http断点续传简单实现（java)

/* a P{xMB#1h  
**SiteFileFetch.java L'aMXNO  
*/ =_^g]?5i  
package NetFox; JYv&It  
import java.io.*; pM(y?zGt  
import java.net.*; X@~sIUXx9  
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public class SiteFileFetch extends Thread { (]7@0d88  
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SiteInfoBean siteInfoBean = null; //文件信息Bean
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long[] nStartPos; //开始位置 >W-e0kkH  
long[] nEndPos; //结束位置 ARQ1H0_B  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 k;LENB2iv  
long nFileLength; //文件长度 y:2o-SJn  
boolean bFirst = true; //是否第一次取文件 0 |F(qR  
boolean bStop = false; //停止标志 g^0  
File tmpFile; //文件下载的临时信息 3>L1}zyM]  
DataOutputStream output; //输出到文件的输出流 Jt)<RMQ^R  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） A=XM(2{aN  
public SiteFileFetch(SiteInfoBean bean) throws IOException kY_UY~E  
{ ?|s[/zPS=  
siteInfoBean = bean; j<l>+., U  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); .-W
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tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); Uj!L:u2b  
if(tmpFile.exists ()) &Q&$J )0  
{ JRodYXjE  
bFirst = false; IgFz[)  
read_nPos(); \H" (*["&  
} 7kJ,;30)  
else G53!wIW2:  
{ b
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nStartPos = new long[bean.getNSplitter()]; pAa{,,Qc  
nEndPos = new long[bean.getNSplitter()]; VFYJXR{  
} eGguq~s`  
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} ]h|GaHiE  
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public void run() Wg$MKc9Vy[  
{ SQz>e  
//获得文件长度 $hEX,  
//分割文件 :^ cA\2=  
//实例FileSplitterFetch UhEnW8^bz1  
//启动FileSplitterFetch线程 gqC:r,a  
//等待子线程返回 ^T<<F}@q  
try{ wiFckF/  
if(bFirst) 3gGF?
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{ `[:f;2(@  
nFileLength = getFileSize(); |5FyfDaFBX  
if(nFileLength == -1) HZP`u >.  
{ EL+}ab2S  
System.err.println("File Length is not known!"); n=yFw\w'  
} bF}~9WEa  
else if(nFileLength == -2) /sYD+*a  
{ M&>Z[o  
System.err.println("File is not access!"); Qp<6qM35  
} yt<K!=7&  
else J@)6]d/,  
{ a"ht\v}1  
for(int i=0;i<nStartPos.length;i++) U9;AU]A  
{ 7d9%L}+q  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); my*/MC^O  
} YxsWY
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for(int i=0;i<nEndPos.length-1;i++) e<IT2tv>u  
{ (IEtjv}D  
nEndPos = nStartPos[i+1]; ,I)/ V>u  
} TYB^CVSZ  
nEndPos[nEndPos.length-1] = nFileLength; 2>UyA.m0  
} /gPn2e;  
} FfP Ce5)  
u/``*=Y@  
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//启动子线程 hDfsqSK0 /  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ^TDHPBlG  
for(int i=0;i<nStartPos.length;i++) ,H.q%!{h_  
{ h"q`gj  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), >-]Y%O;}  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), #Ok*Or  
nStartPos,nEndPos,i); j4Lf6aUOX  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); CjykM])  
fileSplitterFetch.start(); &%INfl>o7.  
} nC2A&n&>  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 4Kx;F 9!%~  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); ~KCOCtiD  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", U*,5t81  
nEndPos = " + nFileLength); RELLQpz3  
// fileSplitterFetch[nPos.length-1].start(); 7]G3yt->  

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//等待子线程结束 e>MC 3D`5  
//int count = 0; rbs:q
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//是否结束while循环 qM]eK\q 1  
boolean breakWhile = false; lB3W|-Ci  
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while(!bStop) rr2|xL?+u  
{ wD"Y
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write_nPos(); -Vw,9VCF  
Utility.sleep(500); @R>J\>  
breakWhile = true; nKufVe  
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for(int i=0;i<nStartPos.length;i++)  sy#CR4X  
{ IU/dY`J1  
if(!fileSplitterFetch.bDownOver) vA:1z$m  
{ $^d,>hJi  
breakWhile = false; WOR~tS
 
break; 0I& !a$:  
} b`fPP{mG  
} a\aJw[d{  
if(breakWhile) h0d;a  
break; yw$er?  

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//count++; ;ukwKfs  
//if(count>4) Hj$JXo[U  
// siteStop(); ?nCG:\&;'=  
} 8?h-H#h  
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+A3@{2  
System.err.println("文件下载结束！"); K1]H~'  
} tJ i#bg%  
catch(Exception e){e.printStackTrace ();} %sbDH  
} STL&ZO  
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//获得文件长度 fOtL6/?  
public long getFileSize() u-$(TyDEl|  
{ 3g`uLA X>u  
int nFileLength = -1; 1c8J yp  
try{ I_oJx  
URL url = new URL(siteInfoBean.getSSiteURL()); 8lg$]  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); nM>oG'm[n  
httpConnection.setRequestProperty("User-Agent","NetFox"); OV_Y`u7YR  
nGZZCsf <  
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int responseCode=httpConnection.getResponseCode(); 4U*J{''L  
if(responseCode>=400) mADq_`j  
{ py6|uGN  
processErrorCode(responseCode); d dkh*[  
return -2; //-2 represent access is error x$tx!%,)/S  
} xlZ"F  
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String sHeader; NiQ`,Q$B  
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for(int i=1;;i++) l\I#^N  
{ *BF5B\[r?  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); $e)d!m.  
//Utility.log(in.readLine()); =* oFs|v  
sHeader=httpConnection.getHeaderFieldKey(i); TL-sxED,,D  
if(sHeader!=null) oi^2Pvauh  
{ e C?adCb  
if(sHeader.equals("Content-Length")) XCc/\  
{ $vlq]6V8  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); mEyJ o|  
break; 8D@H4O.  
} /7/d u[P6  
} d!mtSOh  
else '/trM%<  
break; "l&=a1l  
} Ue^2H[zs-  
} {7.."@Ob<v  
catch(IOException e){e.printStackTrace ();} $hZb<Xz  
catch(Exception e){e.printStackTrace ();} 7p}J]!Z  
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Utility.log(nFileLength); Vf9PHHH|   
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return nFileLength; mrX 2w  
} GVhO}m  
1
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//保存下载信息（文件指针位置） rH Et]Xa  
private void write_nPos() :iqFC >D  
{ G5a PjP  
try{ 6;6a.iZ  
output = new DataOutputStream(new FileOutputStream(tmpFile)); "Ah (EZAR  
output.writeInt(nStartPos.length); ARvT  
for(int i=0;i<nStartPos.length;i++) a$H*C(wL  
{ Z M_ 6A1  
// output.writeLong(nPos); 2[6>h)  
output.writeLong(fileSplitterFetch.nStartPos); &D0suK#  
output.writeLong(fileSplitterFetch.nEndPos); ChO?Lm$y  
} g S xK9P  
output.close(); H'7AIY}  
} HxCq6Y_m<  
catch(IOException e){e.printStackTrace ();} v'gP,UO-%D  
catch(Exception e){e.printStackTrace ();} Ww-%s9N<  
} :ZG^`H/X1d  
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//读取保存的下载信息（文件指针位置） |TM&:4D]^  
private void read_nPos() `2`Nu:r^  
{ Rj6:.KEJ  
try{ ~_<I}!j/B  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); tVVnQX  
int nCount = input.readInt(); hd{Vz{;W  
nStartPos = new long[nCount]; 7yp7`|,p  
nEndPos = new long[nCount]; q,6 y{RyS  
for(int i=0;i<nStartPos.length;i++) W _j`'WN/  
{ C/V{&/5w  
nStartPos = input.readLong(); ?g9mDe;k  
nEndPos = input.readLong(); uis;S)+  
} :a$ZYyD  
input.close(); Q-;ltJ  
} tTrUVuZ
 
catch(IOException e){e.printStackTrace ();} cfI5KLG~#  
catch(Exception e){e.printStackTrace ();} pgT XyAP{  
} $T7hY$2Ql  
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private void processErrorCode(int nErrorCode) wXw pKm  
{ !#cZ!  
System.err.println("Error Code : " + nErrorCode); 18JhC*in  
} F%QZe*m[  
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//停止文件下载 eveGCV
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public void siteStop() Ij;=  
{ @?ntMh6  
bStop = true; XgY( Vv
  
for(int i=0;i<nStartPos.length;i++) yH_L<n  
fileSplitterFetch.splitterStop(); +
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} BOqq=WY  
} aIaydu+\  
//负责部分文件的抓取 KI(9TI*  
**FileSplitterFetch.java "h.}o DS  
*/ ~:7AHK2  
package NetFox; *]G&pmMs  
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import java.io.*;  v|+}>g  
import java.net.*; Fs_,RXW"  
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public class FileSplitterFetch extends Thread { BcV;EEi  
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String sURL; //File URL v8g3]MVj3  
long nStartPos; //File Snippet Start Position u:H@]z(x  
long nEndPos; //File Snippet End Position 6w{^S~rqo  
int nThreadID; //Thread's ID Bu?"b=B*  
boolean bDownOver = false; //Downing is over <LM<,  
boolean bStop = false; //Stop identical 3}O.B r|  
FileAccessI fileAccessI = null; //File Access interface i gzISYC_  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException R`=IYnoOA  
{ lv9Ss-c4  
this.sURL = sURL; E&0A W{  
this.nStartPos = nStart; :6LOb f\01  
this.nEndPos = nEnd;
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nThreadID = id; R=HN>(U  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 @t`|w.]ml  
} #I9|>XE1  
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public void run() 'T[=Uuj"  
{ jsTb0  
while(nStartPos < nEndPos && !bStop) 1DcYc-k#  
{ +Cx~4zEq  
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try{ 9\
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URL url = new URL(sURL); 4s*P5w_'/  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); aq"E@fb  
httpConnection.setRequestProperty("User-Agent","NetFox"); )<
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String sProperty = "bytes="+nStartPos+"-"; GSV,  
httpConnection.setRequestProperty("RANGE",sProperty); T,(IdVlJ  
Utility.log(sProperty); d T/*O8  
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InputStream input = httpConnection.getInputStream(); ,)V*xpp  
//logResponseHead(httpConnection); `{I,!to  
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byte[] b = new byte[1024]; -a3+C,I8g  
int nRead; P;KbS~ SlC  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop)
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{ `(;d+fof  
nStartPos += fileAccessI.write(b,0,nRead); &0f7>.y  
//if(nThreadID == 1) /(n)I  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); L3q)j\ls  
} ~2@U85"o  
~QBf78@Gf  
 g/+M&k$  
Utility.log("Thread " + nThreadID + " is over!"); O,qR$#l   
bDownOver = true; o)}b Fw  
//nPos = fileAccessI.write (b,0,nRead); pRc(>P3;  
} 9Lz)SYd  
catch(Exception e){e.printStackTrace ();} {KwLcSn  
} o~P8=1t  
} 8f^URN<x  
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//打印回应的头信息 8SAz,m!W)  
public void logResponseHead(HttpURLConnection con) K1:F{*  
{ $6!`  
for(int i=1;;i++) AaTtYd  
{ ' 1P_*  
String header=con.getHeaderFieldKey(i); 8x,;B_Zu  
if(header!=null) " "a+Nc  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); tY# F8a&  
Utility.log(header+" : "+con.getHeaderField(header)); mSQ!<1PM  
else $<s@S;Ri  
break; T>f-b3dk  
} l'16B^  
} w5|@vB/pj  
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public void splitterStop() n+uq|sYVa  
{ bMSF-lQ  
bStop = true; gP1$#KgU  
} KMbBow3o*~  
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} (/*-M]>  
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/* uDoSe^0  
**FileAccess.java ["L?t ^*G  
*//文件访问(定位，写) *;gi52tM  
package NetFox; m9e$ZZG$  
import java.io.*; q"52-42  
$(CHwG-  
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public class FileAccessI implements Serializable{ in+`zfUJ9  
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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 7L<oWAq  
RandomAccessFile oSavedFile; k2+Z7#2n  
long nPos; El+]}D"  
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public FileAccessI() throws IOException Xif`gb6`  
{ [FCNW0NV  
this("",0); V&}Z# 9Dx  
} 9n%W-R.  
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public FileAccessI(String sName,long nPos) throws IOException %vThbP#mR|  
{ /KV@Ce\  
oSavedFile = new RandomAccessFile(sName,"rw"); *l9Y]hinq  
this.nPos = nPos; ?PQiVL  
oSavedFile.seek(nPos); ]D]K_`!K  
} v0xi(Wu  
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oD
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public synchronized int write(byte[] b,int nStart,int nLen) \Q)~'P3  
{ 7SM/bJ-M#  
int n = -1;  9q5[W=|  
try{ G?V3lQI1n  
oSavedFile.write(b,nStart,nLen); p_nrua?  
n = nLen; d)AkA\neWo  
} J *B`C^i  
catch(IOException e) 07MLK8jS  
{ zld>o3K}  
e.printStackTrace (); 6x7=0}'  
} 'qD9kJ`  
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return n; z&:[.B  
} h}d7M55#|  
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} rTJWftH!  
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/* 2#[Y/p  
**SiteInfoBean.java oe<Y,%u"6
 
*/ @rF\6I  
package NetFox; WT)")0)[  
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public class SiteInfoBean { h^c'L=dR  
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private String sSiteURL; //Site's URL i_@RWka<  
private String sFilePath; //Saved File's Path S.j
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private String sFileName; //Saved File's Name Rju8%FRO  
private int nSplitter; //Count of Splited Downloading File %!S  
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public SiteInfoBean() O o:jP6r  
{//nSplitter的缺省值为5 _7<U[63  
//default value of nSplitter is 5 P:TpB6.=q  
this("","","",5); ]3,0 8JW=  
} q ha1b$  
2I<T<hFW]  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) C"{on%  
{ g2]-Q.  
sSiteURL= sURL; 1sJN^BvuG  
sFilePath = sPath; NZuFxJ-`  
sFileName = sName; Y<+4>Eh  
this.nSplitter = nSpiltter; e2fct|'  
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:I('xVNPz  
} Uk9g^\H<D  
(n/1:'  
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public String getSSiteURL() Mvv=)?:  
{ sdWl5 "  
return sSiteURL; jhG7sS|  
} qrc/Q;$  
l/^-:RRNKi  
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public void setSSiteURL(String value) 3Y-v1.^j  
{ <3}l8Z  
sSiteURL = value; Wwha?W>  
} 0 l@P]_qq`  
-/%jeDKp  
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public String getSFilePath() +df?N  
{ [R>  
return sFilePath; cloI 6%5r  
} CE,Om^  
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^\  
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public void setSFilePath(String value) .M2&ad :  
{ L@r.R_*H?s  
sFilePath = value; |sa7Y_  
} HW726K*
 
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7V (7JV<>  
public String getSFileName() (dF;Gcw+  
{ g{hA,-3  
return sFileName; }dJ ~Iy  
} %n25Uq  
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public void setSFileName(String value) p0y?GNQ  
{ K)&XQ`&  
sFileName = value; xm5FQ) T  
} P&0cF{  
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public int getNSplitter() NB5B$q_'#  
{ 3b@1Zahz  
return nSplitter; #0^3Wm`X;  
} 8'"/gC{  
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-#;VFSz,9*  
public void setNSplitter(int nCount) *9Js:z7I  
{ M
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nSplitter = nCount; f^sb0nU  
} Y~hd<8 ~  
} )^S^s>3  
h$ iyclX  
W?J*9XQ`  
/* ;To+,`?E;q  
**Utility.java OXX(OCG>  
*/ >m6,xxTR  
package NetFox; R 4QwWSBJ  
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public class Utility { :$Q]U2$mPS  
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public Utility() 1fhK{9#  
{ 7K]U|K#  
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VE"0VB.  
} `)!2E6 =  
VfC[U)w*vm  
//线程睡眠 C\2>7  
public static void sleep(int nSecond) %3#I:>si  
{ :mV7)oWH  
try{ xVz -_z  
Thread.sleep(nSecond); >`?+FDOJ,  
} 'j<:FUDJ  
catch(Exception e) ^_S-s\DW  
{ f+aS2k(e>  
e.printStackTrace (); ~v(M6dz~vk  
} OK2/k_jXN'  
} 9q)nNX<$)  
l)rvh#D  
//日志 q,,>:]f#  
public static void log(String sMsg) -anFt+f-  
{ 0e
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System.err.println(sMsg); {p*hNi)0  
} yZ~eLWz  
5nM9!A\D  
v6DxxE2n  
public static void log(int sMsg) {{[jC"4AY  
{ p5# P r  
System.err.println(sMsg); %f> |fs  
} 3|'#n[3  
} cM<hG:4%wX  
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/* ;'Vipj  
**TestMethod.java 6=g]Y!o$  
*/ T.
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package NetFox; 7k#${,k  
fF9oYOh|  
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public class TestMethod { oB{}-[G  
kSDa\l!W]  
id#k!*$7  
public TestMethod() sg6w7fp>  
{ ///xx/weblogic60b2_win.exe vrm{Ql&  
try{ Va/@#=,q]  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 6aF'^6+a  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); b6WC@j`*T  
SiteFileFetch fileFetch = new SiteFileFetch(bean); o~.o^0Y  
fileFetch.start(); F<ocY0=9p  
} y%IG:kZ,  
catch(Exception e){e.printStackTrace ();} leb^,1/D6  
*/5<L99v  
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} )*TW\v`B  
c2\rjK  
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public static void main(String[] args) Z*vpQBbu  
{ 1y)$[e   
new TestMethod(); +zVcOS*-  
} k}f<'g<H  
} b!^M}s6  
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