http断点续传简单实现（java)

/* x7\b-EC  
**SiteFileFetch.java {\zTE1X9  
*/ 3/_rbPr  
package NetFox; 3-x ;_  
import java.io.*; *\Z9=8yK  
import java.net.*; s^f7w  
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public class SiteFileFetch extends Thread { Buc{dcL/  
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SiteInfoBean siteInfoBean = null; //文件信息Bean J5dwd,FQ  
long[] nStartPos; //开始位置 NxY B)`~  
long[] nEndPos; //结束位置 %8Eu{3  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 @^P<(%p  
long nFileLength; //文件长度 S7pf QF  
boolean bFirst = true; //是否第一次取文件 8Of.n7{  
boolean bStop = false; //停止标志 vH1IVF"DS  
File tmpFile; //文件下载的临时信息 WH|TdU$V  
DataOutputStream output; //输出到文件的输出流 %Q,6sH#  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） >b\{y}[  
public SiteFileFetch(SiteInfoBean bean) throws IOException `Iwl\x[A  
{ |5il5UP  
siteInfoBean = bean; 7v'aw"~  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); Qa`+-Wu8  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 2{U5*\FhVX  
if(tmpFile.exists ()) _[)f<`!g_V  
{ HSwC4y}  
bFirst = false;
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read_nPos(); 2P35#QI[)  
} p1F{ v^  
else 1S[4@rZ  
{ u~rPqBT{d3  
nStartPos = new long[bean.getNSplitter()]; Cb4.N8  
nEndPos = new long[bean.getNSplitter()]; '=AqC,\#  
} ?)NgODU  
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} ^%5;Sc1V  
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public void run() Xsk/U++  
{ CwjKz*
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//获得文件长度 inHlL  
//分割文件 !LR9}Xon  
//实例FileSplitterFetch >O]u4G!  
//启动FileSplitterFetch线程 D :)HKD.  
//等待子线程返回 ?_-5W9  
try{ `y
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if(bFirst)
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{ \B4f5L8k  
nFileLength = getFileSize(); /9b+I/xY"  
if(nFileLength == -1) KzZfpdI92  
{ a#D \8;  
System.err.println("File Length is not known!"); DX0#q#  
} 'QSj-  
else if(nFileLength == -2) &>n:7  
{ ffW-R)U|3  
System.err.println("File is not access!"); -!lSk?l  
} Aflf]G1  
else &t U&Z
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{ '2qbIYanh  
for(int i=0;i<nStartPos.length;i++) [_`<<!u>-  
{ AvVPPEryal  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); fBb:J+  
} !k<k]^Z\  
for(int i=0;i<nEndPos.length-1;i++) vYybQ&E/  
{ FK
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nEndPos = nStartPos[i+1]; a8YFH$Xh  
} !a4`SjOgu  
nEndPos[nEndPos.length-1] = nFileLength; .unlr_eA  
} ~#jnkD  
} T|&u?  
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//启动子线程 _'|C-j`u$  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; *V_b/Vt  
for(int i=0;i<nStartPos.length;i++) z57q|  
{ $a|>>?8  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 5g`J}@"k  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), vA{DF{S4  
nStartPos,nEndPos,i); }tW1\@ =  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); wE-y4V e  
fileSplitterFetch.start(); B qo#cnlG  
} G%junS'zt  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), as73/J6  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); ujn7DB
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// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 6P T)  
nEndPos = " + nFileLength); a$EudD#+  
// fileSplitterFetch[nPos.length-1].start(); 4av  
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S\ K[l/  
//等待子线程结束 uF ;8B]"  
//int count = 0; _}j6Pw'  
//是否结束while循环 g*-}9~  
boolean breakWhile = false; RT2&^9-  
- i{1h"  
8PqlbLo1  
while(!bStop) jgqeDl\=+  
{ k~2FlRoC^  
write_nPos(); tI  
Utility.sleep(500); cpPS8V  
breakWhile = true; m2l0`l~T8  
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for(int i=0;i<nStartPos.length;i++) sHPlNwyy  
{ +f}w+  
if(!fileSplitterFetch.bDownOver) u`XZtF<vf  
{ gk}.LE  
breakWhile = false; LWxP}? =  
break; [B^V{nUBc  
} &Z}}9dd  
} a *bc#!e  
if(breakWhile) @7t*X-P.;-  
break; 4<- E0  
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+jN)$Y3Ya  
//count++; z
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//if(count>4) 7H)tF
&  
// siteStop(); 1lsg|iVz  
} x}f)P  
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System.err.println("文件下载结束！"); >J,IxRGi  
} &m`@6\N(   
catch(Exception e){e.printStackTrace ();} fG<[zt\e  
} #%]?e N  
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//获得文件长度 =T$2Qo8  
public long getFileSize() BOl*. t  
{ P#/s5D
8  
int nFileLength = -1; sDwE,f0h  
try{ IFXnGDG$  
URL url = new URL(siteInfoBean.getSSiteURL()); 'h>l_A
 
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); i7?OZh*f  
httpConnection.setRequestProperty("User-Agent","NetFox"); 4)9Pgp:  
{!t6& A  
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int responseCode=httpConnection.getResponseCode(); BO 3z$c1yU  
if(responseCode>=400) ^
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{ TrVQ]9;jWk  
processErrorCode(responseCode); 6f J5Y iQ  
return -2; //-2 represent access is error OSK:Cb.-?F  
} i;J*9B_U  
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String sHeader; bR=TGL&  
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for(int i=1;;i++) .Pa6HA !  
{ rjHW  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); Tt{ft?H71  
//Utility.log(in.readLine()); +H_
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sHeader=httpConnection.getHeaderFieldKey(i); 3H5<w4yk  
if(sHeader!=null) 7':<I-Fm  
{ <*opVy^  
if(sHeader.equals("Content-Length")) %%Wn:c>  
{ 1k)`
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nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); O.?q8T)n82  
break; s3
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} >kV=h?]Y  
} H
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else Bs-MoT!  
break; ^p~3H  
} (!<G` ;}u  
} =YR+`[bfI  
catch(IOException e){e.printStackTrace ();} EkP(]F  
catch(Exception e){e.printStackTrace ();} &^ =Y76  
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Utility.log(nFileLength); %U$%x  
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return nFileLength; 5{#ya2  
} ~ [=2d a  
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//保存下载信息（文件指针位置） g@S?5S.Av  
private void write_nPos() Va\?"dH>M  
{ LYS[qLpf  
try{ Q#I?nBin  
output = new DataOutputStream(new FileOutputStream(tmpFile)); O:X|/g0Y  
output.writeInt(nStartPos.length); gd;e-.  
for(int i=0;i<nStartPos.length;i++) wk6tdY{&s  
{ u=B,i#>s  
// output.writeLong(nPos); _lG\_6oJ,  
output.writeLong(fileSplitterFetch.nStartPos); .w~zW*M0  
output.writeLong(fileSplitterFetch.nEndPos); ,:3Di (  
} MtK5>mhZI`  
output.close(); -MeO|HWm  
} nB ,&m&  
catch(IOException e){e.printStackTrace ();} JZ0u/x5  
catch(Exception e){e.printStackTrace ();} 9/50+2F  
} (
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//读取保存的下载信息（文件指针位置） qgsKbsl  
private void read_nPos() 4Yl:1rz  
{ AlT04H
  
try{ rxAb]~MMp  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 1)h+xY  
int nCount = input.readInt(); p"/B3  
nStartPos = new long[nCount]; sm @Ot~;  
nEndPos = new long[nCount]; n&}ILLc  
for(int i=0;i<nStartPos.length;i++) }5Pzen
 
{ qn@:A2ed  
nStartPos = input.readLong(); 2;=xHt  
nEndPos = input.readLong(); ,46k8%
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} !4 G9`>n  
input.close(); nK|WzUtp  
} ZIM 5$JdCv  
catch(IOException e){e.printStackTrace ();} =ZN~*HLl}  
catch(Exception e){e.printStackTrace ();} ]+i~Cbj  
} fmq9u(!R  
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private void processErrorCode(int nErrorCode) eI*o9k$Qs  
{ :w 4Sba3  
System.err.println("Error Code : " + nErrorCode); NX:i]t  
} 2M+'9+k~  
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//停止文件下载 Sj<WiQ%<  
public void siteStop() gEU|Bx/!=  
{ sYb(g'W*'  
bStop = true; O9]+Jd4W  
for(int i=0;i<nStartPos.length;i++) + %07J6  
fileSplitterFetch.splitterStop(); ln6Hr^@5  
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} P ||:?3IH  
} KPSHBv-#  
//负责部分文件的抓取 ];1Mg  
**FileSplitterFetch.java pe$l'ur
 
*/ |\MgE.N  
package NetFox;  mVuZ}`  
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import java.io.*; ?ydqmj2[F  
import java.net.*; m|w-}s,  
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public class FileSplitterFetch extends Thread { $.2#G"|  
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String sURL; //File URL 5u-jjUO  
long nStartPos; //File Snippet Start Position >FabmIcC  
long nEndPos; //File Snippet End Position 89[5a  
int nThreadID; //Thread's ID (}u2) 9  
boolean bDownOver = false; //Downing is over C.[abpc  
boolean bStop = false; //Stop identical @Js^=G2  
FileAccessI fileAccessI = null; //File Access interface af<R.  
2\p8U#""  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException r2]KP(T8|  
{ Gd8FXk,.!  
this.sURL = sURL; \'gb{JO  
this.nStartPos = nStart; ~S,R`wo  
this.nEndPos = nEnd; d/O~"d  
nThreadID = id; |99/?T-QW  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 eZMDtB  
} V6C*d:  
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public void run() +I {ZW}rA  
{ D 1Q@4 g  
while(nStartPos < nEndPos && !bStop) TUQ+?[  
{ ,MxTT!9Su  
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try{ 5QjM,"`mp  
URL url = new URL(sURL); |ZAR!u&0  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 5DEK`#*  
httpConnection.setRequestProperty("User-Agent","NetFox"); 0 xUw}T6  
String sProperty = "bytes="+nStartPos+"-"; VM1`:1Z:$  
httpConnection.setRequestProperty("RANGE",sProperty); ebSG|F  
Utility.log(sProperty);  TM1isZ  
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InputStream input = httpConnection.getInputStream(); ;p!|E3o.  
//logResponseHead(httpConnection); 0'IV"eH2  
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byte[] b = new byte[1024]; CHeU?NtFps  
int nRead; 
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) pu:Ie#xTDf  
{ jo8hVWJ7V*  
nStartPos += fileAccessI.write(b,0,nRead); <,r|*pkhp~  
//if(nThreadID == 1) %MQU&H9[  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); =r3%jWH6  
} O]\6Pv@N  
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Utility.log("Thread " + nThreadID + " is over!"); QgZwU$`p0  
bDownOver = true; o"te7nBI  
//nPos = fileAccessI.write (b,0,nRead); "%o,P/<X  
} :ub 4p4h*  
catch(Exception e){e.printStackTrace ();} &Hb;; Ic(  
} 7*9a`p3w  
} eD4qh4|u.  
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Q M#1
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//打印回应的头信息 L9|55z  
public void logResponseHead(HttpURLConnection con) Ho}"8YEXNV  
{ J4yL"iMt  
for(int i=1;;i++) Ry@QJn I<  
{ U
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String header=con.getHeaderFieldKey(i); kK27hfsw  
if(header!=null) h%9>js^~  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ;"}yVV/4  
Utility.log(header+" : "+con.getHeaderField(header)); >tUi ;!cQ  
else M.|cl#  
break; ,f4VV\  
} Q]9+-p(=  
} U7)#9qS4  
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public void splitterStop() [1-1^JY  
{ -Y
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bStop = true; }e7os0;
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} o$*aAgS+  
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} 'pCZx9*c  
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{:D8@jb[  
/* |[)k5nUQ|  
**FileAccess.java PTU_<\  
*//文件访问(定位，写) V`/E$a1&  
package NetFox; UlG8c~p  
import java.io.*; =cwQG&as  
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public class FileAccessI implements Serializable{ U9<AL.  
b`%3>  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 !cLdoX  
RandomAccessFile oSavedFile; Vs[A  
long nPos; ;Av=/hU  
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public FileAccessI() throws IOException }ZQ)]Mr  
{ Ic 5TtN~/>  
this("",0); |fL|tkGEa  
} mH1T|UI  
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&  
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public FileAccessI(String sName,long nPos) throws IOException PykVXZ7j;  
{ ;6 ?a8t@  
oSavedFile = new RandomAccessFile(sName,"rw"); @q98ac*{  
this.nPos = nPos; o1kTB&E4B  
oSavedFile.seek(nPos); IhIz 7.|  
} %DK0s(*w0  
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public synchronized int write(byte[] b,int nStart,int nLen) q9e(YX>  
{ &d%\&fCm(  
int n = -1; X#ZQpo'h  
try{ *^ZJ&.  
oSavedFile.write(b,nStart,nLen); J!{t/_aw  
n = nLen; eD|p1+76  
} f`$F^=  
catch(IOException e) ,4Q1[K35B  
{ 3WVH8Sb  
e.printStackTrace (); TpAE9S  
} fH@P&SX  
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return n; XIGz_g;#'w  
} H*m3i;"4p\  
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} R@X65o  
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/* xU1_L*tu '  
**SiteInfoBean.java oe'f?IY  
*/ %,1xOl4l  
package NetFox; "
t.Jv%0=  
!K8Kw W|X  
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public class SiteInfoBean { |erG cKk  
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private String sSiteURL; //Site's URL jIL+^{
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private String sFilePath; //Saved File's Path o=nF.y  
private String sFileName; //Saved File's Name (#c|San  
private int nSplitter; //Count of Splited Downloading File &G|^{!p/G  
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public SiteInfoBean() u|mTF>L  
{//nSplitter的缺省值为5 VLfc6:Yg  
//default value of nSplitter is 5 }@y(-7t  
this("","","",5); `j1b5&N;7  
} gTS}'w{  
@*9c2\"k  
6MD9DqD  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) AoU
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{ &-$27  
sSiteURL= sURL; 4,P(w+  
sFilePath = sPath; VnYcqeCm  
sFileName = sName; 83adnm  
this.nSplitter = nSpiltter; /fSsh;F  
8\X-]Gh\^  
2Ij,OIcdBE  
} Op'&c0l  
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public String getSSiteURL() ${h1(ec8  
{ M ZAz= )-  
return sSiteURL; S}b^_+UbP  
} {E;oirv&  
ri`;   
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public void setSSiteURL(String value) kz*6%Cg*~  
{ f<{f/lU@  
sSiteURL = value; 2oF1do;  
} Dr)jB*yK  
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public String getSFilePath() N/!(`Z,  
{ ]$,3vYBf  
return sFilePath; :jf/$]p  
}  Zsn@O2  
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public void setSFilePath(String value) 6lPuYEmT  
{ PavW@  
sFilePath = value; | .gE9'"bv  
}
6oI/*`>  
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public String getSFileName() }1DzWS-hh  
{ p'0X>>$  
return sFileName; 1l'JoU.<  
} :Xs4C%H;  
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m5o$Dus+?'  
public void setSFileName(String value) k. NJ+  
{ gZ|!'  
sFileName = value; -<ome~|  
} l;rA}?,.^  
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public int getNSplitter() !9{hbmF#  
{ qg/FI#r  
return nSplitter; *b_Iby-ZD  
} lGt:.p{NG  
))dw[Xa  
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public void setNSplitter(int nCount) rvU^W+d  
{ ,c-*/{3  
nSplitter = nCount; w59q* 2  
} P+Gz'  
} 764eXh  
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/* *kpP)\P  
**Utility.java @u`W(Ow  
*/ OFBEJacy  
package NetFox; }.pqV X{d  
~BqC!v.)@E  
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public class Utility { <d"nz:e  
Fe %Vp/  
d!46`b$rd  
public Utility() Io"3wL)2  
{ d>NO}MR  
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sv&^sARN  
} y@,PTF  
@lX%Fix9  
//线程睡眠 5rfDm  
public static void sleep(int nSecond) J[0

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{ -L4G)%L\  
try{ HI{h>g T  
Thread.sleep(nSecond); cIQbu#[@  
} 8AuE:=?,,  
catch(Exception e) MGq\\hLD\-  
{ }& W=   
e.printStackTrace (); 5]up%.  
} XjCx`bX^<  
} .zl[nx[9"D  
F:d2;  
//日志 zy%0;%
 
public static void log(String sMsg) Q"D5D rj  
{ '&hd^9]Lo  
System.err.println(sMsg); d"IZt;s/,  
} A'rd1"K  
O$;#GpR  
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public static void log(int sMsg) Dn@ZS_f  
{ !H@HgJ -  
System.err.println(sMsg); =+UtAf<n  
} `"}).{N]C  
} /t`,7y3T  
+ue1+#  
k\qFWFR  
/* `)5WA{z  
**TestMethod.java UGd\`*Cj  
*/ \+nV~Pi"A  
package NetFox; &tvtL  
a]7g\rg)  
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public class TestMethod { Zj-U^6^L  
1x=x,lcL  
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public TestMethod() zwU[!i)  
{ ///xx/weblogic60b2_win.exe [*5]NNB  
try{ 8B &EH+  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); {Q37a=;,  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ZfX$q\7  
SiteFileFetch fileFetch = new SiteFileFetch(bean); UimofFmI%  
fileFetch.start(); 9unRMvE u  
} Y2XxfZj  
catch(Exception e){e.printStackTrace ();} ~-6_-Y|  
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} g)^s+Y  
De^
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public static void main(String[] args) 7I'C'.6iM  
{ ~ z3J4s  
new TestMethod(); >W8"Ar  
} 1P[x.t#  
}
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