http断点续传简单实现（java)

/* M=!i>(yG  
**SiteFileFetch.java y%(X+E"n*  
*/ Ub)I66  
package NetFox; =G>(~+EA  
import java.io.*; -e`;bX_N)  
import java.net.*; !e8i/!}^S  
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public class SiteFileFetch extends Thread { L/r{xS  
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SiteInfoBean siteInfoBean = null; //文件信息Bean Cw1(5  
long[] nStartPos; //开始位置 3{J.xWB@:  
long[] nEndPos; //结束位置 Dx+K+(  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 Ek
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long nFileLength; //文件长度 rg&+  
boolean bFirst = true; //是否第一次取文件 Vu]
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boolean bStop = false; //停止标志 SE`l(-tL  
File tmpFile; //文件下载的临时信息 (O5)wej   
DataOutputStream output; //输出到文件的输出流 `.BR=['O  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 2R@%Y/  
public SiteFileFetch(SiteInfoBean bean) throws IOException 9U<Hf32  
{ l8wF0|  
siteInfoBean = bean; S ~|.&0"\  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); QlzQ]:dWC  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 
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if(tmpFile.exists ()) [%8@DC'  
{ 'V!kL, 9ES  
bFirst = false; zXre~b03ZS  
read_nPos(); =HE m)  
} %?tq;~|]Q  
else Z;<ep@gy~  
{ U</+.$b  
nStartPos = new long[bean.getNSplitter()]; &hN,xpC  
nEndPos = new long[bean.getNSplitter()]; (([I]q  
} P^IY: -s  
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} tV`&-
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public void run() ,IjdO(?TC  
{ o/JPYBhdl  
//获得文件长度 k&GHu0z  
//分割文件 a!t V6H  
//实例FileSplitterFetch *T4ge|zUc  
//启动FileSplitterFetch线程 5u,sx664  
//等待子线程返回 R;THA!  
try{ JSjYC0e  
if(bFirst) 8~5|KO >F  
{ S}gD,7@  
nFileLength = getFileSize(); 3?ba 1F0Nw  
if(nFileLength == -1) G[6=u|(M  
{ tA qs2  
System.err.println("File Length is not known!"); < l[
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} V\zsDP  
else if(nFileLength == -2) ryEvmWYu  
{ 1g i}H)  
System.err.println("File is not access!"); ay[+2"  
} k,]{NO   
else !#.vyBK#  
{ D8/sz`N7Q  
for(int i=0;i<nStartPos.length;i++) 4A~)b"j5  
{ T46{*(  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); V_]-`?S  
} @3 "DBJ  
for(int i=0;i<nEndPos.length-1;i++) (46U|P(v  
{ 9p<:LZd~  
nEndPos = nStartPos[i+1];  y h-9u  
} 6D^%'[4t  
nEndPos[nEndPos.length-1] = nFileLength; VRhRwdC  
} 8|<f8Z65!  
} Qa?QbHc  
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\>[gl!B_Rr  
//启动子线程 M9g1d7%  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; @7|)RSBQz  
for(int i=0;i<nStartPos.length;i++) M,{<TpCx  
{ YHh u^}|jQ  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), yHw!#gWM  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), bV7QVu8  
nStartPos,nEndPos,i); rxkBg0Z`a  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); mt.,4  
fileSplitterFetch.start(); 4`0;^K.  
} +-k`x0v  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), /O"0L/hc^  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); gT7I9 (x!W  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", $y4M#yv  
nEndPos = " + nFileLength); JOHp?3"4  
// fileSplitterFetch[nPos.length-1].start(); dh,7iQ s  
g{&PrE'e9  
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//等待子线程结束 <^'{ G  
//int count = 0; V
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//是否结束while循环 {q2<KRU2+#  
boolean breakWhile = false; Px#4pmz  
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while(!bStop) )XZ,bz*jn  
{ m-#d8sD2C  
write_nPos(); ]=pWZ~A  
Utility.sleep(500); 3DHvaq q7  
breakWhile = true; {8i}Ow  
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pb=HVjW<  
for(int i=0;i<nStartPos.length;i++) 6KBHRt  
{ b6$4Ul-.  
if(!fileSplitterFetch.bDownOver) @%7
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{ X)FQ%(H<  
breakWhile = false; g&8.A(  
break; W.sD2f  
} ,|>nF;.Y  
} otZ JY)  
if(breakWhile) vKV{ $|  
break; (BhL/A 4  
Ut=0~x.=<  
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//count++; xKisL=l6Y  
//if(count>4) <#!8?o&i  
// siteStop(); ,P1G?,y  
} kfIbgya  
&A#90xzF  
:'TX"E!  
System.err.println("文件下载结束！"); +0)5H>h  
} {S# 5g2  
catch(Exception e){e.printStackTrace ();} ; vhnA$'a  
} ob)D{4B'  
7{8)ykBU^  
13]y)(  
//获得文件长度 34^Q5B~^J  
public long getFileSize() SwQOFE/Dv~  
{ @V*a
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int nFileLength = -1; U@MOvW)  
try{ $Jt8d|UP  
URL url = new URL(siteInfoBean.getSSiteURL()); cbY3mSfn*  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); &s_}u%iC  
httpConnection.setRequestProperty("User-Agent","NetFox"); 96k(XLR  
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int responseCode=httpConnection.getResponseCode(); VdYOm  
if(responseCode>=400) :K5V/-[|V1  
{ f2 Vpe
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processErrorCode(responseCode); FxMMxY,*%  
return -2; //-2 represent access is error S:DcfR=a  
} + 4++Z  
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String sHeader; 6YB-}>?  

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for(int i=1;;i++) ~p0e=u  
{ E%KC'TN^D  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); "4k"U1  
//Utility.log(in.readLine()); oTZo[T@zRx  
sHeader=httpConnection.getHeaderFieldKey(i); hlt9x.e.A  
if(sHeader!=null) lb=2*dFJ1  
{ h6K!|-Gq.  
if(sHeader.equals("Content-Length")) 6B4hSqjh  
{ <;.}WQC  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); * N2#{eF&]  
break; * ,|)~$=>  
} QLxXp
 
} N2M?5fF  
else q oKQEG2  
break; #p
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} V/+H_=|  
} Tm'lN5}&9  
catch(IOException e){e.printStackTrace ();} 1KNkl,E  
catch(Exception e){e.printStackTrace ();} |Sy}d[VKsZ  
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Utility.log(nFileLength); bUpmU/RW  
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return nFileLength; jKe$&.q@  
} >:(6{}b  
=Td#2V;0  
#h}
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//保存下载信息（文件指针位置） OpbszSl"y  
private void write_nPos() Jc9@VxWY  
{ _S[Rvb1e   
try{ x`b~ZSNJ%  
output = new DataOutputStream(new FileOutputStream(tmpFile)); `Nxo0Q  
output.writeInt(nStartPos.length); Ej9/_0lt  
for(int i=0;i<nStartPos.length;i++) W\ZV0T;<]  
{ fwz5{>ON
]  
// output.writeLong(nPos); D"1vw<Ak  
output.writeLong(fileSplitterFetch.nStartPos); j X^&4f  
output.writeLong(fileSplitterFetch.nEndPos); C"V?yDy2~  
} vgd}09y  
output.close(); loAfFK>g  
} (dw3'W  
catch(IOException e){e.printStackTrace ();} OoA5!HEh  
catch(Exception e){e.printStackTrace ();} ?}!g
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} W_Ws3L1;N  

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//读取保存的下载信息（文件指针位置） !]UU;8h~  
private void read_nPos() NG4eEnic!a  
{ QqT6P`0u  
try{ 4rGO8R  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); Hj-<{#,  
int nCount = input.readInt(); ;RTrRh0v  
nStartPos = new long[nCount]; 0|qx/xo|-  
nEndPos = new long[nCount]; ]-+.lR%vd9  
for(int i=0;i<nStartPos.length;i++)
&9GR2GY  
{ ]y$V/Ij=qK  
nStartPos = input.readLong(); C
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nEndPos = input.readLong(); GhchfI.  
} D|8sjp4  
input.close(); uH~ TugQ~  
} +A.a~Stt  
catch(IOException e){e.printStackTrace ();} @8x6#|D  
catch(Exception e){e.printStackTrace ();} 3e!a>Gl*  
} UlLM<33_)  
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private void processErrorCode(int nErrorCode) ,AFC1t[0  
{ ~ L i%  
System.err.println("Error Code : " + nErrorCode); : Oz7R:  
} Sj=69>m]5  
;^*+:e  
<LOx.}fv  
//停止文件下载 d%[`=fs]|m  
public void siteStop() n+A'XBHk  
{ !D|pbzQc8  
bStop = true; d~xU?)n)  
for(int i=0;i<nStartPos.length;i++) F"HI>t)>  
fileSplitterFetch.splitterStop(); i32_ZBZ?y  
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} +h9l%Pz  
} +X|m>9  
//负责部分文件的抓取 Wvzzjcr(j  
**FileSplitterFetch.java N4JqW  
*/ Q,`2DHhK  
package NetFox; 3R$CxRc:  
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import java.io.*; 7T(OV<q;#  
import java.net.*; O'yjB$j  
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public class FileSplitterFetch extends Thread { ;JD3tM<  
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String sURL; //File URL "a%ASy>?g  
long nStartPos; //File Snippet Start Position M b /X@51  
long nEndPos; //File Snippet End Position $'mB8 S  
int nThreadID; //Thread's ID Ubos#hP  
boolean bDownOver = false; //Downing is over Xxsnpb>  
boolean bStop = false; //Stop identical #Ot*jb1  
FileAccessI fileAccessI = null; //File Access interface R*TGn_J`  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException K {1ZaE
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{ >[P7Zlwv4  
this.sURL = sURL; ws=9u-  
this.nStartPos = nStart; GVHfN5bTqn  
this.nEndPos = nEnd; +68K[s,FD  
nThreadID = id; ~)_
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fileAccessI = new FileAccessI(sName,nStartPos);//定位 :pF]TY"K.  
} O]r3?=  
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public void run() MnrGD>M@|  
{ $rQFM[  
while(nStartPos < nEndPos && !bStop) QGCdeE$K  
{ r)@&2b"q  
("M#R!3  
CTrs\G  
try{ D``NQ`>A  
URL url = new URL(sURL); _*?"[TYfX  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); P@S;>t{TD  
httpConnection.setRequestProperty("User-Agent","NetFox"); 8KELN(o$ 7  
String sProperty = "bytes="+nStartPos+"-"; 8iH;GFNJ7'  
httpConnection.setRequestProperty("RANGE",sProperty); L)nVpqm   
Utility.log(sProperty); BnnUUaE  
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)D-.7m.v]  
InputStream input = httpConnection.getInputStream(); _>)"+z^r  
//logResponseHead(httpConnection); Sph"w08  
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byte[] b = new byte[1024]; "drh+oo.  
int nRead; 0gb]Kjx  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) P)j9\ muc  
{ zhm!sMlO  
nStartPos += fileAccessI.write(b,0,nRead); MfpWow-#{  
//if(nThreadID == 1) C.e|VzQa  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); %LZM5Z^  
} D>#v 6XI  
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Utility.log("Thread " + nThreadID + " is over!"); '<W,-i  
bDownOver = true; HF=C8ZtlL  
//nPos = fileAccessI.write (b,0,nRead); 1*,~1!>  
} ?;#3U5$v  
catch(Exception e){e.printStackTrace ();} _(kwD^x6O{  
} [ *a>{sO[  
} }br<2?y,  
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//打印回应的头信息 cyP*QW
[  
public void logResponseHead(HttpURLConnection con) BNoCE!  
{ .q[sk  
for(int i=1;;i++) pz6- hi7  
{ =|&"/$+s  
String header=con.getHeaderFieldKey(i); A_*Lo6uII  
if(header!=null) }/}`onRZ  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); eHyuO)(xH1  
Utility.log(header+" : "+con.getHeaderField(header)); oYm{I ~"  
else \V- Y,!~5  
break; it|:P  
} e^Wv*OD'  
} .O-DVW Cm  
nu%Nt"~[%  
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public void splitterStop() -V_S4|>   
{ whZ],R*u  
bStop = true; GZ[h`FJg/  
} E=~WQ13Q  
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} K]*ERAfM%m  
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/* 2u H\8A+'f  
**FileAccess.java w8#>xV^~  
*//文件访问(定位，写) z>g& ?vo2  
package NetFox; Ywk[VD+.  
import java.io.*; kJpHhAn4  
9@*>$6  
[>9"RzEl  
public class FileAccessI implements Serializable{ !4.^@^L|\  
19{?w6G<k  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 b/}0 &VXo  
RandomAccessFile oSavedFile; &r%^wfp  
long nPos; r9'H7J  
92_H!m/  
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public FileAccessI() throws IOException :+^l
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{ >b](v)  
this("",0); =0fx6V  
} 959jp85  
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public FileAccessI(String sName,long nPos) throws IOException Ijro;rsEKM  
{ 4n)Mx*{  
oSavedFile = new RandomAccessFile(sName,"rw"); `ViNSr):J  
this.nPos = nPos; :>ST)Y@]w  
oSavedFile.seek(nPos); < io8 b|A  
} N!&VBx^z  
zvC,([  
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public synchronized int write(byte[] b,int nStart,int nLen) :%]R x&08  
{ uQ+$HzxX  
int n = -1; <rmV$_  
try{ rGL{g&_  
oSavedFile.write(b,nStart,nLen); \eN/fTPm  
n = nLen; 0DT2qM[,  
} Px&Mi:4tG  
catch(IOException e) boB{Y7gO4  
{ mU>*NP(L  
e.printStackTrace (); "jMnYEG  
}
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return n; <bppu>&  
} r:Cid*~m  
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} l Nto9  
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/* L KR,CPz  
**SiteInfoBean.java ,R6$SrNcd  
*/ ZWEzL$VWi  
package NetFox; ee` =B  
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public class SiteInfoBean { YWF<2l.  
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tJ=zk3BN~  
private String sSiteURL; //Site's URL M)Q+_c2*  
private String sFilePath; //Saved File's Path 
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private String sFileName; //Saved File's Name swbD q  
private int nSplitter; //Count of Splited Downloading File YHAg4eb8  
<2A'   
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public SiteInfoBean() W4a20KM2  
{//nSplitter的缺省值为5 9oz)E>K4f  
//default value of nSplitter is 5 K#m o+n5-;  
this("","","",5); niBpbsO  
} L]")TQ
 
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) e|y~q0Q$  
{ P .(X]+  
sSiteURL= sURL; [}3Y1t{G  
sFilePath = sPath; .1}(Bywm5  
sFileName = sName; ?!Gt. fb  
this.nSplitter = nSpiltter; OPjh"Hv  
3W0:0I  
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} tgnXBWA`!  
n_glYSV!  
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public String getSSiteURL() Vd~k4  
{ +N:%`9}2V  
return sSiteURL; Zv7)+Q  
} 7X>3WF  
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public void setSSiteURL(String value) H;E{Fnarv  
{ fsu"Lc  
sSiteURL = value; j]^]p;An  
} p(%x&*)f  
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public String getSFilePath() [*v\X %+  
{ x #g,l2_!  
return sFilePath; Q5JeL6t  
} +^:K#S9U  
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HR  
public void setSFilePath(String value) ysPW<  
{ Jsl,r+'H  
sFilePath = value; R)z|("%ec  
} s#3{c@^3  
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public String getSFileName() [Ma9  
{ ]W,g>91m  
return sFileName; m\=u/Zip  
} gE~31:a^  
!5-[kG&  
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public void setSFileName(String value) LX'US-B.!  
{ $'Z!Y;Ue  
sFileName = value; jL<.?HE  
} X(9Ff=0.~  
KNhH4K2iP8  
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public int getNSplitter() lLv0lf  
{ {[+gM?  
return nSplitter; LtBH4A  
} +FR"Gt$g  
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{JJ`|*H$_  
public void setNSplitter(int nCount) C Qebb:y  
{ 4=Zlsp  
nSplitter = nCount; F)G#\r  
} FW4 hqgE@  
} ia[wVxd  
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-uZ^UG!K  
/* gqhW.e}]  
**Utility.java b8Qm4b?:4  
*/ 6yU~^))bx  
package NetFox; cD\Qt9EI  
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public class Utility { -:QyWw/d  
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public Utility() 2:a
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{ )I#kG{z|P;  
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} gDv]n^&  
ch&r.  
//线程睡眠 xfzR>NU  
public static void sleep(int nSecond) gOkO8P6P8  
{ {MS&t09Wh  
try{ k}/: xN"  
Thread.sleep(nSecond); d09
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} Kk,->q<1  
catch(Exception e) +0OQ"2^&  
{ sk5\"jna  
e.printStackTrace (); ^Iz.O  
} v6GWD}HH,  
} %F7aFvl*  
m} V,+E  
//日志 YP7<j*s8  
public static void log(String sMsg) %nIjRmqM~  
{ Kq*^*vWC  
System.err.println(sMsg); iPIA&)x}  
} IoX(Pa  
qHj4`&  
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public static void log(int sMsg) R[Rs2eS_  
{ s(dox; d  
System.err.println(sMsg); +X< Z 43  
} aV ^2  
} ~$cw]R58,9  
(T^aZuuS  
[7B&<zY/?  
/* ;HC"hEc!  
**TestMethod.java D&'".N,}  
*/ 5!Guf?i  
package NetFox; ed{9UJWh  
."lY>(HJ  
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public class TestMethod { K+7xjFoDIR  
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koUH>J:  
public TestMethod() g5cR.]oz  
{ ///xx/weblogic60b2_win.exe -,rl[1ZYZ  
try{ PvM<#zq_  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); d ][E;$  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); (d (whlF  
SiteFileFetch fileFetch = new SiteFileFetch(bean); CN >q`[!  
fileFetch.start(); | zAey\  
} $UH_)Q2#J^  
catch(Exception e){e.printStackTrace ();} \/5 8#  
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} cO<x:{`  
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 $%jV%k  
public static void main(String[] args) d BJM?/  
{ J/mLB7^
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new TestMethod(); fpzTv3D=I  
} k'{lo_  
} a E#s#Kv   
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