http断点续传简单实现（java)

/* 0j!ke1C&C  
**SiteFileFetch.java b2X'AHK S  
*/ P
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package NetFox; A?D"j7JD=L  
import java.io.*; 0tCOb9  
import java.net.*; &U$8zn~[k  
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public class SiteFileFetch extends Thread { K=Z]#bm  
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SiteInfoBean siteInfoBean = null; //文件信息Bean b^,Mw8KsO  
long[] nStartPos; //开始位置 x)VIA]  
long[] nEndPos; //结束位置 ;5Vk01R  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 +yb$[E*  
long nFileLength; //文件长度 f'6qJk%J  
boolean bFirst = true; //是否第一次取文件 4ZJT[zi  
boolean bStop = false; //停止标志 X!rQ@F3  
File tmpFile; //文件下载的临时信息 >}DjHLTW\  
DataOutputStream output; //输出到文件的输出流 ~"q,<t  
N _~KZQ11^  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） sb|3|J6=  
public SiteFileFetch(SiteInfoBean bean) throws IOException 
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{ K>R;~ o  
siteInfoBean = bean;  m-'(27  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); R8[iXXjku  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); #i+P(xV  
if(tmpFile.exists ()) Qw<kX*fxrI  
{ [pW1=tI  
bFirst = false;
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read_nPos(); N=Uc=I7C  
} @ojg`!
,  
else I,<>%Z|'  
{ \'??  
nStartPos = new long[bean.getNSplitter()]; Jn<e"  
nEndPos = new long[bean.getNSplitter()]; LPapD@Z  
} t
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} n4vXm
 
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public void run() t?9;cS4  
{ i_0,BVC  
//获得文件长度 WAwfL?  
//分割文件 9*=@/1  
//实例FileSplitterFetch qX p,d  
//启动FileSplitterFetch线程 1akD]Z
 
//等待子线程返回 YMj7  
try{ )&Kn(l)  
if(bFirst) kj{rk^x  
{ TOco({/_/  
nFileLength = getFileSize(); fXu~69_  
if(nFileLength == -1) P34LV+e  
{ yZ;k@t_WRD  
System.err.println("File Length is not known!"); `rz`3:ZH  
} CRc!|?  
else if(nFileLength == -2) xH"W}-#[  
{ f/0v'
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System.err.println("File is not access!"); Siz!/O!'  
} r*i$+ Z  
else kMl@v`  
{ 6+Wr6'kuH  
for(int i=0;i<nStartPos.length;i++) V#gF*]q  
{ 6bbZ<E5At  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ,5eH2W  
} ;&+[W(7Sy  
for(int i=0;i<nEndPos.length-1;i++) Sv~YFS :oy  
{ V@#*``M,3  
nEndPos = nStartPos[i+1]; *R_'$+  
} >9o,S3  
nEndPos[nEndPos.length-1] = nFileLength; z"6ZDC6
 
} 7>PF~=  
} 4f4 i1i:  
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//启动子线程 ']d!?>C@o  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; T6h;Y  
for(int i=0;i<nStartPos.length;i++) 8zQ_xE  
{ c
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fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ( }]37  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), #*yM2H"7,;  
nStartPos,nEndPos,i); ASzzBR;?_  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ^8?j
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fileSplitterFetch.start(); ="3a%\  
} `a9k!3_L  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), [cGt  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 5
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// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", _`bS[%CJ  
nEndPos = " + nFileLength); QL)>/%yU  
// fileSplitterFetch[nPos.length-1].start(); 1DEO3p  
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IF&g.
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//等待子线程结束 O`wYMng)  
//int count = 0; qDby!^ryc  
//是否结束while循环 n0rerI[R  
boolean breakWhile = false; S2J#b"Y  
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while(!bStop) QD$}-D[  
{ X'V+^u@W  
write_nPos(); hlAR[]  
Utility.sleep(500); TK;\_yN  
breakWhile = true; RGT_}ni  
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for(int i=0;i<nStartPos.length;i++) r?64!VS;  
{ )^t!|*1LA  
if(!fileSplitterFetch.bDownOver) )8pcf`h{  
{ uk`T+@K  
breakWhile = false; zc6Ho  
break; !"g=&Uy&  
} VDB$"T9#  
} a`7%A H)  
if(breakWhile) OOCQsoN
  
break; E^b pckP  
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q<-%L1kc1  
//count++; n=f`AmF;  
//if(count>4) >$2E1HW.  
// siteStop(); |'ZN!2u  
} X3P&"}a  
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System.err.println("文件下载结束！"); ~k9O5S{  
} V-[2jC{  
catch(Exception e){e.printStackTrace ();} ^[ET&"  
} ;LHDh_.pX  
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VVs{l\$=ZV  
//获得文件长度 `Jn,IDq  
public long getFileSize() %/P=m-K  
{ 0;}Aj8Fle  
int nFileLength = -1; ?sV[MsOsC  
try{ Kn']n91m  
URL url = new URL(siteInfoBean.getSSiteURL()); bX7EO 8  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Xa4GqV9M/-  
httpConnection.setRequestProperty("User-Agent","NetFox"); FI\IY R  
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int responseCode=httpConnection.getResponseCode(); ppEJs  
if(responseCode>=400) S,lxM,DL&  
{ doLkrEm&
 
processErrorCode(responseCode); Ymq3ty]Pe  
return -2; //-2 represent access is error S2ark,sp6  
} Zotz?jVVr  
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String sHeader; Z*9L'd"D|  
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for(int i=1;;i++) pP3U,n   
{ xFOBF")  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); A 6:Q<  
//Utility.log(in.readLine()); QO@6VY@  
sHeader=httpConnection.getHeaderFieldKey(i); for{  
if(sHeader!=null) sN-oEqS  
{ ]5N zK=2{  
if(sHeader.equals("Content-Length")) Z #EvRC  
{ 9x(}F<L  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); [ dGO,ndE  
break; "r@G@pe  
} U M@naU  
} K${}r0   
else *MI)]S  
break;
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} SWT:frki`  
} r]9e^  
catch(IOException e){e.printStackTrace ();} TaOOq}8c#  
catch(Exception e){e.printStackTrace ();} )Lb72;!?  
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Utility.log(nFileLength); ^+M><jE9  
}
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return nFileLength; zwnw'  
} Oo kxg *!5  
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pzg&/m&F`  
//保存下载信息（文件指针位置） 0vDg8i\  
private void write_nPos() $:e)$Xnn-  
{ ?s%v 3T  
try{ dsK/6yu  
output = new DataOutputStream(new FileOutputStream(tmpFile)); QTYYghz  
output.writeInt(nStartPos.length); m`c#:s'_  
for(int i=0;i<nStartPos.length;i++) SBX|Bcyk*  
{ Yc d3QRB  
// output.writeLong(nPos); rhIGOk1k  
output.writeLong(fileSplitterFetch.nStartPos); ]/_G-2.R  
output.writeLong(fileSplitterFetch.nEndPos); ~6kJ~R4  
} [%jxf\9jJ_  
output.close(); FOSbe]  
} ) oxIzF  
catch(IOException e){e.printStackTrace ();} QNb>rLj52  
catch(Exception e){e.printStackTrace ();} dhW<p5  
} !_dR'  
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//读取保存的下载信息（文件指针位置） =5Wp
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private void read_nPos() |YRY!V_w  
{ 2A>C+Y[7\  
try{ y^G>{?Tha  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 3%2jwR  
int nCount = input.readInt(); PPj[;(A  
nStartPos = new long[nCount]; xZyeX34{M;  
nEndPos = new long[nCount]; /$Z m~Mp  
for(int i=0;i<nStartPos.length;i++) \6:>
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{ 2h<U  
nStartPos = input.readLong(); y@
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nEndPos = input.readLong(); b_l3+'#ofM  
} wLUF v(&C  
input.close(); jN6b*-2  
} y AOg\+  
catch(IOException e){e.printStackTrace ();} "5}%"-#  
catch(Exception e){e.printStackTrace ();} +2Ql~w@$^l  
} waCboK'  

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private void processErrorCode(int nErrorCode) ;E#\  
{ 's.~$  
System.err.println("Error Code : " + nErrorCode); `NSy"6{Z  
} %[ /<+
  
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//停止文件下载 .LObOR5J7  
public void siteStop() h@@d{{IqT  
{ *NlpotW,f  
bStop = true; &6/%kkv  
for(int i=0;i<nStartPos.length;i++) U CRAw3=  
fileSplitterFetch.splitterStop(); _q)!B,y-/N  
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} {zP#woz2Q  
} 0[)VO[  
//负责部分文件的抓取 PrSkHxm  
**FileSplitterFetch.java DbtF~`3, .  
*/ 5V@&o`!=h  
package NetFox; s}ADk-7  
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import java.io.*; VNj@5s  
import java.net.*; ]'k[u  
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public class FileSplitterFetch extends Thread { ],[)uTZc  
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String sURL; //File URL K%gP5>y*9>  
long nStartPos; //File Snippet Start Position rY,PSK/j  
long nEndPos; //File Snippet End Position HH8;J66I&  
int nThreadID; //Thread's ID etyCrQ ?U  
boolean bDownOver = false; //Downing is over c@(1:,R  
boolean bStop = false; //Stop identical hH`Jb77L  
FileAccessI fileAccessI = null; //File Access interface @o#+5P  
$"8d:N?I[  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException %LQ/q3?_  
{ .GCR!V  
this.sURL = sURL; ?4G(N=/&  
this.nStartPos = nStart; JMlV@t7y<  
this.nEndPos = nEnd; n3ZAF'  
nThreadID = id; cJ
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fileAccessI = new FileAccessI(sName,nStartPos);//定位 //.>>-~1m  
} U-EhPAB@  
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public void run() b/<mRQ{  
{ [AR>?6G-  
while(nStartPos < nEndPos && !bStop) K\&o2lo]  
{ 1b3(  
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try{ z(H?VfJo  
URL url = new URL(sURL); q4ipumy*  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); l}}UFEA^  
httpConnection.setRequestProperty("User-Agent","NetFox"); *eUc.MX6x  
String sProperty = "bytes="+nStartPos+"-"; ~Ltr.ci  
httpConnection.setRequestProperty("RANGE",sProperty); nbmc[!PwG  
Utility.log(sProperty); tZA:  
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InputStream input = httpConnection.getInputStream(); {DBIonY];  
//logResponseHead(httpConnection); >F3.c%VU]w  
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}U[-44r:  
byte[] b = new byte[1024]; 9y^/GwUQ  
int nRead; 6E|S  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) {QQl$ys/  
{ ai;\@$ cq  
nStartPos += fileAccessI.write(b,0,nRead); 6>DLp}d  
//if(nThreadID == 1) Qhy#r  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); rLF*DB3l  
} #?&0D>E?k  
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Utility.log("Thread " + nThreadID + " is over!"); ;&f1vi4  
bDownOver = true; ^od<JD4  
//nPos = fileAccessI.write (b,0,nRead); !/
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} 2P9J' L  
catch(Exception e){e.printStackTrace ();} 8S  U%  
} KcXpH]>!9  
} F
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:a3xvN-l  
//打印回应的头信息 [B9;?G  
public void logResponseHead(HttpURLConnection con) 'MQ%)hipA  
{ -9o{vmB{  
for(int i=1;;i++) G!Zyl^  
{ v0@)t&O  
String header=con.getHeaderFieldKey(i); w sY}JT  
if(header!=null) [uR/M
 
//responseHeaders.put(header,httpConnection.getHeaderField(header)); };S0 G!  
Utility.log(header+" : "+con.getHeaderField(header)); (Uk,  
else n%$ &=-Fk  
break; [ee30ELn  
} mX\ ;
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} B9M>e'H%<  
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public void splitterStop() &erm`Ho  
{ DDw''  
bStop = true; (-"`,8K 2}  
} pbn\9C/  
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} IOEM[zhb$  
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/* A';QuWdT  
**FileAccess.java {p/YCch,  
*//文件访问(定位，写) ]vo_gKZ  
package NetFox; A3+6#?:;  
import java.io.*; $sgH'/>  
T+CajSV  
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public class FileAccessI implements Serializable{ Ceg!w#8Z,  
"s_Z&  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 kGHC]Fb)  
RandomAccessFile oSavedFile; |_zO_Frtp  
long nPos; bd\=h1  
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public FileAccessI() throws IOException b{&FuvQg2  
{ '3;v] L?G  
this("",0); 2 ZG@!Y|  
} JwP:2-o  
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public FileAccessI(String sName,long nPos) throws IOException o4Q3<T7nI  
{ oH-8r:{  
oSavedFile = new RandomAccessFile(sName,"rw"); 9l
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this.nPos = nPos; :.&{Z"  
oSavedFile.seek(nPos); L *Y|ey  
} U[||~FW'  
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public synchronized int write(byte[] b,int nStart,int nLen) pP.'wSj  
{ DW2>&|  
int n = -1; 4v.d-^  
try{ 3 ^}A %-bS  
oSavedFile.write(b,nStart,nLen); fx?$9(r,  
n = nLen; (bm;*2  
} )[&zCqDc  
catch(IOException e) m5-9yQ=.  
{ ]gP5f@`  
e.printStackTrace (); >.DC!QV  
} |wp,f%WK  
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return n; :uK btoA  
} -%m3-xZA  
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} C`K^L=8`{  
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/* .C!vr@@]  
**SiteInfoBean.java f j<H6|3  
*/ VmvQvQ/9R  
package NetFox; 3V;gW%
>  
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public class SiteInfoBean { 4Z5#F]OA7  
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private String sSiteURL; //Site's URL ;YH[G;aJ  
private String sFilePath; //Saved File's Path A lwtmDa  
private String sFileName; //Saved File's Name -9+se  
private int nSplitter; //Count of Splited Downloading File Z4q~@|+%  
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public SiteInfoBean() <hvRP!~<
)  
{//nSplitter的缺省值为5 1>pe&n/  
//default value of nSplitter is 5 !Q%P%P<$  
this("","","",5); Q{y{rC2P  
} q``wt  
}[!92WS/ee  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 6X_\Ve  
{ rAukHeH  
sSiteURL= sURL; j]5WK_~M  
sFilePath = sPath; ZFxLBb:  
sFileName = sName; ;JTt2qQKo  
this.nSplitter = nSpiltter; M$S]}   
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} b"CAKl  
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public String getSSiteURL() YT-=;uK^S  
{ #&Is GyU  
return sSiteURL; 2F+gF~znQ  
} w*!wQ,o  

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public void setSSiteURL(String value) {1Eu7l-4  
{ w1^QD^KnH  
sSiteURL = value; [r-}bp'Gp  
} ?6N3tk-2  
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public String getSFilePath() /@YCA}|/  
{ J"CJYuGW,  
return sFilePath; <"tDAx  
} "@ E3MTW  

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public void setSFilePath(String value) ocQWQ   
{ v#oi0-9o[  
sFilePath = value; 3S
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} 9lzQ\}  
q{' ~+Nq  
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public String getSFileName() IOl+t,0x&  
{ l
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return sFileName; dt,3"J  
} M]rO;^;6?  
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public void setSFileName(String value) 2U$"=:Cf  
{ k&6I f0i  
sFileName = value; 2}WDw>V  
} {ERMGd6Jp  
1=)r@X/6d  
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public int getNSplitter() ${r[!0|  
{ /n{1o\  
return nSplitter; "&o,yd%  
} 2xxB\J  
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>hsuAU.UOR  
public void setNSplitter(int nCount) [~mGsXV  
{ F jrINxL7^  
nSplitter = nCount; AR&:Q4r|  
} +]wuJSxc  
} q9*MNHg}  
<M+R\SH-  
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/* v;2CU  
**Utility.java )b4$A:  
*/ grom\  
package NetFox; :1wrVU-?h  
R= 5**  
n! h7
 
public class Utility { X
@wm1{!  
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public Utility() vZAv_8S)  
{ O[q\e<V<  
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}  Lc2QXeo8  
q!lP"J  
//线程睡眠 P,xwSvO#M  
public static void sleep(int nSecond) '+y_\  
{ 9^ed-h Bf  
try{ KG9t3<-`  
Thread.sleep(nSecond); zc+@lJy  
} J%rP$O$  
catch(Exception e) msx-O=4g  
{ +Ic ~ f1zh  
e.printStackTrace (); k5BXirB  
} 3'I^lc  
} !u|Tu4G^  
lU4}B`#"v  
//日志 PS>x,T  
public static void log(String sMsg) [AzO:A  
{ > 0>  
System.err.println(sMsg); Qd`T5[b\  
} ]ya; v '  
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public static void log(int sMsg) '0aG N<c  
{ }d Ad$^  
System.err.println(sMsg); k3Cz9Vt%  
} hvV_xD8|  
} c-1q2y  
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/* z!wDpG7b  
**TestMethod.java M4f;/`w  
*/ U.0kR/>Z=  
package NetFox; MN8H;0g-  
qa'gM@]  
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public class TestMethod { >4i>C  
1}m3;  
@r7:NU}  
public TestMethod() l&(l$@t  
{ ///xx/weblogic60b2_win.exe 3c'#6virz  
try{ 8;gXg  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 8F5|EpB9M  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 'xK.UI  
SiteFileFetch fileFetch = new SiteFileFetch(bean); UmU:j@xvg  
fileFetch.start(); S]/b\B.h+  
} mqtg[~dNc  
catch(Exception e){e.printStackTrace ();} s}5+3f$f  
uXZg1F)  
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} wFS2P+e;X  
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'o4p#`R:8  
public static void main(String[] args) r`'y?Bra;  
{ R=)55qu  
new TestMethod(); wD\ZOn_J  
} f>9s!Hpu_  
} ??qq:`s  
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