http断点续传简单实现（java)

/* QzS=oiL  
**SiteFileFetch.java ~Z' /b|x<3  
*/ X8y :=k,E  
package NetFox; 6G7+&g`  
import java.io.*; jwmPy)X|s\  
import java.net.*; {$Z S 27  
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public class SiteFileFetch extends Thread { M}]4tAyT  
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SiteInfoBean siteInfoBean = null; //文件信息Bean X3'd~!a)  
long[] nStartPos; //开始位置 {9vMc  
long[] nEndPos; //结束位置 31cZ
6[  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 T_[  
long nFileLength; //文件长度 X 4\V4_  
boolean bFirst = true; //是否第一次取文件 }kSP p  
boolean bStop = false; //停止标志 %k @4}M>  
File tmpFile; //文件下载的临时信息 S 9|^VU  
DataOutputStream output; //输出到文件的输出流 g%okYH?  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） YmD~&J  
public SiteFileFetch(SiteInfoBean bean) throws IOException w5=<}1`St  
{ kRV]`'u,  
siteInfoBean = bean; .|@2Uf  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); +I+RNXR/{  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); cZ3A~dTOR  
if(tmpFile.exists ()) pnUL+UYeM  
{ a:KL{e[  
bFirst = false; -Gjz+cRns  
read_nPos(); eoJ*?v  
} P|ftEF  
else #vc!SI  
{ udPLWrPF\  
nStartPos = new long[bean.getNSplitter()]; bnN&E?{hF1  
nEndPos = new long[bean.getNSplitter()]; XB a^ A  
} nfh<3v|kvR  
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} <pM6fI6BD  
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public void run() 7!;zkou  
{ k"E|E";B  
//获得文件长度 _Td#C1g3  
//分割文件 KN&|&51p}  
//实例FileSplitterFetch J!">L+Zcx  
//启动FileSplitterFetch线程 QcX&q%*0  
//等待子线程返回 MRT<hB  
try{ HkY#i;%N  
if(bFirst) ru|*xNXKgC  
{ Hs6Kki1  
nFileLength = getFileSize(); -j
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if(nFileLength == -1) 7>F[7_  
{ ( X+2vN  
System.err.println("File Length is not known!"); uX%$3k  
} 4UND;I&  
else if(nFileLength == -2) B~b ='jN  
{  bDD29  
System.err.println("File is not access!"); x$FcF8  
} TD78&a#  
else "U$](k.<VA  
{ x:h)\%Dg<  
for(int i=0;i<nStartPos.length;i++) qyh]v[  
{ (W}DMcuSd  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); gSf>+|  
} Sggl*V/q  
for(int i=0;i<nEndPos.length-1;i++) TX7dwmt)N  
{ &VcO,7 A|  
nEndPos = nStartPos[i+1]; OX?E3 <8`  
} F!w|5,)  
nEndPos[nEndPos.length-1] = nFileLength; JB=L{P J  
} irP*:QM  
} y\[q2M<  

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//启动子线程 j?g#8L;W\w  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; d(Hqj#`-31  
for(int i=0;i<nStartPos.length;i++) ` k(Q:  
{ G:`So  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), E,cQ9}/  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), RD;A  
nStartPos,nEndPos,i); }J2f$l>R  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ^(@]5
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fileSplitterFetch.start(); Ps;4]=c  
} xMa9o  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), nZG zez  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 9[lk=1.qN  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", @ScC32X  
nEndPos = " + nFileLength); de[NIDA;`  
// fileSplitterFetch[nPos.length-1].start(); .[1@wW&L  
8@|{n`n]  
.ud&$-[a  
//等待子线程结束 sGpAaGY>  
//int count = 0; t2|0no  
//是否结束while循环 )J2UNIgN  
boolean breakWhile = false; DF-.|-^9I  
oa[O~z{~  
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while(!bStop) Zv?"1Y< L  
{ P{Q$(rOe  
write_nPos(); ] ;HCt=I~  
Utility.sleep(500); ps:E(\  
breakWhile = true; "9N;&^I  
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D=Yr/qc?  
for(int i=0;i<nStartPos.length;i++) qv|}>wU  
{ 6\.LG4@LO  
if(!fileSplitterFetch.bDownOver) _::ssnG3jT  
{ ikb77?.  
breakWhile = false; OKk"S_`  
break; aSgKh  
} Vock19P  
} &5[+p{2  
if(breakWhile) AsvH@
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break; r`RLDN!`  
A]drNFE  
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//count++; /s+S\ djk  
//if(count>4) +Hp`(^(  
// siteStop(); e@/' o/  
} 6Ypc]ym=J  
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System.err.println("文件下载结束！"); A>HCX 4i  
} /FC(d
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catch(Exception e){e.printStackTrace ();} 7KJ0>0~Et  
} oTcf[<  
;d_<6|*M  
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//获得文件长度 #\ysn|!J,  
public long getFileSize() (Jk[%_b>_  
{ <aI}+  
int nFileLength = -1; `U>2H4P  
try{ 'C#[iRG4  
URL url = new URL(siteInfoBean.getSSiteURL()); G%= gCR  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); s#")hMJQ  
httpConnection.setRequestProperty("User-Agent","NetFox"); >.G#\w  
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int responseCode=httpConnection.getResponseCode(); uY/CiTWr  
if(responseCode>=400) h^''ue"  
{ '* /$66|  
processErrorCode(responseCode); >m{>0k(^`  
return -2; //-2 represent access is error 'iDkAmvD  
} RZ ?SiwE  
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String sHeader; -z se+]O`  
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for(int i=1;;i++) 9
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{ x-4d VKE*z  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); vz1I/IdTd  
//Utility.log(in.readLine()); `~41>mM%  
sHeader=httpConnection.getHeaderFieldKey(i); R\/tKZJjb  
if(sHeader!=null) NmF8BmIj  
{ &fU48n1Uh  
if(sHeader.equals("Content-Length")) YIb7y1\UM  
{ `9P`f4x  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); :m/qR74+"  
break; ,Z! I^  
} vGI)c&C>  
} K,*-Y)v2W  
else W
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break; zG
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} I }8b]  
} }Gx@1)??  
catch(IOException e){e.printStackTrace ();}
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catch(Exception e){e.printStackTrace ();} Hc8!cATQk  
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Utility.log(nFileLength); ;ZP!:,  
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return nFileLength; :/t_5QN  
} :2:%  
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//保存下载信息（文件指针位置） -mLu!32I<  
private void write_nPos() 1|:;~9n<t  
{ +[$Td%6  
try{ aOsc_5XDR;  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ;sz_W%-;@  
output.writeInt(nStartPos.length); &SPr#OkW  
for(int i=0;i<nStartPos.length;i++) ^BW8zu@=O  
{ G9K& }_,  
// output.writeLong(nPos); ?MFXZ/3(ba  
output.writeLong(fileSplitterFetch.nStartPos); \nL@P6X  
output.writeLong(fileSplitterFetch.nEndPos); l\d[S]  
} ^$RpP+d  
output.close(); #c'}_s2F[  
} D}-HWJQA3  
catch(IOException e){e.printStackTrace ();} \{ C ~B;=  
catch(Exception e){e.printStackTrace ();} <dz_7hR"  
} `FX?P`\@I  
{Hvkn{{'  
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//读取保存的下载信息（文件指针位置） 57;( P  
private void read_nPos() %?8.UW\m  
{ vVsaGW   
try{ <7/7+_y  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); r'XWt]B+[  
int nCount = input.readInt(); .v9i|E=<~  
nStartPos = new long[nCount]; C/ ]Bx  
nEndPos = new long[nCount]; |O"Pb`V+  
for(int i=0;i<nStartPos.length;i++) 2+R]q35-  
{ -Q ];o~  
nStartPos = input.readLong(); 5p3:8G7  
nEndPos = input.readLong(); F#qc#s  
} l SuNZYaO  
input.close(); zhyf}Ta'  
} 6k+tO%{~  
catch(IOException e){e.printStackTrace ();} i=fhK~Jd  
catch(Exception e){e.printStackTrace ();} h_g"F

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} 
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private void processErrorCode(int nErrorCode) VwXR,(  
{ D?H|O[  
System.err.println("Error Code : " + nErrorCode); X6?Gxf,  
} `1FNs?j  
(;HO3Z".q$  
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//停止文件下载 v)*eLX$  
public void siteStop() i/C0 (!  
{ ma`sv<f4-!  
bStop = true; f uH3C~u7<  
for(int i=0;i<nStartPos.length;i++) ?9*[\m?-  
fileSplitterFetch.splitterStop(); |I.5]r-EK  
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} GzT?I 7|M  
} Q"oJhxS  
//负责部分文件的抓取 X{h[   
**FileSplitterFetch.java dcE(uf  
*/ KF`m
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package NetFox; |Y(  
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import java.io.*; mx2Ov u  
import java.net.*; RF\h69]:I  
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public class FileSplitterFetch extends Thread { hXx:D3h  
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String sURL; //File URL xQqZi b5I  
long nStartPos; //File Snippet Start Position |j$$0N  
long nEndPos; //File Snippet End Position \6/!{D,  
int nThreadID; //Thread's ID }jNVR#D:  
boolean bDownOver = false; //Downing is over \T;(k?28HN  
boolean bStop = false; //Stop identical
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FileAccessI fileAccessI = null; //File Access interface 3C#Sr6  
!@
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException zR}vR9Ls  
{ 3X1 U  
this.sURL = sURL; }y%mG&KSz  
this.nStartPos = nStart; =jRC4]M})  
this.nEndPos = nEnd; ?"p.Gy)  
nThreadID = id; v=YI%{tx)  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 /J&_ZDNV~  
} }wGy#!CSza  
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public void run() #-g2p?+i&  
{ *47%|bf`  
while(nStartPos < nEndPos && !bStop) MAgoxq~;V  
{ TnPx.mwK\  
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try{ 8fQXif\z  
URL url = new URL(sURL); `=I@W  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); AH#Dk5#G  
httpConnection.setRequestProperty("User-Agent","NetFox"); 
-$(2Z[  
String sProperty = "bytes="+nStartPos+"-"; -p20UP 1I  
httpConnection.setRequestProperty("RANGE",sProperty); G2FD'Sf  
Utility.log(sProperty); ^FK-e;J  
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InputStream input = httpConnection.getInputStream(); N-Sjd%Z  
//logResponseHead(httpConnection); jp#/]>(9Z  
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byte[] b = new byte[1024]; O
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int nRead; m%i!;K"{s  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) I<$m%  
{ F3<Ip~K  
nStartPos += fileAccessI.write(b,0,nRead); r-c1_ [Q#  
//if(nThreadID == 1) 8"J6(KS  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ROr| <  
} ~|=G3(I[  
^ V8?6E  
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Utility.log("Thread " + nThreadID + " is over!"); ag"Nf-o/Y  
bDownOver = true; )|L#i2?:  
//nPos = fileAccessI.write (b,0,nRead); $R/@%U)-o  
} m7,;Hr(  
catch(Exception e){e.printStackTrace ();} v^1n.l %E  
} >SHW  
} (^LR9 CW  
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//打印回应的头信息 "o$)z'q
 
public void logResponseHead(HttpURLConnection con) F;)qM|7  
{ .jbT+hhM  
for(int i=1;;i++) txemu*  
{ e><,WM,e
 
String header=con.getHeaderFieldKey(i); D>"!7+t|@a  
if(header!=null) S)G*+)  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); hO4* X  
Utility.log(header+" : "+con.getHeaderField(header)); SI/p8 ^  
else ;F\sMf{  
break; 9c=`Q5  
} zZ{(7Kfz  
} kaZ_ra;<  
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public void splitterStop() F=~LVaF/_  
{ p$@l,4@{  
bStop = true; 84M*)cKR~  
} WEk3 4crk  
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} DO9_o9'  
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/* ;$rh&ET  
**FileAccess.java nSeb?|$D6  
*//文件访问(定位，写) J2Z?}5>  
package NetFox; wGAeOD  
import java.io.*; q OX=M  
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public class FileAccessI implements Serializable{ d m$iiRY  
%Y<3v\`_  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 f&L8<ASFo  
RandomAccessFile oSavedFile; @rt}z+JF  
long nPos; Lo^gg#o  
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public FileAccessI() throws IOException b?%Pa\,!  
{ ^DOQ+  
this("",0); /H<tv5mXJ  
} 'v'=t<wgl  
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public FileAccessI(String sName,long nPos) throws IOException %][6TZ}  
{ uT2w2A;  
oSavedFile = new RandomAccessFile(sName,"rw"); UA}N  
this.nPos = nPos; 37nGFH`K2m  
oSavedFile.seek(nPos); hxx`f-#=  
} Nkg^;-CV0  
^9A,j}>o-  
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public synchronized int write(byte[] b,int nStart,int nLen) Onj)AJ9M0r  
{ t6a$ZN;  
int n = -1; vK,.P:n  
try{ u[?M{E/HU  
oSavedFile.write(b,nStart,nLen); wl:[Ad
 
n = nLen; lko k2  
} GMQKR,6VM  
catch(IOException e) I18<brZJ  
{ i
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e.printStackTrace (); T
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} <A@qN95m  
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return n; Q_M:v  
} N/i {j.=  
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7  
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} 2!;U.+(  
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/* pA?2UZ  
**SiteInfoBean.java 35PIfqm  
*/ p~NFiZ,  
package NetFox; pIP^/
H  
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q$BS@   
public class SiteInfoBean { 6UnWtLE  
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private String sSiteURL; //Site's URL *e}1KcJ  
private String sFilePath; //Saved File's Path XYdr~/[HPy  
private String sFileName; //Saved File's Name V/W{d[86G  
private int nSplitter; //Count of Splited Downloading File
}hA h'*(  
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public SiteInfoBean() 0o&B 7N  
{//nSplitter的缺省值为5 <Pg<F[eDM  
//default value of nSplitter is 5 6 ~d\+aV  
this("","","",5); w6FVSU]sY  
} _l||69|.  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) }j6<S-s~  
{ d6ABgQi0  
sSiteURL= sURL; f$p7L.d<  
sFilePath = sPath; )!jX$bK  
sFileName = sName; 5B,HJax  
this.nSplitter = nSpiltter; 5x1_rjP$|  
)*I%rN8b   
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} QLum=YB  
a-Ef$(i_  
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public String getSSiteURL() |cd=7[B  
{ |{JJ2c\W  
return sSiteURL; 5X=ik7m^  
} !|`vW{
v  
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public void setSSiteURL(String value) D>).^>|q  
{ ?7CHHk  
sSiteURL = value; J0a#QvX!  
} 2-!n+#Cdf  
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public String getSFilePath() 08JVX'X-mr  
{ cAAyyc"yJ  
return sFilePath; &6}] v:  
} qtLXdSc  
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J 8""}7D  
public void setSFilePath(String value) $bi@,&t;  
{ [J6b5  
sFilePath = value; Up|>)WFw"  
} ^vH3 -A;*  
jQ[M4)>_k`  
7
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public String getSFileName() "-;l{tL  
{ A}cGag+sp  
return sFileName; Rf.b_Y@O  
} F6h|AF|"  
;4rTm@6  
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public void setSFileName(String value) wRi` L7  
{ `!$I6KxT  
sFileName = value; =P.m5e<  
} %Kq`8  
l[J'FR:  
30Z RKrW"~  
public int getNSplitter() -n`igC  
{ bkgJz+u  
return nSplitter; s s*% 3<  
} CrIt h/Z  
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public void setNSplitter(int nCount) WhR j@y  
{ -OS&(7  
nSplitter = nCount; LJ|2=lI+jb  
} 0`
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} d:"]*EZ [  
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ZE*m;  
/* lc71Pp>  
**Utility.java >7VOytc  
*/ WYb\vm=r  
package NetFox; -H3tBEvoI  
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public class Utility { V2I"m
 
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public Utility() &_^t
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{ `;ofQz4  
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} L*Mt/  
+h}>UK\  
//线程睡眠 I]"wT2@T;7  
public static void sleep(int nSecond) >[=fbL@N<@  
{ 2FxrMCC  
try{ UN <s1  
Thread.sleep(nSecond); y\DR,$Py  
} bqHR~4 #IR  
catch(Exception e) .a%D:4GYR  
{ 0^41dfdE  
e.printStackTrace (); -kh O4,  
} 9Ij=~p]p  
} W=fw*ro  
#,0PLU3%  
//日志 u%J04vG"D  
public static void log(String sMsg) jP?YV  
{ y9cDPwi:b  
System.err.println(sMsg); jN\} l|;q  
} t6GL/
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(!72Eaw:]  
public static void log(int sMsg) 9qUc{ydt  
{ #-xsAKi  
System.err.println(sMsg); uD=i-IHT  
} /gkHV3}fu  
} LU
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Y}<w)b1e|  
/* {tUjUwhz(  
**TestMethod.java B?BB  
*/ \qx$h!<  
package NetFox; D=hy[sDBw  
{BkTJQ)  
+Bg$]~T  
public class TestMethod { kD&% 7Vz  
)Gf"#TM[  
x=1Iuc;&3  
public TestMethod() K(&I8vAp  
{ ///xx/weblogic60b2_win.exe ;VhilWaF-  
try{ =L,s6J8_'  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); {+`'ZU6C  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); V}?*kx~T2C  
SiteFileFetch fileFetch = new SiteFileFetch(bean); -~ w5yd  
fileFetch.start(); 'R'P^  
} uY{zZ4iw  
catch(Exception e){e.printStackTrace ();} *P\$<4l  
F8u;C:^d  
1r!o,0!d-'  
} 7Cx*Ts$  
0:NCIsIm<  
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public static void main(String[] args) =t[hsl  
{ GyirE`  
new TestMethod(); ,]A|z ~q  
}  fP+RuZ  
} %y7&~me  
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