http断点续传简单实现（java)

/* KE`}P<K&  
**SiteFileFetch.java -S OP8G  
*/ egxh  
package NetFox; )VID ;l;4  
import java.io.*; Tz]t.]!&E  
import java.net.*; U|={LU  
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public class SiteFileFetch extends Thread { \IbGNV`q  
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SiteInfoBean siteInfoBean = null; //文件信息Bean Tf)qd\  
long[] nStartPos; //开始位置 VChNDHiH  
long[] nEndPos; //结束位置 hMh8)S  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 UYn5Pix  
long nFileLength; //文件长度 $rv&!/}]e  
boolean bFirst = true; //是否第一次取文件 T$)&8"Xya  
boolean bStop = false; //停止标志 O{uc
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File tmpFile; //文件下载的临时信息 V<Q''%k  
DataOutputStream output; //输出到文件的输出流 ;"$Wfy  

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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） @r^a/]5D  
public SiteFileFetch(SiteInfoBean bean) throws IOException A'HFpsa  
{ JwL}|o6  
siteInfoBean = bean; lM~ 3yBy  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); Z1 %"w*U  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); _8Cw_  
if(tmpFile.exists ()) ;fw}<M!6  
{ ZgK[,<2  
bFirst = false; SKt&]H  
read_nPos(); j\iE3:94$  
} "`qmeZ$rg  
else 6e0tA()F  
{ $(/=Wn  
nStartPos = new long[bean.getNSplitter()]; z{Z4{&M  
nEndPos = new long[bean.getNSplitter()]; Z:9xf:g*  
} vVQwuV  
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} Wu3or"lcw*  
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public void run() wV8_O)[  
{ 0M=A,`qk  
//获得文件长度 (7Su{tq  
//分割文件 E/[>#%@i  
//实例FileSplitterFetch O*0%AjT
6  
//启动FileSplitterFetch线程 Q*4{2oQ  
//等待子线程返回 Y;2WY0eq  
try{ U )kl!  
if(bFirst) o;#:%  
{ w5fVug/;P  
nFileLength = getFileSize(); OlRtVp1  
if(nFileLength == -1) FQY{[QvF~  
{ @^P<(%p  
System.err.println("File Length is not known!"); s0r::yO  
} nv$>iJ^~H  
else if(nFileLength == -2) gOiZ8K!  
{ tofX.oi+C$  
System.err.println("File is not access!"); Sc b'  
} g0({$2Q7R  
else 0?V{u`*  
{ 2{U5*\FhVX  
for(int i=0;i<nStartPos.length;i++) /q1k)4?E  
{ (\8IgQ{  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); TAL,(&[s  
} wrP3:!=  
for(int i=0;i<nEndPos.length-1;i++) gXJtk;  
{ p1F{ v^  
nEndPos = nStartPos[i+1]; _2Zc?*4  
} ^VI\:<\{  
nEndPos[nEndPos.length-1] = nFileLength; \/XU v(  
} 3~q#P  
} >c`r&W.t  
{Jbouj?V!  
M

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//启动子线程 #W$6[#7=I  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; -HwqR Ys  
for(int i=0;i<nStartPos.length;i++) rX(Ol,&oP  
{ 8|JPQDS7  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), J]W? Vvv  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), vzX%x ul  
nStartPos,nEndPos,i); xs 1V?0  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); D :)HKD.  
fileSplitterFetch.start(); M{z&h>  
} -,186ZVZ  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 0g8ykGyx  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); ''^2
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// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", (N6=+dNY  
nEndPos = " + nFileLength); h3e %(a  
// fileSplitterFetch[nPos.length-1].start(); + L[a  
]FNe&o1zX  
c( _R xLJ  
//等待子线程结束 5X PoQ^  
//int count = 0; I*z|_}$  
//是否结束while循环 lLur.f  
boolean breakWhile = false; `#*`hH8  
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while(!bStop) Ts\PZQ!q  
{ B.A;1VE5  
write_nPos(); Fs}B\R/J  
Utility.sleep(500); ,\-4
X  
breakWhile = true; :x,dYJm  
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for(int i=0;i<nStartPos.length;i++) }ssP%c]  
{ ]`q]\E
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if(!fileSplitterFetch.bDownOver) 1! j^  
{ :IO"' b  
breakWhile = false; _b`/QSL  
break; !
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} Z,-J tl  
} e= XC$Jv  
if(breakWhile) IL,iu
 
break; aI>F8R?  
} rX)A\ g6  
SmS6B5j\R  
//count++; DoNN
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//if(count>4) vjVa),2  
// siteStop(); Rzyaicj^
c  
} ]|N"jr?7H  
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System.err.println("文件下载结束！"); [s+FX5'K  
} FzOlM-)m   
catch(Exception e){e.printStackTrace ();} .]0:`Y,;  
} >[N6_*K]  
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/g1;`F(MS/  
//获得文件长度 7H4\AG\>  
public long getFileSize() /eBcPu"[Vb  
{ "u'dd3!  
int nFileLength = -1; lmIphOUoIw  
try{ R2qz>kyyB  
URL url = new URL(siteInfoBean.getSSiteURL()); _dc,}C  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); F ~e}=Nb  
httpConnection.setRequestProperty("User-Agent","NetFox"); Q>xp 90&.n  
|}: 
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int responseCode=httpConnection.getResponseCode(); Bnz}:te}  
if(responseCode>=400) J!"m{ 8-  
{ " ;o,D  
processErrorCode(responseCode); Ko!a`I2M}  
return -2; //-2 represent access is error fc<,
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} bv``PSb3  
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String sHeader; }5d|y*  
 "2}n(8  
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for(int i=1;;i++) :UfaMe5  
{ yn2k!2]&T<  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ());
?#:!!.I:  
//Utility.log(in.readLine()); t&C0V|s79$  
sHeader=httpConnection.getHeaderFieldKey(i); ^
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if(sHeader!=null) 9x1
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{ CbMClnF  
if(sHeader.equals("Content-Length")) >BjZ{7?Ok  
{ /b{Ufo3v  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); s="cg0PD  
break; c-[IgX e  
} K14{c1  
} Egl1$,e  
else pS!N<;OWr  
break; <*opVy^  
} zENo2#{_N  
} {z# W-  
catch(IOException e){e.printStackTrace ();} af/;Dr@  
catch(Exception e){e.printStackTrace ();} ibgF,N  
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Utility.log(nFileLength); EkP(]F  
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return nFileLength; 68!=`49r>  
} zh4m`}p  
~ [=2d a  
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//保存下载信息（文件指针位置） 7=4V1FS6i  
private void write_nPos() ":^cb =  
{ [u8JqX  
try{ Q#I?nBin  
output = new DataOutputStream(new FileOutputStream(tmpFile)); 7/Mhz{o;W  
output.writeInt(nStartPos.length);
n4EZy<~m  
for(int i=0;i<nStartPos.length;i++) 4Bq
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{ #]Q.B\\  
// output.writeLong(nPos); _+nlm5  
output.writeLong(fileSplitterFetch.nStartPos); tP/R9Ezp  
output.writeLong(fileSplitterFetch.nEndPos); 9/50+2F  
} q*{Dy1Tj  
output.close(); Ks^EGy+O:-  
} 4";[Xr{pW  
catch(IOException e){e.printStackTrace ();}
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catch(Exception e){e.printStackTrace ();} AlT04H
  
} w77"?kJ9X  
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//读取保存的下载信息（文件指针位置） 6Vc&g  
private void read_nPos() 2;=xHt  
{ WUqfY?5  
try{ [y$sJF7;I  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); /bv4/P  
int nCount = input.readInt(); xn4-^2
 
nStartPos = new long[nCount]; 5J<ghv>\P  
nEndPos = new long[nCount]; R>. %0%iq  
for(int i=0;i<nStartPos.length;i++) W%cJ#R[o  
{ 'x!
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nStartPos = input.readLong(); ~m.@{Do0p  
nEndPos = input.readLong(); )k|_ CW~  
} bT{iei]?  
input.close(); 6'qC *r  
} uvf}7  
catch(IOException e){e.printStackTrace ();} uVw|fT  
catch(Exception e){e.printStackTrace ();} S-k:+4  
} }Qm: g  
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private void processErrorCode(int nErrorCode) J-g<-!>RM  
{ mdTCe HX  
System.err.println("Error Code : " + nErrorCode); qA6;Q$  
} /^<Uy3F[p  
.d>TU bR;  
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//停止文件下载 %^$7z,>;  
public void siteStop() 3@/\j^U  
{ S @MO  
bStop = true; /&#Gh?
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for(int i=0;i<nStartPos.length;i++) U6@Hgi>  
fileSplitterFetch.splitterStop(); kq kj.#u  
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} = j,Hxq  
} @Js^=G2  
//负责部分文件的抓取 54%@q[-  
**FileSplitterFetch.java 9zKrFqhNo  
*/ Ej]:j8^W  
package NetFox; =k\V~8XZ  
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import java.io.*; x$;I E  
import java.net.*; S_VZ^1X]  
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public class FileSplitterFetch extends Thread { zMf.  
Is $I;`  
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String sURL; //File URL |ZAR!u&0  
long nStartPos; //File Snippet Start Position j[Y$)HF  
long nEndPos; //File Snippet End Position J7`fve  
int nThreadID; //Thread's ID N:]71+  
boolean bDownOver = false; //Downing is over 8tR(i[L   
boolean bStop = false; //Stop identical +$-@8,F
>  
FileAccessI fileAccessI = null; //File Access interface ]b"Oy}ARW  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException PE~umY]  
{ XvU^DEfW  
this.sURL = sURL; Stkyz:,(  
this.nStartPos = nStart; E*!
  
this.nEndPos = nEnd; xV_,R'l  
nThreadID = id; R
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fileAccessI = new FileAccessI(sName,nStartPos);//定位 M?iU$qI  
} *f[nge&.  
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public void run() F3XB};  
{ "B~c/%#PH  
while(nStartPos < nEndPos && !bStop) /A8ua=Kn  
{ ^u?#fLr  
(h}5*u%h  
! z^%$;p  
try{ ~$GRgOn  
URL url = new URL(sURL); x}Y  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); `OL@@`'^{S  
httpConnection.setRequestProperty("User-Agent","NetFox"); E<j}"W$a  
String sProperty = "bytes="+nStartPos+"-"; cjf 8N:4N0  
httpConnection.setRequestProperty("RANGE",sProperty); wxa?.  
Utility.log(sProperty); Nl[]8G};  
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InputStream input = httpConnection.getInputStream(); iP7 Cku}l  
//logResponseHead(httpConnection); F;4*,Ap  
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byte[] b = new byte[1024]; VH.mH<  
int nRead; L}E~CiL0n  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) WR&>AOWAD  
{ qc(R /[  
nStartPos += fileAccessI.write(b,0,nRead); #GDnV/0)  
//if(nThreadID == 1) {X85  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); @/MI Oxg[  
} Zj+S"`P  
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Utility.log("Thread " + nThreadID + " is over!"); (i1JDe  
bDownOver = true; ($Cy-p  
//nPos = fileAccessI.write (b,0,nRead); ~4 ~c+^PF  
} 9H~2 iW,Q;  
catch(Exception e){e.printStackTrace ();} :U6"HP+?g-  
} HE;}B!>  
} 8#m,TOp  
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//打印回应的头信息 M id v  
public void logResponseHead(HttpURLConnection con) _Sq*m=  
{ /C[Q?  
for(int i=1;;i++) Uuxx^>"h\  
{ ',WnT:  
String header=con.getHeaderFieldKey(i); F@]9oF  
if(header!=null) $U_M|Xa  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); i;flK*HOZ9  
Utility.log(header+" : "+con.getHeaderField(header)); Ulf'gD4e  
else 3X;k c>  
break; &RJ*DAmL  
} x%v[(*F#y  
} Udi  
R)@2={fd}  
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public void splitterStop() L@5j? N?F  
{ (-no
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bStop = true; DruiiA  
} wD\viuq0  
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} AMw#_8Y  
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.E:3I!dH7  
/* E/3i_R  
**FileAccess.java WYUel4Z  
*//文件访问(定位，写) }@y(-7t  
package NetFox; ~n"?*I`  
import java.io.*; nO+-o;DbC  
f7SMO-3a  
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public class FileAccessI implements Serializable{ Ob&m&2
s,  
/fSsh;F  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 yPd6{% w  
RandomAccessFile oSavedFile; h6Q~Di  
long nPos; Yyr qO^9m  
= yFOH~_  
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public FileAccessI() throws IOException O**
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{ 'ln o#  
this("",0); 7>E>`Nc6  
} tb^/jzC  
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public FileAccessI(String sName,long nPos) throws IOException I/*^s  
{ *EwDwS$$  
oSavedFile = new RandomAccessFile(sName,"rw"); 2lCgUe)N  
this.nPos = nPos; ]6 HR  
oSavedFile.seek(nPos); 9/`3=r@  
} 9sN#l  
-@tj0OHg  
M2$
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public synchronized int write(byte[] b,int nStart,int nLen) ? *v*fs0  
{ ^;9<7h[l  
int n = -1; %g~&$oZmq  
try{ <L('RgA@X  
oSavedFile.write(b,nStart,nLen); Ou4 `#7FR  
n = nLen; :}R,a=N  
} f5Hv![x  
catch(IOException e) ?t/G@  
{ *10qP?0H  
e.printStackTrace (); 4TTrHs  
} Cw"[$E'J  
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return n; Qo!F?i/ n  
} njZJp|y6  
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} (< >Lfn  
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/* m] yUcj{F  
**SiteInfoBean.java Eg&:yF}?(  
*/ *fs[]q'Q  
package NetFox; &8pGq./lr=  
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public class SiteInfoBean { "TP~TjXfq  
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private String sSiteURL; //Site's URL %wXjP`#  
private String sFilePath; //Saved File's Path omGzyuPF  
private String sFileName; //Saved File's Name 5JEOLPS
  
private int nSplitter; //Count of Splited Downloading File }]#z0'Aqsu  
8#HnV%|N  
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public SiteInfoBean() yMu G? x+  
{//nSplitter的缺省值为5 |h%HUau  
//default value of nSplitter is 5 Sa%%3_&  
this("","","",5); IdMwpru(  
} 4x&Dz0[[S  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) EADN   
{ H2H[DVKv  
sSiteURL= sURL; 2@lGY_O!m  
sFilePath = sPath; {]cr.y]\  
sFileName = sName; V9SL96'[I  
this.nSplitter = nSpiltter; t#@z_Mn\  
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:
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} 3!\h'5{  
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public String getSSiteURL() gKl9Nkd!R  
{ k7Qs#L  
return sSiteURL; NiWAJ]Z  
} Ynvf;qs  
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public void setSSiteURL(String value) @8>bp#x/1  
{ Ihf)gfHj  
sSiteURL = value; M49l2x=]9  
} 3N-pND0>p  
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8#
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public String getSFilePath() f,E7eL@  
{ 1++g@8  
return sFilePath; J9!/C#Fm  
} KpYezdPF)  
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public void setSFilePath(String value) lH`TF_  
{ ~G@YA8}  
sFilePath = value; ?RS:I
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} s5{=lP  
>h\u[I$7  
" (O3B  
public String getSFileName() ssx#|InY  
{ !CX WoM  
return sFileName; 2[Lv_<i|  
} Ad>81=Z  
-*4*hHmb  
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public void setSFileName(String value) /P@%{y  
{ 6QY;t:/<  
sFileName = value; ap )B%9  
} Rr%x;-  
c/tB_]  
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public int getNSplitter() p>+9pxx~U  
{ "}qs+  
return nSplitter; G2kU_  
} C
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public void setNSplitter(int nCount) $~.YB\3  
{ NT*r7_e  
nSplitter = nCount;  #O}}pF  
} <A)M^,#o  
} XP?jsBE  
sd\p[MXX  
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/* Icrnu}pl_  
**Utility.java {owuYVm  
*/ ?$109wZ:9  
package NetFox; `T[@-  
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public class Utility { Yw3'9
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7:
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public Utility() !="q"X/*  
{ +,>%Yb=EA  
0W*{ 1W  
{s0%XG1$  
} Om0$6O  
Uv *Aa7M  
//线程睡眠 mfQ#n!{ZH  
public static void sleep(int nSecond) )Wk_|zO-  
{ h
HE~
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try{ f?sm~PwC-  
Thread.sleep(nSecond); aP  
} 2P"9m  
catch(Exception e) nL:&G'd  
{ w_56y8Pd4  
e.printStackTrace (); p5fr}#en  
} eTS}-  
} M@A3+v%K  

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//日志 {'O><4  
public static void log(String sMsg) 0!|d .jZI  
{ I$xZV?d.  
System.err.println(sMsg); R#d~a;j  
} +{I_%SsG  
NZq-%bE  
!,[#,oy;  
public static void log(int sMsg) =*,SD
 
{ %PYl  
System.err.println(sMsg); q`<:CfCt  
} ^&
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} BY6#dlDi  
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!LN8=u.  
/* QO'Hyf t  
**TestMethod.java Ht Fr(g\"$  
*/ 6$k#B ~~  
package NetFox; x4
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public class TestMethod { X8|H5Y:  
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+94)BxrY  
public TestMethod() p&<Ssc  
{ ///xx/weblogic60b2_win.exe QJ2]8K)+C  
try{ )O1
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SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); Dl;hOHvKk  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); }\"EI<$s  
SiteFileFetch fileFetch = new SiteFileFetch(bean); B@,r8)D  
fileFetch.start(); Z,).)y#B  
} pp"X0  
catch(Exception e){e.printStackTrace ();} AWR :~{  
8MJJ w;  
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}
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public static void main(String[] args) H5K Fm#  
{ Dp'urf\*$  
new TestMethod(); -/Q5?0z  
} 9z7_D_yN2  
} NdXHpq;  
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