http断点续传简单实现（java)

/* U*R  
**SiteFileFetch.java `BGU   
*/ n~e#Y<IP\1  
package NetFox;  (r!d4  
import java.io.*; $At,D.mGkb  
import java.net.*; 8ba*:sb  
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public class SiteFileFetch extends Thread { \~{b;$N}  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 45DR%cz  
long[] nStartPos; //开始位置 w*-1*XNA  
long[] nEndPos; //结束位置 \@eC^D2  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 o@!!I w  
long nFileLength; //文件长度 gvi]#|  
boolean bFirst = true; //是否第一次取文件 w-3 B~e  
boolean bStop = false; //停止标志 Z"u|-RoBV  
File tmpFile; //文件下载的临时信息 @m99xF\e  
DataOutputStream output; //输出到文件的输出流 V1= (^{p8  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） A[mm_+D>  
public SiteFileFetch(SiteInfoBean bean) throws IOException Pp9nilb_(  
{ Hc"FW5R  
siteInfoBean = bean; (qQ|s@O  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); |vLlEN/S  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); u}L;/1,B  
if(tmpFile.exists ()) &
8^1:CcE  
{ SyWLPh  
bFirst = false; g0n 5&X  
read_nPos(); c{SD=wRt,y  
} TzW1+DxM5  
else W2CQk  
{ }K%y'D  
nStartPos = new long[bean.getNSplitter()]; "VfV;)]|w  
nEndPos = new long[bean.getNSplitter()]; mEM/}]2  
} V
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} A` iZ"?  
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public void run() w&E*{{ot
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{ oB8x_0#n  
//获得文件长度 V,W":&!x  
//分割文件 B,]:<1l~  
//实例FileSplitterFetch ,7{}}l  
//启动FileSplitterFetch线程
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//等待子线程返回 nLfITr|5  
try{ ]rs7%$ZW  
if(bFirst) H|K}m,g  
{ =%Yw;%0)Y  
nFileLength = getFileSize(); YhzDi>hob  
if(nFileLength == -1) w=txSF&Qr  
{ '/@]V  
System.err.println("File Length is not known!"); t;~H6  
} E{-W#}#  
else if(nFileLength == -2) KJf~9w9U  
{ >[U.P)7;  
System.err.println("File is not access!"); ny,a5zEnF  
} ^:yg,cS|Be  
else pOz
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{ *YI>Q@F9  
for(int i=0;i<nStartPos.length;i++) npW1Z3n  
{ vG7aT  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); b3,&R
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} :<}.3Q?&  
for(int i=0;i<nEndPos.length-1;i++) -}W`  
{ 0qV"R7TW  
nEndPos = nStartPos[i+1]; Zk4(  
} Y.<&phv  
nEndPos[nEndPos.length-1] = nFileLength; J:c]z9&!  
} .$k2.-k
 
} mR? } gR  
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>;;tX3(  
//启动子线程 _cW(R,i  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 6.!3g(w  
for(int i=0;i<nStartPos.length;i++) H(1(H0Kj"  
{ t[.wx.y&0  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), G}lP'9/  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), Ofyz,% |Q  
nStartPos,nEndPos,i); %Ny`d49&  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); #xopJaY  
fileSplitterFetch.start(); ?B&@  
} l9 |x7GB  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), XgfaTX*  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); O;ty k_yM  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", FZEK-
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nEndPos = " + nFileLength); 2`o}neF{  
// fileSplitterFetch[nPos.length-1].start(); J01Y%W  
#e!4njdM  
&d`z|Gx9  
//等待子线程结束 wK7wu.  
//int count = 0; :jFKTG  
//是否结束while循环 !"dbK'jb^  
boolean breakWhile = false; SQZUkKfb  
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while(!bStop) iE|qU_2Y  
{ S!<1CFh  
write_nPos(); =.]>,N`C  
Utility.sleep(500); w
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breakWhile = true; G2nL#l~@)  
Z(8'ki  
 ^vPt Ppt  
for(int i=0;i<nStartPos.length;i++) _PPW9US{  
{ >tq,F"2amC  
if(!fileSplitterFetch.bDownOver) @R|Gz/  
{ CTbz?Kn  
breakWhile = false; %("Bq"Q8  
break; NjCdkT&g  
} Y!kz0([  
} J#0oL_xY#  
if(breakWhile) C^hHt,&  
break; k+"+s bsW'  
',MiD=_  

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//count++; vFK&63  
//if(count>4) 7H-,:8  
// siteStop(); pX:FXzYQ  
} $>3/6(bW  
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System.err.println("文件下载结束！"); 0`KB|=>  
} M1MpR+7S  
catch(Exception e){e.printStackTrace ();} ]to"X7/
 
} ::y+|V/  
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e
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//获得文件长度 _l&`* 2d  
public long getFileSize() KUdpOMYX  
{ >+[uV^2[  
int nFileLength = -1; ZD9UE3-  
try{ ~h~K"GbC?  
URL url = new URL(siteInfoBean.getSSiteURL()); Fr}e-a  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); H?M#7K~[  
httpConnection.setRequestProperty("User-Agent","NetFox"); AQ!FJ(X(  
'oZ/fUl|7  
({ 7tp!@
 
int responseCode=httpConnection.getResponseCode(); DRo@gYDn  
if(responseCode>=400) y&0&K4aa  
{ uA?_\z?  
processErrorCode(responseCode); 8 oHyNo  
return -2; //-2 represent access is error \(a9rZ9  
} fq){?hk~O  
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String sHeader; zX-6]j;  
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s  
for(int i=1;;i++) =a`l1zn8=  
{ ~-,P1u!  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); +e0]Y8J{  
//Utility.log(in.readLine());
!*:Zcg?7n  
sHeader=httpConnection.getHeaderFieldKey(i); u"K-mr#$[o  
if(sHeader!=null) ~RVx
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{ J?XEF@?'G  
if(sHeader.equals("Content-Length")) Ve,_;<F]S  
{ 1NO<K`  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ExDH@Lb  
break; Jy'ge4]3  
} H!Y`?Rc  
} *'+OA
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else Gd)@PWK  
break; BJ3st  
} 29K09 0f  
} D?rQQxb  
catch(IOException e){e.printStackTrace ();} #&G^
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catch(Exception e){e.printStackTrace ();} IKM=Q. 7j  
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Utility.log(nFileLength); jg?B][  
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return nFileLength; )-824?Nl:  
} W:uIG-y~  
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//保存下载信息（文件指针位置） 4
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private void write_nPos() ZpPm>|w  
{ 9YMUvd,u  
try{ J{=by]-rD,  
output = new DataOutputStream(new FileOutputStream(tmpFile)); --0z"`@{  
output.writeInt(nStartPos.length); ,UQ4`Mh^L  
for(int i=0;i<nStartPos.length;i++) }XCHoB  
{ o/9(+AA>  
// output.writeLong(nPos); Hw34wQX  
output.writeLong(fileSplitterFetch.nStartPos);  Tx35~Z`0  
output.writeLong(fileSplitterFetch.nEndPos); \xk`o5/{  
} guv)[:cd;  
output.close(); ,MwwA@,9-  
} $|!VP'VI  
catch(IOException e){e.printStackTrace ();} /sENoQR  
catch(Exception e){e.printStackTrace ();} dL>0"UN}-  
} v709#/cR  
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//读取保存的下载信息（文件指针位置） GLA,,i'i9  
private void read_nPos() jRK<FK  
{ w,]cFT  
try{ ]%(hZZ  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); Kz!-w  
int nCount = input.readInt(); <tAn2e!  
nStartPos = new long[nCount]; %;9f$:U  
nEndPos = new long[nCount]; DY?`Y%"  
for(int i=0;i<nStartPos.length;i++) HE+y1f]  
{ .x$+7$G  
nStartPos = input.readLong(); 2EsKC)  
nEndPos = input.readLong(); xfqgK D>  
} E0}`+x  
input.close(); ?3Wh.%n  
} 4~4PZ  
catch(IOException e){e.printStackTrace ();} }4L
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catch(Exception e){e.printStackTrace ();} L #p-AK  
} ]*U\ gm%  
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private void processErrorCode(int nErrorCode) qHg\n)R"x!  
{ ?)-*&1cv  
System.err.println("Error Code : " + nErrorCode); eh nN  
} (7`&5md  
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//停止文件下载 BqK|4-Pf  
public void siteStop() 'Wl))lB  
{ !)ey~Suh  
bStop = true; "jmi "O*  
for(int i=0;i<nStartPos.length;i++) cnC&=6=a<  
fileSplitterFetch.splitterStop(); cC1nC76[  
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} 15#v|/wI'  
} `4}zB#3  
//负责部分文件的抓取 )!hDF9O  
**FileSplitterFetch.java $ w:QJ~,s  
*/ C78YHjy  
package NetFox; 8Z:NT_Ss  
{_|~G|Z  
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import java.io.*; _sbZyL  
import java.net.*; \06fP4?  
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public class FileSplitterFetch extends Thread { 'y}l9alF  
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String sURL; //File URL NtkEb :  
long nStartPos; //File Snippet Start Position 
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long nEndPos; //File Snippet End Position 0vQ@n
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int nThreadID; //Thread's ID &9, 6<bToP  
boolean bDownOver = false; //Downing is over n
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boolean bStop = false; //Stop identical ;S"^O AM  
FileAccessI fileAccessI = null; //File Access interface YMj z,N  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 4&!`Yi_1L  
{
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this.sURL = sURL; s[nXr  
this.nStartPos = nStart; D&0*+6j((  
this.nEndPos = nEnd; o?b$}Qrl  
nThreadID = id; Ra&HzK?  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 }ARWR.7Cc  
} i*#Gq6qZq  
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public void run() tcSn`+Bu_`  
{ lJpD>\$}@R  
while(nStartPos < nEndPos && !bStop) HtgVD~[]  
{ he8y  
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try{ BR8z%R  
URL url = new URL(sURL); =&U JFu  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); E[/<AY^@!z  
httpConnection.setRequestProperty("User-Agent","NetFox"); k+5:fB)z  
String sProperty = "bytes="+nStartPos+"-"; J)oa:Q  
httpConnection.setRequestProperty("RANGE",sProperty); id\0yRBt  
Utility.log(sProperty); iS&fp[Th  
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InputStream input = httpConnection.getInputStream(); l"*qj#FD  
//logResponseHead(httpConnection); m@;X%wf<U  
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byte[] b = new byte[1024]; w[I%Id;E  
int nRead; ((7~o?Vbg  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) UtIwrR[  
{ c|X.&<lX  
nStartPos += fileAccessI.write(b,0,nRead); QxwZ$?w%  
//if(nThreadID == 1) f$Q#xlQM  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); $u|p(E:*  
} mhH[jO)  
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Utility.log("Thread " + nThreadID + " is over!"); HTao)`.  
bDownOver = true; UO5^4  
//nPos = fileAccessI.write (b,0,nRead);  Xt(w+  
} N8m|Y]^H#  
catch(Exception e){e.printStackTrace ();} K 4j'e6  
} ~e@QJ=r  
} {xi$'r  
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;hA>?o_i(  
//打印回应的头信息 ^*#5iT8/  
public void logResponseHead(HttpURLConnection con) T3u%V_  
{ :/c=."z.  
for(int i=1;;i++) \`;FL\1+W  
{ eLJW  
String header=con.getHeaderFieldKey(i); P#\L6EO.  
if(header!=null) Qv(}*iq]  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); }_u1'  
Utility.log(header+" : "+con.getHeaderField(header)); j#$ R.  
else vQ2kL`@  
break; P6&@fwJ<  
} zGHP{a1O7  
} j!B+Q  

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public void splitterStop() wqx@/--E(  
{ 8G; t[9  
bStop = true; ?DzKqsS'  
} x* *]@v"g  
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} lZ.x@hDS  
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/* I7ZY9W(S  
**FileAccess.java Uh'3c"  
*//文件访问(定位，写) jw?/@(AC6  
package NetFox; ;:,h
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import java.io.*; k(+EY%  
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public class FileAccessI implements Serializable{ /5 B{szf  
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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 58\Rl  
RandomAccessFile oSavedFile; bq/m?;  
long nPos; {P"$;_Y"<  
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3%{A"^S=}
 
public FileAccessI() throws IOException I:CnOpR>A  
{ mYJ%gdTpo  
this("",0); srXGe`VL  
} .Qm"iOyM  
/)sA{q 4  

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public FileAccessI(String sName,long nPos) throws IOException ~B;kFdcVXn  
{ 3[B*l@}j  
oSavedFile = new RandomAccessFile(sName,"rw"); 
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this.nPos = nPos; |Wd]:ijJ  
oSavedFile.seek(nPos); `9E:V=  
} @GDe{GG+  
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public synchronized int write(byte[] b,int nStart,int nLen) |=
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{ ^2%_AP0=  
int n = -1; :IlRn`9X`  
try{ [* ,k  
oSavedFile.write(b,nStart,nLen); ,*$L_itL  
n = nLen; `WQz_}TqB  
} /yPFts_q  
catch(IOException e) ^BIB'/Kh)  
{ [y-0w.V=oE  
e.printStackTrace (); JwG$lGNJ  
} S&_Z,mT./  
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return n; 4Xt.}S!  
} }tA77Cm)45  
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} mz$)80ly  
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<9z2:^  
/* (8qD'(@  
**SiteInfoBean.java piKYO+;W'  
*/ R#gt~]x6k  
package NetFox; nt.A X  
&?UIe]  
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public class SiteInfoBean { Gx/sJ(  
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private String sSiteURL; //Site's URL cdiDfiE  
private String sFilePath; //Saved File's Path TbX#K:l  
private String sFileName; //Saved File's Name c-3-,pyM_T  
private int nSplitter; //Count of Splited Downloading File Afa|6zZ>  
2L"$p?  
lz=$Dz  
public SiteInfoBean() LA &W@  
{//nSplitter的缺省值为5 \) DJo  
//default value of nSplitter is 5 )7!q>^S{B  
this("","","",5); Z Ear~  
} {=mf/3.r  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Y3@\uM`2#  
{ Y~z3fd  
sSiteURL= sURL; Ua0fs|t1v  
sFilePath = sPath; '-C%?*ku  
sFileName = sName; vF yl,S5A  
this.nSplitter = nSpiltter; c1 aCN  
"Kky|(EQ$$  
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} ,dn6z#pb+  

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public String getSSiteURL() eaLR-+vEB  
{ (ndXz  
return sSiteURL; u'Ja9m1  
} 3ht>eaHi  

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public void setSSiteURL(String value) c#o(y6  
{ 3j<:
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sSiteURL = value; {l/j?1Dxq  
} ab"6]%_  
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,liFo.kT8%  
public String getSFilePath() w_zUA'n+  
{ X*ZTn 7<
 
return sFilePath; '"u>;Bq  
} 8 KDF*%7'  
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public void setSFilePath(String value) 2?vjj:P+h  
{ G bW1Lq&"  
sFilePath = value; JF{yhx,+p  
} 0_nY70B  

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public String getSFileName() a^:on?:9  
{ 3JhT  
return sFileName; ( X(61[Lu  
} IQz"FH?  
]rwHr;.  
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public void setSFileName(String value) _FpZc?=  
{ GjVq"S  
sFileName = value; V2Iqk]V%y  
} 2pr#qh8  
+M )ep\j  
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public int getNSplitter() ?+3vK=Rf}  
{ _LVwjZ
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return nSplitter; >z{*>i,m1  
} h=?V)WSM  
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@*Y"[\"$  
public void setNSplitter(int nCount) 6YErF|  
{ 31VDlcnE  
nSplitter = nCount; tW^oa  
} gu1:%raXd  
} WFr;z*  
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/* t(~V:+W9  
**Utility.java B=ckRWq  
*/ cd&^ vQL8  
package NetFox; o*]Tqx  
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public class Utility { m8jQ~OS  
j\I{
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public Utility() xX !`0T7Y  
{ z_i(o  
|2
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} `j#zwgUs  
:D|5E
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//线程睡眠 W?>C$_p C  
public static void sleep(int nSecond) [TW?sW^0  
{ DPWt=IFU  
try{ l1M %   
Thread.sleep(nSecond); AfAlDM'  
} h0cdRi  
catch(Exception e) LL0Y$pHV  
{ Ri   
e.printStackTrace (); #oYPe:8|m  
} 6
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} B5A/Iv)2  
I>bO<T`  
//日志
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public static void log(String sMsg) @sr~&YhA  
{ A,'F`au  
System.err.println(sMsg); Y:?cWO  
} t6,bA1*5y  
mhNX05D  
5V $H?MW>  
public static void log(int sMsg) mi';96

  
{ iJ&jg`"=F  
System.err.println(sMsg); P Nf_{4  
} OGR2Y  
} SzTa[tJ+  
2FVO@D  
"y9]>9:$-  
/* X7~^D[X  
**TestMethod.java cb3Q{.-.#  
*/ ZLGglT'EW>  
package NetFox; R/WbcQ)  
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j&N {j_M
 
public class TestMethod { im&Nkk4n@  
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ymW? <\AD,  
public TestMethod() Oxp!G7qfo  
{ ///xx/weblogic60b2_win.exe "- ?uB Mz  
try{ n1Wo<$#  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); Ql1J?9W  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); kf:Nub+h t  
SiteFileFetch fileFetch = new SiteFileFetch(bean); A"}Ib'  
fileFetch.start(); &}rmDx  
} Z}AhDIw!G  
catch(Exception e){e.printStackTrace ();} <r1/& RW,  
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} (&KBYiwr  
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public static void main(String[] args) dJ9v/k_  
{ Y6[O s1  
new TestMethod(); m S4N%Q  
} cakwGs_{  
}

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