http断点续传简单实现（java)

/* ~&lQNl3`m6  
**SiteFileFetch.java eA`]KalH  
*/ I|$'Q$m~  
package NetFox; }j&O/Up  
import java.io.*; #uQrJh1o8  
import java.net.*; ,yTN$K%M  
].LJt['%8  
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public class SiteFileFetch extends Thread { cL6 6gOEL  
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SiteInfoBean siteInfoBean = null; //文件信息Bean Vz%"9`r  
long[] nStartPos; //开始位置 HTxB=Q|  
long[] nEndPos; //结束位置 bAUHUPe  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 b21}49bHN  
long nFileLength; //文件长度 :RPVT,O}  
boolean bFirst = true; //是否第一次取文件 P~&O4['<  
boolean bStop = false; //停止标志 baqn7k"  
File tmpFile; //文件下载的临时信息 O ,l\e3;  
DataOutputStream output; //输出到文件的输出流 C=8H)Ef,l  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） `$H7KIG  
public SiteFileFetch(SiteInfoBean bean) throws IOException bC6X?m=  
{ g .3
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siteInfoBean = bean; ,KT<4  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ,A
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tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); bG52s  
if(tmpFile.exists ()) &Y{F? c^  
{ 9_eS`,'  
bFirst = false; bS,etd  
read_nPos(); ma3Qi/  
} <Uf|PFVj$  
else 0(\p
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{ {d8^@UL  
nStartPos = new long[bean.getNSplitter()]; X+@s]  
nEndPos = new long[bean.getNSplitter()]; fTTm$,f5N  
} B.El a  
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} fa"\=V2S  
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public void run() 8*vFdoE_oO  
{ R!9qQn?  
//获得文件长度 :u AjV  
//分割文件 ATo}FL 2  
//实例FileSplitterFetch L,6MF,vx  
//启动FileSplitterFetch线程 YjX*)Q_sl?  
//等待子线程返回 Mg+4huT  
try{ ekrBNDs9  
if(bFirst) _$!`VA%  
{ KLW&bJ$|j  
nFileLength = getFileSize(); gbJG`zC>U  
if(nFileLength == -1) rJX\6{V!_  
{ uO"y`$C$_  
System.err.println("File Length is not known!"); 2av*o~|J*:  
} \PzN XQ$  
else if(nFileLength == -2) ,^HS`!s[ E  
{
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System.err.println("File is not access!"); SijS5irfk  
} %oR>Uo  
else <;aJ#qT  
{ UPR/XQ  
for(int i=0;i<nStartPos.length;i++) Ep<YCSQy$i  
{ .5]{M\aA  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); IEc>.J|T&  
} {-J:4*`  
for(int i=0;i<nEndPos.length-1;i++) a/:]"`)  
{ *CzCUu:%t  
nEndPos = nStartPos[i+1]; *{Yh6{  
} ^B|YO8.v  
nEndPos[nEndPos.length-1] = nFileLength; G8noQ_-  
} VJ*\pM@no  
} V\"1wV~E  
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//启动子线程 'd+
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; O<>#>[  
for(int i=0;i<nStartPos.length;i++) xFU5\Zuw  
{ VE*j*U j  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ,2ME2@OP  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), ]H>+m 9  
nStartPos,nEndPos,i); _=?2 3
 
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); `2,a(Sk#  
fileSplitterFetch.start(); %6Rn4J^^  
} 5=Suj*s{D#  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(),
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 9{$8\E9*nd  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", z,avQR&  
nEndPos = " + nFileLength); qfa}3k8et  
// fileSplitterFetch[nPos.length-1].start(); =!<^
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//等待子线程结束 aLYLd/ KV  
//int count = 0; aiJnfU]W  
//是否结束while循环 o)p[ C   
boolean breakWhile = false; O2% `2h  
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while(!bStop) -Uri|^t  
{ %Ci^*zb  
write_nPos(); ^4 8\>-Q\  
Utility.sleep(500); QkL@JF]Re  
breakWhile = true; q1w|'V  
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for(int i=0;i<nStartPos.length;i++) u1N1n;#  
{ 0E1=W6UZ  
if(!fileSplitterFetch.bDownOver) p/3B
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{ @701S(0'7  
breakWhile = false; aHC%19UN  
break; _YLUS$Zw  
} 'bPk'pj9  
} ;iQ
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if(breakWhile) +9C;<
f  
break; jq[x DwPG  
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//count++; U!0E_J  
//if(count>4) 4w;~4#ZPp  
// siteStop(); :3 y_mf>  
} O|7yP30?M  
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System.err.println("文件下载结束！"); 3q?5OL^$  
} `iQqh
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catch(Exception e){e.printStackTrace ();} 0bSz4<}  
} 7k~Lttuk  
N Bz%(?\  
:".w{0l@  
//获得文件长度 ?+\E3}:  
public long getFileSize() fv2=B)8$  
{ ?:/|d\,7@  
int nFileLength = -1; mW +tV1XjG  
try{ lhxdx   
URL url = new URL(siteInfoBean.getSSiteURL()); ^yJ:+m;6K  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); <xqba4O  
httpConnection.setRequestProperty("User-Agent","NetFox"); L/fRF"V  
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int responseCode=httpConnection.getResponseCode(); 6v>z h  
if(responseCode>=400) >)3VbO  
{ `pm>'  
processErrorCode(responseCode); pX_b6%yX(  
return -2; //-2 represent access is error v ):V  
} `)tA YH  
}dKLMNqPA  

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String sHeader; rN#\AN  
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for(int i=1;;i++) N"1QX6  
{ Y`^o7'Z2^P  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); /[?Jylj  
//Utility.log(in.readLine()); EY$?^iS  
sHeader=httpConnection.getHeaderFieldKey(i); u]bz42]  
if(sHeader!=null) sUc
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{ iaRR5
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if(sHeader.equals("Content-Length")) 9|3o<  
{ =:/>6H1x  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); A{(T'/~"  
break; Mpm#GdT  
} ls @5^g  
} ]]/lC  
else ?!7 SzLll  
break; ?0z)EPQ|  
} Rcf=J){D6  
} t:T?7-XIE  
catch(IOException e){e.printStackTrace ();} '=#5(O%pp  
catch(Exception e){e.printStackTrace ();} jb3.W  
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Utility.log(nFileLength); >a@>N  
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return nFileLength; N
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} F.0d4:A+  
7&#m]t^^  
.YC;zn^  
//保存下载信息（文件指针位置）
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private void write_nPos() 1i+FL''  
{ 7E(%9W6P  
try{ <r;o6>+  
output = new DataOutputStream(new FileOutputStream(tmpFile)); PCZ]R  
output.writeInt(nStartPos.length); 4#h?Wga  
for(int i=0;i<nStartPos.length;i++) ppFYc\&=  
{ Bk@WW#b  
// output.writeLong(nPos); \xeVDKJH+n  
output.writeLong(fileSplitterFetch.nStartPos); 7}o6_i  
output.writeLong(fileSplitterFetch.nEndPos); !-RwB@\  
} o&,Y<$!:VH  
output.close(); -#%X3F7/w  
} 4|F#gK5E  
catch(IOException e){e.printStackTrace ();} I%i:)6Un-y  
catch(Exception e){e.printStackTrace ();} Mciq-c)  
} 1LyT7h  
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//读取保存的下载信息（文件指针位置） <`+zvUx^?  
private void read_nPos() 9`INC~h  
{ H/`G  
try{ oAnigu;  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); Y-]YDXrPQ  
int nCount = input.readInt(); ?@3&dk~ni  
nStartPos = new long[nCount]; DM'qNgB7  
nEndPos = new long[nCount]; J|q^+K  
for(int i=0;i<nStartPos.length;i++) uP Rl[tS0  
{ ngLJ@TP-  
nStartPos = input.readLong(); 1I \tu  
nEndPos = input.readLong(); t9Vb~ Ubdb  
} Xy!&^C` J`  
input.close(); 3G.r-  
} J&_3VKrN  
catch(IOException e){e.printStackTrace ();} 'z-D%sCA  
catch(Exception e){e.printStackTrace ();} y7La_FPrl  
} ~?-qZ<9/  
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private void processErrorCode(int nErrorCode) wibwyzo  
{ sbA2W~:  
System.err.println("Error Code : " + nErrorCode); ?UJSxL  
} Q]T BQ&  
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//停止文件下载 (Z 8,e  
public void siteStop() Oa1'oYIHg  
{ IhwN],-V  
bStop = true; Ysl9f1>%  
for(int i=0;i<nStartPos.length;i++) 3t*#!^$  
fileSplitterFetch.splitterStop(); }\VX^{K j  
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} @ge LW!  
} qS|AdkNL  
//负责部分文件的抓取 b@!:=_Mr  
**FileSplitterFetch.java DU`v J2  
*/ NFV_+{X\  
package NetFox; BtID;^Dz  
*V-
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import java.io.*; 4gya]  
import java.net.*; vU{jda$$#  
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public class FileSplitterFetch extends Thread { fQ1 0O(`g,  
(s;zRb!4L  
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String sURL; //File URL H<XlUCr_~+  
long nStartPos; //File Snippet Start Position `^zQ$au'u  
long nEndPos; //File Snippet End Position 0NrTJ R`  
int nThreadID; //Thread's ID .X^43 q  
boolean bDownOver = false; //Downing is over .c03}RTC^  
boolean bStop = false; //Stop identical -?Ejbko  
FileAccessI fileAccessI = null; //File Access interface Stt* 1gT  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 1MpX] j8C#  
{ a 1NCVZ  
this.sURL = sURL; @| P3  
this.nStartPos = nStart; _Po#ZGm~  
this.nEndPos = nEnd; *n,UOHlO  
nThreadID = id; ZRUh/<\[  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 F46O!xb%  
} AsD1-$  
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public void run() 6Z$b?A3zM  
{ (%.</|u  
while(nStartPos < nEndPos && !bStop) Iht@mE  
{ }~V,_Fv  
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try{ ynxWQ%d(`  
URL url = new URL(sURL); 5vYsA1Z
 
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); V!\n3i?i  
httpConnection.setRequestProperty("User-Agent","NetFox"); qq/_yt  
String sProperty = "bytes="+nStartPos+"-"; ^fG`DjA)  
httpConnection.setRequestProperty("RANGE",sProperty); cK/PQs
MP  
Utility.log(sProperty); Qf"6PJ  
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InputStream input = httpConnection.getInputStream(); C CLfvex  
//logResponseHead(httpConnection); e W9)@nVJ  
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byte[] b = new byte[1024]; xu`d`!Tx  
int nRead; N"&$b_u[  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) Feh"!k <6k  
{ O\3r%=TF  
nStartPos += fileAccessI.write(b,0,nRead); ,o4r,.3[s  
//if(nThreadID == 1) w/hh 4ir  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); -,
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} (/To?`  
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Utility.log("Thread " + nThreadID + " is over!"); X S6]C{  
bDownOver = true; ;L#LDk{Za  
//nPos = fileAccessI.write (b,0,nRead); XB6N[E  
} {hlT`K  
catch(Exception e){e.printStackTrace ();} cw*(L5bu  
} |^ 2rtI  
} S(@*3]!q  
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//打印回应的头信息 (YaOh^T:|  
public void logResponseHead(HttpURLConnection con) Xi1q]ps  
{ u>JqFw1  
for(int i=1;;i++) @1/Q  
{ B
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String header=con.getHeaderFieldKey(i); Y*]l|)a6_]  
if(header!=null) wghFGHgw  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ~gSF@tz@  
Utility.log(header+" : "+con.getHeaderField(header)); uzat."`d'  
else COxZ
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break; !gD 3CA  
} xCDA1y;j  
} 2@"0}po#  
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public void splitterStop() (cPeee%Q  
{ c,g]0S?gu  
bStop = true; +ZD[[+
 
} ?qq!%4mTB  
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} luP'JUq  
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/* Vq)|gF[6i  
**FileAccess.java "-~D!{rS  
*//文件访问(定位，写) [[.&,6  
package NetFox; (;Dn%kK  
import java.io.*; ~/]\iOL  
;f\R$u-  
]$XBd{\D{  
public class FileAccessI implements Serializable{ 5 b#" G"  
xv(xweV+d  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 #J<`p  
RandomAccessFile oSavedFile; @xW"rX#7f  
long nPos; `E4!u=%  
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public FileAccessI() throws IOException zBrWm_R5T  
{ Fw_bY/WN{  
this("",0); Jnu}{^~  
} .zSimEOF  
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Z<,CzKs+||  
public FileAccessI(String sName,long nPos) throws IOException f)ucC$1=  
{ tnKpn-LPA  
oSavedFile = new RandomAccessFile(sName,"rw"); r['=a/.C  
this.nPos = nPos; Xdp`Z'g  
oSavedFile.seek(nPos); dl3LDB  
} h
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5qeS|]^`  
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public synchronized int write(byte[] b,int nStart,int nLen) #P,[fgNy  
{ -Uhl9 =  
int n = -1; mw4'z,1Q  
try{ 1>*UbV<R;u  
oSavedFile.write(b,nStart,nLen); 5LhJ
8$W  
n = nLen; A aF5`  
} GqK&'c  
catch(IOException e) Z%HEn$t  
{ }TAGr 0  
e.printStackTrace (); < 4EB|@E  
} 0u&?Zy9&  
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return n; :v WYII7  
} A86lyBDQ*  
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} Ppo^qb  
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/* 2I(@aB+  
**SiteInfoBean.java HTtGpTsF  
*/ >.nt'BQ  
package NetFox; yM#trqv
5  
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public class SiteInfoBean {
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private String sSiteURL; //Site's URL !y2h`ZAZ  
private String sFilePath; //Saved File's Path )]>Y*<s }  
private String sFileName; //Saved File's Name !=Kay^J~.  
private int nSplitter; //Count of Splited Downloading File [sO<6?LY  
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public SiteInfoBean() 6x3Ew2  
{//nSplitter的缺省值为5 vJjj+:  
//default value of nSplitter is 5 }${ZI  
this("","","",5); Jm1AJ4mw  
} d8q$&(]<  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Y(!)G!CMc  
{ 9(
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sSiteURL= sURL; 3SB7)8Id1  
sFilePath = sPath; _G8y9!J  
sFileName = sName; r-"`Abev  
this.nSplitter = nSpiltter; z'}t@R#H  
)mZy>45  
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} l0bT_?LhK  
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public String getSSiteURL() $MEbePxe  
{ F-OZIo  
return sSiteURL; ez9M]! 8Lt  
} e5\1k#@  
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public void setSSiteURL(String value) gwjv&.T6^  
{ DppvUiQB!a  
sSiteURL = value; %_LHD|<  
} w`Aw+[24  
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public String getSFilePath() CxN@g'  
{ Z]+Xh  
return sFilePath; +|w~j#j9`  
} v%e"4:K}?  
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public void setSFilePath(String value) X)+sHcE~#  
{ o) ?1`7^BA  
sFilePath = value; c{P
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} juZ3""  
qk"=nAJX  
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public String getSFileName() Q$5:P&  
{ /[T8/7;_l  
return sFileName; !|QeYGnq6  
} %),O9*[9  
7ZnQ] ?  

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public void setSFileName(String value) 5gEWLLDp  
{ O|m-k0n  
sFileName = value; PKG ,4v=  
} k&;L(D  
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u^[v{hv'H  
public int getNSplitter() c?Qg:yU  
{ 'gH#\he[Dh  
return nSplitter; e5]0<s$  
} _kLoDju%  
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public void setNSplitter(int nCount) jO.E#Ei}~  
{ FeMu`|2  
nSplitter = nCount; C5 !n{  
} b)@x@3"O  
} '>$A7  
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m%3Kq%?O  
/* > `M\xt  
**Utility.java s[bK
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*/ R[t[M}q  
package NetFox; ?[">%^  
u] b6>  
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public class Utility { "de:plMofy  
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eu;^h3u;b  
public Utility() `#bcoK5  
{ ma~`&\xE  
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} mt'#j"mU  
2XpGgG`2`C  
//线程睡眠 f*Bc`+G  
public static void sleep(int nSecond) ]CYe=m1<2Q  
{ Af~AE2b3"  
try{ n
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Thread.sleep(nSecond); g9JtWgu  
} +L6$Xm5DAv  
catch(Exception e) P/5r(l
5  
{ {`> x"Y5  
e.printStackTrace (); |99eDgK,  
} k,,}N9  
} I%Z&i-33y  
|QdS;  
//日志 B7;MY6h#  
public static void log(String sMsg) f63q  
{ W2^R$"U  
System.err.println(sMsg); +zvK/Fj2q  
} 4M}/PoJ  
rxA<\h,A  
X+iULr.^`~  
public static void log(int sMsg) #<{MtK_  
{ k?,g:[4!  
System.err.println(sMsg); IkkrnG8  
} RA}PM?D/  
} [B Al  
81&!!qhfS  
NNX/2  
/* I g`#U~  
**TestMethod.java bc-"If Z&  
*/ f 36rU  
package NetFox; iBQftq7  
6tM{cK%v1  
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public class TestMethod { D c^d$gh  
Rp#SqRy`  
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public TestMethod() ,=FYf|Z  
{ ///xx/weblogic60b2_win.exe N{'k ]&  
try{ *T3"U|0_y  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); V+Z22  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); J0`?g6aY  
SiteFileFetch fileFetch = new SiteFileFetch(bean); pw,.*N3P  
fileFetch.start(); R9HRbVBJf  
} _+U`afV  
catch(Exception e){e.printStackTrace ();} |67UN
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/cg!Ap5  
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} >v(Xc/oI
 
wGB'c's*  
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public static void main(String[] args) Y9Pb  
{ 9wYbY* j  
new TestMethod(); = #`FXO1C  
} ?h5Y^}8Qg  
} :=/DF  
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