:s#9  
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public void setSFilePath(String value) ^879sI  
{ >X'-J{4R  
sFilePath = value; *4}NLUVX
 
} VJ&<6  
,m5i(WL  

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public String getSFileName() UU MB"3e  
{ 6[c|14l  
return sFileName; !$oa6*<1  
} ^jwzCo-  
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J
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public void setSFileName(String value) t^FE]$,  
{ fx[&"$X  
sFileName = value; 1BZ##xV*:G  
} ce}A!v  
}6/M5zF3  
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public int getNSplitter() fe98Y-e  
{ HbsNF~;  
return nSplitter; F}ATY!  
} )
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public void setNSplitter(int nCount) \\#D!q*  
{ 5P"R'/[PA_  
nSplitter = nCount; kaB|+U9^  
} n9}BT^4 v  
} 85q/|9D  
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,v>;/qm  
/* $S|+U}]C  
**Utility.java C1=&Vm>g+  
*/ "T5oUy&i  
package NetFox; k1f<(@*`  
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public class Utility { TZt;-t`  
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public Utility() oMj"l#a*  
{ uH%b rbrU  
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} Mh-"B([Z  
Sl,DZ!  
//线程睡眠 ocZ}RI#Q  
public static void sleep(int nSecond) D5@=#/
?*  
{ ofQs 
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try{ O0L]xr  
Thread.sleep(nSecond); s)r!3HS  
} "I/05k K  
catch(Exception e) K
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{ _Fa\y ZX  
e.printStackTrace (); Jj>Rzj!m  
} N wk  
} )-&@8`  
t,|Apl]  
//日志 O@a OKk  
public static void log(String sMsg) E489
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{ ?96r7C|  
System.err.println(sMsg); xOj#%;  
} z@~H{glo  
_.; PLq~0  
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public static void log(int sMsg) scH61Y8`  
{ /g{*px|  
System.err.println(sMsg); MLHCBRi  
} Sc>mw   
} 'sUOi7U  
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/* l%"DeRp,/  
**TestMethod.java hHJvLs>^  
*/ k4LrUd  
package NetFox; }vZf&ib-   
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~iH a^i?2*  
public class TestMethod { :a;F3N
J  
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public TestMethod() > UZ-['H  
{ ///xx/weblogic60b2_win.exe k}fC58q  
try{ Tty'ysH  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); yO)xN=o^\  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); }? / Blr  
SiteFileFetch fileFetch = new SiteFileFetch(bean); lz#.f,h  
fileFetch.start(); 7gf(5p5ZV  
} q=88*Y  
catch(Exception e){e.printStackTrace ();} (x2?{\?  
q x)\{By  
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} {TNORbZz  
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public static void main(String[] args) I#(lxlp"Ho  
{ Hvk~BP' m  
new TestMethod(); /ZV2f3;t  
} yHw @Z  
} m)p|NdTZc8  
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