http断点续传简单实现（java)

/* $fmTa02q>  
**SiteFileFetch.java *%Rmdyn  
*/ .xN<<+|_v'  
package NetFox; X`.##S KC  
import java.io.*; {y9G "  
import java.net.*; z&6_}{2,]  
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public class SiteFileFetch extends Thread { 4j={ 9e<  
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SiteInfoBean siteInfoBean = null; //文件信息Bean x4WCAqi/2  
long[] nStartPos; //开始位置 cUY-  
long[] nEndPos; //结束位置 geme_  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 eFG/!b<17  
long nFileLength; //文件长度 3`bQ0-D;  
boolean bFirst = true; //是否第一次取文件 fpR|+`k  
boolean bStop = false; //停止标志 PVIOe}N  
File tmpFile; //文件下载的临时信息 QTy=VLk43  
DataOutputStream output; //输出到文件的输出流 <T}^:2G|  
|J-X3`^\H  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） .9bi%=hP  
public SiteFileFetch(SiteInfoBean bean) throws IOException V&*IZt&  
{ }u_D{bz  
siteInfoBean = bean; `HX:U3/  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 2_q/
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tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); %e~xO x  
if(tmpFile.exists ()) W/qXQORv  
{ L7$f01*  
bFirst = false; KN}#8.'>3  
read_nPos(); E_ wVAz3  
} j%6p:wDl  
else ("8Hku?  
{ D0Dz@25-  
nStartPos = new long[bean.getNSplitter()]; /6')B !&  
nEndPos = new long[bean.getNSplitter()]; ,"EaZ/Bl/  
} 2lTt  
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} J :O!4gI  
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public void run() UY3)6}g6  
{ ZC?~RXL(  
//获得文件长度 v\:AOY'  
//分割文件 jZA1fV  
//实例FileSplitterFetch tm~9XFQ<  
//启动FileSplitterFetch线程 ,X|Oe@/  
//等待子线程返回 0Y8gUpe3P6  
try{ G"/;Cq=t  
if(bFirst) K2xB%m1LK  
{ LKM018H>  
nFileLength = getFileSize(); \lbH   
if(nFileLength == -1) WZ'<iI  
{ >V"{]v  
System.err.println("File Length is not known!"); E=I'$*C\D  
} ]3 "0#Y  
else if(nFileLength == -2) w){B$X
  
{ W`[VLi}fe  
System.err.println("File is not access!"); Ca~8cQ  
} w|f+OlPXq  
else "S;4hO  
{ f)Qln[/  
for(int i=0;i<nStartPos.length;i++) B ~v6_x  
{ nt2b}u>*  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); Cff
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} j,OA>{-$  
for(int i=0;i<nEndPos.length-1;i++) P.Ntjz/B  
{ 9K$ x2U  
nEndPos = nStartPos[i+1]; zqA>eDx  
} sl$6Zv-l%0  
nEndPos[nEndPos.length-1] = nFileLength; ^(q .f=I!a  
} QD-\'Bp/X  
} mnA_$W3~I  
S)EF&S(TC  
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//启动子线程 sVh)Ofn  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; OLx;j+p  
for(int i=0;i<nStartPos.length;i++) }ILBX4c  
{ #6M |T+=  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 5Ew( 0K[  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), T6/P54S  
nStartPos,nEndPos,i); U6-47m0%  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); cxR.:LD}  
fileSplitterFetch.start(); .rBU"Rbo  
} KpGx<+0p  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ;-3&yQ7N)  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); X5o*8Bg4M  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", G8}owszT  
nEndPos = " + nFileLength); - +a,Ej  
// fileSplitterFetch[nPos.length-1].start(); Zq4%O7%  
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#x.v)S  
//等待子线程结束 6.]~7n  
//int count = 0; H'i\N?VL  
//是否结束while循环 #w''WOk@ZG  
boolean breakWhile = false; f>Rux1Je4  
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R
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while(!bStop) +(!/(2>~  
{ uihH")Mo  
write_nPos(); _OGv2r  
Utility.sleep(500); qlM<X?  
breakWhile = true; o
}
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for(int i=0;i<nStartPos.length;i++) 4rDVCXE  
{ huZ5?'/Fg  
if(!fileSplitterFetch.bDownOver) Xm# +Z`|N  
{ q]1p Q)\'p  
breakWhile = false; 4V9BmVS|Th  
break; ;8<HB1 &,  
} oLkzLJ  
} g{Av =66Z  
if(breakWhile) ASdW!4.p  
break; (g@X.*c8  
>,Y+1  
!n;3jAl&$  
//count++; fln[Q2zl  
//if(count>4) w7`pbcY,  
// siteStop(); S0StC$$1  
} Ab[o~X"  
b"\lF1Nf&o  
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System.err.println("文件下载结束！"); 1
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} COsy.
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catch(Exception e){e.printStackTrace ();} &yP|t":HWX  
} ^W sgAyCB  
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//获得文件长度 V]Te_ >E;w  
public long getFileSize() NU_^*@k  
{ a;bmlV04  
int nFileLength = -1; 2c]751
  
try{ Ep(xlHTv  
URL url = new URL(siteInfoBean.getSSiteURL()); mxEe -q  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); }J?,?>Z  
httpConnection.setRequestProperty("User-Agent","NetFox"); >-V632(/{o  
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int responseCode=httpConnection.getResponseCode(); rV\G/)xL  
if(responseCode>=400) UB+~K/  
{ kxJs4BY
0  
processErrorCode(responseCode); 0e&&k  
return -2; //-2 represent access is error 5=*i!c _m  
} <#8}![3Q  
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String sHeader; Jqzw94  
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for(int i=1;;i++) :ek^M
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{ $S' TW3  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); Wtaz@+  
//Utility.log(in.readLine()); 8a)4>B  
sHeader=httpConnection.getHeaderFieldKey(i); ]O}e{Q>  
if(sHeader!=null) V5-!w0{  
{ %h(%M'm?  
if(sHeader.equals("Content-Length")) MtwlZg`c3  
{ 9:g A0Z  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); _1RvK? ;.{  
break; J;<dO7j5  
} fn/?I\  
} ,){#
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else X*MK(aV3  
break; iOIq2&sV  
} 4<tbZP3/6)  
} rRe^7xGe7  
catch(IOException e){e.printStackTrace ();} M._E$y,5  
catch(Exception e){e.printStackTrace ();} "c} en[  
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Utility.log(nFileLength); >l
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return nFileLength; S@!_{da  
} s]e`q4ip  
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//保存下载信息（文件指针位置） &x B^  
private void write_nPos() g?|Z/eVJ  
{ q|%+?j(  
try{ J<H]vs  
output = new DataOutputStream(new FileOutputStream(tmpFile)); TDZ==<C  
output.writeInt(nStartPos.length); @"
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for(int i=0;i<nStartPos.length;i++) I@z@s}x>  
{ Wm"q8-
<<  
// output.writeLong(nPos);
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output.writeLong(fileSplitterFetch.nStartPos); "6IZf>N@#  
output.writeLong(fileSplitterFetch.nEndPos); )2wf D  
} "5dke^yk0  
output.close(); _t"[p_llo  
} A`M-N<T  
catch(IOException e){e.printStackTrace ();} uv-O`)  
catch(Exception e){e.printStackTrace ();} 2%fzRXhu%  
} ~tTn7[!  
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//读取保存的下载信息（文件指针位置） 117lhx].'  
private void read_nPos() UrciCOQf  
{ lvODhoT  
try{ /~s<@<1!X  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); '\d ldg#P  
int nCount = input.readInt(); *tT}N@<%  
nStartPos = new long[nCount]; PA803R74  
nEndPos = new long[nCount]; \VEnP=*:W  
for(int i=0;i<nStartPos.length;i++) 9W(&g)`  
{ \>*.+?97  
nStartPos = input.readLong(); ud(0}[  
nEndPos = input.readLong(); w%TrL+v  
} |15!D  
input.close(); iku*\,
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} Gjq7@F'  
catch(IOException e){e.printStackTrace ();} 2o9B >f&g  
catch(Exception e){e.printStackTrace ();} SJX9oVJeZ  
} `-CN\  
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private void processErrorCode(int nErrorCode) ld#x'/  
{ {[:C_Up)f  
System.err.println("Error Code : " + nErrorCode); xMQ>,nZ  
} At[Q0'jkc  
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//停止文件下载 e(0cz6  
public void siteStop() 9[X'9*,  
{ KwMt@1Z  
bStop = true; Fh
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for(int i=0;i<nStartPos.length;i++) k7@QFw4 j  
fileSplitterFetch.splitterStop(); ]=ApYg7!  
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} At<MY`ka  
} )M"NMUuU"  
//负责部分文件的抓取 e<{d{  
**FileSplitterFetch.java V,VL?J\  
*/ 9XQE5^  
package NetFox; W+u,[_  
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import java.io.*; QsxvA;7%  
import java.net.*; ?[bE/Ya+S  
2V%z=  
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public class FileSplitterFetch extends Thread { yU/?4/G!  
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String sURL; //File URL toDi70o  
long nStartPos; //File Snippet Start Position ( sl{Rgxe*  
long nEndPos; //File Snippet End Position zOMxg00  
int nThreadID; //Thread's ID b'SP,}s5"  
boolean bDownOver = false; //Downing is over Kv1~,j6  
boolean bStop = false; //Stop identical zRLJ|ejMP  
FileAccessI fileAccessI = null; //File Access interface ;CS[Ja>e  
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- |DWPU!"  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 5tkKd4VfL
 
{ h]~FYY  
this.sURL = sURL; Op9 ^Eu%n  
this.nStartPos = nStart; re%XaL  
this.nEndPos = nEnd; [/*;}NUv  
nThreadID = id; ;Qq_  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 r{d@74  
} CeOA_M  
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public void run() VFF5Tp  
{ j+-`P5  
while(nStartPos < nEndPos && !bStop) 2/t;}pw8  
{ Y~I>mc]  
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try{ 6J JA"] `  
URL url = new URL(sURL); S}h d,"I  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Z R=[@Oi  
httpConnection.setRequestProperty("User-Agent","NetFox"); 2uT6M%OC  
String sProperty = "bytes="+nStartPos+"-"; UE5,Ml~X  
httpConnection.setRequestProperty("RANGE",sProperty); ;xw9#.d#D  
Utility.log(sProperty); _~CJitR3  
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InputStream input = httpConnection.getInputStream(); gn/]1NN
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//logResponseHead(httpConnection); O^./)#!#  
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,vvfk=-  
byte[] b = new byte[1024]; !wd wo0  
int nRead; wDoCc:  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop)  (t5y$bc  
{ }y
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nStartPos += fileAccessI.write(b,0,nRead); zb[kRo&a0W  
//if(nThreadID == 1) g%]<sRl:-  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); PCgr`
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} ]Z\W%'q+  
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Utility.log("Thread " + nThreadID + " is over!"); [c
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bDownOver = true; #
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//nPos = fileAccessI.write (b,0,nRead); &,PA+#  
} Z>3~n  
catch(Exception e){e.printStackTrace ();} |
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} Mi(6HMA.SF  
} 7=X6_AD  
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Glw|*{$  
//打印回应的头信息 *]<=04v]R  
public void logResponseHead(HttpURLConnection con) BHgs,  
{ N#-.[9!  
for(int i=1;;i++) =bJ$>Djp  
{ }D)eS |B  
String header=con.getHeaderFieldKey(i); 3I}AA.h'00  
if(header!=null) n{<@-6  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); AIQ {^:  
Utility.log(header+" : "+con.getHeaderField(header)); {U3jJ#K  
else
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break; ?Q=(?yR0]  
} /{8Y,pZbu  
} @##}zku  
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public void splitterStop() {P?DkUO}  
{ txnH~;(  
bStop = true; t'W6Fmwkx  
} B[8RBTsA  
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} GFbn>dY  
G] tT=X[  
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/* B$s6|~  
**FileAccess.java a}VR>!b  
*//文件访问(定位，写) OraT$lV)_  
package NetFox; d!&LpODI]*  
import java.io.*; 0]DX KI  
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public class FileAccessI implements Serializable{ 6-?/kY6  
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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 JF}i=}
 
RandomAccessFile oSavedFile; ?Y\WSI?i  
long nPos; hTby:$aCg  
J'=s25OWU  
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public FileAccessI() throws IOException ]moBVRd  
{ p\'X%R  
this("",0); G^|b*n!!  
} UDJ#P9uy  
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public FileAccessI(String sName,long nPos) throws IOException 5)k/4l '  
{ [.$%ti
*!  
oSavedFile = new RandomAccessFile(sName,"rw"); {#z47Rz  
this.nPos = nPos; ]+qd|}^  
oSavedFile.seek(nPos); g_tEUaiK  
} Fgwe`[  
:nnch?J_  
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public synchronized int write(byte[] b,int nStart,int nLen)  L=!h`k  
{ 't(#HBU  
int n = -1; si]MQ\i+  
try{ v/]xdP^Z  
oSavedFile.write(b,nStart,nLen); Y@ ;/Sf$Q  
n = nLen; qB
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} Te)%L*X  
catch(IOException e) BgCEv"G5  
{ ,T 3M  
e.printStackTrace (); V+0pvgS[  
} 6,~ %  
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1#>uqUxah  
return n; 8BS Nm  
} w[QC  
=
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} <Z~Nz>'r  
#>5T,[{?j  
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/* 6+>X`k%D  
**SiteInfoBean.java |P9)*~\5  
*/ @frV:%  
package NetFox; Opy{i#>  
)&)tX.  
W Kd:O
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public class SiteInfoBean { jM{5nRQ  
4|eI_u{_  
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private String sSiteURL; //Site's URL -=1>t3~\  
private String sFilePath; //Saved File's Path cUi6 On1C  
private String sFileName; //Saved File's Name hG9Mp!d91  
private int nSplitter; //Count of Splited Downloading File h;cw=G  
KUq(&H7  
^\VVx:]  
public SiteInfoBean() ]nxSVKE4p  
{//nSplitter的缺省值为5 '2<N_)43$  
//default value of nSplitter is 5 ?LvxEQ-g  
this("","","",5); TPN1Rnt0`  
} PP_ar{|7  
$9Xn.,W  
1':};}dCJ  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 90<a'<\|  
{ mG*Yv  
sSiteURL= sURL; /(s N@kt  
sFilePath = sPath; w);Bet  
sFileName = sName; v&66F`
  
this.nSplitter = nSpiltter; cSTL.QF  
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FA%BzU5^  
} CA/Lv{[2  
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J?&%fI
 
public String getSSiteURL() 6LT.ng  
{ bSTTr<W  
return sSiteURL; z=rSb4"W  
} >8`;SEnv  
mLHl]xs4  
Ci3 b(KR  
public void setSSiteURL(String value) !i{5mc\  
{ @GQtyl;q  
sSiteURL = value; ICWHEot  
} weOga\  
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W>u$x=<T  
public String getSFilePath() Fcn@j#[J  
{ &D7Mv5i0@  
return sFilePath; =AuxM
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} u$"Ew^C  
|Yi_|']#  
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public void setSFilePath(String value) 8tT/w5  
{ _tnoq;X[  
sFilePath = value; /EVXkf0  
} |[/XG2S  
EhOB+Mc1  
}%,LV]rGEZ  
public String getSFileName() ~.S/<:`U  
{ $|19]3T@Z  
return sFileName; 3HndE~_C&  
} l
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wr6(C:  
#<w2xR]:  
public void setSFileName(String value) dhr-tw  
{ llpgi,-=  
sFileName = value; r)dXcus  
}
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*W4~.peoE  
V67<Ky>  
public int getNSplitter() pvM`j86 _  
{ +'9xTd  
return nSplitter; xI5zP? _v  
} V:8{MO(C\  
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`6*1mE1K&  
public void setNSplitter(int nCount) 1W>0  
{ @WzrrCpj  
nSplitter = nCount; %/K;!'7  
} H<3ayp$  
} TzV~I\a|  

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/* "Qe2U(U
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**Utility.java #\O?|bN'q  
*/ 3=^B &AB  
package NetFox; v*@R U  
kE{-h'xADD  
)!l1  
public class Utility { iuoZk5O  
KyzdJ^xC"  
9+frxD&pO  
public Utility()  11-?M  
{ !4+@b s  
{MmK:C  
cq1)b\|  
} JjBlje  
=K6{AmG$  
//线程睡眠 ,@@FAL  
public static void sleep(int nSecond) D^H4]
7wG@  
{ SrvC34<7  
try{ ia%U;M  
Thread.sleep(nSecond); '# J/e0o@  
} b5UIX Kim  
catch(Exception e) g;</|Z  
{ pIvr*UzY  
e.printStackTrace (); {9h`h08?z  
} _I#a`G  
} yJHFo[wGMJ  
(!diPwcv  
//日志 ,mD{4 >7  
public static void log(String sMsg) (fC U+  
{ h_xzqElZu  
System.err.println(sMsg); FmtV[C#  
} (L7%V !  
M}!E :bv'  
S>EO6z#   
public static void log(int sMsg) sKL"JA T  
{ @D=i|f  
System.err.println(sMsg); Ug^vVc)  
} A@ 4Oq  
} Qr*7bE(a  
+bc
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G/_9!lE  
/* 1(m[L=H5>  
**TestMethod.java NvjKB)J  
*/ zFO#oW,D  
package NetFox; ]*yUb-xY  
j{H
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public class TestMethod { o<i\1<eI  
,V #r  
ey) 8q.5  
public TestMethod() $ud\CU:r  
{ ///xx/weblogic60b2_win.exe "I&,':O+  
try{ PQ4)k
VT  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); n~v*  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5);

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SiteFileFetch fileFetch = new SiteFileFetch(bean); Gbc2\A\  
fileFetch.start(); 0D^c4[Y'l  
} kk7M$)>d  
catch(Exception e){e.printStackTrace ();} [X'u={  
\={A%pA;@{  
U jB5Xks  
} U
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public static void main(String[] args) H!uq5`j0K  
{ sWX\/Iyy2p  
new TestMethod(); Nmu=p~f}3`  
} ,~qjL|9  
} )W$@phY(I  
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