http断点续传简单实现（java)

/* k:P$LzIB  
**SiteFileFetch.java SFO&=P:U  
*/ koH4~m{  
package NetFox; 1!/-)1t  
import java.io.*; v.`+I-\.z)  
import java.net.*; k!E"wJkpz  
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public class SiteFileFetch extends Thread { f9'] jJ+  
*]{=8zc2  

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SiteInfoBean siteInfoBean = null; //文件信息Bean ,h!X k  
long[] nStartPos; //开始位置 )vHi|~(  
long[] nEndPos; //结束位置 /2h][zrZ[.  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 rl|Q)A{  
long nFileLength; //文件长度 ahp1!=Z-=  
boolean bFirst = true; //是否第一次取文件 &|=?acv  
boolean bStop = false; //停止标志 5<N~3 1z  
File tmpFile; //文件下载的临时信息 v>at/ef  
DataOutputStream output; //输出到文件的输出流 _0]QS4a][c  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） OROqT~6G  
public SiteFileFetch(SiteInfoBean bean) throws IOException k5X b}@
  
{ /c^e&D  
siteInfoBean = bean; aQh?}=da  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 2v\W1VF  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); |#cAsf_{  
if(tmpFile.exists ()) D-iUN  
{ 5bBCpNa  
bFirst = false; 1NGyaI  
read_nPos(); s]bPV,"p  
} qC.i6IL  
else qvTKfIl{  
{ :A*0]X;  
nStartPos = new long[bean.getNSplitter()]; vXf:~G]  
nEndPos = new long[bean.getNSplitter()]; lA4hm4"i(,  
} ._ih$=   

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} k
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public void run() &oc_a1R  
{ tGqQJT#mr7  
//获得文件长度 +_-Y`O!Q  
//分割文件 )"-fHW+fy  
//实例FileSplitterFetch \6LcVik  
//启动FileSplitterFetch线程 ] ?9t-  
//等待子线程返回 *JS"(. '(  
try{ 9
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if(bFirst) 9;pzzZ  
{ wXcMt>3  
nFileLength = getFileSize(); /KP_Vc:g2_  
if(nFileLength == -1) 1:YAn  
{ Vs|sw  
System.err.println("File Length is not known!"); h=Oh9zsz8  
} ,0.|P`|w  
else if(nFileLength == -2) J5-rp|  
{ &]*|6cR$E  
System.err.println("File is not access!"); `~|DoSi^d  
} s79q5  
else 2| $k`I,  
{ Y 0]Kl^\A  
for(int i=0;i<nStartPos.length;i++) N[]U%9[=2F  
{ `:R-[>5P8  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); w0$R`MOR+  
} #a.\P.{L  
for(int i=0;i<nEndPos.length-1;i++) ]'E}   
{ Z3Gm  
nEndPos = nStartPos[i+1]; Jtpa@!M  
} 7Qt2gf  
nEndPos[nEndPos.length-1] = nFileLength; |9x%gUm  
} sD
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} 6l<1A$BQ  
2!{N[*)  
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//启动子线程 `M,Nd'5&|  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; oq243\?Y  
for(int i=0;i<nStartPos.length;i++) v=j>^FZ  
{ |O%:P}6c  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), |o|gP8  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), Ys)+9yPPn  
nStartPos,nEndPos,i); v'K % %z  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); XEa~)i{O  
fileSplitterFetch.start(); FBcm;cjH  
} BjwMb&a;  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 5nY9Ls(e  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); N JXa_&_  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", :mzCeX8 *  
nEndPos = " + nFileLength); G^ K*+  
// fileSplitterFetch[nPos.length-1].start(); 4VC/-.At  
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8IpxOA#jQ  
//等待子线程结束 Ko@zk<~"[  
//int count = 0; !+5C{Hs2  
//是否结束while循环 |x*{fXdMhr  
boolean breakWhile = false; P_v0))n{  
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while(!bStop) SHytyd  
{ 5FZ47m ~{Z  
write_nPos(); `D4oAx d9  
Utility.sleep(500); ?VU
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breakWhile = true; 9/FG,9  
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for(int i=0;i<nStartPos.length;i++) fm[_@L% x  
{ +}kO;\  
if(!fileSplitterFetch.bDownOver) /A0 [_  
{ P=&'wblm?  
breakWhile = false; c6f|y_2  
break; OiYNH~hv  
} xq#U4E  
} ULV)0SB  
if(breakWhile) ?e"Wu+q~L  
break; '" ^ B&W  
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//count++; xX[?L9RGz  
//if(count>4) bl$+8!~  
// siteStop(); <j{0!J@:  
} "xL;(Fqu  
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System.err.println("文件下载结束！"); sM#!Xl;  
} &G0l&8pa  
catch(Exception e){e.printStackTrace ();} tZdwy>;  
} N>Vacc_[  
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//获得文件长度 [`y:M&@  
public long getFileSize() cWgbd^J  
{ 6F@zCv"w  
int nFileLength = -1; *?EO n-  
try{ {E;2&d  
URL url = new URL(siteInfoBean.getSSiteURL()); -3C* P  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); DZ%g^D
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httpConnection.setRequestProperty("User-Agent","NetFox"); ZMdM_i?  
4 *Bp  
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int responseCode=httpConnection.getResponseCode(); <QYCo1_  
if(responseCode>=400) fO[Rf_  
{ >{phyBy
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processErrorCode(responseCode); JZs|~@  
return -2; //-2 represent access is error CPc"  
} 7p P|  
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String sHeader; qk_p}l-F1  
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for(int i=1;;i++) ~C}
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{ 34X(J-1\|i  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); Bpk@{E9  
//Utility.log(in.readLine()); /Ki0+(4  
sHeader=httpConnection.getHeaderFieldKey(i); n@G:e-m{A  
if(sHeader!=null) A8_\2'b  
{ Sf+(1_^`t  
if(sHeader.equals("Content-Length")) }9L 40)
8  
{ a)I=U[  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); Hv[d<ylO  
break; 2(+RIu0d  
} <Cf7E  
} Zp/qs z(]  
else XD_P\z  
break; &*jxI[  
} s|{^ }4{  
} 30sC4}   
catch(IOException e){e.printStackTrace ();} kGB#2J  
catch(Exception e){e.printStackTrace ();} yRgDhA  
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Utility.log(nFileLength);  IgzCh  
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return nFileLength; (hhdbf  
} UPfFT^=y  
^yn[QWFO  
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//保存下载信息（文件指针位置） 1Y H4a|bc  
private void write_nPos() ?#VP)A  
{ eEZ|nEU  
try{ *
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output = new DataOutputStream(new FileOutputStream(tmpFile)); @&~OB/7B:  
output.writeInt(nStartPos.length); zxk??0]/  
for(int i=0;i<nStartPos.length;i++) Y(#d8o}}#  
{ 902!M65[rG  
// output.writeLong(nPos); 4=?Ok":8  
output.writeLong(fileSplitterFetch.nStartPos); *@\?}cX  
output.writeLong(fileSplitterFetch.nEndPos); J9b?}-O)  
} FT|/WZR  
output.close(); ZaukMEq  
} wu&|~@_s@  
catch(IOException e){e.printStackTrace ();} H3p4,Y}'#  
catch(Exception e){e.printStackTrace ();} ~aauW?  
} L]/\C{}k  
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//读取保存的下载信息（文件指针位置） Xa?6#
  
private void read_nPos() zVc7q7E  
{ nJ'>#9~a'>  
try{ h-?q6O/|  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); SU_]C+  
int nCount = input.readInt(); =0@d|LeZ  
nStartPos = new long[nCount]; zJy 89ib'  
nEndPos = new long[nCount]; (!XYH@Mz<w  
for(int i=0;i<nStartPos.length;i++) UtW"U0
A  
{ *0Wi^f  
nStartPos = input.readLong(); s60:0>  
nEndPos = input.readLong(); Qq;m"M/  
} O5G<O(,\  
input.close(); HggR=>s  
} Y1U"HqNl*  
catch(IOException e){e.printStackTrace ();} V<~_OF  
catch(Exception e){e.printStackTrace ();} c]g<XVI  
} 07T;IV3#C5  
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private void processErrorCode(int nErrorCode) T;4gcJPn"M  
{ bgzT3KZ  
System.err.println("Error Code : " + nErrorCode); wH(vX<W-E  
} XoH[MJC  
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}0Kqy;  
//停止文件下载
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public void siteStop() ?|Q5]rhs  
{ }(g+:]p-  
bStop = true; !q=Q~ea  
for(int i=0;i<nStartPos.length;i++) RV#uy]  
fileSplitterFetch.splitterStop(); g'}`FvADi  
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} Q#J>vwi=  
} "j.oR}s9?#  
//负责部分文件的抓取 02J6Pn3  
**FileSplitterFetch.java r0?hX  
*/ X#Dhk6  
package NetFox; @KXz4PU  
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import java.io.*; LjH&f 4mY  
import java.net.*; q~g&hR}K  
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public class FileSplitterFetch extends Thread { FSYjp{z5  
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String sURL; //File URL }^GV(]K  
long nStartPos; //File Snippet Start Position ~Q$c!=
  
long nEndPos; //File Snippet End Position ,# jOf{L*  
int nThreadID; //Thread's ID Y;> p)'z  
boolean bDownOver = false; //Downing is over xV n]m9i  
boolean bStop = false; //Stop identical %:be{Y6  
FileAccessI fileAccessI = null; //File Access interface *09
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 53u.pc  
{ (;Q <@PZg  
this.sURL = sURL; ,QHx*~9  
this.nStartPos = nStart; h@>rjeY@  
this.nEndPos = nEnd; *p#YK|  
nThreadID = id; C_^R_  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 R0YC:rAt  
} ^?^|Y?f2P?  
9h,yb4jPP  
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public void run() dS;|Kl[Om  
{ t6L^ #\'  
while(nStartPos < nEndPos && !bStop) ^K77V$v  
{ E~Up\f  
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try{ [vjkU7;7A  
URL url = new URL(sURL); ]-s`#  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); _7j/[  
httpConnection.setRequestProperty("User-Agent","NetFox"); b1>$sPJ+  
String sProperty = "bytes="+nStartPos+"-"; 7dg 5HH  
httpConnection.setRequestProperty("RANGE",sProperty); |_xiG~  
Utility.log(sProperty); 73sAZa|  
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InputStream input = httpConnection.getInputStream(); >A'!T'"~  
//logResponseHead(httpConnection); Ff#N|L'9_  
%C
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byte[] b = new byte[1024]; rW%'M#! =  
int nRead; !{~7)iq  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) _Fh0^O@  
{ ;'
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nStartPos += fileAccessI.write(b,0,nRead); Y)j,(9  
//if(nThreadID == 1) %{VI-CQ  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); eUw;!Du  
} (zLIv9$  
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Utility.log("Thread " + nThreadID + " is over!"); O"-PNF,J  
bDownOver = true; J0WXH/:  
//nPos = fileAccessI.write (b,0,nRead); e/% ;  
} W4rw;(\  
catch(Exception e){e.printStackTrace ();} eP'kY(g8   
} LYq2A,wm$  
} $XU$?_O  
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5~R{,]52  
//打印回应的头信息 w>q_8V_K  
public void logResponseHead(HttpURLConnection con) [MXXY  
{ <sFf'W_3{  
for(int i=1;;i++) ;o@`l$O   
{ 0JRBNh  
String header=con.getHeaderFieldKey(i); v*]Xur6e}  
if(header!=null) S+xGHi)  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); W6/p
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Utility.log(header+" : "+con.getHeaderField(header)); C
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else 8}0y)aJ  
break; _ktSTzH0  
} KeO
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} <fxjj  
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public void splitterStop() .&Gtw _  
{ 5'Ay@FJ:  
bStop = true; &E'
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} 0|Ft0y`+  
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} k
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/* U"kK]Stk<  
**FileAccess.java td$6:)  
*//文件访问(定位，写) ^[z\KmUqt  
package NetFox; k+G4<qw  
import java.io.*; 2}Plr{s9  
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public class FileAccessI implements Serializable{ G8-d%O p  
p;Ok.cXVp  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 so&3A&4cL  
RandomAccessFile oSavedFile; ^a5~FI:  
long nPos; :*%\i' $!/  
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public FileAccessI() throws IOException Y tj>U  
{ 2m}]z.w#  
this("",0); K{h]./%  
} `CouP-g.  
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public FileAccessI(String sName,long nPos) throws IOException / ^M3-5@Q  
{ J@{Bv%  
oSavedFile = new RandomAccessFile(sName,"rw"); 'N/%SRk  
this.nPos = nPos;  cJ{P,K  
oSavedFile.seek(nPos); ",GC\#^v  
} r~a}B.pj  
@].aFhH`)  
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public synchronized int write(byte[] b,int nStart,int nLen) b|'LtL$Y  
{ 1@@]h!>k:  
int n = -1; $}
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try{ \aRB   
oSavedFile.write(b,nStart,nLen); ;b2>
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n = nLen; LYKm2C*d  
} iU|C<A%Hh  
catch(IOException e) *Y>'v%  
{ <"9Z7" >  
e.printStackTrace (); 7cQw?C  
} `u)V9{  
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return n; w8zQDPVB%  
} JsdEA  
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} c
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/* "lMWSCas  
**SiteInfoBean.java O3^@"IY  
*/ ld0WZj  
package NetFox; A#\X-8/  
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public class SiteInfoBean { u(qpdG||7  
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private String sSiteURL; //Site's URL ^B]t4N2i  
private String sFilePath; //Saved File's Path 3 g!h4?^  
private String sFileName; //Saved File's Name C_;6-Q%V  
private int nSplitter; //Count of Splited Downloading File oOw"k*,h:S  
yw^,@'  
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public SiteInfoBean() ? -tw*2+  
{//nSplitter的缺省值为5 ;">hCM7  
//default value of nSplitter is 5 WfI~l)  
this("","","",5); Z r*ytbt  
} tp0*W _<4  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) DtX{0p<T3  
{ =!2  
sSiteURL= sURL; Il[WXt<S  
sFilePath = sPath; 3x$#L!VuU  
sFileName = sName; dv:
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this.nSplitter = nSpiltter; Z$gY}Bz  
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} -R]S)Odml  
0J B"@U&-  
LPClE5  
public String getSSiteURL() f+RDvgkKU  
{ / ffWmb_4  
return sSiteURL; UJ+JVj  
} ~M=`f{-$K  
g.qp _O  
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public void setSSiteURL(String value) a7R7Ks|q  
{  G%{jU'2  
sSiteURL = value; 6I<`N  
} +-i@R%  
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public String getSFilePath() `,z{70  
{ }#@LZ)]hK  
return sFilePath; 
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} N~_gT Jr~P  
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public void setSFilePath(String value) K,Vl.-4?  
{ *%.*vPJ  
sFilePath = value; od>.
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} ~drNlt9jf  
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7UiU3SUcg  
public String getSFileName() qIl@,8T  
{ %$U+?lk}  
return sFileName; +VDB\n  
} H}/1/5L  
}OZfsYPz}T  
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public void setSFileName(String value) Cq=c'(cX  
{ C\Rd]P8\  
sFileName = value; 5;+Bl@zGu  
} n/-I7Q!;u  
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u
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public int getNSplitter() : s
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{ +|N"i~f>j  
return nSplitter; (]L=$u4  
} 9(Z)c  
& |r)pl0$  
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public void setNSplitter(int nCount) 2zAS \Y  
{ ]dH;+3}  
nSplitter = nCount; u<[Y6m  
} "Y6f.rB  
} qohUxtnTK>  
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/* 6K6ihR!d  
**Utility.java 4^ A
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*/ _?8T'?-1  
package NetFox; .nnA
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tO#y4<  
public class Utility { 8V@3T/}  
%q@@0qenv  
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public Utility() }6\p7n  
{ t_3XqjuA  
`R\0g\  
Z+4J4Ka^!(  
} KpWQ;3D2  
Y,{Xv  
//线程睡眠 8AK#bna~-  
public static void sleep(int nSecond) ?6|EAKJ`lK  
{ D n^RZLRhy  
try{ +'l@t bP  
Thread.sleep(nSecond); h c"n?  
} S;= D/)[mr  
catch(Exception e) Wh
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{ :jA~zHO  
e.printStackTrace (); VHy$\5oYg  
} 2Tp.S3  
} G
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-YYQnN  
//日志 Pp?J5HW  
public static void log(String sMsg) *v6'I-#  
{ v6FYlKU@8  
System.err.println(sMsg); hTF]-& hZ  
} { Uh/ ~zu  
) Limt<S  
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public static void log(int sMsg) h_J'd
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{ 3K{'~?mM  
System.err.println(sMsg); {epsiHK@tK  
} 1L3L!@  
} ZJS7#<-7o  
s iC/k*  
I-^Y$6-  
/* 8[eH8m#~$  
**TestMethod.java ZT!DTb B  
*/ /P320[B}m&  
package NetFox; 'wDNP_  
0q81H./3  
 'y1=Z  
public class TestMethod { 0^4Tem@  
l%U{Unwu  
rTQrlQ:@  
public TestMethod() S?&ntUah  
{ ///xx/weblogic60b2_win.exe J 5~bs*a8  
try{ 4]B(2FR[8  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); Xfe,ZC)  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); mI-$4st]  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 2\_}81hM  
fileFetch.start(); !fY'^Ya?  
} ZPHB$]ri  
catch(Exception e){e.printStackTrace ();} Y*0mC"n}  
GC.   
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} )D Y?Y-n  
1O8RGk4  
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public static void main(String[] args) d(<[$3.  
{ n"*A.  
new TestMethod(); |-bAzt  
} "??$yMW  
} yi PMJ  
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