http断点续传简单实现（java)

/* n>U5R_T  
**SiteFileFetch.java z,%$+)K  
*/ 2SR:FUV/  
package NetFox; d4z/5Oa  
import java.io.*; X+]G-  
import java.net.*; 3%=~)7cF  
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public class SiteFileFetch extends Thread { y Fq&8 x<X  
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SiteInfoBean siteInfoBean = null; //文件信息Bean _``=cc  
long[] nStartPos; //开始位置 >t_6B~x9  
long[] nEndPos; //结束位置 ?=fyc1  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 F`]2O:[  
long nFileLength; //文件长度 WQO) =n  
boolean bFirst = true; //是否第一次取文件 G9<X_  
boolean bStop = false; //停止标志 4)o  
File tmpFile; //文件下载的临时信息 h;NYdX5  
DataOutputStream output; //输出到文件的输出流 @bP)406p  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） vd4ytC  
public SiteFileFetch(SiteInfoBean bean) throws IOException PXNh&N  
{ WVvvI9  
siteInfoBean = bean; (7=9++uU  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); %vi<Aseg  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); As<bL:>dE  
if(tmpFile.exists ()) Jo23P.#<  
{ 1|-Dj|  
bFirst = false; \=0Vi6!Mc  
read_nPos(); x{WD;$J  
} "wh ,Ue  
else fPW@{~t  
{ "OnGE$  
nStartPos = new long[bean.getNSplitter()]; -_eLf#3  
nEndPos = new long[bean.getNSplitter()]; $5Ff1{  
} ))'<_nD  
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} N_[*H  
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public void run() O/(xj2~$J  
{ vTw>JNVI  
//获得文件长度 GYUn6P  
//分割文件 yd
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//实例FileSplitterFetch 'u<juFr  
//启动FileSplitterFetch线程 y;@:ulv[  
//等待子线程返回 [RTs[3E^  
try{
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if(bFirst) Aj+F |l  
{ 
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nFileLength = getFileSize(); 7g}w+p>  
if(nFileLength == -1) gQ1;],_  
{ t" Z6[XG  
System.err.println("File Length is not known!"); :
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} .];=Pu^  
else if(nFileLength == -2) (n9gkO&8"  
{
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System.err.println("File is not access!"); HJYScwjQ;`  
} ]1pIj i[  
else 3fQuoQuD"}  
{ Dy8r 9  
for(int i=0;i<nStartPos.length;i++) 6MdiY1Lr!K  
{ agW@{c  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ysf~|r4s  
} W'+:'_{j:  
for(int i=0;i<nEndPos.length-1;i++) n3 r3"~i  
{ j Dv{/)  
nEndPos = nStartPos[i+1]; G?/DrnK:  
} u.Tcg^v  
nEndPos[nEndPos.length-1] = nFileLength; v^iL5y!  
} yFlm[K5YD  
} 9.B KI/  
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//启动子线程 PGV/ h  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; qE3UO<FA  
for(int i=0;i<nStartPos.length;i++) %m$Sp47  
{ ?|B&M\}g  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), P:]^rke~&  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), _?0}<kQ&  
nStartPos,nEndPos,i); Ob&<]  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); h6`6tk  
fileSplitterFetch.start(); UVIKQpA]A  
} uT7B#b7  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 1 \6D '/G  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); KE3;V2Ym f  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", eHNyNVz  
nEndPos = " + nFileLength); r/6o \-  
// fileSplitterFetch[nPos.length-1].start(); _#8RSr8'y  
Ur=(.%@  
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//等待子线程结束 6wECo  
//int count = 0; !.(P~j][  
//是否结束while循环 I(7NQ8Hx  
boolean breakWhile = false; VYImI>.t{  
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while(!bStop) :;fHDU|  
{ 1rF]yi:X  
write_nPos(); mahJSz(3  
Utility.sleep(500); c?&X?<  
breakWhile = true; s6.M\^  
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for(int i=0;i<nStartPos.length;i++) ^mO~W!"  
{ V"G*N<q  
if(!fileSplitterFetch.bDownOver) WQL\y3f5  
{ !SdSE^lz`  
breakWhile = false; E+g@M8D  
break; n!xt5=xP{  
} /Uy"M:|V1  
} 9}F*P669f  
if(breakWhile) Vi]W|bP  
break; kbMWGB%;  
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//count++; k=JrLfD4  
//if(count>4) T1Z;r*}  
// siteStop(); ={d>iByq  
} [)zP6\
I  
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# ,_u_'C*!  
System.err.println("文件下载结束！"); ,-d0b0  
} /-+xQn]  
catch(Exception e){e.printStackTrace ();} MUREiL9L|  
} 4UvZ)^r  
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,*hLFaR-  
//获得文件长度 pR
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public long getFileSize() {NFr]LGOp  
{ @ljA  
int nFileLength = -1; "wnzo,  
try{ h"_;IUZ!  
URL url = new URL(siteInfoBean.getSSiteURL()); {rH@gz|@i  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); :LRYYw  
httpConnection.setRequestProperty("User-Agent","NetFox"); LzXmb 7A  
%9N7Ln|%  
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int responseCode=httpConnection.getResponseCode(); p#?7w  
if(responseCode>=400) ?Unb? {,&2  
{ GyIT{M}KV  
processErrorCode(responseCode); *|C^=*j9  
return -2; //-2 represent access is error xLWwYK  
} $oU*9}}Rn  
b TM{l.Aq3  
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String sHeader; s!&#c`=  
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for(int i=1;;i++) p~^D\jR.  
{ IsM}'.  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ]#l/2V1  
//Utility.log(in.readLine()); o(LFh[  
sHeader=httpConnection.getHeaderFieldKey(i); PHXZ=A+  
if(sHeader!=null) &cHV7  
{ `
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if(sHeader.equals("Content-Length")) Q$1bWUS&  
{ X
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nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); G{ sOR  
break; vss(twg  
} : $Y9jR  
} m)v"3ib  
else Nj xoTLI  
break; bE#,=OI$  
} zHL@i0>^  
} ICs\ z  
catch(IOException e){e.printStackTrace ();} PQnF  
catch(Exception e){e.printStackTrace ();} !^=*Jq>  
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Utility.log(nFileLength); 1[qLA!
+  
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return nFileLength; O[s{ Gk'>  
} s'a/j)^  
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//保存下载信息（文件指针位置） 9XyYHi  
private void write_nPos() P'*)\faw  
{ V=qwwYz~  
try{ pP?MWe Eg  
output = new DataOutputStream(new FileOutputStream(tmpFile)); cc&axc7I  
output.writeInt(nStartPos.length); ^xHTWg%9  
for(int i=0;i<nStartPos.length;i++) v'qG26
  
{ jR22t`4  
// output.writeLong(nPos); ^ZhG>L*  
output.writeLong(fileSplitterFetch.nStartPos); V
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output.writeLong(fileSplitterFetch.nEndPos); ') gi%  
} :xD=`ib  
output.close(); v!Pb`LCqK  
} u7[ykyV  
catch(IOException e){e.printStackTrace ();} %Nhx;{  
catch(Exception e){e.printStackTrace ();} ,TPISs  
} SAK!z!t  
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//读取保存的下载信息（文件指针位置） ,M6Sy]Aj  
private void read_nPos()
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{ (TwnkXrR,  
try{ "@d[h,TM  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); wsN?[=l{s  
int nCount = input.readInt(); }YMy6eW4  
nStartPos = new long[nCount]; t!x5fNo)  
nEndPos = new long[nCount]; C\nhqkn  
for(int i=0;i<nStartPos.length;i++) 6morum  
{ 4%}*&nsI-Z  
nStartPos = input.readLong(); HA`@7I  
nEndPos = input.readLong(); `V"sOTb  
} [}8|R0KF  
input.close(); 2?,EzBeal  
} Y"Ql!5=  
catch(IOException e){e.printStackTrace ();} ,(?po(']  
catch(Exception e){e.printStackTrace ();} W#BM(I  
} x~{;TZa[I  
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private void processErrorCode(int nErrorCode) H nUYqhZS  
{ Eu-RNrYh#  
System.err.println("Error Code : " + nErrorCode); Xn,v]$M!  
} \X&H;xnC5  
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//停止文件下载 gO,25::")  
public void siteStop() .I'o  
{ c`WHNky%j  
bStop = true; (v|}\?L  
for(int i=0;i<nStartPos.length;i++) WxJf{=-  
fileSplitterFetch.splitterStop(); DrBUe'RH:M  
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} ]Xf% ,iu  
} @`Eg(  
//负责部分文件的抓取 x-<)\L&  
**FileSplitterFetch.java .YnFH$;$  
*/ [],1lRYI9_  
package NetFox; 13%t"-@bh  
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import java.io.*; t|!j2<e  
import java.net.*; E)7F\w  
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public class FileSplitterFetch extends Thread { $w0lrh[+  
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String sURL; //File URL f7~9|w&  
long nStartPos; //File Snippet Start Position I,VH=Yn5,  
long nEndPos; //File Snippet End Position 3a 1u   
int nThreadID; //Thread's ID Cc<,z*T  
boolean bDownOver = false; //Downing is over d,tU#N{Q6  
boolean bStop = false; //Stop identical ]f: v,a  
FileAccessI fileAccessI = null; //File Access interface TsUOpEuX  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException k`9)=&zX+  
{ g'u?Rn7*J  
this.sURL = sURL; <[J[idY1he  
this.nStartPos = nStart; pM&Y
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this.nEndPos = nEnd; V8wKAj Ux  
nThreadID = id; B Ma)O  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 @81Vc<dJ  
} >'xGp7}y  
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public void run() ,i6RE  
{ V&|Ed  
while(nStartPos < nEndPos && !bStop) ?EpSC&S\  
{ E)-r+ <l  
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try{ ,7)C"  
URL url = new URL(sURL); RQB]/D\BO  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Gqcz<=/  
httpConnection.setRequestProperty("User-Agent","NetFox"); j.ldaLdG  
String sProperty = "bytes="+nStartPos+"-"; kR@Yl Yo  
httpConnection.setRequestProperty("RANGE",sProperty); 7Irau_  
Utility.log(sProperty); B
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InputStream input = httpConnection.getInputStream(); p,<&zHb>K  
//logResponseHead(httpConnection); `)h6j)xiQ  
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byte[] b = new byte[1024]; Hiv!BV|  
int nRead; wpt='(  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) %?hsoj&k  
{ m8JR@!t7  
nStartPos += fileAccessI.write(b,0,nRead); Ty@=yA17  
//if(nThreadID == 1) ,j ',x\  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ).HDru-2  
} \[>9UC%  
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Utility.log("Thread " + nThreadID + " is over!"); hv$m4,0WB  
bDownOver = true; H,<7G;FPT  
//nPos = fileAccessI.write (b,0,nRead); g3sUl&K  
} %F9{EXJy  
catch(Exception e){e.printStackTrace ();} o}'bv  
} )|<_cwz  
} 4YMX|1wd)  
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//打印回应的头信息 #W2[  
public void logResponseHead(HttpURLConnection con) |nk3^
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{ l\!-2 T6Y  
for(int i=1;;i++) ]G}B 0u3  
{ Q2%QLM:.,  
String header=con.getHeaderFieldKey(i); O:/yAc`  
if(header!=null) 0l#)fJo  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); R
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Utility.log(header+" : "+con.getHeaderField(header)); :9Y$'+ <&H  
else =}fd6ea(o  
break; @C-dG7U.P  
} R,!Q Zxmg  
} Ld,5iBiO:  
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public void splitterStop() x2#qg>`l  
{ s&{Qdf  
bStop = true; Lj%{y.Rj  
} q 'a  
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} F{\gc|!i  
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/* oXt,e  
**FileAccess.java >Dg#9  
*//文件访问(定位，写) =`C4qC_  
package NetFox; DV]7.Bm  
import java.io.*; l??;3kh1  
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public class FileAccessI implements Serializable{ 8Chu"PM%-J  
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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 I5);jgb  
RandomAccessFile oSavedFile; m>e3vu  
long nPos; dYojm1MQ  
;}.Kb
 
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public FileAccessI() throws IOException l t]B#, '  
{ F X1ZG!  
this("",0); f|aDTWF  
} Y"eEkT\  
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public FileAccessI(String sName,long nPos) throws IOException fd8#Ng"1  
{ %xyX8c{sP  
oSavedFile = new RandomAccessFile(sName,"rw"); -#A:`/22  
this.nPos = nPos; c;I, O  
oSavedFile.seek(nPos); x@cN3
O  
} 88a<{5 :z  
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public synchronized int write(byte[] b,int nStart,int nLen) s3lwu :4f  
{ @#b0T:+v'  
int n = -1; mg+k'Myo+  
try{ ~HUZ#rUHm>  
oSavedFile.write(b,nStart,nLen); 9 K  
n = nLen; P-JfV7(O8  
} +ydm,aKk  
catch(IOException e) WA.\*Nqze  
{ kJ: 2;t=  
e.printStackTrace (); ZAg;q#z j  
} 3On JWuVfZ  
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return n; dNVv4{S  
} dTD5(}+J  
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} CYB=Uq,  
? Ekq6uz\)  
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/* ~'  =lou  
**SiteInfoBean.java voRfjsS~  
*/ <qiICb)~  
package NetFox; DB&SOe  
:?r*p>0$  
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public class SiteInfoBean { g^o_
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private String sSiteURL; //Site's URL 5&4F,v[zp  
private String sFilePath; //Saved File's Path yCM{M  
private String sFileName; //Saved File's Name <
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private int nSplitter; //Count of Splited Downloading File zw:/!MS  
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public SiteInfoBean() gB CC  
{//nSplitter的缺省值为5 {>.>7{7  
//default value of nSplitter is 5 S+*cbA{J|  
this("","","",5); 4IGxI7~27#  
} T=? bdIl  
.{N\<01  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) yer> x  
{ .g-3e"@  
sSiteURL= sURL; {u]CHN`%Z  
sFilePath = sPath; O=O(3Pf>  
sFileName = sName; -"Gl 4)  
this.nSplitter = nSpiltter; L/k40cEI^z  
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} HRRngk#lV  
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public String getSSiteURL() _XN~@5elrC  
{ F|]rA*2u  
return sSiteURL; 9c5!\m1  
} oBUh]sR{.  

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public void setSSiteURL(String value)  g@(30{  
{ mahi7eU P  
sSiteURL = value; m0iV m|  
} x[m'FsR4  
F>Mr<k=@;  
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public String getSFilePath() rAatJc"0  
{ QBjY&(vY  
return sFilePath; ;^.9#B,<  
} /2:Q6J  
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public void setSFilePath(String value) !`h~`-]O  
{ :+pPrGj"  
sFilePath = value; bVmvjY4  
} (j`l5r#X#/  
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8c?8X=|D7  
public String getSFileName() Alh?0Fk3)  
{ '?L%F{g/9  
return sFileName; ?lG;,,jc,W  
} (E]"Srwh  
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,yi2O]5e>!  
public void setSFileName(String value) vcD'~)G(*  
{ 6Wu*.53  
sFileName = value; InX{V|CW?  
} :,=Fx</H  
'!j(u@&!  
>?Qxpqf2  
public int getNSplitter() :dbV2'vIQ  
{ B(EtXB9  
return nSplitter; v7$9QVze  
} ^AH-+#5  
wO\!xW:  
@>9A$w$H|a  
public void setNSplitter(int nCount) v*gLNB,ZH  
{ H.;yLL=  
nSplitter = nCount; ?ZM^%]/+  
} Kk56/(_S  
} kBUufV
~  
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/* 6g5]=Q@U:  
**Utility.java *kV#)j  
*/ v @_?iC"`  
package NetFox; ]LY^9eK)>{  
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public class Utility { oYGUjI  
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$/
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public Utility() 7@\GU].2  
{ #s/{u RYQ  
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} )m>6hk  
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//线程睡眠 r8H7TJI0   
public static void sleep(int nSecond) rQuOt  
{ pIrv$^  
try{ ]b!R-G!gV  
Thread.sleep(nSecond); >pJ6{Ip  
} cEtZ}2,j  
catch(Exception e) (O<abB(  
{ 1pl2;!  
e.printStackTrace (); Ld'EABM  
} u<J2p?`\&`  
} QDl)92z  
%j!z\pa  
//日志 cKSfqqPm$"  
public static void log(String sMsg) L_`Xbky  
{ "&s9cO.H  
System.err.println(sMsg); -!JlM@  
} " -<}C%C  
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U5-zB)V  
public static void log(int sMsg) ]VmzKA|h+  
{ +EQpD.  
System.err.println(sMsg); YGi/]^Nba  
} `mWQWx$V!  
} o7hH9iY  

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/* DPR;$yV  
**TestMethod.java z;``g"dSw  
*/ =ulr_i%Xs  
package NetFox; / N*HE  
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public class TestMethod { |q9,,i}!  
b"*mi  
o x03c  
public TestMethod() -(|7`U  
{ ///xx/weblogic60b2_win.exe Qj{$dqmDN  
try{ {A
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SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); CAA tco5  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); H,01o5J  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 7Q<Kha  
fileFetch.start(); ]wJ}-#Kx  
} ZJ)3GF}4  
catch(Exception e){e.printStackTrace ();} wCTcGsw W  
)<m=YI ;<  
~t1O]aO(  
} z|taa;iM  
M^!C?(Hx^x  

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public static void main(String[] args) &zaW"uy3T  
{ o9DYr[  
new TestMethod(); \a9D[wk;@  
} OcyiL)tv5  
} cWX"e6  
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