http断点续传简单实现（java)

/* Z-%zR'-?*  
**SiteFileFetch.java ~cr##Ff5  
*/ iy!SqC  
package NetFox; @=<B8VPJd  
import java.io.*; d)>b/0CZ  
import java.net.*; fM/~k>wl  
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public class SiteFileFetch extends Thread { 5]f6YlJZ  
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SiteInfoBean siteInfoBean = null; //文件信息Bean <S ae:m4  
long[] nStartPos; //开始位置 Tfq7<<0$N  
long[] nEndPos; //结束位置 +h]~m_O  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 N=T 0Td  
long nFileLength; //文件长度 Kj53"eW  
boolean bFirst = true; //是否第一次取文件 w`YN#G  
boolean bStop = false; //停止标志 h-.xx4D  
File tmpFile; //文件下载的临时信息  ^t}1$H  
DataOutputStream output; //输出到文件的输出流 9QP-~V{$  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） v
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public SiteFileFetch(SiteInfoBean bean) throws IOException -#Bk  
{ ]A=yj@o$xN  
siteInfoBean = bean; \X2
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//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); icK>
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tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 0?o<cC1Z  
if(tmpFile.exists ()) eC{St0  
{ 8AVtUU  
bFirst = false; AXpg_JC  
read_nPos(); .QU]  
} U3**x5F_  
else v?Zo5uVoq  
{
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nStartPos = new long[bean.getNSplitter()]; :y.~IQN  
nEndPos = new long[bean.getNSplitter()]; Y'y yrn}  
} Y(RB@+67  
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} :u]QEZ@@  
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public void run() e_YTh^wU  
{ &#zx/$
  
//获得文件长度 FLo`EE":O(  
//分割文件 7#&e0fw/I  
//实例FileSplitterFetch 8S` j6  
//启动FileSplitterFetch线程 ;w7s>(ITZ  
//等待子线程返回 h_HPmh
5  
try{ B3|G&Kg  
if(bFirst) D"msD"  
{ Q h{P>}  
nFileLength = getFileSize(); !^'6&NR#K  
if(nFileLength == -1) ]f~!Qk!I7r  
{ dv Vz#  
System.err.println("File Length is not known!"); <v6W l\  
} $[g#P^  
else if(nFileLength == -2) Te
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{ F%f)oq`B  
System.err.println("File is not access!"); _lDNYpv  
} |%oI,d=ycv  
else :6:,s#av  
{ $0gGRCCG;  
for(int i=0;i<nStartPos.length;i++) @_$Un&eo  
{ R`J.vMT  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); IISdC(5  
} Q@1SqK#-DQ  
for(int i=0;i<nEndPos.length-1;i++) iA<'i8$P  
{ R=<%!  
nEndPos = nStartPos[i+1]; 4,08`5{  
} @'A0Lq+#  
nEndPos[nEndPos.length-1] = nFileLength; F/PH=Dk  
} T/FZn{I  
} u9m ~1\R*  
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//启动子线程 BNgm+1?L  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; :='I>Gn  
for(int i=0;i<nStartPos.length;i++) Z,tHyyF?j  
{ "ql$Rz8  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), zR4]buHnE  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), naM~>N  
nStartPos,nEndPos,i); ~s yWORiXm  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); aL*}@|JL"  
fileSplitterFetch.start(); OIK46D6?.  
} 0NK|3]p  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ~Ajst!Y7=  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 3Vbt(K  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", ({zWyl  
nEndPos = " + nFileLength); UxxX8N  
// fileSplitterFetch[nPos.length-1].start(); cm0$v8  
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- ~4na{6x  
//等待子线程结束  =W&m{F96  
//int count = 0; D|amKW7  
//是否结束while循环 z9!OzGtIR  
boolean breakWhile = false; .C.b5x!  
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while(!bStop) k }{o: N  
{ .Cf!5[0E  
write_nPos(); PCHKH  
Utility.sleep(500); JVGTmS[3  
breakWhile = true; `8r$b/6  
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for(int i=0;i<nStartPos.length;i++) 4K\o2p?4  
{ l,~`o$_  
if(!fileSplitterFetch.bDownOver) :+ mULUi  
{ XjdHH.) S  
breakWhile = false; -k@1#c+z  
break; W/3sJc9  
} vvG"rU  
} ExQ\qp3  
if(breakWhile) 4*L*"vKa  
break; #.!#"8{0_  
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//count++; 4AKr.a0q  
//if(count>4) =j{tFxJ  
// siteStop(); Z\]{{;%4b7  
} )&O6d .  
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System.err.println("文件下载结束！"); -Lq2K3JHyn  
} V1,/qd_  
catch(Exception e){e.printStackTrace ();} g*(z.  
} GXIzAB(  
&2U%/JqY  

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//获得文件长度 a#
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public long getFileSize() YQ.ci4.f  
{ :|$cG~'J  
int nFileLength = -1; BU4IN$d0Po  
try{ "GR*d{  
URL url = new URL(siteInfoBean.getSSiteURL()); vcsSi%M\U  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); (w{T[~6  
httpConnection.setRequestProperty("User-Agent","NetFox"); nF_q{e7  
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int responseCode=httpConnection.getResponseCode(); 3y+~l H
:  
if(responseCode>=400) Ep;i],}  
{ h_{f_GQ"  
processErrorCode(responseCode); ]8fn
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return -2; //-2 represent access is error L"/?[B":  
} )bR0>3/  
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String sHeader; sQj]#/yK:  
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for(int i=1;;i++) 2m]4  
{ P3]K'*Dyd  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); c|JQ0] K  
//Utility.log(in.readLine()); NmXRA(m  
sHeader=httpConnection.getHeaderFieldKey(i); s9a`2Wm  
if(sHeader!=null) ,(a~vqNQW3  
{ ]{q=9DczG(  
if(sHeader.equals("Content-Length")) qJ(uak  
{ K#N9N@WjR  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); J4"A6`O  
break; ap'La|9t>  
} {@iLfBh5  
} >Oj$Dn=  
else tq~4W% p/  
break; l^}u S|c(  
} )c&ya|h  
} (oR~%2K  
catch(IOException e){e.printStackTrace ();} xZ)K#\  
catch(Exception e){e.printStackTrace ();} Y.) QNTh  
 ;}?ZH4.S  
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Utility.log(nFileLength); W^h,O+vk  
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return nFileLength; %3~miP  
} qR!ZtJ5j  
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//保存下载信息（文件指针位置） 2
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private void write_nPos() gm2|`^Xq$  
{ ?gUraS
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try{ 87[ ,.W  
output = new DataOutputStream(new FileOutputStream(tmpFile)); .%{B=_7  
output.writeInt(nStartPos.length); Y
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for(int i=0;i<nStartPos.length;i++) S*=^I2;  
{ LdH1sHy*d`  
// output.writeLong(nPos); S9P({iZK  
output.writeLong(fileSplitterFetch.nStartPos); oJ %Nt&q  
output.writeLong(fileSplitterFetch.nEndPos); >qB`03>  
} ULxQyY;32  
output.close(); F<4:P=  
} ;M0`8MD  
catch(IOException e){e.printStackTrace ();} JZ`SV}\`  
catch(Exception e){e.printStackTrace ();} O5vfcX4>  
} krFp q;  
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//读取保存的下载信息（文件指针位置） b9vudr  
private void read_nPos() C5-u86F  
{ :0Jn`Ds4o  
try{ gk6R#  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); )W 5g-@  
int nCount = input.readInt();
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nStartPos = new long[nCount]; }a[]I%bu2  
nEndPos = new long[nCount]; XWAIW=.  
for(int i=0;i<nStartPos.length;i++) }dzVwP=  
{ p@%Pdx  
nStartPos = input.readLong(); $3l#eKZA  
nEndPos = input.readLong(); 5hy7}*dR  
} NZv8#  
input.close(); Z2m^yRQ(  
} U5N|2  
catch(IOException e){e.printStackTrace ();} U ->vk{v  
catch(Exception e){e.printStackTrace ();} APF`b  
} 6]%=q)oL[  
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private void processErrorCode(int nErrorCode) &4|]VOf  
{ hG.}>(VV  
System.err.println("Error Code : " + nErrorCode); Q2Ey RFT  
} ?OF$J|h  
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//停止文件下载 (^FMm1@T  
public void siteStop() 9)]`le  
{ 0@b<?Ms9  
bStop = true; $peL1'Evo  
for(int i=0;i<nStartPos.length;i++) 5I6?gv/  
fileSplitterFetch.splitterStop(); T88$sD.2 '  
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} 9 c9$
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} xj
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//负责部分文件的抓取 Zy3F%]V0  
**FileSplitterFetch.java `Zo5!"'  
*/ jrN 5l1np  
package NetFox; #e-7LmO~  
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import java.io.*; *vRHF1)L  
import java.net.*; .Qn
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public class FileSplitterFetch extends Thread { Z"Hq{?l9  
:RB7#v={  
9-m_ e=jk6  
String sURL; //File URL /G7^l>pa  
long nStartPos; //File Snippet Start Position ,Aq, f$5V  
long nEndPos; //File Snippet End Position c/bT5TIEWs  
int nThreadID; //Thread's ID 6Zw$F3 <  
boolean bDownOver = false; //Downing is over u;^H=7R  
boolean bStop = false; //Stop identical [= E=H*j  
FileAccessI fileAccessI = null; //File Access interface }])j>E  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException uv$5MwKU  
{ M^WoV }'  
this.sURL = sURL; |n,O!29  
this.nStartPos = nStart; u"v$[8  
this.nEndPos = nEnd; "[["naa  
nThreadID = id; '!Va9m*w7  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 B &Z0ZWx  
} n~`jUML2d  
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public void run() 5?>Q[a.Ne  
{ "N%W5[C{  
while(nStartPos < nEndPos && !bStop) s!YX<V  
{ <LBC
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try{ 5C`Vno~v  
URL url = new URL(sURL); H/x9w[\+[  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); QrmGrRH  
httpConnection.setRequestProperty("User-Agent","NetFox"); lp$,`Uz`  
String sProperty = "bytes="+nStartPos+"-"; :k.>H.8+~  
httpConnection.setRequestProperty("RANGE",sProperty); JK^%V\m  
Utility.log(sProperty); U/U_q-z]  
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InputStream input = httpConnection.getInputStream(); A;C4>U Y  
//logResponseHead(httpConnection); C&d,|e "\  
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byte[] b = new byte[1024]; tJd/uQJ  
int nRead; 
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) <4?(|Vh[m]  
{ ;erx
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nStartPos += fileAccessI.write(b,0,nRead); !&KE">3Qu  
//if(nThreadID == 1) 65&+Fv  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); w"Zws[pm]  
} z9AX8k(B6  
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Utility.log("Thread " + nThreadID + " is over!"); !C' Y 7  
bDownOver = true; +)( "!@  
//nPos = fileAccessI.write (b,0,nRead); K nn<q=';G  
} %7TG>tc  
catch(Exception e){e.printStackTrace ();} b7M)  
} 1?p:66WmR  
} `a7b,d  
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//打印回应的头信息 p_g8d&]V  
public void logResponseHead(HttpURLConnection con) g ?%]()E  
{ = p2AK\  
for(int i=1;;i++) QA!'p1{#  
{ M|z4Dy  
String header=con.getHeaderFieldKey(i); .0y .0=l  
if(header!=null) Y5IQhV.  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); Y-DHW/Z~  
Utility.log(header+" : "+con.getHeaderField(header)); $*0XWrE  
else rJd-
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break; F+Hmp\rM#  
} %`d
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} Y#-pK)EeU  
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public void splitterStop() 3AuLRI  
{ L{6Vi&I84[  
bStop = true; R/c-sV  
} Wzh#dO?7  
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} h5H#xoCXp  
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/* 7tT L,Nxe  
**FileAccess.java wAF#N1-k  
*//文件访问(定位，写) r$d'[ZcX  
package NetFox; 6CWm;%B#G  
import java.io.*; {1wjIo"ptg  
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public class FileAccessI implements Serializable{ v.H@Ey2  
hKK"D:?PRs  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 o:/ymeG  
RandomAccessFile oSavedFile; fJG!TQJ[Y  
long nPos; Ria*+.k@"B  
]:]w+N%7  
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public FileAccessI() throws IOException b;(BMO,(  
{ O#D N3yu?  
this("",0); {D8[pG%z  
} 3)py|W%X$  
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'%A*Z,f  
public FileAccessI(String sName,long nPos) throws IOException V)r6bb{^  
{  %?:eURQ  
oSavedFile = new RandomAccessFile(sName,"rw"); =g^JJpS  
this.nPos = nPos; {B6tGLt#bf  
oSavedFile.seek(nPos); 7;:Uv=  
}
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}W R?n  
public synchronized int write(byte[] b,int nStart,int nLen) ;=ERm=  
{ Z
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int n = -1; Q pbzx/2h  
try{ Wp$'#HhB  
oSavedFile.write(b,nStart,nLen); 3HmJixy  
n = nLen; SE!0f&  
} *e-+~/9~  
catch(IOException e) VbzW4J_  
{ Jyu*{  
e.printStackTrace (); {[.<BU-  
} 3LD`Ep   
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return n; ib)AC,LT  
} Bso3Z ^X.  
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} _"%-=^_  
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/* %g*AGu`  
**SiteInfoBean.java o]*#|4-  
*/ 09u@
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package NetFox; onAC;<w  
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public class SiteInfoBean { kFHtZS(  
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private String sSiteURL; //Site's URL PG/xX H  
private String sFilePath; //Saved File's Path d$`NApr  
private String sFileName; //Saved File's Name ueazAsk3g  
private int nSplitter; //Count of Splited Downloading File RZ&T\;m,7  
GE[J`?E]  
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public SiteInfoBean() }EZd=_kAq~  
{//nSplitter的缺省值为5 9nPc>O$  
//default value of nSplitter is 5 ?5g0#wqI  
this("","","",5); 564)ha/^(  
} !*C9NX  
?N*|S)B
N  
r8E)GBH-|  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) /Z*XKIU6v/  
{ g4 |s9RMD  
sSiteURL= sURL; JH;\wfrD  
sFilePath = sPath; 6-<>P E2  
sFileName = sName; 36U zfBa  
this.nSplitter = nSpiltter; ?R}a,k  

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} 3o=K?eOdg  
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public String getSSiteURL() fc#zhp5bX  
{ &u'$q  
return sSiteURL; f6h!wx  
} [nam H a  
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public void setSSiteURL(String value) C"P40VQoo  
{ Z'vGX,:  
sSiteURL = value; Je#vl4<L  
} X^U)j N2  
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public String getSFilePath() 9_z u*  
{ ,5_Hen=PI  
return sFilePath; 5@6%/='I q  
} Wm/0Y'$r&k  
*L3>:],7  
ul$^]ZWkI  
public void setSFilePath(String value) Wa{>R2h\  
{ ;U=RV&  
sFilePath = value; .'
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} /{
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public String getSFileName() m|
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{ C[ ehw  
return sFileName; I'h6!N"  
} 0P<b
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public void setSFileName(String value) rVx%"_'*-  
{ ",c(cYVW  
sFileName = value; cboue LEt  
} RY(\
/W#$  
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S'NZb!1+  
public int getNSplitter() X/_e#H0  
{ yk4Huq&2  
return nSplitter; q#$4Kt;  
} 3:f<cy   
3JiJ,<,7  
~@x@uY$5  
public void setNSplitter(int nCount) <(YmkOS+  
{ xbFoXYqgP  
nSplitter = nCount; ZLBv\VQ  
} R)AFaP |  
} Ub%al
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/* +)#d+@-  
**Utility.java P~V0<$C  
*/ q^ {Xn-G  
package NetFox; pv.
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public class Utility { 30(O]@f~  
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public Utility() (%huWW j  
{ D6trqB  
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;&Q8xC2  
} P#/k5]g  
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//线程睡眠 :*aBiX"  
public static void sleep(int nSecond) xF'9`y^]!@  
{ FqOV/B /z2  
try{ Y|t]bb  
Thread.sleep(nSecond); OAu?F}O  
} }LDH/# u  
catch(Exception e) [-X=lJ:+h  
{ aHosu=NK  
e.printStackTrace (); Ctpr
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} #%4-zNS  
} jg]_'^pVzr  
=}Np0UP  
//日志 )1%l$W  
public static void log(String sMsg) >5{Z'UWxh  
{ [HJ^'/bB'  
System.err.println(sMsg); >yC1X|d~t  
} +$KUy>  
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};[~>Mzl  
public static void log(int sMsg) TSHsEc
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{ e&G!5kz!  
System.err.println(sMsg); B w1ir  
} Om%{fq&  
} LXr yv;H  
b !FX]d1~k  
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/* CQf!<  
**TestMethod.java cXx?MF5  
*/ &n>\ +Q   
package NetFox; EQDsbG0x  
c"w}<8  
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public class TestMethod { _
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public TestMethod() UPs*{m  
{ ///xx/weblogic60b2_win.exe ?{W@TY@S  
try{ H#IJ&w|  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); gF(aYuk  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); MA\"JAP/  
SiteFileFetch fileFetch = new SiteFileFetch(bean); .CI {g2  
fileFetch.start(); q@K;u[zF
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} rPoPs@CBD  
catch(Exception e){e.printStackTrace ();} vdFy}#X  
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} Ca]+*Eb9z{  
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public static void main(String[] args) uGIA4CUm  
{ 1!,xB]v1Ri  
new TestMethod(); 3.M<ATe^  
} :<ye:P1s  
} %|L+~=  
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