http断点续传简单实现（java)

/* -`RJk(  
**SiteFileFetch.java s%:fB(  
*/ 5[3hw4  
package NetFox; d!d 3r W;A  
import java.io.*; ^Y&Cm.w  
import java.net.*; ^d"J
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public class SiteFileFetch extends Thread { S ~_%  
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{)[i\=,`{  
SiteInfoBean siteInfoBean = null; //文件信息Bean BOWTH{KR<<  
long[] nStartPos; //开始位置 r:q#l~;^  
long[] nEndPos; //结束位置 q!,do2T  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 wx!*fy4hL  
long nFileLength; //文件长度 QA3l:D}u  
boolean bFirst = true; //是否第一次取文件 zm:=d>D..  
boolean bStop = false; //停止标志 *"5a5.`%,  
File tmpFile; //文件下载的临时信息 `%Ghtm*  
DataOutputStream output; //输出到文件的输出流 y"hM6JI  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） d3$<|mG$  
public SiteFileFetch(SiteInfoBean bean) throws IOException yI%> w4Z  
{ cjR.9bgn  
siteInfoBean = bean; SQ!lgm1bA  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ]UI+6}r  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); t[maUy_A  
if(tmpFile.exists ()) >R:+ml  
{ b[k 1)R"  
bFirst = false; GlZ9k-ZRF  
read_nPos(); [E^X=+Jnz  
} g-^m\>B  
else oD7H6\_  
{ -7$'* V9$  
nStartPos = new long[bean.getNSplitter()]; F:g{rm[
  
nEndPos = new long[bean.getNSplitter()]; U
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} NQJqS?^W&M  
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} iK]g3ew|  
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public void run() StL[\9~:  
{ gB(W`:[  
//获得文件长度 ~ t H s+  
//分割文件
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//实例FileSplitterFetch kn"x[{d  
//启动FileSplitterFetch线程 jq]"6/xxb  
//等待子线程返回 GN9_ZlC  
try{ 9/M!S[N9  
if(bFirst) ?>8zU;Aj  
{ qtN29[x  
nFileLength = getFileSize(); I`TD*D  
if(nFileLength == -1) !S!03|  
{ @qDrTH]5  
System.err.println("File Length is not known!"); @,&m`qzd+  
} @>@Nug2   
else if(nFileLength == -2) QL2y,?Mz7  
{ 3R*@m  
System.err.println("File is not access!"); X-,y[ )  
} LwPM7S~ *  
else cv4M[]
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{ 2S6EDXc  
for(int i=0;i<nStartPos.length;i++) =.oWguzu  
{ ws?s  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); I0vnd7  
} D,j5k3< #  
for(int i=0;i<nEndPos.length-1;i++) @>IjfrjV  
{ ,rI |+  
nEndPos = nStartPos[i+1]; A4FDR#  
} emB D@r  
nEndPos[nEndPos.length-1] = nFileLength; -ikuj  
} :"^< aLj  
} PL$F;d  
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~ p.W*skD  
//启动子线程 k#5e:VOb  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; a.IF%hP0xo  
for(int i=0;i<nStartPos.length;i++) Y^Q|l%Qrb  
{ ?1:/ 6  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), SQU%N  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), ]~Vu-@ /}  
nStartPos,nEndPos,i); #ljg2:I+  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 9:i,WJO  
fileSplitterFetch.start(); (y=o]Vy  
} (I ds<n"  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), K=?F3tX^  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); Ju7C?)x  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", $cK B+}  
nEndPos = " + nFileLength); QeJ.o.m{  
// fileSplitterFetch[nPos.length-1].start(); _1> 4Q%  
}!]x|zU.=  

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//等待子线程结束 ENWB|@B  
//int count = 0; wV&f|JO0+  
//是否结束while循环 doO Ap9%  
boolean breakWhile = false; <lmJa#  
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while(!bStop) >DUE8hp;<  
{ Hq\E06S@  
write_nPos(); M|#5gKXd  
Utility.sleep(500); Z)i1?#  
breakWhile = true; ([CnYv  
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for(int i=0;i<nStartPos.length;i++) `6N-MsP  
{ Y+u-J4bj  
if(!fileSplitterFetch.bDownOver) UxcDDa/j2T  
{ {dA ~#fW<  
breakWhile = false; >_aio4j}r  
break; ,V]A63J  
} RvSq KW8  
} sMS9!{A  
if(breakWhile) Wj j2J8B  
break; ;#yu"6{  
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//count++; h@,e`Z  
//if(count>4) IO!1|JMr6  
// siteStop(); )=E~CpKV  
} ,J(5@8(>a  
9^QYuf3O  
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System.err.println("文件下载结束！"); #}!>iFBcH  
} r d6F"W  
catch(Exception e){e.printStackTrace ();} Ls>u`hG  
} 8yWu{'G
 
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//获得文件长度 Q_kT}6#(J=  
public long getFileSize() Z0ncN])  
{ =tc`:!$  
int nFileLength = -1; _:gGD8  
try{ S $_Y
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URL url = new URL(siteInfoBean.getSSiteURL()); $EQT"ZX>%i  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); [|[sYo  
httpConnection.setRequestProperty("User-Agent","NetFox"); mfngbFa1  
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int responseCode=httpConnection.getResponseCode(); ?z@v3(b[  
if(responseCode>=400) %O&m#)|  
{ sUbz)BS#.  
processErrorCode(responseCode); S#h'\/S  
return -2; //-2 represent access is error (~7m"?  
} Z<N&UFw7QJ  
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String sHeader; up
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for(int i=1;;i++) tt7PEEf  
{ gVa+.x]  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); f3zfRhkIk  
//Utility.log(in.readLine()); c}IX"  
sHeader=httpConnection.getHeaderFieldKey(i); Tr+h$M1_Ja  
if(sHeader!=null) S!jF:Uc
 
{ &Mhv XHI  
if(sHeader.equals("Content-Length")) [+%d3+27  
{ {1Ju}=
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nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 1 ;\]D9i  
break; ']ITuP8  
} KUp  
} *>aZc::  
else U0h)pdo  
break; T2:oWjC3$  
} 8tLT'2+H#  
} f@! fW&  
catch(IOException e){e.printStackTrace ();} i
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catch(Exception e){e.printStackTrace ();} <78$]Z2we  
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Utility.log(nFileLength); I&pr_~.  
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return nFileLength; )IFl 0<d  
} ;wJ7oj<  
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//保存下载信息（文件指针位置） Uz6{>OCvk|  
private void write_nPos() c~gNH%1XN  
{ 'v\1:zi  
try{ &/>;LgN  
output = new DataOutputStream(new FileOutputStream(tmpFile)); 0" U5oP[  
output.writeInt(nStartPos.length); "UQr:/  
for(int i=0;i<nStartPos.length;i++) Gur8.A;Y  
{ V[o7Jr~  
// output.writeLong(nPos); :DtZ8$I`]C  
output.writeLong(fileSplitterFetch.nStartPos); xSpMyXrQ  
output.writeLong(fileSplitterFetch.nEndPos); cWN d<=Jp  
} '}jf#C1$c  
output.close(); BIxV|\k  
} h8f!<:rTS  
catch(IOException e){e.printStackTrace ();} O.@g/05C  
catch(Exception e){e.printStackTrace ();} ,wtFs!8  
} 5^/,aI  
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//读取保存的下载信息（文件指针位置） Qg'c?[~W@  
private void read_nPos() + ,@ FxZl  
{ FU_fCL8yA  
try{ K0tV'Ml#"  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); PD6MyW05%9  
int nCount = input.readInt(); F(Lb8\to\M  
nStartPos = new long[nCount]; i{o#3  
nEndPos = new long[nCount]; 9#v-2QY  
for(int i=0;i<nStartPos.length;i++) @v>l[6]>^  
{ 3jvx2  
nStartPos = input.readLong(); N]B)Fb  
nEndPos = input.readLong(); y,MPGW_  
} 0CPxIF&  
input.close(); _Zh2eXWdjM  
} qBT_! )h   
catch(IOException e){e.printStackTrace ();} KMUK`tbaI  
catch(Exception e){e.printStackTrace ();} u@<Pu@?xm  
} yC0C`oC  
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private void processErrorCode(int nErrorCode) U z"sdi  
{ ?n)Xw)]  
System.err.println("Error Code : " + nErrorCode); Z:K+I+:t  
} $z*@2Non  

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//停止文件下载 7$!yfMttu  
public void siteStop() z8IPhE@  
{ ^;.T}c%N  
bStop = true; 4w'lu"U  
for(int i=0;i<nStartPos.length;i++) `,+#!)  
fileSplitterFetch.splitterStop(); Z;#%t.  
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} FC6xFg^  
} x Sv-;!y  
//负责部分文件的抓取 <>%,}j 9  
**FileSplitterFetch.java vkJ)FEar  
*/ M)L/d_4ka  
package NetFox; Kl{-zX  
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import java.io.*; KE<kj$  
import java.net.*; [>f]@>  
<?YA,"~  
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public class FileSplitterFetch extends Thread { gw^'{b  
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String sURL; //File URL bHE7yv [  
long nStartPos; //File Snippet Start Position #jBN?Z#  
long nEndPos; //File Snippet End Position )s)_XL  
int nThreadID; //Thread's ID [[WF0q  
boolean bDownOver = false; //Downing is over v8m`jxII64  
boolean bStop = false; //Stop identical w~|1Wd<v  
FileAccessI fileAccessI = null; //File Access interface Pz%~ST  
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^ q?1U?4  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException ^/toz).Q  
{ 8YX)0i'  
this.sURL = sURL; 3-C
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this.nStartPos = nStart; Ja|{1&J.  
this.nEndPos = nEnd; px=]bALU  
nThreadID = id; 2/B)O)#ls  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 [}-3PpF  
} xzm@ v(  
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public void run() oh~:,  
{ M&KyA  
while(nStartPos < nEndPos && !bStop) +Rwx%=  
{ wfR&li{  
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try{ E7nFb:zlV  
URL url = new URL(sURL); _w!a`w*3  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ;hHi@Z9  
httpConnection.setRequestProperty("User-Agent","NetFox"); 20tO#{Li  
String sProperty = "bytes="+nStartPos+"-"; aC!EWgwW[  
httpConnection.setRequestProperty("RANGE",sProperty); .WX,Nd3@  
Utility.log(sProperty); ^:KO_{3E  
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InputStream input = httpConnection.getInputStream(); rjk( X|R*  
//logResponseHead(httpConnection); 0fArF*  
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byte[] b = new byte[1024]; vWjnI*6T#  
int nRead; X
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) V5p0h~PK  
{ jVWK0Zba  
nStartPos += fileAccessI.write(b,0,nRead); qf#)lyr<D6  
//if(nThreadID == 1) poT&-Ic[  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); (=u'sn:s  
} 94/BG0  
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Utility.log("Thread " + nThreadID + " is over!"); Y@uh[aS!  
bDownOver = true; )C~9E 5E  
//nPos = fileAccessI.write (b,0,nRead); Q@S-f:!  
} $IX\O  
catch(Exception e){e.printStackTrace ();} O )d[8jw"  
} F #`=oM$5  
} fjG&`m#"  
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//打印回应的头信息 91Z'  
public void logResponseHead(HttpURLConnection con) =(o']ZaaA  
{ d`y!cu2}  
for(int i=1;;i++) n3KI+I%nQ  
{ ZZxk]D<  
String header=con.getHeaderFieldKey(i); :"1|AJo)  
if(header!=null) ]a'99^?\  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); )[Z!*am  
Utility.log(header+" : "+con.getHeaderField(header)); lioc`C:  
else Dw6fmyJ:  
break; 0~Gle:  
} eiVC"0-c}  
} 12UD19!  

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public void splitterStop() qv*7K@  
{ @N@F,~[RR2  
bStop = true; 3gEMRy*+  
} 9=`Wp6Gmn  
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} oUZoj2G1  
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/* XvTCK>1  
**FileAccess.java hX:"QXx  
*//文件访问(定位，写) \ 0W!4
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package NetFox; zUJZ`seF  
import java.io.*; <
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p>w]rE:}  
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public class FileAccessI implements Serializable{ <ABX0U[*  
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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 $sHP\{  
RandomAccessFile oSavedFile; )!:sFa 1  
long nPos; c2nKPEX&5  
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public FileAccessI() throws IOException $;N*cH~  
{ yw-8#y  
this("",0); 'a6<ixgo0  
} O^Q7b7}y  
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public FileAccessI(String sName,long nPos) throws IOException n{*D_kM(H  
{ "*1f;+\  
oSavedFile = new RandomAccessFile(sName,"rw");  {^a36i  
this.nPos = nPos; D,v U  
oSavedFile.seek(nPos); "\C$   
} Yb3mP!3q8Z  
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^!<dgBNj  
public synchronized int write(byte[] b,int nStart,int nLen) a8k;(/  
{ ~}EMk3  
int n = -1; \wcam`f
  
try{ {%lXYMyu  
oSavedFile.write(b,nStart,nLen); W]M)Q}:Y  
n = nLen; {9Y
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} ?'86d_8  
catch(IOException e) 3<?   
{ X|f7K  
e.printStackTrace (); ]V l]XT$Um  
} vX0f,y  
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zi R5:d3   
return n; 6tHO!`}1  
} M5nWVK7c  
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} N'r3`8tS  
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/* 0R{dNyh{  
**SiteInfoBean.java ('wY9kvL&  
*/ &qpr*17T  
package NetFox; 1tTgP+  
An;MVA  
5pr"d@.  
public class SiteInfoBean { +/,icA}PI  
@SZM82qU2z  
{^(ACS9mL  
private String sSiteURL; //Site's URL ?0? R  
private String sFilePath; //Saved File's Path Q_* "SRz  
private String sFileName; //Saved File's Name L pR''`2BT  
private int nSplitter; //Count of Splited Downloading File p&+;w  
5^']+5_vb  
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public SiteInfoBean() kt`nbm|aw  
{//nSplitter的缺省值为5 ];.pK  
//default value of nSplitter is 5 '!l1=cZD  
this("","","",5); 4wC+S9I#E^  
} l^ZI* z7N  
/VmR<C?
h  
zi`b2h
 
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) rSXh;\MfB4  
{ 'RRmIx2X  
sSiteURL= sURL; -~?J+o+Pr"  
sFilePath = sPath; C<KrMRWh^  
sFileName = sName; /}Jj
 
this.nSplitter = nSpiltter; ono4U.C9  
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} >2bK
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public String getSSiteURL() Y3Vlp/"rB"  
{ $)
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return sSiteURL; O@p]KSfk  
} /|xra8?H
[  
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public void setSSiteURL(String value) !9Aaj<yxm  
{ T&Lb<'f  
sSiteURL = value; ^i:`ZfA#
 
} (aD_zG=k5  
5:'hj$~|\1  
B}PIRk@a1  
public String getSFilePath() 8\{^|y9-  
{ X]P:CY  
return sFilePath; zZVfj:i8  
} z dO#0tN  
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public void setSFilePath(String value) f=)2f=  
{ (SKVuR%Jj  
sFilePath = value; -_`>j~  
} @)Ofi j  
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public String getSFileName() eImn+_ N3  
{ 0v9rv.Y"  
return sFileName; HttiX/2~  
} `w]s
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public void setSFileName(String value) qWmQ-|Py  
{ YW{C} NA  
sFileName = value; N^3N[l
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} Fd0%lnui  
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public int getNSplitter() s`0QA!G{-  
{ rF]h$Z8o  
return nSplitter; } \ZaE~  
} qi_Jywd:w  
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r#XT3qp$d  
public void setNSplitter(int nCount) ?M[ A7?  
{ OoWyPdC+P  
nSplitter = nCount; .k,kTr$S  
} )I3NeKWz  
} ?Wz8[u  
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0:+WO%z  
/* y-1 pR  
**Utility.java j$+nKc$  
*/ TA{\PKA)  
package NetFox; g1jTy7g?  
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public class Utility { o LvZ  
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ra o[VZ  
public Utility() V3"=w&2]K  
{ 5=f|7yl  
K

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} K"r*M.P>  
X-wf:h?i  
//线程睡眠 8O38#{[S  
public static void sleep(int nSecond) kkQVNphc  
{ [D!jv"  
try{ ~c&bH]cj  
Thread.sleep(nSecond); bFW=ylF9  
} @7B$Yy#  
catch(Exception e) .C--gQpIv  
{ (;q;E\Ejq  
e.printStackTrace (); zzyHoZJP  
} OVV]x{  
} NgY=&W,  
ll C#1  
//日志 :53)Nv  
public static void log(String sMsg) nVi[  
{ /AW=5Ck-#  
System.err.println(sMsg); RRI"d~~F6  
} v#!%GEg1r  
%T~ig[GstX  
v-PXZ'7~  
public static void log(int sMsg) {|'E  
{ ZSG
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System.err.println(sMsg); 9<>wIl*T`  
} `b^Ru+(dM  
} 'nwx9]q  
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/* gntxNp[9T  
**TestMethod.java uB]b}
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*/ VSSu&Q  
package NetFox; Ba!J"b]  
*3?'4"B{8  
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public class TestMethod { 2n
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!Ze5)g%H  
4 XAQVq5  
public TestMethod() sashzVwJ-=  
{ ///xx/weblogic60b2_win.exe aXoVy&x=  
try{ jJ5W>Q1mK$  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); K|Di1)7=/  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ;NHt7p8SE  
SiteFileFetch fileFetch = new SiteFileFetch(bean); RR]CW  
fileFetch.start(); WUh$^5W  
} h"/<?3{  
catch(Exception e){e.printStackTrace ();} Zd')57{  
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^G.B+dG@`x  
} apu4DAy&8  
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public static void main(String[] args) W#hj 1  
{ =,UWX3`f  
new TestMethod(); Y$?9Zkp>  
} tQBRA/  
} , T8>}U(  
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