http断点续传简单实现（java)

/* g/WDAO?d  
**SiteFileFetch.java .:
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*/ Z\]LG4N?  
package NetFox; 6xY6EC  
import java.io.*; }eI9me@Aa  
import java.net.*; mKyF<1,m  
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public class SiteFileFetch extends Thread { M= |is*t  
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SiteInfoBean siteInfoBean = null; //文件信息Bean B*E"yB\NV  
long[] nStartPos; //开始位置 I[gPW7&S@  
long[] nEndPos; //结束位置 O*lIZ,!n  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 H|,d`@U  
long nFileLength; //文件长度 68w~I7D>  
boolean bFirst = true; //是否第一次取文件 Z-pZyDz  
boolean bStop = false; //停止标志 mey -Bn  
File tmpFile; //文件下载的临时信息 YXmy-o>  
DataOutputStream output; //输出到文件的输出流 ttHRc!  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 1HqN`])l/j  
public SiteFileFetch(SiteInfoBean bean) throws IOException t/%[U,m  
{ tUW^dGo.  
siteInfoBean = bean; 6i~<,;Cn  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); UUM:*X  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ydRS\l  
if(tmpFile.exists ()) p&0 G  
{ .wTb/x  
bFirst = false; aIr"!. 4  
read_nPos(); Sn 7h$  
} 1
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else !>wu7u-  
{ a+CJJ3T-  
nStartPos = new long[bean.getNSplitter()]; ??|,wIRz  
nEndPos = new long[bean.getNSplitter()]; A[`c+&  
} ~(NFjCUY?  
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} =Lb(N61  
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public void run() R<hsG%BS(D  
{ O*N:.|dUw  
//获得文件长度 1W-kZ(e  
//分割文件 :/Z1$xS  
//实例FileSplitterFetch 0B2f[A  
//启动FileSplitterFetch线程 foY]RkW9  
//等待子线程返回 <VQ@I  
try{ > PL}7f&:  
if(bFirst) M1k_ldP  
{ V$iA3)7W%  
nFileLength = getFileSize(); /,j'Vr\"  
if(nFileLength == -1) 3j[<nBsn.  
{ /qq*"R  
System.err.println("File Length is not known!"); |%rRALIY  
} KG96;l@'(  
else if(nFileLength == -2) M\Wg|gpy  
{ V`i(vC(  
System.err.println("File is not access!"); 7fd,I%v  
} 9"L!A,&'  
else o4j!:CI  
{ L$ ^ew0C  
for(int i=0;i<nStartPos.length;i++) !c0x^,iE  
{ .<YfnW5/K  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); sYSq>M  
} gdh|X[d  
for(int i=0;i<nEndPos.length-1;i++) Cv&>:k0V  
{ T :^OW5d  
nEndPos = nStartPos[i+1]; :RYYjmG5;  
} U+(qfa5(  
nEndPos[nEndPos.length-1] = nFileLength; &N3a`Ua  
} y1Wb/ d  
} }s#4m  
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//启动子线程 P.=Dd"La  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; F4~O-g.<  
for(int i=0;i<nStartPos.length;i++) h CV(O2jL  
{ jxq89x  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), !wKN
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), jd"YaZOQ  
nStartPos,nEndPos,i); :;LaV  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); >m=
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fileSplitterFetch.start(); v0;dk(  
} ]C|xo.=?]  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), .Rb1%1bdc  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); N>g6KgX{K  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", ;qUd]c9oi  
nEndPos = " + nFileLength); 0&Iu+hv  
// fileSplitterFetch[nPos.length-1].start(); bHTTxZ-%  
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//等待子线程结束 NID2$p  
//int count = 0; B
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//是否结束while循环 {n<1uh9~$8  
boolean breakWhile = false; UD5
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while(!bStop) 6pZ/C<Y|W  
{ 6$csFW3R  
write_nPos(); O\@0o|NM  
Utility.sleep(500); b=L|GV@$  
breakWhile = true; n
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}Py Z{yS  
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for(int i=0;i<nStartPos.length;i++) ?fpI,WFu  
{ O31.\ZR2  
if(!fileSplitterFetch.bDownOver) |+<o(Q(  
{ [W dxMU  
breakWhile = false; k4^!"~<+0  
break; S6_dmTV*  
} 0nR_I^  
} w'mn O'%  
if(breakWhile) wqX!7rD/g)  
break; -.Z;n1'^  
#,!/Cnqis  
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//count++; u1Wixjd|  
//if(count>4) G?:5L0g  
// siteStop(); >k~3W> D  
} xR&Le/3+  
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System.err.println("文件下载结束！"); -t125)6I  
} 99b"WH^3$y  
catch(Exception e){e.printStackTrace ();} 1ZWr@,\L  
} :ee'|c  
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//获得文件长度 Dd)L~`k{)  
public long getFileSize() o4aFgal1  
{ O tR  
int nFileLength = -1; T{F 'Y%  
try{ U-q:Y-
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URL url = new URL(siteInfoBean.getSSiteURL()); 5j5}c`:  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Wr4Ob*2iD  
httpConnection.setRequestProperty("User-Agent","NetFox"); 8J2UUVA`1  
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int responseCode=httpConnection.getResponseCode(); &Z7NF|  
if(responseCode>=400) rp!{QG  
{ l<s6Uu"  
processErrorCode(responseCode); <VT|R~  
return -2; //-2 represent access is error okbW. ~  
} ( D
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String sHeader; QnIF{TS=  
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for(int i=1;;i++) zf[KZ\6H  
{ ]%h|ox0  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 73+)> "x>  
//Utility.log(in.readLine()); r}#,@<  
sHeader=httpConnection.getHeaderFieldKey(i); qu/b:P  
if(sHeader!=null) e:n3@T,
R  
{ U%tpNWB  
if(sHeader.equals("Content-Length")) @$o^(my  
{ ygqWy1C  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); XhJYsq]]J  
break; .:SY:v r  
} K5\;'.9M  
} /)XN^Jwa;m  
else n%ZOR1u)k#  
break; wD $sKd  
} @t3&#I}mc  
} )'$'?Fn  
catch(IOException e){e.printStackTrace ();} )"Dl,Fig:/  
catch(Exception e){e.printStackTrace ();} q_h/zPuH'  
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Utility.log(nFileLength); JP6+h>ft  
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return nFileLength; -Dr)+Y  
} OZ Hfd7K4A  
+^|=MK%  
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//保存下载信息（文件指针位置） 1&utf0TX6q  
private void write_nPos() OUtMel_
 
{ ~s) `y2Y  
try{ 5_Oxl6#  
output = new DataOutputStream(new FileOutputStream(tmpFile)); p4wx&VLi
 
output.writeInt(nStartPos.length); w(!COu  
for(int i=0;i<nStartPos.length;i++) *o#P)H  
{ Xm~N Bt  
// output.writeLong(nPos); |OO2>(Fj  
output.writeLong(fileSplitterFetch.nStartPos); K,f- w2!  
output.writeLong(fileSplitterFetch.nEndPos); VNxhv!w  
} h`V#)Q  
output.close(); i0{sE  
} [?VkwFD0  
catch(IOException e){e.printStackTrace ();} 7DWHADr  
catch(Exception e){e.printStackTrace ();} M}N[> ,2'  
} ::p(ViYG  
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//读取保存的下载信息（文件指针位置） ^wb$wtL('  
private void read_nPos() Q>l5:2lq  
{ G"F:68  
try{ &z;
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DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); >~rytg]f  
int nCount = input.readInt(); A=\:b^\  
nStartPos = new long[nCount]; CdTE~O<)  
nEndPos = new long[nCount]; &u9@FFBT8  
for(int i=0;i<nStartPos.length;i++) Jm]P,jaLc  
{ ,qK3 3Bn  
nStartPos = input.readLong(); Qjd<%!]+\  
nEndPos = input.readLong(); IF<<6.tz  
} kZ<"hsh,Y'  
input.close(); v|;}}ol  
} g I@I.=y  
catch(IOException e){e.printStackTrace ();}  [?moS!  
catch(Exception e){e.printStackTrace ();} Kb*X2#;*  
} !)LVZfQ0  
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private void processErrorCode(int nErrorCode) W
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{ *dX 7  
System.err.println("Error Code : " + nErrorCode); g66SCr}  
} U$=#yg2 :  
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\CZD.2p#&  
//停止文件下载 NrWgaPO)i  
public void siteStop() #;F*rJ[XY  
{ )o_Pnq9_  
bStop = true; !ZzDSQ;  
for(int i=0;i<nStartPos.length;i++) 9{XV=a v  
fileSplitterFetch.splitterStop(); uN9J?j*ir  
,?`Zrxe[  
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} -=a,FDeR  
} nn{PhyK  
//负责部分文件的抓取 ^?-wov$  
**FileSplitterFetch.java 4-~S"T8<u  
*/ roHJ$~q?  
package NetFox; i 3i  
{6gY6X-R  
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import java.io.*; "aJfW  
import java.net.*; tIL ]JB  
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public class FileSplitterFetch extends Thread { GfL:0  
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String sURL; //File URL -~WDv[[  
long nStartPos; //File Snippet Start Position J6RzN'j  
long nEndPos; //File Snippet End Position ,^uQw/  
int nThreadID; //Thread's ID 3&KRG}5  
boolean bDownOver = false; //Downing is over Gq0`VHAn  
boolean bStop = false; //Stop identical ]@hN&W(+x  
FileAccessI fileAccessI = null; //File Access interface b+e9Pi*\  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException {P!1VYs5  
{ 4O:y ?D/e  
this.sURL = sURL; @"O|[%7e  
this.nStartPos = nStart; gfly?)VnF  
this.nEndPos = nEnd; ]Wx?k7T  
nThreadID = id; GVld]ioycG  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 agp7zw=N  
} ],l\HHQ  
 } @4by<  
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public void run() 2OsS+6,[x  
{ w>TTu: 7  
while(nStartPos < nEndPos && !bStop) /SD(
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{ r!y3VmJ'm  
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try{ }}gtz-w  
URL url = new URL(sURL); 4{CeV7  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 0Q!/A5z  
httpConnection.setRequestProperty("User-Agent","NetFox"); uXo?  
String sProperty = "bytes="+nStartPos+"-"; cN%@ nW0i  
httpConnection.setRequestProperty("RANGE",sProperty); KK, t!a  
Utility.log(sProperty); -xL^UcG0  
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InputStream input = httpConnection.getInputStream(); F-%Hw  
//logResponseHead(httpConnection); f:KZP;/[c  
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byte[] b = new byte[1024]; (qDPGd*1  
int nRead; k]9+/$  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) tx,q=.(  
{ rBZ0Fx$/[  
nStartPos += fileAccessI.write(b,0,nRead); W}'l8z]   
//if(nThreadID == 1) sny$[!)  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); U%rq(`;  
} PM`iqn)@  
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Utility.log("Thread " + nThreadID + " is over!"); aI_[h v  
bDownOver = true; <7_s'UAL!  
//nPos = fileAccessI.write (b,0,nRead); ,C0D|q4/!.  
} Q)2i{\GPVn  
catch(Exception e){e.printStackTrace ();} <HH\VG\H6  
} dheobD  
} e5#?@}?  
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//打印回应的头信息 PC3?eS}  
public void logResponseHead(HttpURLConnection con) 6 l7iX]  
{ ]\ t20R{z  
for(int i=1;;i++) g9@H4y6fe=  
{ pch8A0JAl)  
String header=con.getHeaderFieldKey(i); !p!^[/9"c  
if(header!=null) pMd!Jl#(N  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); (Rh$0^)A  
Utility.log(header+" : "+con.getHeaderField(header)); }h1y^fuGi  
else A$70!5*  
break; bMB*9<c~  
} <RuLIu  
} {'sp8:$a  
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public void splitterStop() mwO9`AU;  
{ ujS
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bStop = true; sq{=TB{  
} WOi+y   
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} :QIf0*.O  
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/* 9D]bCi\  
**FileAccess.java S4VM(~,o  
*//文件访问(定位，写) l'7'G$v  
package NetFox; uc aa;zj  
import java.io.*; >~jl0!2z@  
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public class FileAccessI implements Serializable{ l~mj>$  
Zi{vEI]  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 U#:N/ts*(  
RandomAccessFile oSavedFile; X 4\V4_  
long nPos; >dXB)yl  
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public FileAccessI() throws IOException o:`^1  
{ %E[ $np>  
this("",0); 8ib e#jlg  
} |

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public FileAccessI(String sName,long nPos) throws IOException Kx02 2rgDU  
{ /0b7"Kr  
oSavedFile = new RandomAccessFile(sName,"rw"); N ;Cs? C  
this.nPos = nPos; ySHpN>U  
oSavedFile.seek(nPos); 
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} Y>x3`f]  
a]!u go}  
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public synchronized int write(byte[] b,int nStart,int nLen) 1BSn#Dnj  
{ Q-J} :U  
int n = -1; Q5]rc`} 5  
try{ m[ER~]L/C  
oSavedFile.write(b,nStart,nLen); Tnas$=J  
n = nLen; V`@/"Djj  
} Z%JAX>v&B  
catch(IOException e) x>+sqFd\  
{ = u&dU'@q  
e.printStackTrace (); f9t+x+ Z  
} I#;.;%u  
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return n; 5b->pc  
} %4})_h?j  
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} lQxEiDIL  
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/* *0m|`- T  
**SiteInfoBean.java 3;88a!AA!  
*/ P MI?PC[;  
package NetFox; O"1HO[  
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public class SiteInfoBean { 'sTc=*p/  
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private String sSiteURL; //Site's URL Oj8D+sC{  
private String sFilePath; //Saved File's Path jQ8 T  
private String sFileName; //Saved File's Name y5XFJj  
private int nSplitter; //Count of Splited Downloading File ^4xl4nbx  
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public SiteInfoBean() OW#G{#.6R  
{//nSplitter的缺省值为5 ";^_[n
 
//default value of nSplitter is 5 `|mV~F|  
this("","","",5); c*i,z  
} \eAV: qV  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) $01~G?:]`  
{ 9*XT|B  
sSiteURL= sURL; ilZQ/hOBH  
sFilePath = sPath; J+wnrGoK  
sFileName = sName; `l %,4qR  
this.nSplitter = nSpiltter; {REGoe=W%  
:w)9
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ED);2*qP}  
} A@-U#UvN  
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UzW]kY[A<  
public String getSSiteURL() =CO'LyG  
{ j%}9tM6[  
return sSiteURL; c4zGQoeH:  
} olKM0K  
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public void setSSiteURL(String value) /. H(&  
{ Oz
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sSiteURL = value; 2`A[<S  
} 5W=Jn?y2  
m -0EcA/  
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public String getSFilePath() 7~;)N$d\  
{ xrI9t?QaCb  
return sFilePath; d%K{JkD-  
} ca5;Z@t$S  
]f}(iD  
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public void setSFilePath(String value) qyh]v[  
{ #o,FVYYj  
sFilePath = value; nzF2Waa-  
} \f=kQbM  
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public String getSFileName() -9Ygn_M  
{ aj=-^iGG  
return sFileName; /1uGsE+[  
} h iK}&  
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public void setSFileName(String value) F!w|5,)  
{ KTwP.!<v  
sFileName = value; h"'}Z^  
} p*Yx1er1  
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public int getNSplitter() b `bg`}x  
{ +;=>&XR0m  
return nSplitter; /c6]DQ<?  
} o)$eIu}Wg  
LI^D\  
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public void setNSplitter(int nCount) cl |}0Q5  
{ "xn,'`a  
nSplitter = nCount; S~&
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} 8iM:ok  
} x(p/9$.#  
m\E=I5*/  
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/* ooP{Q r  
**Utility.java o 9(x\g  
*/  j8]M}Q$  
package NetFox; P>$+XrTE  
;jO+<~YP!  
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public class Utility { lR
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`:jF%3ks+0  
public Utility() e)}=T0 s  
{ zU!d(ge.E  
7!)VOD8Z  
k~
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} e2g`T{6M  
66$hdT$  
//线程睡眠 C~'.
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public static void sleep(int nSecond) &JD^\+7U:  
{ Qz_4Ms<o  
try{ s OLjT34  
Thread.sleep(nSecond); UIU6rilB  
} 06v'!M  
catch(Exception e) >%slzr  
{ }o\} qu*  
e.printStackTrace (); xsNOjHk  
} jj]|}G  
} HiD%BL>%  
$BG]is,&5  
//日志 91DevizXx  
public static void log(String sMsg) z46Sh&+  
{ } :gi<#-:G  
System.err.println(sMsg); [HQ/MkP-Z  
} }_H\75Iv  
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kf#S"[/E  
public static void log(int sMsg) NzN"_ojM  
{ Zv?"1Y< L  
System.err.println(sMsg); y{~tMpo<  
} t**d{P+  
} m9]Ge]  
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/* IGab~`c-[  
**TestMethod.java DJqJ6z:'  
*/ zsR5"Vi=  
package NetFox; n</Rd=  
=}Q|#C  
jM-5aj[K  
public class TestMethod { "v0SvV<7  
hW6Ksn,*  
c `.BN(  
public TestMethod() 6$zd2N?  
{ ///xx/weblogic60b2_win.exe -3 "<znv  
try{ ^g"p}zf L"  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); Vi
0D>4{+  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); QjYw^[o  
SiteFileFetch fileFetch = new SiteFileFetch(bean); v yt|x5  
fileFetch.start(); <'BsQHI  
} .CNwuN\  
catch(Exception e){e.printStackTrace ();} FPPl^  
rEbH<|  
.'h^  
} oiD{Z  
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public static void main(String[] args) (uC@cVkP  
{ 'Z%1Ly^b  
new TestMethod(); SwaPRAF  
} !XM*y  
} 1s(i\&B  
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