http断点续传简单实现（java)

/* ex^9 l b  
**SiteFileFetch.java (BngwLVDK  
*/ +43~4_Oj  
package NetFox; vvs2:87zvJ  
import java.io.*; / !y~Q|<|=  
import java.net.*; dkY
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public class SiteFileFetch extends Thread { irvd>^&jDC  
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SiteInfoBean siteInfoBean = null; //文件信息Bean i8p$wf"aW  
long[] nStartPos; //开始位置 }%AfZ2g;h  
long[] nEndPos; //结束位置 .R#-u/6g(  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 ?JTTl;  
long nFileLength; //文件长度 5;G0$M0  
boolean bFirst = true; //是否第一次取文件 )Gk?x$pY@  
boolean bStop = false; //停止标志 )\PX1198  
File tmpFile; //文件下载的临时信息 A
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DataOutputStream output; //输出到文件的输出流 ~
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） /n6ZN4  
public SiteFileFetch(SiteInfoBean bean) throws IOException H:OpS-b  
{ aOd|;Z  
siteInfoBean = bean; zbr^ulr  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); gK(G1  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); X @pm!c#  
if(tmpFile.exists ()) Jw#7b[a  
{ ZJ~0o2xZ'  
bFirst = false; rqnxR
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read_nPos(); ;(jL`L F  
} FFcIOn  
else 8)1=5n  
{ CBNt _y  
nStartPos = new long[bean.getNSplitter()]; q`.=/O'  
nEndPos = new long[bean.getNSplitter()]; &}0QnO_mj  
} [La}h2gz  
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} {:b~^yW  
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public void run() H "5,To  
{ E:k]Z  
//获得文件长度 .{ZJywE<  
//分割文件 /d">}%Jn  
//实例FileSplitterFetch *D
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//启动FileSplitterFetch线程 <L11s%5-  
//等待子线程返回 P-$ ,  
try{ bfEH>pQ>#  
if(bFirst) Aqz $WTHW+  
{ J]w3iYK  
nFileLength = getFileSize(); s;E(51V<>  
if(nFileLength == -1) 3$Vx8:Rhdn  
{ $E[M[1j  
System.err.println("File Length is not known!"); 7[uN;B#V  
} 3 {hUp81>  
else if(nFileLength == -2) tw=A] a*  
{ a(*"r:/lD  
System.err.println("File is not access!"); u8<[Q]5  
} 7E#h(bt j  
else G<k.d"<  
{ Qds:*]vGS  
for(int i=0;i<nStartPos.length;i++) h-sO7M0E]  
{ #_`p 0wY  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); c
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} JiO8EIM  
for(int i=0;i<nEndPos.length-1;i++) );yZyWDV
 
{ #H<}xC2  
nEndPos = nStartPos[i+1]; (d@(QJ  
} @o*~\E<T  
nEndPos[nEndPos.length-1] = nFileLength; Vgkj4EE  
} _?y3&4N)  
} 6v]`s  
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//启动子线程 -!mtL
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; [` }w7  
for(int i=0;i<nStartPos.length;i++) |pbetA4&  
{ EYZ&%.Sy5  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), GVu[X?q@|  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), yB/F6/B~  
nStartPos,nEndPos,i); #8 ^b]  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); "w0~f6o  
fileSplitterFetch.start(); b<#zgf  
} MxI*ml8z?  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), -5]lHw}  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); @8w5Oudvx  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", lq]8zm<\)]  
nEndPos = " + nFileLength); M;'GnGFf  
// fileSplitterFetch[nPos.length-1].start(); 0u&x%c  
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//等待子线程结束 JUj.:n2e  
//int count = 0; P*>?/I`G  
//是否结束while循环 -{J0~1'#-  
boolean breakWhile = false; :;hX$Qz  
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6  
while(!bStop) \CE+P5  
{ 0H.bRk/P+  
write_nPos(); q4Bw5
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Utility.sleep(500); qmGHuQVe  
breakWhile = true; trjeGSt&  
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for(int i=0;i<nStartPos.length;i++) hR:i!  
{ 8''1H<f
 
if(!fileSplitterFetch.bDownOver) X(17ESQ/Y  
{ wu11)HFL|z  
breakWhile = false; [`E_/95  
break; xhCQRw  
} "X._:||8  
} C`3XOth  
if(breakWhile) 7QZyd-  
break; sa/9r9hc+  
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//count++; {R[V  
//if(count>4) bA$ElKT  
// siteStop(); :SO4@JT{W  
} `s\[X-j]  
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System.err.println("文件下载结束！"); hH-!3S2'  
} B-L@
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catch(Exception e){e.printStackTrace ();} 7@y}J5,  
} a #s Nd  
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//获得文件长度 y?3u6q++  
public long getFileSize() vl}}h%BC  
{ _Gb7n5p  
int nFileLength = -1; N>sT@ > )  
try{ qJK9
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URL url = new URL(siteInfoBean.getSSiteURL()); 4AvIU!0w  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); J8@+)hn  
httpConnection.setRequestProperty("User-Agent","NetFox"); PR(KDwsT&l  
}TuMMO4+  
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int responseCode=httpConnection.getResponseCode(); @m:' L7+  
if(responseCode>=400) <&B]p  
{ N!v>2"x8q  
processErrorCode(responseCode); Bd;EI)J
T  
return -2; //-2 represent access is error BVH)!]m0  
} 2\O!vp>|-  
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String sHeader; 0|0IIgy  
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for(int i=1;;i++) %wu,ce]*  
{ A]o3MoSt  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 6"rS?>W/mO  
//Utility.log(in.readLine()); fHI@' '0  
sHeader=httpConnection.getHeaderFieldKey(i); 673G6Nk  
if(sHeader!=null) Zw/??Tq b  
{ _x`:Ne?  
if(sHeader.equals("Content-Length")) X.q#ZpK  
{ +, rm  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader));  %\B?X;(  
break; $SniQ  
} 9NU-1vd~  
} *>o@EUArN  
else f_hG2Sk  
break; 7-9HCP  
} bOV]!)o  
} NX]6RZr-  
catch(IOException e){e.printStackTrace ();} \tS| N40  
catch(Exception e){e.printStackTrace ();} +K;%sAZy  
)D]LPCd[  
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Utility.log(nFileLength); 0d`lugf  
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return nFileLength; WS@8Z0@RD  
} ::/vDUDc  
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//保存下载信息（文件指针位置） y] $-:^  
private void write_nPos() g^\>hjNX  
{ j2n 4; m  
try{ n!NA}Oa  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ]ddL'>$c$  
output.writeInt(nStartPos.length); gvP.\,U  
for(int i=0;i<nStartPos.length;i++) A2fuNV_  
{ 8{CBWXo$)  
// output.writeLong(nPos); 4'`*Sce}  
output.writeLong(fileSplitterFetch.nStartPos); K5+ONA<c  
output.writeLong(fileSplitterFetch.nEndPos); h#|Ac>fz  
} ~@D!E/
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output.close(); *NIhYg6  
} AAc2u^spx  
catch(IOException e){e.printStackTrace ();} ).$kp
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catch(Exception e){e.printStackTrace ();} .8CfCRq  
} 9v}vCg  

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//读取保存的下载信息（文件指针位置） s! sG)AR.J  
private void read_nPos() L7.LFWq$S  
{ H<`7){iG  
try{ 1|3vwgRhs  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); \3j4=K'nE  
int nCount = input.readInt(); 
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nStartPos = new long[nCount]; xn7bb[g;  
nEndPos = new long[nCount]; "LVN:|!  
for(int i=0;i<nStartPos.length;i++) jouT9~[L'  
{ '494^1"io  
nStartPos = input.readLong(); qNbgN{4  
nEndPos = input.readLong(); o7:"Sl2AD  
} v
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input.close(); uF-Rl## >  
} O'W[/\A56M  
catch(IOException e){e.printStackTrace ();} 1swqs7rR|  
catch(Exception e){e.printStackTrace ();} {=E,.%8  
} e= _7Q.cn  
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private void processErrorCode(int nErrorCode) Dt+uf5o(  
{ ,#80`&\%  
System.err.println("Error Code : " + nErrorCode); *3!ixDX[r  
} ebB8.(k9G3  
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//停止文件下载 D?? \H\  
public void siteStop() eP|hxqM&9  
{ ;8<lgZ9H<  
bStop = true; xo(3<1mD  
for(int i=0;i<nStartPos.length;i++) >zcp(M98  
fileSplitterFetch.splitterStop(); n0'"/zyc  
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} zzyD'n7D  
} g6<D 1r  
//负责部分文件的抓取 0[SrRpD  
**FileSplitterFetch.java |K$EULzz  
*/ u]QG^1.qYe  
package NetFox; VxGR[kq$]  
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import java.io.*; o_%gFV[q  
import java.net.*; r1Cq8vD*m  
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public class FileSplitterFetch extends Thread { w,zgYX&  
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String sURL; //File URL 6SmawPPP  
long nStartPos; //File Snippet Start Position i@spd5.  
long nEndPos; //File Snippet End Position ;"DI)hdz  
int nThreadID; //Thread's ID ?O#,|\v?]  
boolean bDownOver = false; //Downing is over V']
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boolean bStop = false; //Stop identical Qx}hiv/  
FileAccessI fileAccessI = null; //File Access interface tY$4k26  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException {,C
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{ $iAd)2LT  
this.sURL = sURL; 1 gx(L*y,  
this.nStartPos = nStart; nL-kBW Ed>  
this.nEndPos = nEnd; q#!c6lG  
nThreadID = id; 5Lm<3:7Q+  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 /kK:{  
} 5QJ
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public void run() 8qQrJFm|3*  
{ a$P$Ngi?S  
while(nStartPos < nEndPos && !bStop) Q?TXM1Bp  
{ &IgH]?t  
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try{ _i+7O^=d6X  
URL url = new URL(sURL); dW>$C_`?  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); s~MCt|a  
httpConnection.setRequestProperty("User-Agent","NetFox"); w?zY9Fs=s  
String sProperty = "bytes="+nStartPos+"-"; kv'gs+,e  
httpConnection.setRequestProperty("RANGE",sProperty); d<B=p&~  
Utility.log(sProperty); 9$:+5f,%a  
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InputStream input = httpConnection.getInputStream(); 66shr  
//logResponseHead(httpConnection); 0}y-DCuQ  
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byte[] b = new byte[1024]; OLM}en_L  
int nRead; :#zv,U&OC  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) dX:#KdK  
{ AT]Ty  
nStartPos += fileAccessI.write(b,0,nRead); JPfE`NZ  
//if(nThreadID == 1) U/I+A|S[  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); /C)FS?=  
} P_3U4J  
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Utility.log("Thread " + nThreadID + " is over!");
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bDownOver = true; f.y~Sew  
//nPos = fileAccessI.write (b,0,nRead); O:3DIT1#>  
} !2Q>  
catch(Exception e){e.printStackTrace ();} (N25.}8Y  
} K~JXP5`(  
} z ''-AH,  
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//打印回应的头信息 ``4lomz>  
public void logResponseHead(HttpURLConnection con) LQrm/)4bF5  
{ H0.,h
;  
for(int i=1;;i++) %!e;sL~&  
{ 6C|]Fm  
String header=con.getHeaderFieldKey(i); \9t6#8  
if(header!=null) r@m2foaO  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); uuMHD{}?}  
Utility.log(header+" : "+con.getHeaderField(header)); &,B91H*#  
else N$SJK  
break; h8lI#Gs  
} d~b#dcv$"  
} P?P))UB5  
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public void splitterStop() ep3iI77/  
{ kbkq
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bStop = true; XUyoZl?  
} T>;Kq;(9  
)c$)am\I{  
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} `e!hT@Xxa  
{?
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/* 1"82JN|!  
**FileAccess.java Z/ypWoV(  
*//文件访问(定位，写) on q~wEr  
package NetFox; Qb;5:U/x  
import java.io.*; BsX# ~  
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9  
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public class FileAccessI implements Serializable{ `1[GY){?)  
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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 nBVknyMFNF  
RandomAccessFile oSavedFile; T?Dq2UW  
long nPos; ;|Ja|@82  
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public FileAccessI() throws IOException igW>C2J  
{ *I}_
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this("",0); :tA|g  
} ,T|%vqbmw  
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public FileAccessI(String sName,long nPos) throws IOException 9$xEktfV  
{ -~HlME*~f  
oSavedFile = new RandomAccessFile(sName,"rw"); Ht'jm(  
this.nPos = nPos; V!SB9t`E  
oSavedFile.seek(nPos); ,A>i)b
rc  
} {mp;^/O`er  
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public synchronized int write(byte[] b,int nStart,int nLen) E5%ae (M^  
{ j{nkus2  
int n = -1; M]>JI'8  
try{ ,K'}<dm|x  
oSavedFile.write(b,nStart,nLen); W`PK9juu  
n = nLen; "Jp6EL%  
} %V$ujun`  
catch(IOException e) Ik#>6  
{ ?ExfxR!~  
e.printStackTrace (); i`g>Y5  
} sv^;nOAc  
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return n; JHf}LZu  
} i#jCf3%+ h  
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} "z }bgy  
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/* #oYX0wvl  
**SiteInfoBean.java Dz&4za+{  
*/ |jV4]7Luq  
package NetFox;  <C4^Vem  
K@{jY\AZNx  
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public class SiteInfoBean { O'."ca]:5  
&%Hj.  
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private String sSiteURL; //Site's URL WII_s|YSt%  
private String sFilePath; //Saved File's Path 0zpP$q$  
private String sFileName; //Saved File's Name H[x9 7r  
private int nSplitter; //Count of Splited Downloading File 8IC((  
>t8eVMMa  
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public SiteInfoBean() e_6 i896  
{//nSplitter的缺省值为5 Y@.> eS  
//default value of nSplitter is 5 #%e`OA(b  
this("","","",5); ,ASY &J5)7  
} 6x@-<{L  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) #U/B,`= >  
{ $)@zlnU  
sSiteURL= sURL; &F#X0h/m=  
sFilePath = sPath; oRu S_X  
sFileName = sName; TF^]^XS'  
this.nSplitter = nSpiltter; kXX RMR  
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.: 7h=neEW  
} of& vQ  
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public String getSSiteURL() dl{3fldb  
{ v;K\#uc_  
return sSiteURL; y+:<  
} wU#Q>ut'%  
m Xw1%w[*  
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public void setSSiteURL(String value) 5o~Z>  
{ hGus!p"lw  
sSiteURL = value; T  |j^  
} <E\BKC%M  
w\t{'  
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public String getSFilePath() DTIy/  
{ 9J
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return sFilePath; Ar'5kPzY>  
} OC\C^Yh*U  
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public void setSFilePath(String value) hcaH  
{ 3 oWCQ  
sFilePath = value; 1g/mzC
  
} x@k9]6/zs  
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public String getSFileName() jN {ED_  
{ t1~*q)!Mo  
return sFileName; L,kF]
 
} lMO0d_:b1  
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public void setSFileName(String value) fg1 zT~  
{ cALu  
sFileName = value; 3> fuH'=  
} WD)[Ac[  
$4M3j%S  
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public int getNSplitter() be@MQ}6>  
{ }M~AkJL  
return nSplitter; $Y4 Ao-@  
} '",5Bu#C  
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public void setNSplitter(int nCount) qzyQ2a_p  
{ >ab=LDoM  
nSplitter = nCount; $ `ho+  
} -J6}7>4^8}  
} [,e_2<  
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/* DuFlN1Z  
**Utility.java Z3/zUtgs  
*/ }z*p2)v`  
package NetFox; \4&g5vE  
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public class Utility { +*!!  
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public Utility() p*'?(o:=  
{ SVHtv0Nx  
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} K4tX4U[Z  
D;E&;vP6%  
//线程睡眠 c
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public static void sleep(int nSecond) a|>MueJ  
{ aD:+,MZ  
try{ ls5S9R 5  
Thread.sleep(nSecond); <*\J 6:^n  
} 8;5/_BwMu  
catch(Exception e) GQQ!3LwP\O  
{ S&0x:VW  
e.printStackTrace (); p[$I{F*a  
} (+@.L7>m+t  
} TvP# /qGgG  
o]j*  
//日志 _`(g?  
public static void log(String sMsg) 'SY&-<t(  
{ *SW,pHYnLb  
System.err.println(sMsg); ^Ve^}|qPc  
} bM'AD[  
;Cy@TzO/|  
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public static void log(int sMsg) 4>W`XH  
{ G1l(  
System.err.println(sMsg); 4M]8po/;  
} :8ZxOwwv  
} tX_eN  
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/* Y:a(y*y<  
**TestMethod.java y{N9.H2  
*/ `4=b|N+b"  
package NetFox; zaZnL7ZJX  
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public class TestMethod { |);>wV"  
MXy{]o_H~  
A>?fbY2n  
public TestMethod() NR*SEbUU*  
{ ///xx/weblogic60b2_win.exe L`#+ZLo  
try{ EDo (  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); {G}HZv%S U  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ~JXHB
X  
SiteFileFetch fileFetch = new SiteFileFetch(bean); GXfVjC31z
 
fileFetch.start(); Vo%d;>!G\;  
} )~/U+,  
catch(Exception e){e.printStackTrace ();} qEAF!iB]L  
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|(%H O@i  
} Zx_m?C_2_  
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public static void main(String[] args) {OOt+U!  
{ cGp^;> ]M  
new TestMethod(); zCHr  
} ,B2-'O  
} wGvgMZ]?'  
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